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News from Rohde & Schwarz

Audio measurementsAnalysis, monitoring, data transmission

EMC test cellFavourably priced alternative to anechoic chambers

Customized radiomonitoringfrom 10 kHz to 18 GHz

151

2 News from Rohde & Schwarz Number 151 (1996/II )

Number 151 1996/II Volume 36

Audio Analyzer UPL is able to perform practicallyall audio measurements on analog and digitalinterfaces. As the “younger brother” of the inter-nationally successful UPD, which still holds thetop position in audio measurements, UPL is t h esolution for budget-conscious users. For more details see article on page 4. Photo 42 458(Beethoven picture: Amadeus-Verlag, Winterthur)

Frank Körber Testing GSM/PCN/PCS base stationsin production, installation and service with CMD54/57. . . . . . . . . . . . . . . . . . . . . . .28

Thomas Kneidel Container location from space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Tilman Betz Automatic measurements on tape recorders using Audio Analyzer UPD . . . . . . . .32

Dr. Jürgen Lauterjung DVTS – video sequence for assessing MPEG encoders . . . . . . . . . . . . . . . . . . . . . . . .33

Michael Manert RF switch units simplify type-approval tests for mobile radio. . . . . . . . . . . . . . . . . . . .35

Wolfgang Kernchen Analyzer UPLAudio analysis today and tomorrow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Dr. Klaus-Dieter Göpel EMC Test Cell S-LINECompact EMC test cell of high field homogeneity and wide frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Johann Klier Signal Generator SME06/SMT06Analog and digital signals for receiver measurements up to 6 GHz . . . . . . . . . . . .10

Gregor Kleine Satellite Receiver CT200RSTV reception with analog and digital sound from outer space. . . . . . . . . . . . . . . . . .13

Peter Singerl; Christian Krawinkel Audio Data Transmission System ADAS and Audio Monitoring System AMONData transmission without data line,audio measurements without program interruption . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Reiner Ehrichs; Claus Holland; Radiomonitoring System RAMONGünther Klenner Customized radiomonitoring from VLF through SHF . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Dr. Christof Rohner BTS Antennas HF.../HK...The right antenna for every mobile-radio base station . . . . . . . . . . . . . . . . . . . . . . . . .22

Thomas Rieder Paging System P2000Flexible, multiprotocol radiopaging system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Articles

Peter Hatzold Digital modulation and mobile radio (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Application notes

Refresher topic

3News from Rohde & Schwarz Number 151 (1996/II )

Published by ROHDE & SCHWARZ GmbH & Co. KG Mühldorfstraße 15 D -81671 MunichTelephone (0 89) 41 29-0 · international *(4989) 41 29-0 · Telex 523703 (rs d) · Editors: H. Wegener and G. Sönnichsen (German); C. B. Newberry, G. Koranyi (English) · Photos: S. Huber · Circulation100 000 three times a year · ISSN 0028-9108 · Supply free of charge · State company or position ·Printed in the Federal Republic of Germany by peschke druck, Munich · Reproduction of extracts permitted if source is stated and copy sent to R & S Munich

Imprint

Software

Volker Janssen ESxS-K1 – attractively priced Windows software for EMC measurements . . . .40

Thomas Kneidel ALADIN and ARAMIS message-handling software – convenient data transmission by shortwave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Jürgen Rauch; Karl Scalet Object-oriented software development for computer-aided, mobile data transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

Panorama

Dr. Andreas Waßerburger Mass Spectrometer Airsense 500 –fast gas analyzer for automobile industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

Franz Ketterle The “lifeline” to rescuers in the air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Leo Terneven Rohde & Schwarz FM and TV transmitters provide Greater Brussels with entertainment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

Karl-Heinz Wagner A vision comes true – trunked radio for United Arab Emirates. . . . . . . . . . . . . . . . . .50

Dr. Pekka Eskelinen R&S signal generators at Finnish Institute of Technology . . . . . . . . . . . . . . . . . . . . . . .51

Jean-Paul Hosdain New radio stations for Belgian navy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Regular features

In short: Rohde & Schwarz now on Internet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Werner Mittermaier Test hint: Alignment of I/Q modulators by narrowband RF spectrum analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Newsgrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

Information in print. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

Press comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Wilhelm Kraemer Final article: Microwave Generator SMP – top-class performance to customer’s benefit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

Because of their low operating costs radiopagingservices are becoming increasingly popularworldwide, with more and more new standards(eg ERMES, POCSAG) being established. PagingSystem P2000 from Rohde & Schwarz is a flexible, multiprotocol radiopaging system that meets all present and future requirements of net-work operators (see article on page 25).

Photo 42 457/1


While audio-signal processing is nolonger conceivable without the use ofdigital techniques, analog techniquescontinue to exist and undergo constantimprovement – the human ear is analogafter all. A state-of-the-art audio ana-lyzer like UPL (FIG 1) must therefore be able to handle both analog and dig-ital signals. UPL is capable of fast andaccurate frequency-response measure-ments, spectrum display of demodulat-ed wow-and-flutter signals, generationof multitone signals comprising several

thousand spectral lines, output of digitalaudio signals via loudspeaker, jittermeasurements on digital audio signals,and so on. In short, there is hardly anytask UPL cannot solve. And on top ofthis, UPL offers excellent technical data:analog sinewave generation with har-monics suppressed by typically 115 dB,spectrum displays with a noise floor as low as –140 dB at analog and –160 dB at digital interfaces, and fastFourier transform with maximum fre-quency resolution of 0.05 Hz.

Analysis concept

UPL performs all its measurements usingdigital signal processing. Analog signalsto be tested undergo extensive prepro-cessing on analog modules before theyare digitized and measured by meansof digital routines. This concept pro-vides an extended dynamic range andguarantees performance and flexibility

far superior to instruments performingpurely analog or digital measurements.

The test routines performed on analogand digital interfaces are identical. Thisallows, for example, direct comparisonof results obtained ahead of and after a converter. All test functions and testsignals are available both at the analogand the digital interfaces. This makes it possible to measure at any point of acombined analog and digital transmis-sion path. Only this ensures efficientand complete testing. The filters too areimplemented digitally, resulting in an almost infinite number of filters, and thisalso for measurements on analog inter-faces. All the user has to do is choosethe type of filter (highpass, bandpass,etc), frequency and attenuation to loopa new filter into the test path (FIG 2).

The measurement speed provided by UPL is as a rule higher than thatachieved with analog techniques sincedigital test routines can adapt theirspeed to the input frequency. Oper-ation is the same for the analog andthe digital interfaces – a feature thatshould not be underestimated, espe-cially if different types of applicationare to be handled.

UPL offers the following analysis func-tions:• selective and broadband level

measurements with rms, peak orquasi-peak weighting,

• up to three filters of the integrateddigital filter bank can be looped intothe signal path (14 weighting filtersin addition to user-programmable filters),

• intermodulation measurements (totalharmonic distortion (THD), modula-tion distortion, difference frequencydistortion); each type of intermodula-tion can also be represented as abar chart,

• wow-and-flutter measurements toDIN/ IEC, NAB, JIS or 2-sigma method with additional spectrum display of the demodulated signal,

• frequency, phase and group-delaymeasurements,

Articles

Audio Analyzer UPL

Audio analysis today and tomorrowRohde & Schwarz has extended its range of audio analyzers by UPL, the “younger brother” of UPD, which still holds the top position in audio measure-ments. UPL is mainly for use in production tests on digital and analog audio unitsboth in the consumer and professional sectors.

FIG 1 Audio Analyzer UPL, specialist for allanalog and digital audio signals

Photo 42 383/2


• waveform function for representingtest signals in the time domain withoptional smoothing of waveform by interpolation and compression of slow sequences (eg for tests onAGC circuits),

• spectral analysis (FFT) with zoomfunction for maximum frequency resolution of 0.05 Hz (FIG 3).

The following test signals are avail-able:• sinewave that can be applied to

an equalizer with user-selectablenominal frequency response, eg for compensating the frequency response of a test setup,

• two-tone signal for intermodulationmeasurements (amplitude ratios and frequencies continuously ad-justable),

• multitone signal comprising up to7400 frequencies with selectableamplitude distribution (frequencyspacing can be linked to resolutionof fast Fourier transform, thus en-abling rapid and accurate single-shotmeasurement of frequency responseof EUT),

• arbitrary signal for generating anytrace of up to 16,384 points,

• sine burst and sine2 burst signal withadjustable interval and on-time,

• noise with a variety of amplitude dis-tributions,

• dither with adjustable level and se-lectable amplitude distribution to beadded to digital audio signals.

UPL is able to perform amplitude andfrequency sweeps for all test signalsand in addition interval and on-timesweeps for bursts.

Use in production

UPL is particularly attractive for applica-tions in production. For example, it canperform all test functions simultaneouslyin two channels. This feature alone re-duces the time for stereo measurementsby 50% compared with most analyzersavailable on the market. Intermod-ulation measurements are carried out using patented, digital procedures thatcombine high accuracy with highmeasurement speed. Fast frequency-response measurement using a special,FFT-coupled multitone signal affords adecisive time advantage especially inintermodulation measurements, whichare often required. Digital signal pro-cessing reduces setting and transienttimes as against those achieved withcomparable, purely analog instruments.

An integrated program generator, whichtranslates each manual control step intoa complete IEC/IEEE-bus program lineof correct syntax in the logging mode,considerably speeds up control-programgeneration. Furthermore, instrument set-ups generated on Audio Analyzer UPD

[1; 2] in the development lab can be used on UPL in production, whichsubstantially reduces the time for test-program generation. Long calibrationintervals, resulting from the extensiveuse of digital circuits, make for highavailability of the instrument.

Measurements on digital audio interfaces

UPL has balanced, unbalanced andoptical inputs and outputs for con-necting consumer electronics and pro-fessional studio equipment. Additionalinputs and outputs allow the analyzerand generator to be synchronized to thedigital audio reference signal (DARS),and the generator to wordclock, videosync signals and to 1024-kHz refer-ence clocks. The generator and the analyzer can be driven at separate,variable clock rates between 27 and55 kHz. This allows the use of non-standard clock rates as encountered in sample converters, which are em-ployed to an increasing extent, and inmultimedia applications.

Of course UPL is also capable of ana-lyzing additional data of the digital audio signal and physical interfaceparameters. For example, channel-

Articles

FIG 2 Easy definition of filters by means of afew entries

FIG 3 Zoom FFT function for displaying side-bands just a few hertz from main line of audiosignal


status data can be input and output inbinary form or coded to professional,consumer or any user-defined format (FIG 4). UPL further provides display ofjitter spectrum (FIG 5), measurement ofjitter amplitude, generation of jitteredoutput signals and is able to remove jitter from input signals.

Bit- and word-synchronous sync signalsallow accurate analysis of digital audiosignals on an oscilloscope. The pre-amble, eye pattern and superimposednoise can be displayed, for example.Moreover, the phase differencebetween the audio and the reference input can be measured, and a phasedifference can be generated betweenthe audio and the reference output. De-lay times of equalizers, audio mixers,etc can be determined by measuringthe time difference between the outputand the input signal. Common-modesignals at the balanced input (fre-quency, amplitude, spectrum) can beanalyzed and a common-mode signalcan also be superimposed on the out-put signal. Audio Analyzer UPL furtherprovides measurement of input-pulseamplitude and sampling frequency. The adjustable output level makes itpossible to determine the sensitivity ofdigital audio inputs. Long cables canbe simulated by means of a switchablecable simulator.

Future-proof investment

Who can predict for sure today whateffects growing digitization will haveon the audio world and what test re-quirements will result from this? In thisrespect there will be no problems with Audio Analyzer UPL. With all testfunctions implemented digitally, UPLcan be adapted to changing require-ments by simply loading the necessarysoftware – and this also for the analoginterfaces.

Wolfgang Kernchen

REFERENCES

[1] Kernchen, W.: Audio Analyzer UPD gener-ates and measures analog and digital audiosignals. News from Rohde & Schwarz(1992) No. 139, pp 13 –15

[2] Hempel, J.: Automatic audio measurementswith user-friendly control system of AudioAnalyzer UPD. News from Rohde &Schwarz (1993) No. 143, pp 29 – 30

Articles

FIG 4 Analysis of additional data of digitalaudio signal coded in professional format

FIG 5 Jitter spectrum of digital audio signal

Condensed data of Audio Analyzer UPLAnalog analyzer

Frequency range 10 Hz to 110 kHz

Voltage range 0.1 µV to 35 V (rms, sine)

Inherent distortion (THD) typ. < –115 dB

Analog generator

Frequency range 10 Hz to 110 kHz

Voltage range 0.1 mV to 20 V (rms, sine, open-circuit)

Harmonics typ. < –115 dB (< –120 dB at 1 kHz)

Digital analyzer and generator

Clock rate 27 to 55 kHz

Frequency range 10 Hz to 21.75 kHz

Inputs and outputs XLR, BNC, optical

Inherent distortion (THD) typ. < –130 dB

Reader service card 151/01


With the expiry of the transitional period for the electromagnetic com-patibility law at the beginning of thisyear, all manufacturers of electrical and electronic products in Europe are nowrequired to supply EMC conformitydeclarations for their products and label them with the CE mark. Small andmedium-sized businesses in particularhave to decide which of the requiredmeasurements they can perform ontheir own with due consideration oftheir facilities and budget. Test setupsand systems conforming to standardscall for relatively high investment. Par-ticularly interesting, therefore, are solu-tions that offer low-cost EMC measure-ments in preliminary testing, ie precer-tification, prior to acceptance testing.Such measurements can further provideproof of the effectiveness of EMC mea-sures already at the development stage,so standard-conforming measurementsperformed by external test houses canbe reduced to a minimum.

EMC measurements are divided intoelectromagnetic interference (EMI) andelectromagnetic immunity or suscep-tibility (EMS) measurements. For EMImeasurements, test receivers or spec-trum analyzers are required. Many users have already invested in instru-mentation of this type. Rohde &Schwarz offers the budget-priced TestReceiver ESPC [1], for example, whichwas presented in the spring of 1995 at the EMC show in Zurich.

For susceptibility measurements, signalgenerators and power amplifiers areneeded and, like in EMI measurements,coupling networks or antennas in addi-tion. Unlike EMI measurements, electro-magnetic susceptibility measurementsmust be carried out in shielded en-closures. Standards stipulate a shielded

(anechoic) chamber as test environ-ment, which must be partially fitted with absorbers to achieve the requireduniform field strength (referred to as uniform area). Since the constructionand furnishing of anechoic chambersinvolve a lot of technology and ex-pense, cheaper alternatives have al-ready appeared on the market. Exam-ples of this are TEM cells or GTEM (GHz Transverse Electromagnetic)Cells, compact anechoic chambers andprecompliance test cells [2].

S-LINE, developed by Rohde &Schwarz, is a new type of EMC test cell (FIG 1) offering the user decisivebenefits:• substantially lower costs compared

with anechoic chambers,

Articles

FIG 1 EMC Test Cell S-LINE, favourably pricedalternative to anechoic chambers

Photo 42 456

EMC Test Cell S-LINE

Compact EMC test cellof high field homogeneityand wide frequency rangeIn S-LINE, Rohde & Schwarz offers a favourably priced test cell for measuring susceptibility to electromagnetic fields in the frequency range 150 kHz to 1 GHzin the development phase. The test cell, which comes in two sizes, is an attractivelypriced alternative to compact anechoic chambers. By generating the field using a symmetrical line, S-LINE offers a larger test volume than conventional cells.


• uniform field strength throughout testvolume,

• highly compact size allowing easyinstallation in existing rooms,

• correlation with standard-conformingtest methods.

Mechanical design

S-LINE comes in two sizes. The largermodel with dimensions of 1.5 m x 1 mx 1 m offers a test volume comparableto that of compact anechoic chambers.This small size makes S-LINE suitablefor use in any development lab. Com-pared with conventional precompli-ance cells, S-LINE has clear advan-tages with respect to radio-frequencycharacteristics. The enclosure preventsthe emission of electromagnetic energyinto the surroundings. It is fitted with anRF-shielded door which provides easy access to the inside. The EUT is taken

Operation

Conventional test cells can be regardedas widened unsymmetrical coaxial lineswith the EUT exposed to the EM fieldbetween the inner and the outer con-ductor. By contrast, S-LINE consists ofsymmetrical, two-wire TEM lines pro-vided in the electrically shielded en-closure (FIG 2). The lines are fed withan RF signal at one end and terminatedwith their characteristic impedance atthe other. In this case too, the EM fieldgenerated between the lines is used for determining the electromagnetic susceptibility of the EUT. However, due to the symmetrical arrangement, amuch greater test volume is obtainedthan with conventional cells of the samesize.

A theoretical assessment of the field dis-tribution in a transverse plane of S-LINEcan be made using a simple charge dis-tribution model. The enclosure surfacesform the mirror lines in the transverseplane. The potential field and con-sequently all other field parameters are

accordance with IEC 1000-4-3. S-LINEfulfills the standard requirements overan area of 50 cm x 50 cm. Practicalmeasurements confirm the calculationsand show that the requirement for a uniform area is fulfilled even in a vol-ume of 50 cm x 50 cm x 50 cm almostin the entire frequency range.

Articles

up by a level worktop in the cell. Sincethe EUT functions must be monitoredduring measurements in S-LINE, ashielded window is fitted in the doorand the cell can be illuminated insidefor visual monitoring. For electricalmonitoring, standard filtered feed-throughs are provided and, in addition,screwed-on access panels allowing thecell to be configured as required.

obtained by superimposing the poten-tials of all charges. In the case of TEMtransmission, this assessment can beapplied to the E-field components. FIG 3illustrates the area of the ±3-dB and ±6-dB limits of the relative field strengthdetermined in the way described over the complete transverse plane of S-LINE. This is the plane in which the uniform area is to be proven in

FIG 4 shows the relative field strengthmeasured in S-LINE as a function ofheight above EUT worktop. This heightis normalized to the total height of the cell. The values measured in a con-ventional precompliance test cell areshown for comparison. It can clearly beseen that with a conventional cell afield-strength variation of almost 20 dBis to be expected, whereas with S-LINEthe variation is just about 4 dB.

EMC systems and setups with S-LINE

S-LINE can be used to complement existing measuring equipment. Rohde &Schwarz also offers complete EMC test setups incorporating S-LINE. For example, an EMC test system for thefrequency range 150 kHz to 1 GHzcan be implemented with Signal Generator SMY, Power Meter NRVD,

RF input

Transformer,antennasplitter

Cell interior

Line group 1

Line group 2

EUT Terminations

FIG 2 Electrical design of EMC Test Cell S-LINE(block diagram)

FIG 3 Field distribution in transverse plane oftest cell. Coloured areas show regions of constantfield strength, lines mark constant field strength insteps of 3 dB. Dotted red lines indicate uniformarea of approx. 50 cm x 50 cm with relative field-strength variation of less than 6 dB.


a power amplifier and S-LINE. SystemSoftware EMS-K1 [3] allows fully auto-matic tests to be performed.

Dr. Klaus-Dieter Göpel

REFERENCES

[1] Janssen, V.: EMI Test Receiver ESPC – EMCprecertification measurements for every-one. News from Rohde & Schwarz (1995)No. 149, pp 16–18

[2] Stumpf, M.; Lehmann, M.: EMC Test SystemsTS9977 and TS9987 – GTEM cell, the favourably priced alternative to the anechoicchamber. News from Rohde & Schwarz(1993) No. 140, pp 8 –10

[3] Göpel, K.-D.: System Software EMS-K1under Windows – Automatic measurementof electromagnetic susceptibility. News from Rohde & Schwarz (1995) No. 148, pp 12–15

Articles

Condensed data of EMC Test Cell S-LINEFrequency range 150 kHz to 1 GHz

Input power max. 100 W CW

Input impedance 50 Ω

VSWR of empty cell <2.5; typ. <1.5

Size of uniform area

Large model approx. 50 cm x 50 cm

Small model approx. 35 cm x 35 cm

Field strength 10 V/m at 20 W input power(large model, calculated in center of S-LINE)

Dimensions (L x W x H)

Large model 1.5 m x 1 m x 1 m

Small model 1.0 m x 0.7 m x 0.7 m

EUT monitoring visually through shielded window,and supply electrically via access panel with

integrated filters,AC: 220 V/4 A, DC: 12 V/2 A, 5 V/4 A


FIG 4Relative field strengthas function of heightabove cell base. Test positions are referred to totalheight of cell (con-tinuous line: S-LINE with symmetricallines, dotted: unsym-metrical lines).

Rela

tive

field

stre

ngth

Relative height

In shortRohde & Schwarz now on Internet

• The third category “Products” is the key offerand is arranged according to activity fieldsand applications. Written and display infor-mation about products can be called up.

• “Events” presents the complete Rohde &Schwarz training program in German andEnglish and a list of known participation inshows for a whole year in advance.

Online information thrives on news. For this reason our pages are continually revised so thatthey are always right up-to-date.

We recommend use of the Netscape Navigator as an access program (Browser). This programensures troublefree display of data. Ba

Since the beginning of March, Rohde & Schwarzhas been using its own Web site, ie a server forWorld Wide Web. The network address is:

http://www.rsd.de

The offer comprises four categories of informa-tion, mostly in English:

• “What’s new” offers the latest news such as thepress releases of the past months in Germanand English.

• “About Rohde & Schwarz” comprises generalinformation about the company, history, tech-nical milestones and international marketingaddresses.


Since 1993, Rohde & Schwarz SignalGenerators SME and SMT for up to 3 GHz have been highly successful onthe market. Now this signal-generatorfamily has grown by two new members:models SME06 (FIG 1) and SMT06for applications up into the 6-GHzrange. Good news for customers whohave to meet requirements which stipulate immunity to interference testson electrical equipment up to 4 GHz.SMT06 is an ideal and at the sametime cost-effective signal source for this purpose. Further applications willopen up in the 5-GHz range, whereintensive R&D is under way on newsystems such as WLAN (wireless localarea network), WLL (wireless localloop) and electronic road toll systems.

With SME06 and SMT06, the mea-surement technology for these applica-tions is in place well ahead of time.

The two new models are based on theirlower-frequency “brothers” and weredeveloped using frequency doubling.In other words, SME06 and SMT06 areidentical to SME03 and SMT03 up to 3 GHz except for overvoltage protec-tion, which is not provided on the newmodels since it would result in a consid-erable deterioration of the output reflec-tion coefficient at 6 GHz. Despite this,reflected RF power up to 1 W is per-missible with SME06 and SMT06. Toeliminate any danger when working on transceivers, which often have RFoutput powers above 1 W, an external

priced solution with a single-loopsynthesizer, and for SME, which fea-tures direct digital multiloop frequencysynthesis, short settling times and digital modulation. From the differentsynthesizer concepts, different fields ofapplication are obtained.

SMT covers the complete range of conventional analog receiver and EMCmeasurements, while SME is capableof both analog and digital modulation.Moreover, thanks to its fast frequencysynthesis, SME is ideal for measure-ments on frequency-hopping systemsand for tasks where every millisecondcounts, eg tests on integrated circuits,since test time for the IC manufacturer isequivalent to test costs. A reduction of

high-power attenuator (eg 10 or 20 dB)can be switched in. This external atten-uation can be taken into account inSME and SMT as an offset, and the signal generator then indicates the levelafter the attenuator. In this way mea-surement errors are prevented.

Synthesizer concept

The market success of the Rohde &Schwarz signal generators proves thatthe right concepts were chosen. Thisholds both for SMT, which is a budget-

Articles

Signal Generator SME06/SMT06

Analog and digital signals for receiver measurements up to 6 GHzThe boom in the communications sector is continuing. More and more mobile-radio networks and new radiocommunication applications are being devised. As the frequency bands below 3 GHz are already densely occupied, increasinguse will have to be made of the region above 3 GHz. Rohde & Schwarz has responded to this trend by extending its line of signal generators by two newmodels: SME06 and SMT06 for the frequency range up to 6 GHz.

FIG 1Externally identicalmodels SME06 and SMT06 extendsignal-generator family to cover analog and digitalreceiver measure-ments up to 6 GHz.Photo 42 455


test time from 20 to a few milliseconds,for example, will substantially reducemanufacturing costs. With 500 µs settling time in the list mode, SME offersan excellent prerequisite for cuttingdown on these costs.

The difference between the two synthe-sizer concepts can clearly be seen, forexample, from the SSB phase noise (FIG 2), where SME features excellentvalues close to the carrier up to 10 kHz.With –115 dBc at 1 kHz from a 1-GHzcarrier, SME can compete with the verybest of today’s low-noise generators. Its favourable SSB phase-noise valuesmake SME ideal for substituting a localoscillator, especially when it comes tocritical applications in digital trans-mission and radar systems. SMT, on theother hand, shows its strength at morethan 100 kHz from the carrier. WithSSB phase noise of –150 dBc at 1 MHzfrom a 1-GHz carrier, SMT is suitablefor blocking measurements even onhigh-end receivers.

Modulation

SME and SMT feature versatile mod-ulation modes for tests on communi-cations, navigation, telemetry andbroadcast receivers. The generatorsare capable of simultaneous AM, FM(ϕM) and pulse modulation. For two-tone modulation, internal and externalsources can be combined. The AM frequency range is DC to 100 kHz, the FM range DC to 8 MHz (SMT) or 2 MHz (SME) with maximum deviationof 40 MHz (SMT) and 4 MHz (SME). A special control circuit ensures highcarrier-frequency accuracy in the FMDC mode. DC coupling is possible alsowith phase modulation. The ϕM band-width is 2 MHz for SMT and 100 kHzfor SME. Another valuable feature isthe high-quality pulse modulation, fea-turing a rise/fall time shorter than 10 nsand an on/off ratio better than 80 dB.

The versatile modulation capabilitiesare backed up by a variety of modu-lation sources. In addition to a fixed-frequency generator incorporated as

standard, an LF generator can be fitted to SME/SMT to supply sinewave,triangular, squarewave and noisesignals. The maximum frequency forsinewaves is 500 kHz. A multifunctiongenerator provides the same signals as the LF generator over an extendedfrequency range up to 1 MHz and, in addition, stereo multiplex andVOR/ILS modulation signals. The mul-tifunction generator makes SME/SMTsuitable even for highly demandingmeasurements on FM stereo andVOR/ILS navigation receivers. A pulsegenerator supplies single and doublepulses up to 10 MHz. It can be inter-nally or externally triggered. The pulsedelay can be selected between 40 nsand 1 s. The signals generated bySME/SMT are available at separateoutputs for external applications so thatin some cases there is no need for anexternal AF or pulse generator.

Besides the analog modulation modesnamed above, SME06 provides virtuallyall types of digital modulation used intoday’s mobile-radio networks: GMSK,GFSK, FSK, FFSK, 4FSK, QPSK, O-QPSK and π/4-DQPSK, the data ofthe QPSK-based modulation modes degrading in the range above 3 GHz.The bit rate, filters and frequency de-viation can be selected over a widerange, and a variety of combinations is possible. With 4FSK and QPSK, thebit rate can be set in the ranges 1 to24.3 kbit/s and 27 to 48.6 kbit/s [1].

PRBS sequences can be selected asfixed standard patterns of variouslengths or user-programmed with theaid of a list editor. Moreover, exter-nally generated data sequences up to a length of 8 Mbits can be stored inSME. Such sequences are needed, forexample, for propagation measure-ments in GSM networks. In SME, spu-rious AM and FM can be added to the digital modulation. This allows receivers to be tested not only with virtually ideal signals but also with interference signals as encountered inpractice [2].

Ease of operation

Despite the wealth of functions provided,operation of SME is extremely easythanks to a well thought-out operatingconcept featuring a large LCD displayand menu guidance. All parametersand conditions selectable for a specificfunction are logically arranged in a single display. The user can be sure ofnot overlooking any hidden criteria oroptions associated with a particularfunction.

Another feature that greatly facilitatesoperation is the patented, magneticallylocking tuning knob. Although smooth-running, it provides fine stepping whichthe user can clearly distinguish. As a result, the display of SME/SMT neednot be watched all the time, eg in step-wise tuning. Tiresome turning from one

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FIG 2SSB phase noise of SME and SMT

at 1 GHz


display to another, eg when operatingSME/SMT and another instrument atthe same time, is a thing of the past.

Operator convenience is further en-hanced by a variety of useful features.Every RF specialist is aware of the prob-lem: the higher the operating frequencyin a test system, the more difficult it is toapply the RF signal to the EUT withoutany losses or appreciable frequency response occurring on the connectinglines. Here the user correction functionis helpful: level correction values for upto 160 frequency points can be storedin SME/SMT, the values between thesepoints being determined automaticallyby interpolation (FIG 3). This allows thefrequency response of external cablesto be corrected and the level at the EUTto be kept constant. The user correctionfunction is equally valuable in EMCmeasurements, where the frequency response of amplifiers, antennas orTEM cells connected after the signalgenerator are to be compensated. Thisdoes away with complicated, externallevel controls or test routines.

For frequently repeated measurementseries or sequences of different types of single measurements, the memorysequence function affords convenienceotherwise obtained only through pro-cessor control. Up to 50 instrument set-tings can be stored in nonvolatile mem-ory. After programming the sequenceof measurements (up to 256 steps) and

the step time in a list, the automatic testrun can be started.

Remote control of SME/SMT is normal-ly via the IEC/IEEE-bus interface. If noIEC/IEEE-bus interface is available onthe external PC, the RS-232-C interfacecan be used instead. This is expedient,for example, if a long data sequencehas to be reprogrammed in SME andSME should remain in the test system. Insuch cases SME can be reprogrammedon site via the RS-232-C interface withthe aid of a laptop.

Future-proof investment

It is difficult to say at present what newapplications lie ahead in radiocom-munications. There are however tworeasons pointing to a strong increase inthe demand for test equipment for the3-to-6-GHz range: first, the range up to2.7 GHz is already densely occupiedso that higher frequencies will have to be used to an increasing extent. Second, the trend towards higher fre-quencies is being speeded up throughnew technologies allowing the use ofsmall, favourably priced components.With its Signal Generators SME06 andSMT06, Rohde & Schwarz takes ac-count of this trend already now, makingsure that the right instrumentation isready and in place.

Johann Klier

REFERENCES

[1] Klier, J.: Extensions to Signal GeneratorSME for testing new digital networks. Newsfrom Rohde & Schwarz (1994) No. 146, pp 40 –41

[2] Klier, J.: Simulating vector errors with Signal Generator SME. News from Rohde &Schwarz (1995) No. 148, pp 32 – 33

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Condensed data of Signal Generator SME06/SMT06Frequency range 5 kHz to 6 GHz

Setting time SME06/SMT06 <10 ms (<500 µs in list mode) / <15 ms

Spurious (f < 1.5/3/6 GHz) <–80/–74/–68 dBc

SSB phase noise(f = 1 GHz, at 20 kHz from carrier)SME06/SMT06 <–126 dBc/<–116 dBc

Level range –144 to +13 dBm (overrange 16 dBm)

AM/FM/ϕM SME06 DC to 100 kHz/2 MHz/100 kHz

AM/FM/ϕM SMT06 DC to 100 kHz/8 MHz/2 MHz

Digital modulation (SME only) GMSK, GFSK, FSK, FFSK, 4FSK, QPSK, O-QPSK and π/4-DQPSK

Pulse modulationOn/off ratio >80 dBRise/fall time <10 ns

Pulse generator single pulse, double pulse, external triggerPulse repetition period 100 ns to 85 sPulse width 20 ns to 1 sPulse delay 40 ns to 1 s

Multifunction generator sinewave, triangular, squarewave, noise,VOR/ILS modulation signals, stereo MPX signals


FIG 3Level frequency response of SMT06 at 0 dBm output level


A large number of TV programs arebroadcast in Europe via the satellitesAstra and Eutelsat. Normally, stereosound programs are also transmittedwith the satellite signal. It seems there-

fore expedient to abandon the use of expensive modulation lines, inter-ference-prone terrestrial relay receiversor complex microwave links for feedingsignals, for example, to CATV headendequipment and terrestrial transmittersand to utilize satellites that can be received everywhere with a minimumof outlay. For this purpose Rohde &Schwarz developed the Satellite Re-ceiver CT200RS (FIG 1). It extends the

then frequency-demodulated (FIG 2).This second satellite IF is available formonitoring and external processing.An AGC (automatic gain control) circuitmatches the gain in a wide input-levelrange (–65 to –20 dBm). The switch-able AFC (automatic frequency correc-tion) compensates frequency offsetseven in case of weak input signals (egsignals impaired by heavy rain) andthus ensures optimum picture quality.

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Satellite Receiver CT200RS

TV reception with analog and digital sound from outer spaceAs an extension to the CATV Headend Equipment CT200, Rohde & Schwarz now offers a satellite receiver for analog TV programs able to receive both conventional two-channel analog and digital ADR programs. Thanks to the comprehensive remote-control capabilities of the system components, a new concept for broadband cable networks can be implemented.

CATV Headend Equipment CT200 [1]and, like the latter, can be remotely con-trolled and monitored via a Windowsuser interface. But stand-alone opera-tion is possible too, without restrictions.

Function

The satellite signal arriving from the antenna on the first IF is converted in atuner module with high image-frequencyrejection to an internal (second) IF and

FIG 1 Satellite Receiver CT200RS used ascomponent of Rohde & Schwarz CATV HeadendEquipment CT200 or as stand-alone unit

Photo 42 440


The subsequent polarity switch makesSatellite Receiver CT200RS also suitablefor C-band reception (3/4 GHz) which,contrary to the Ku band (11/12 GHz)commonly used in Europe, employs in-verted deviation. After the deemphasiscircuit prescribed by CCIR Rec. 405-1the baseband signal consisting of a video component (0 to 5 MHz) andsubcarriers (6 to 9 MHz) is availablefor video and sound signal processing.

In the video section of the receiver thesound subcarrier is separated and onlythe video signal is allowed to passthrough. A clamping circuit removes thesuper-imposed energy-dispersal signal,which ensures that intermodulationproducts generated in the satellite transponder do not cause visible inter-ference on the transmission link. If theinput level is too low or if no sync signalis received, a noise trap switches off the video signal at the program output.The monitoring output remains activefor measurements.

The sound section of Satellite ReceiverCT200RS consists of two FM subcarrierdemodulators which receive the analogsound signal accompanying the TV signal or one of the audio programs asa mono or stereo signal. CT200RS

may optionally be equipped with ADR Demodulator/Decoder CT200DR forretrieving the digital ADR-modulatedsubcarriers (ADR = Astra Digital Radio[2]). The option comprises the QPSKdemodulator required for ADR, a Viterbi decoder (error protection) andthe MUSICAM decoder. Ancillary datatransmitted with ADR signals are avail-able for further processing, eg for anRDS coder.

Since it is common for sound pro-grams to be transmitted in the satellitesignal as subcarrier pairs besides the TV sound signals, it would seemappropriate to use the baseband of

Satellite Receiver CT200RS severaltimes. For this reason, one of theCT200RS models, Sound SubcarrierDemodulator CT200SS, comprises only the sound section of the satellitereceiver and is fed from the basebandoutput. Thus several subcarrier demod-ulators can be operated from onebaseband signal. The ADR demodula-tor/decoder option may also be fittedin the subcarrier demodulator.

With several satellite receivers con-nected to one antenna, Active SatelliteSplitter CT200A8 provides eight out-puts each for horizontal and vertical polarization and covers the frequencyrange 920 to 2050 MHz. A low-noiseamplifier compensates for the distri-bution loss. Redundant power suppliesensure optimum operational reliability.CT200A8 may optionally be equippedwith an (n+1) output giving access tothe two types of polarization.

Uses

CATV headends mostly handle severalsignals from a satellite. Active SatelliteSplitter CT200A8 distributes the ver-tically and horizontally polarized IF sig-nals from the antenna to seven channelpaths (FIG 3). The eighth output is re-quired for the (n+1) standby channel. A Satellite Receiver CT200RS is con-nected to each of the two times sevendirect outputs of CT200A8, each ofwhich provides a TV program consist-

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DC+920 to 2050 MHz

Vertical

Modulatorpath

Modulatorpath

Modulatorpath

Modulatorpath

Modulatorpath

(n+1) standby configuration

Cou

plin

g ne

twor

k

Act

ive

Sate

llite

Spl

itter

CT2

00A

8

CCVS

CCVS

CCVS

CCVS

CCVS

Broadbandcommunicationnetwork

FM + DSRFM + DSR

2nd IF (479.5 MHz)

Satellite IF (920 to2050 MHz)

Power supplylow-noise block

Satellitetuner

PLLdemod.

Ku bandC band

SERBUSdecoder

Polarity

Baseband

Synchroni-zation

Clampingcircuit

Noisetrap

Videosignal

Base-bandAudiosignalleft

Audiosignalright

Noisereduction

Noisereduction

OptionADR Demodulator/Decoder

CT200DR

AF

AF

Sound Subcarrier Demodulator CT200SS

FIG 3 Satellite Receiver CT200RS in CATVheadend equipment with (n+1) standby

FIG 2 Block diagram of Satellite ReceiverCT200RS and Sound Subcarrier DemodulatorCT200SS


ing of a video and stereo signal or atwo-channel sound signal. Each satellitereceiver is followed by a CT200 mod-ulator comprising Vision-Sound Mod-ulator CT200VS, Sound-2 Coder Modulator CT200S2 and UpconverterCT200UP. If additional IF inputs and RF outputs or higher output level are required, CATV Interface CT200CImay be added. TV signals, FM soundprograms and possibly a DSR signalare combined by passive or activecoupling networks (eg CT200C6,CT200A4) and the sum signal is for-warded to the broadband communica-tion network.

Satellite Receiver CT200RS and SoundSubcarrier Demodulator CT200SS maybe used not only in CATV headendsystems but also in converter systemsand gap-filler transmitters. Sincenowadays many broadcasting author-ities emit their TV programs togetherwith their own sound programs via satellite, a TV and FM converter systemor gap fillers fed from satellites can easily be set up (FIG 4). Satellite Re-ceiver CT200RS receives the signalsfrom the desired satellite transponderand, in addition to the video signal withtwo-channel sound, it provides a base-band signal comprising the FM pro-

shown in the example. In the case ofADR subcarriers, QPSK demodulationas well as Viterbi and MUSICAM de-coding are performed in the optionalADR Demodulator/Decoder CT200DR.

Gregor Kleine

REFERENCES

[1] Schönberger, P.; Sturm, P.; Scheide, R.:CATV Headend System CT200 – CATV signal processing intelligent, compact, ver-satile. News from Rohde & Schwarz (1995)No. 148, pp 23–25

[2] Kleine, G.: Astra Digital Radio – Die Technik.Funkschau 68 (1995) No. 10, pp 44–47

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Comprehensive monitoring and re-mote-control capabilities of all activeCT200 components permit for the firsttime an (n+1) standby configuration tobe implemented. The supplementarychannel (satellite receiver and modula-tor) may replace any of the operatingchannels. The software used by Con-troller CT200CO holds the configura-tion of the headend equipment. Thecontroller monitors the whole headendsystem. If a component fails, the stand-by transmitter can be remotely tuned tothe respective satellite transponder.CT200RS selects one of the two pola-rizations with the aid of its LNB (low-noise block) feed voltage and the (n+1)option in the IF satellite splitter. The controller finally tunes the standby mod-ulator to the required output frequencyand connects it through. The inopera-tive channel path is remotely switchedoff and signalled defective to the con-trol center. The (n+1) standby configu-ration can be retrofitted any time in existing systems.

grams in the form of analog or digital (ADR) subcarriers. This baseband sig-nal is looped through Sound SubcarrierDemodulators CT200SS, each of whichretrieves one of the three FM programs

Condensed data of Satellite Receiver CT200RS andSound Subcarrier Demodulator CT200SSFrequency range 920 to 2050 MHz

Input sensitivity –65 to –20 dBm/50 Ω

Image-frequency rejection >45 dB

AFC capture range ±10 MHz

IF bandwidth 27/32 MHz, selectable

Video polarity selectable for C and Ku band

Video deemphasis CCIR Rec. 405 -1

Video S/N ratio >60 dB

Video output voltage 1 Vpp into 75 Ω

Subcarrier frequency range 5.5 to 9.99 MHz

Stereo channel separation >80 dB

Unweighted S/N ratio >64 dB

Audio deemphasis 50 µs/75µs, J.17

Audio output level +9 dBm into 600 Ω


FIG 4Example of convertersystem for one TVprogram and threeFM programs

DC+920 to 2050 MHz

Baseband

TV exciter

FM stereotransmitter



FM

CCVS


Operation

Audio Data Transmission System ADAS(FIG 1) is used for transmitting addi-tional data from the studio to the trans-mitter site via the program feed on ana-log modulation lines. Data are insertedinto the program signal at the upperend of the audio band at 14.85 kHzand use a bandwidth of 300 Hz persound channel at a bit rate of 400 bit/s.The data are removed at the end of thetransmission link (input of sound-broad-cast transmitter) by means of a steep-edged lowpass filter. In addition to thedata transmitted via the serial interface,an 8-bit data word is available for eachsound channel for remote-control ap-plications. The inputs at the studio areungrounded (optocoupler) and the out-puts are floating relay contacts.

For Audio Monitoring System AMON,which includes the functions of ADAS,the audio signal is subjected to an FFTanalysis at the beginning and end of atransmission link to obtain its audiospectral components. To reduce the volume of measured data, the signal isdistributed in 14 frequency bands, for which the corresponding rms level is determined and transmitted to the decoder (FIG 2). The phase differenceof the two channels is transmitted to the decoder to determine any polarityerrors for stereo signals. The decoderalso analyzes the incoming signal and compares it with the data of the source. The characteristics of thetransmission link are obtained by sub-traction. Each measurement, carried outonce per second, generates 15 values.

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Audio Data Transmission System ADAS andAudio Monitoring System AMON

Data transmission without data line, audio measurementswithout program interruptionBroadcasting 24 hours a day leaves no time for classic transmitter measurements.With Audio Monitoring System AMON it is now possible for the first time to monitor the quality of the supplied and transmitted television/radio program during program time. This means programs no longer have to be interrupted tocarry out measurements, not even for a short time. Moreover, no additional datalines from the studio to the transmitter are required since additional data – suchas dynamic RDS data – are transmitted via modulation feed lines by AMONand/or Audio Data Transmission System ADAS.

FIG 1Audio Data TransmissionSystem ADAS and Audio Monitoring SystemAMON for quality control of audio trans-mission equipment without program interruptionPhoto 42 442


This enables the following transmission parameters to be determined depend-ing on the program signal:• level error,• frequency response,• S/N ratio,• polarity (phase L/R),• channel interchange,• program interchange.

An additional stereo test input at theAMON decoder serves for monitoringtransmission equipment located at thesame site. The signal at this input is directly compared with the program input, through which the quality of a sound-broadcast transmitter can bechecked. If a data channel with a defined delay to the program signal is available, the system can also beused for digitally coded audio links.The signals are compared in the analogdomain.

The test results are compared with selectable tolerance tables. Inner andouter tolerance limits are determinedfor each test parameter. If any of thelimit values is exceeded, a message willbe sent via a relay contact. Each limitvalue has a hysteresis to avoid frequentmessages being issued if a measuredvalue fluctuates around a tolerance limit. An optional automatic measure-

ment according to CCITT 0.33 allowsmeasurements to be made on audiotransmission equipment during pro-gram breaks. This option can be usedboth in the AMON coder and AMONdecoder and enables separate mea-surements of the transmission line andthe sound-broadcast transmitter.

design, which allows upgrading of Audio Data Transmission System ADASto a full -featured Audio MonitoringSystem AMON at any time. The AMON/ADAS hardware with high-resolution sigma-delta A/D convertersin the audio paths provides for highquality without comprehensive analogsignal pre- and postprocessing beingrequired. Customer requirements caneasily be met thanks to digital signalprocessors that are used for filtering,modulation, demodulation and FFT.

A separate process controller servingthe serial and parallel interfaces as wellas the IEC/IEEE bus and the display (FIG 3) controls communication with external units. The two units can alsobe conveniently integrated into a testand monitoring system via IEC/IEEEbus. The complete test and monitoring values can be queried and displayedvia IEC/IEEE bus. Software updatescan easily be carried out via the RS-232-C interface from the front panelusing flash EPROMs without any re-moval or replacement of units being required.

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Configuration

Although these two units offer a varietyof functions, they only require a mini-mum of space. The standard configura-tion is a 19-inch desktop (1 height unit,approx. 44 mm), which is also suitablefor installation into system racks. Thiscompact size is due to modern modular

Uses

Continuous quality control of the mod-ulation-line network and the broadcasttransmitters during the ongoing pro-gram is indispensable to ensure highprogram availability. This is state of the art for picture transmission with useof the test-signal-insertion technique [1].

Source analysis Transmission link Reception analysis

AMON(coder)

AMON(decoder)

External data External dataProgram+data

Program ProgramMeasured values

Level Level Level

Level Level

Frequency Frequency Frequency

Data carrier

Frequency Frequency

Tim

e

Tim

e

FFT analysis,data conditioning,data transmission

FFT analysis,data reception,data conditioning,comparison of source with reception analysis

Audio filter Modulator FFT

(only with AMON)

Analog input

Analog output

Test input(only with AMON)

Control logicController

IEC/IEEEbus

Remotecontrol RS-232-C

R

R

RL

L

L

FIG 2 Principle ofaudio monitoringby means ofprogram signal

FIG 3Block diagram of

AMON and ADAS


With Audio Monitoring System AMONit is now also possible to monitor thequality of audio transmissions while the program is on the air. Thanks to itsintegrated monitoring functions (inde-pendent limit monitoring of measuredvalues for program and test input, mon-itoring of program identification, time-controlled start of a CCITT 0.33 se-quence) issuing warnings via relay con-tacts AMON is an optimized, indepen-dent monitoring system. Even higherfunctionality (operation, statistics, etc)can be achieved by integration into amonitoring system such as TS6100 [2].FIG 4 gives an example for a favour-ably priced vision/sound monitoringsystem including program-feed check atthe transmitter site in combination withVideo Measurement System VSA with

Transmitter remote control is also pos-sible. Multilevel addressability allowsaccess to individual units or unit groups,

Audio Monitoring System AMON is also equipped with these functions. Thecapacity of the data channel is partlyutilized for transmitting the measure-ment data.

Peter Singerl; Christian Krawinkel

REFERENCES

[1] Bichlmaier, T; Finkenzeller, R.: Video Mea-surement System VSA – Four TV measuring instruments plus controller in one compactunit. News from Rohde & Schwarz (1995)No. 147, pp 18–21

[2] Lehmann, M.; Strauss, G.: TV Monitoringand Test Systems TS6100 – Video and audioparameters of TV transmitters all under con-trol. News from Rohde & Schwarz (1996)No. 150, pp 16 –18

[3] Finkenzeller, R.; Polz, E.: Measuring all TVRF and video parameters for the first time in a compact unit. News from Rohde &Schwarz (1996) No. 150, pp 44–45

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FIG 4 Monitoring of transmission link and TVtransmitter by means of test-signal-insertion tech-nique and Audio Monitoring System AMON

Video program

Video program + test lines

Audioprogram

Audioprogram

TV transmitter

RF

AudioAudio program

+ data

Audio monitoringof transmission link

Audio monitoringof transmitting equipment

AMON coder AMON decoder

built-in Test Receiver option VSA-B10[3], which may, in the simplest case,use the integrated PC to control thewhole monitoring system. If data-carrierinsertion into the sound channel is notpossible or not desired, the source datacan be transmitted via an external datachannel. This may be done in the dataline while monitoring the televisionsound (FIG 5).

Audio Data Transmission System ADASis employed wherever data have to betransmitted to a transmitter site. Thesedata can be program identification ortransparent serial data such as RDSdata or remote-control data for con-trolling any functions at the transmittersite. Thus, for example, the stereocodercan be controlled or traffic announce-ment identification can be activated.

ie all the decoders of a program, all the decoders of a site or individual decoders.

Condensed data of Audio Data Transmission System ADASand Audio Monitoring System AMON

ADAS and AMON

Data transmission program signal path 4DPSK

Frequency response (40 Hz to 14.5 kHz) +0.1/–0.2 dB

Stopband attenuation above 14.71 kHz >70 dB

AMON only

Analyzer level range +9 to –74 dB

Monitoring measurement time approx. 200 ms

Measurement speed approx. one measurement/s

Measurement parameters level error, frequency response,S/N ratio, channel interchange,program interchange

Optional measurement functions CCITT 0.33, program no. 01


FIG 5Monitoring of tele-vision sound with Audio MonitoringSystem AMON andtransmission ofsource data in dataline (line 329, word 9)

Transmitter siteModulation lineStudio

Data-linecoder

Data-linedecoder

Fieldpulse

Fieldpulse

RS-232-C RS-232-C

AMON(coder)

AMON(decoder)

Word 9


The purpose of interception and moni-toring is to provide information aboutradiocommunications for the determi-nation of a scenario (systems, positions,movements, distribution, concentrations,intentions). A few typical activities ofradiomonitoring are:• searching for known and unknown

signals,• monitoring of radiocommunication

activities and alarm frequencies, • identification, detection or recogni-

tion of transmitters,• direction finding and location of

radio stations,• aural monitoring and recording of

radio messages,• analysis under technical and textual

aspects,

• preparation of reports,• evaluation and comparison of ob-

tained data,• setting up and updating of a data-

base,• preparation of statistics.

Modular design

To permit the great variety of tasks to be performed, RadiomonitoringSystem RAMON is of modular design.The number of modules used and theirassociated tasks vary depending onapplication. RAMON may be con-figured as required from a compactsystem with only one operator positionthrough to a hierarchical system withan appropriate number of operatorpositions (FIG 1). Thus each systemcan be optimally adapted to the desired application and reliability isensured through the use of tried and tested modules. The followingmodules are available:

• RAMON-supervise,• RAMON-search,• RAMON-monitor,• RAMON-analyze,• RAMON-locate,• RAMON-compact.

Each module is a configurable unitcomprising radiomonitoring equipment,a controller and software tailored to the particular application and com-plement. Operators of the individualmodules exchange data within thesystem via LAN for sending messages,giving orders or storing reports. The variety of systems that can be set upwith the aid of these modules rangesfrom single-position systems (RAMON-compact) through medium-sized systems

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Radiomonitoring System RAMON

Customized radiomonitoring from VLF through SHFRadiomonitoring System RAMON from Rohde & Schwarz detects and monitorsemissions in the frequency range 10 kHz to 18 GHz. Made up of tried and tested standard components, it allows comprehensive radiomonitoring systemsto be set up to customer requirements. A graphics user interface ensures easy-to-learn and convenient operation.

Order,basic information

Report,scenario

Search order

Report

Report

Monitoring order Monitoring orderMonitoring order

FIG 1 Radiomonitoring System RAMON-search with application-specific add-ons asdesktop Photo 42 134/2

FIG 2 Block diagram of

medium-sized radio-monitoring system


(FIG 2) to large, hierarchically orga-nized systems made up of several sub-systems.

The operator position RAMON-super-vise offers functions allowing the super-visor to control radiomonitoring andprepare reports. Thus assignments canbe issued, their handling checked, re-ports or results examined and allocatedto individual radio stations. The super-

visor is the interface with the superordi-nate level, from where he receives or-ders and further information. The super-visor prepares search and monitoringorders and passes them on to the oper-ators. Results obtained by the operatorsare stored as reports in a database. Ifthe results are not post-processed, thesupervisor carries out evaluation withthe aid of the database and supportingfunctions (FIG 3). He utilizes the infor-

mation obtained to control monitoringactivities. Based on this informationand his specialist knowledge and ex-perience he prepares reports for thesuperordinate level, which is his con-tribution to fixing the scenario. All his activities are supported by the graphicsuser interface of RAMON-supervise,permitting fast acquisition of results.

RAMON-search (FIG 4) comprises aSearch Receiver ESMA [1] and one ormore Compact Receivers ESMC [2].The module permits a fast searchthrough frequency bands and rapid signal identification. The search opera-

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tor scans specified frequency bands for active transmitters with his receiverin the overview mode (see box). In thismode the search receiver scans the defined range at maximum speed. Detected signals are shown in a pan-oramic display. Frequencies of interestare marked in the display and sent at a click to the compact receiver, wherethey are aurally identified and mea-sured. If a signal is to be further moni-tored and analyzed, he sends an auto-matically prepared order to the moni-toring operator by a single keystroke.Supported by RAMON-search the operator is able to respond quickly to

FIG 3Evaluation of reportsusing database

FIG 4 Single-rack operator position RAMON-search

Overview mode in search operationThe figure shows a snapshot of a search receiver operating in overview mode. Single frequencies and frequency bands are combined to a scan sequence of up to 10,000 channels. Known signals or unwanted bands may

be suppressed. The overview provides tools permitting signals to be measuredor the display to be zoomed or frozen. Recommended search receivers areESMA and ESMC.


new signals, identify a multitude ofemissions and execute a great numberof search orders.

RAMON-monitor (FIG 5) contains several aural-monitoring receivers andat least one recorder. The software ofthe position guarantees efficient moni-toring performance. The monitoring operator receives an order from thesupervisor or search operator and thesystem immediately tunes a receiver to the frequency to be monitored. Herecords the detected signal and notesdown important information in a reportin which receiver settings are automati-

aural-monitoring receiver and a re-corder. The software includes all mainfunctions of RAMON-supervise, -searchand -monitor. The tasks normally per-formed at the supervisor, search andmonitoring positions are concentratedin one position. Procedures are similarto those performed at the separate positions but the individual tasks arecarried out at a less detailed level. Thismakes system software support so particularly important. With RAMON-compact a single operator is able to obtain all essential information bymeans of radiomonitoring and to addthis information to the scenario.

Optimization and upgrading

Rohde & Schwarz continuously enhancesexisting modules and is developingnew ones like RAMON-analyze and

RAMON-locate. This allows systems inuse to be upgraded and improved byupdates. Thanks to the modular design,upgrading may be carried out in stepsso that even a small installation can beexpanded to an increasingly powerfulradiomonitoring system.

Reiner Ehrichs; Claus Holland;Günther Klenner

REFERENCES

[1] Oberbuchner, E.: Search Receiver ESMA –The ideal frontend for VHF-UHF monitoringsystems. News from Rohde & Schwarz(1995) No. 149, pp 7–9

[2] Boguslawski, R.; Egert, H.-J.: VHF-UHF Com-pact Receiver ESMC – Easy radio detectionin VHF-UHF range. News from Rohde &Schwarz (1994) No. 143, pp 11–13

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cally included. The operator locates thetransmitter with the aid of direction find-ers and is able to view the position onhis map (FIG 6). Detected emissions arerecorded on tape for subsequent evalu-ation. Depending on the technical facil-ities of his position, the operator maycarry out detailed signal measurements.The results are also noted down in the report. RAMON-monitor allows theoperator to monitor several frequenciessimultaneously and speedily prepare detailed reports.

The single-position system RAMON-compact includes a search receiver, an

Modules of Radiomonitoring System RAMONRAMON-supervise coordinator position

RAMON-search search and identification position

RAMON-monitor monitoring position

RAMON-analyze analyzer position (in development)

RAMON-locate radiolocation position (in development)

RAMON-compact compact single-position system


FIG 5 Rack layout of RAMON-monitor

FIG 6 Direction finding and radiolocation in monitoring mode with map (R&S MapView software)


Mobile-radio networks are spreading atbreakneck speed, meeting the growingdemand worldwide for speech anddata communication that is afford-able and possible for everyone andeverywhere using small, favourablypriced terminals. Standards GSM andDCS1800 for digital modulation arebecoming more and more popular.GSM networks are in operation in well over 50 countries, often severalnetworks are installed in a country, and there is a strong upward trend.DCS1800 networks are already in usein Great Britain, Switzerland, Thailand,

Malaysia and Germany, and intro-duction is imminent in another 15 coun-tries.

Standards GSM and DCS1800 differbasically in their frequency band (GSM:900 MHz, DCS1800: 1800 MHz) andthe transmitting power of base stationsand terminals. In DCS1800 networks,which are mainly intended for commu-nication via hand-held phones, trans-mitting power is lower and coveragearea smaller than in GSM networks.Modern mobile-radio networks are organized in cells of varying size depending on the topography of the area in question and the traffic volumeto be handled.

To reliably eliminate coverage gapsand thus prevent the interruption of radio links for an area, the directionalpatterns of antennas installed at BTS

Design

Basically, BTS antennas are made up of vertically stacked dipoles [1]. Ifcoverage is to be provided not for the whole surrounding area but only fora sector of it, the dipoles are mountedin front of a reflector. Antennas of thistype are commonly classified by thehorizontal half-power beamwidth oftheir directional patterns. For example,one speaks of 65° antennas (FIG 2).Another parameter determining thecharacteristics of a BTS antenna is itsgain. The gain is proportional to thenumber of stacked dipoles and thus tothe total length of the antenna. The gainand half-power beamwidth to be select-ed for a specific coverage area mainlydepend on the topography and on theexpected traffic volume (see table inblue box). Omnidirectional antennasare mainly used in areas with low traf-

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BTS Antennas HF.../HK...

The right antennafor every mobile-radio base stationBesides offering the complete range of test equipment required for radio networks,Rohde & Schwarz supplies antennas for base stations providing radio coverage forassigned areas. Directional and omnidirectional antennas from Rohde & Schwarzcan be used in all networks operating in the 900-MHz or 1800-MHz band: GSM,DCS1800 (PCN), TACS, Qualcomm, NMT900, NTT etc, thus opening up a virtuallyunlimited range of customers.

stations (base transceiver stations) mustfulfill stringent requirements. Further cri-teria of interest to network operatorsare reliability and – last but not least –economy. Based on these requirements,Rohde & Schwarz has developed twofamilies of antennas for the 900-MHzand 1800-MHz bands. These omni-directional (HK...) and directional(HF...) antennas come in a variety oftypes of various gain levels, allowingfor all conceivable applications of net-work operators (FIG 1).

FIG 1 Examples from Rohde & Schwarz BTSantenna program: sector antennas providing coverage in mobile-radio networks

Photo 41 835/7


fic volume and often replaced by direc-tional antennas (sector antennas) as thenumber of subscribers increases.

Radiation patterns

The vertical pattern of a BTS antenna isshaped by the type of feed used for thevertically stacked dipoles. If all dipolesare fed with signals of the same ampli-tude and phase, maximum gain will be obtained. But this is not always theoptimum solution. For example, it is often an advantage to lower the main

lobe of the antenna electrically (downtilt) to achieve better illumination of the coverage area and reduce the riskof interference with an adjacent cell (FIG 3). The down tilt is usually between1° and 6°. In practice, sector antennasoften use a combination of electricaland mechanical down tilt. The latter is implemented by means of a swivelholder, which is of course included in the Rohde & Schwarz range of accessories.

tennas (beam forming, beam shaping).It is generally true that not only gain increases with the number of stacked dipoles but also the number of sidelobes and minima (nulls). The side lobesabove the main lobe provide no cover-age but increase the risk of interferencewith adjacent cells; it is therefore ad-visable to suppress them as far as pos-sible, which may afford higher gain atthe same time. By contrast, the minimalocated between the side lobes below

Articles

the radiation peak result in coveragegaps especially in the vicinity of thebase station, which may cause break-down of links even in digital networks.Therefore, BTS antennas are requirednot only to feature side-lobe sup-pression but also a certain amount ofnull fill-in (FIG 4). Carefully designednull fill - in contributes considerably towards reliable coverage, which has been verified not only in theory but also by numerous mobile tests [2] (FIG 5).

It goes without saying that Rohde &Schwarz antennas meet the standardrequirements of network operators withregard to null fill-in and side-lobe sup-pression. In most cases much betterspecifications are achieved than thosestipulated. Omnidirectional AntennaHK612, for example, fulfills particularlystringent requirements with respect

Apart from down-tilting, further mea-sures are recommended for optimizingthe radiation characteristics of BTS an-

Half-power beamwidth Topographical conditions Traffic volumeOmnidirectional antennas rural low160° and 120° antennas mountains, national borders random120° and 90° antennas rural high65° antennas urban high33° antennas traffic routes random

FIG 4Null fill-in and

side-lobe suppression(schematic)

FIG 3Electrical down tilt

(bottom) focusesenergy to coverage

area (schematic)

FIG 2 65° Sector Antenna HF065E1 for1800-MHz band Photo 41 835/5


to vertical radiation pattern shaping. Generally it can be said that all BTS antennas from Rohde & Schwarz arethe result of elaborate optimization [3]and meet all of the described require-ments.

Antenna feed

The antenna dipoles are fed with volt-ages of defined amplitude and phasevia a power distribution network de-signed as a stripline. The stripline is anintegral part including all junctions,phasing lines, transformers and match-ing pads required, doing away with error-prone adjustments and alignmentsand allowing high manufacturing pre-cision to be maintained throughout abatch. Only a single solder joint is required between the antenna inputand the stripline. This and the use ofsnap-in connections have drastically reduced the failure rate in productionand increased MTBF by a factor of 80 compared with antennas featuring conventional coaxial-line connectors.Another essential advantage affordedby this concept is the extremely lowintermodulation.

The stripline is fitted between two metalplates and fixed in position by dielectricsupports. This design, which is knownas a triplate line, makes for extremely

low-loss feed of the dipoles and wastherefore given preference over thecommonly used method of depositingthe stripline directly on a dielectric as in the case of PCBs. Another advan-tage of this feed concept is the small parameter spread of the antennas inproduction.

Characteristics

Through complete simulation of all pa-rameters relevant to antenna character-istics, including dipoles, reflectors anddistribution networks, the following features and benefits were achievedin all BTS antennas from Rohde &Schwarz:• modularity, allowing application-

specific gain figures to be imple-mented,

• effective suppression of radiation inunwanted directions,

• compact size,• pattern shaping to avoid coverage

gaps,• extremely high reliability,• favourable price/performance ratio.

Finally it should be emphasized that it is not only the electrical data of the BTSantennas but also their high resistance

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Condensed data of BTS Antennas HF.../HK...Frequency band 860 to 960 MHz,

1710 to 1880 MHz

VSWR ≤1.3

Max. permissible wind speed 200 km/h

MTBF 40,000,000 hrs


FIG 5 Received signal level in vicinity of mobile-radio base station (right with and left without nullfill-in on BTS antenna)

to environmental stresses that plays adecisive role for network operators. Accommodated in a weatherproof radome, all parts of the antenna areperfectly protected against environmen-tal effects. Due to their very slim design,the antennas resist wind speeds up to200 km/h without any appreciable impairment of their radiation patternsand thus of coverage (for example, ahurricane of wind force 12 has a speedof about 125 km/h). And, last but notleast, the high quality standard main-tained at Rohde & Schwarz – certifiedto ISO 9001 – guarantees not only theelectrical and mechanical data but alsoa long service life for all BTS antennas.

Dr. Christof Rohner

REFERENCES

[1] Stark, A.; Nielsen, L.; Rohner, C.: Favourablypriced omnidirectional and sector antennasfor PCN base stations. News from Rohde &Schwarz (1993) No. 143, p 35

[2] Schmitz, U.: Zwei Tage Stress an den Schalt-knöpfen der mobilen Kommunikation – Unter-wegs im Funk-Messmobil. VDI-NachrichtenNo. 3 (21.1.1994), p 11

[3] Stark, A.; Rohner, C.: Optimizing the Cover-age of DCS1800 Base Stations by RadiationPattern Forming. Microwave Engineering Europe (Oct. 1994), p 59


Doctors, fire brigades and businesspeople too want to be or have to beavailable at all times and whereverthey may be. This is made possible by modern mobile-radio systems. Theadvantages of a radiopaging systemare relatively low costs for the user incomparison with a cordless phone forexample, small size and light weightand very long operating times of thebattery-operated pagers. The beepers,as they are usually called, come in a variety of models. There are evenwatch-integrated beepers. The requiredsystem infrastructure generally remainshidden to the public.

FIG 1 shows the structure of a simplepaging system with which a city can becovered from a high antenna site, forexample. It consists of a network con-

trol center with access controller and apaging base station. A public nationalradiopaging system comprises a mul-tiple of these individual elements. Theaim of optimizing the network topologyis to minimize the investment and oper-ational costs of radio coverage and thenetwork.

R & S BICK Mobilfunk is the right partnerfor the network operator as it not onlyprovides complete radiopaging infra-structures but also individual compo-nents such as paging base stations orpaging centers for the professional net-work operator. The compliance of thesystems with all important paging standards allows their integration in already existing networks. In additionto the hardware Rohde & Schwarz alsooffers accompanying services such asplanning and optimization of thesystem concept and radio coverage,site acquisition as well as training andmaintenance.

Paging System P2000 (FIG 2) is the firstmodel of a new generation of multi-protocol radiopaging systems coveringcurrent paging standards in the fre-quency bands commonly used for mobile radio. The most widespreadstandard in Europe for the air interfaceis the POCSAG code (Post Office CodeStandardization Advisory Group), astandard that was already recommend-ed in 1982 by ITU and allows datarates of up to 2400 Baud. The Euro-pean Telecommunications Standards Institute (ETSI) passed the European

Radio Messaging Standard (ERMES) in1992. This standard specifies not onlythe air interface with a data rate of6250 Baud but also the used frequen-cies and the interfaces between the in-dividual system components with theaim of implementing a European-widepaging-system network.

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Paging System P2000

Flexible, multiprotocolradiopaging systemRadiopaging services are becoming more and more popular worldwide. Systemoperators are continuously expanding their existing networks and installing newfacilities. R & S BICK Mobilfunk offers a complete service package covering plan-ning, installation, training and maintenance. A new generation of radiopagingsystems meets world-market requirements for a multiprotocol infrastructure.

FIG 1 Structure of simple paging system

FIG 2 Base station of Paging System P2000Photo 42 441


Elements of radiopagingsystem

The professional Paging System P2000consists of four basic elements (FIG 3):• access systems,• network control center including

operation administration and main-tenance accesses,

• distribution system between networkcontrol center and base stations,

• paging base stations ensuring de-fined radio coverage.

Access systemsThe call requests are routed to thesystem via different accesses. The net-work operator can select any combi-nation from a large variety of differentaccess systems.

Network control centerThe basic software package supportsthe standard functions of a public radio-paging system. Extending the numberof subscribers is optional just as addi-tional features. All the system elementsare integrated into a general operationadministration and maintenance con-cept. Subscriber handling and billingsystems are incorporated into thesystem via open interfaces.

Distribution systemsDifferent distribution media and net-works can be used according to net-work operator requirements to distrib-ute calls from the control center to thetransmitters and to route back opera-tional and maintenance messages fromthe base stations.

Paging base stationsThe number and sites of paging basestations depend on area coverageplanning. Well over 1000 paging basestations can be installed according tothe configuration level of the pagingsystem.

The connection of the access systems to the network control center and thedistribution system is via industrial com-puter networking in cooperation withATM of Constance, Germany. The prin-ciple of distributed processing can thusalso be fully utilized in paging systems.Moreover, a distributed informationsystem is a convenient platform for the static and dynamic division of thefunctionality of a complex system intoseveral principally independent systemunits. The capacity of the accesssystems, the network control center aswell as the distribution system can beextended in economical stages so thatthe requirements of national networkoperators using several radiopagingfrequencies on which different pagingstandards are possible can be fully metwithout causing capacity bottlenecks.

Characteristics

In addition to basic features such ashigh availability and operation on allinternational frequencies in the VHFand UHF band, features minimizing thecost of ownership for the network oper-

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FIG 4 National satellite-supported radiopagingnetwork

FIG 3 Structure of complex radiopaging network

Access systems

Distribution system

Network control center Paging base station

Pagingservice

controller

Accesssystems

Accesssystems

UplinkcontrollerPOCSAG

UplinkcontrollerERMES

Other networkseg GSM(SMS)

Maintenancesystem

Router

SATmodem

SATmodem

OAM

Subscriberhandling

RemoteLANs

PSDNetc

Decentralized access PCs X terminals

Uplink Downlink

Downlinkcontroller

Pagingbase stationPOCSAG


ator are major highlights of PagingSystem P2000:• market-oriented scaling from less

than 100 to more than 5 millionsubscribers,

• linking of different accesses viaopen interfaces,

• traffic-load distribution and redun-dancy through decentralized, dis-tributed call-data processing,

• distribution networking both terres-trial and via satellite,

• support of different paging protocolsand baud rates by software down-load,

• cost-optimized and unobtrusive out-door installation of base stations,

• requirement-oriented solutions for in-house coverage and on-site paging,

• intelligent and comprehensive oper-ation administration and mainte-nance concept down to componentlevel,

• easy servicing of base stations byelectricians.

Standardized interfaces between cer-tain system units allow for flexible up-grading or retrofitting of units. An inter-face between different paging systems

is of course available and allows mes-sages to be sent either via an ERMES,POCSAG or another high-speed pag-ing system. A further interface is pro-vided for external and cost-effective satellite uplink. The interface betweenthe downlink controller and the radio-paging transmitter is configured so thatexisting transmitters from other manu-facturers can easily be connected to thenew infrastructure.

FIG 4 illustrates the structure of a na-tional paging system for standardsPOCSAG and ERMES with satellite uplink of the individual paging basestations for call distribution as well as a terrestrial communication channel foroperation administration and mainte-nance. Thanks to consistent use of thedistributed data-processing principle,any access system such as an operatorworkstation, Internet access or speech-recognition system can accept pagingcalls for any subscriber authorized inthe paging system and forward them in the system. Prior to call-acceptanceacknowledgement to the calling parts,the subscriber number and the type ofpager is checked for validity.

All the services including cascading ofdifferent functions are basically avail-able to any subscriber. Which of theservices may be used by the individualsubscriber depends on authorizationby the system operator and the tech-nical facilities of the pager itself. Thepaging call is converted into the formatrequired prior to sending the call viaone or several paging transmitters inthe downlink controller. The necessarytransmission bandwidth of the satellitelink is thus drastically reduced, whichsubstantially cuts the operating costs ofthe whole paging system.

Thomas Rieder

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Combinations and functional scope of Paging System P2000

Access system Network control center Distribution network Paging base station

Voice access Services Satellite Frequency bandsOperator High calling-rate subscriber VSat VHFPhone (DTMF) Calling party pays SCPC UHFVoice box Calling party contributes Data networks Output powerData access Receiving party pays HDLC 25 WModem Info call/news TCP/IP 200 W (400 W)X.25 Call diversion Leased lines Paging standardsX.400 Paging standards CCITT M.1020 ERMESInternet / WWW ERMES ISDN POCSAGT-online POCSAG Dial-up lines High-speed pagingFax access High-speed paging Analog Mechanical designFax box Operation administration ISDN RackFax → text and maintenance (OAM) Microwave links Unobtrusive outdoor cabinet

SW download/parametrization Compact cabinet for indoor coverageRemote control/service Service conceptSubscriber handling Continuous built-in testAuthorization Service by electriciansBilling data



Base stations for digital mobile radiomust function reliably at all times. Toguarantee this, the transceivers are subjected to stringent quality tests at allstages of production from the individu-al module to the ready-made product,and key RF parameters are measuredduring on-site installation and duringservice. However different the measure-ment tasks may be, they can all be performed with a single compact testsystem – Digital RadiocommunicationTester CMD54/57 (FIG 1)*. It coversthe frequency ranges for GSM, PCN (DCS1800) and optionally also PCS (DCS1900). With the aid of an optionthe two models can also be used in the field of European train radio. Sincesignalling has not yet been defined

for this application, measurements arein compliance with current GSM specifi-cations.

The following features make CMD54/57ideal for measurements in the applica-tions outlined above:• flexibility for production,• Abis control for installation and final

testing in production and,• unique worldwide, uninterrupted

operation while checking or retro-fitting transceiver modules duringservicing.

The following parameters of the basestation (BTS = base transceiver station)can be measured with the radiocommu-nication tester:

Transmitter• Transmitter power to an accuracy

of ± 0.6 dB with integrated peak-power meter

• Power ramping at full dynamic range(72 dB) using the zoom function

• Phase and frequency errors withgraphic and numeric display

• Modulation spectrum in only 60 s for500 bursts on 23 frequencies (FIG 2)

• Switching spectrum

Receiver• Bit error rate (BER) (single or con-

tinuous) with various evaluation andconnection capabilities, eg loop-back in CMD, loopback in BTS, Abis monitoring, IEC/ IEEE-bus or RS-232-C interface

• Bit pattern to CCITT standard• Transmitter level with high accuracy

(eg error <1 dB at –104 dBm).

Use in module production

Important aspects for selecting testequipment in production are easy inte-gration into existing production linesand measurement speed. Thanks to agreat variety of synchronization andtrigger facilities and a number of analog measurement functions, CMDcan be matched optimally to the DUT.The SCPI-compatible IEC/IEEE bus

Application notes

Testing GSM/PCN/PCS base stations in production, installation and service with CMD54/57

* Schindlmeier, R.: Digital Radiocommunication Tester CMD54/57 – GSM/PCN base-station testersfor production, installation and service. News fromRohde & Schwarz (1994) No. 146, pp 16 –18

FIG 1 Digital Radiocom-munication TesterCMD57, ideal com-pact tester for pro-duction, installationand service ofGSM/PCN/PCSbase stationsPhoto 42 362/1

FIG 2 Modulation spectrum

of base-station transmitter


ensures fast remote control (FIG 3).Transmitter measurements are possiblewithout signalling – an indispensablefeature in module testing – with trigger-ing to pulsed and non-pulsed signals.The built-in RF signal generator allowsmeasurements to be carried out on receiver modules. The DC ammeter and voltmeter of CMD are optimizedfor measuring pulsed signals and anoptional AF generator/analyzer is pro-vided for AF measurements includingfrequency measurements.

and outgoing calls, location update,call cleardown, frequency hopping,channel and time-slot changing. Withthe realtime speech encoder/decoderoption (CMD-B5) integrated, the audio quality of the base station canbe tested.

CMD offers an interesting concept forAbis control for final testing in produc-tion and installation. The Abis interfaceis a digital interface with a data rate of2048 kbit/s capable of handling up to120 voice channels of 16 kbit/s eachand two 64-kbit/s signalling channels.Equipped with an Abis plug-in card anda BTS-specific control software, CMD

Abis control comes in two variants, either for control via an external con-troller or by CMD alone (FIG 4). Withvariant 1, CMD executes Abis appli-cation programs remotely controlled,eg from a notebook. The applicationprograms serve for controlling the BTS.If special measurement tasks are to becarried out, the user may modify in anyway the application program suppliedby Rohde & Schwarz. Once the pro-gram on the external controller matchesthe user’s requirements, it can be loaded into CMD for controlling theBTS from CMD (variant 2). The menusof the external controller will be dis-played on CMD. The supplied softwarecomprises an application program forvariants 1 and 2 for manual BTS con-trol. Switchover between Abis controland RF measurement is possible by means of a softkey. An application program permitting fully automatic BTSmeasurements is supplied in addition.

Use in service

Once a base station has been put intooperation, it should only be switchedoff in cases of emergency. This meansthat any service work is to be per-formed with the transceiver in full oper-ation. CMD is worldwide the first compact radio tester to carry out trans-mitter and receiver measurements onbase stations in operation. CMD per-mits even transmitter and receiver mod-ules to be retrofitted without interruptingthe operation. For this application CMDhas been upgraded by a number of

Application notes

Abiscontrol

Abismonitoring

Transmitter test

Receiver test

Base-stationcontroller

DUT

Radio network

IEC/IEEE bus

Manufacturer-specificcontrol bus,eg RS-232-C,RS-484

Trigger signals

Receiver test

Transmitter test

DUT

Use in final testing in production and installation

Main tasks of CMD54/57 for final testsin production and on-site installation ofa BTS are measurements with signal-ling, call setup for signalling tests, audio check, control of the completeBTS system via the Abis interface andautomatic testing.

In final testing measurements on activebase stations have to be carried out, ie stations which, driven by externalequipment, emit RF carriers with signal-ling information. Even the CMD basicmodel evaluates and indicates impor-tant network codes, permits synchron-ization to the C0 carrier (broadcast carrier) and gives an overview of RFparameters. Optionally, software per-mitting complete call setup with signal-ling to the RF interface can be loadedinto CMD. Supported are incoming

performs the following functions via the Abis interface: BTS reset, BTS con-figuration, software download, BTS reconfiguration as well as transmitter/receiver activation and deactivation.

FIG 5 CMD54/57

servicing base station on the air

FIG 3 Typical test setup in module production

FIG 4 Abis control with external notebook orCMD54/57

RS-232-C/IEC/IEEEbus

Abiscontrol

Receiver testTransmitter test

DUTVariant 1

Variant2


important functions making it a test mobile phone. CMD is connected to the RF interface of the base station, acall is set up and then all RF parametersare measured (FIG 5).

The signalling software performs callsetup, holding (even under adverseconditions) and cleardown. It also sup-ports, for instance, a change of channeland time slot as well as authentication.Signalling protocols complying with the OSI reference model required for the measurements are implementedin CMD.

Like a real telephone, the test mobilephone CMD54/57 obtains access tothe network only via a registered SIM

card. The required SIM-card reader is fitted below the instrument without enlarging the size of the basic unit.

After call setup CMD allows Abis moni-toring. To do so it feeds RF signals modulated with a CCITT bit pattern tothe base-station receiver. Depending on the quality and sensitivity of the receiver, the bits are received correctlyor with errors. The BTS forwards the received bits via the Abis interface to the base-station controller and then tothe network. CMD connected with highimpedance to this line measures the received bits at the respective time slot.Errors detected between the transmittedand received bits are displayed as biterror rate on CMD.

In the GSM network up to 16 RF car-riers with a channel spacing of 600 kHzmay be on the air simultaneously. Oneof these carriers is assigned to the testmobile phone CMD54/57 and has tobe measured selectively. For this reasonall other channels are suppressed by means of a special SAW (surfaceacoustic wave) filter so that they cannot impair measurement results.

Frank Körber

Reader service card 151/09 for further informa-tion on CMD54/57

Application notes

Container location from space

In COLOS (Container Location System)Rohde & Schwarz offers one of themost advanced and powerful systemsfor locating straddle carriers. Rohde &Schwarz is the first company world-wide to install an automatic, satellite-

based position location system of thistype in a container terminal, situated atthe Buchard quay in Hamburg, withturnover of around 15 million tons ofgoods and space for 35,000 standard-ized containers (FIG 1). These figures

make the Hamburger Hafen- und La-gerhaus AG (HHLA = Hamburg portand warehouse company) Hamburg’sleading port and transport enterprise.

At the container terminal of the HHLA,where around 1.5 million standardizedcontainers are handled per year, andin ports of comparable size, additionalcosts incurred in the search for mis-placed containers are considerable. Expenses for a single day of lay-off pership amount to around 100,000 DM,which makes searching for a misplacedcontainer a costly business. A searchbecomes necessary every time a straddle carrier operator fails to depos-it a container at the assigned location.At a terminal where 70 vehicles areused around the clock, this happens on

FIG 1 Container terminalof Hamburger Hafen- und Lagerhaus AGPhoto: Author


the average twice a day. The HHLAcame to the conclusion that looking for containers occurs too often and istoo expensive. So it ordered the satel-lite-based Container Location System COLOS from Rohde & Schwarz. COLOS automatically identifies the position of the containers and provides information on weight, length andstacking level whenever a container isdeposited or picked up at the terminal.

Another benefit of knowing the exactposition of all containers is that storagecapacity can be increased. So far thetop level of the terminal had to remainempty so as not to obstruct access bycarriers. If a container were to be liftedover two vertically stacked containers,the third level had to be left free for manoeuvring. With all container posi-tions and the loading sequence known,an intelligent storage managementsystem can also use the top level forstorage. In the described example thiscorresponds to an increase in storagecapacity of 50% in the ideal case.

Container Location System COLOS isbased on the Global PositioningSystem (GPS). This satellite-based loca-tion system allows positioning on theground within a circle with a radius of100 m around the actual position. TheDifferential Global Positioning System (DGPS)*, evolved from GPS, ensuresconsiderably better positioning accu-racy (uncertainty less than 1 m). It is due to this development that the systemcan now fulfill the stringent requirementsof container positioning at a terminal.

DGPS corrects the received GPS posi-tion data by using correction data obtained from a reference station. Thecorrection data are transmitted from thereference station to the mobile units (at 9600 Baud) via a telemetry link (FIG 2). The carrier vehicles can thusimprove their GPS position data. Posi-tion and other data of the containersdeposited at the terminal are trans-mitted to the control center via an

operational data link. Here the positionand other data of all containers arehandled and all actions relating tothese data are coordinated. Converse-ly, the carrier operators are informedvia this channel of where to move next.

As the positions of the straddle carriersare dynamically determined with pin-point accuracy, these data can basi-cally also be used to ward off collisions.This is of particular interest at terminalsusing unmanned carriers. Dynamic positioning of the vehicles is also a pre-requisite for effective fleet management.This means that the movement of emptycarriers is reduced to a minimum, dis-tances to be covered are optimizedand capacities are used as required.The utilization of available transport capacities is thus increased.

Use of the DGPS location system is not limited to container positioning. It issuitable for all applications requiringdynamic and highly accurate locationsuch as, for instance, piloting of vehi-cles at airports, locating well holes onoil fields or positioning bucket-wheelexcavators in brown-coal open-pit mining.

Rohde & Schwarz offers a series of satellite-based location systems withvarious degrees of positioning accu-racy. COLOS offering pinpoint accu-racy to within 1 m is the most accurateDGPS system from Rohde & Schwarz.

Thomas Kneidel


Application notes

FIG 2 Principle of container location with COLOS

* Krüger, G.; Springer, R.: Highly precise localization on land, at sea and in the air withGPS and DGPS. News from Rohde & Schwarz(1993) No. 140, pp 26–27


Live transmission of sound and TV pro-grams tends to be the exception. Nor-mally programs are stored on magnetictapes and replayed whenever requiredor when broadcast. Sound and TV pro-grams are also filed away on magnetictapes. It must be ensured, of course,that this conservation does not impairaudio or video quality. In large broad-casting stations several hundred of thesetape recorders and video recordersmay be in permanent use. They are subject to wear and tear, so they re-quire regular maintenance to preservethe quality of reproduction. Dependingon the complexity of the equipment,manual measurements on a recordermay take several hours and in the case of regular maintenance of a greatnumber of units this may lead to ca-pacity problems – not to speak of thecosts involved for the service personnel.In the past a number of computer pro-grams were available for automaticmeasurements on tape recorders but,

as a great number of measuring instru-ments and a PC were required, theycould only be used in a stationary role.

In Audio Analyzer UPD an instrument is available which is able to carry outpractically all necessary audio mea-surements [1]. Whole test sequencescan be performed automatically withthe aid of the optional Universal Sequence Controller UPD-K1 [2]. Theapplication software “Automatic mea-surements on tape recorders” makes use of this capability and allows evencustom program functions to be included in the automatic sequence.The large numbers of Sony Betacam recorders used in broadcasting stationscan thus be remotely controlled by UPD and measurements are carried outfully automatically. No other measuring instruments or an additional PC are required. Tape recorders can thus bemeasured directly on site (FIG 1). Theprogram allows automatic checking

and documentation of the recordingand reproduction quality of tape re-corders and of the sound section of video tape recorders with the aid of industrial standard reference tapes,custom recordings or custom testtapes.

The control program TAPE.BAS com-prises the following selectable menus:• Measure with reference tape• Record with tape monitoring• Record without measurement• Measure with recorded tape• Read stored test data• Manual single measurements

For measurements with referencetapes no manual action of any kind is required. In the case of a Betacamrecorder with remote control and a reference tape with time code, the necessary testpoints on the tape areautomatically selected in CUE-UPmode. Without remote control, the reference tape has to be rewound andstarted at the beginning. The requiredtestpoints on the tape are automati-cally selected and the measurement is performed.

Recording with simultaneous tapemonitoring is possible with a user-defined sequence and usually donewithout remote control. Remote controlis required however for measuringerasure attenuation, as in this case the particular tape section has to betracked several times.

Recording without simultaneous mea-surement with a user-definable se-quence allows the generation of a test tape for recorders without tapemonitoring.

The “Measure with recorded tape” menu is called up for testing reproduc-tion with a previously recorded tape(eg a custom reference tape).

Application notes

Automatic measurements on tape recorders using Audio Analyzer UPD

FIG 1 Automatic measure-ment on tape recorder with AudioAnalyzer UPD Photo 42 400/2


Loading and reading of stored mea-surement data is required for display or comparison with current measure-ments.

Manual measurements are required,for instance, for service settings or ad-justments.

The following single measurementscan be combined into any sequence:• output level,• azimuth (10 kHz),• reference level for frequency-re-

sponse measurement,• frequency response with reference

tape (definition acc. to referencetape table),

• frequency response short (63 Hz/1/2/4/10/12.5/15/20 kHz),

• frequency response long (31.5/40/63/125/250/500 Hz /1/2/4/6.3/8/10/12.5/14/15/16/17/18/19/20/22 kHz),

• S/N ratio (weighted and unweight-ed),

• FM S/N ratio (60 Hz/–20 dB with400-Hz highpass filter),

• distortion d3 (1 kHz or dependingon reference tape),

• crosstalk 1 > 2 ( 1 kHz),• crosstalk 2 > 1 ( 1 kHz),• crosstalk 1 > 2 (10 kHz),• crosstalk 2 > 1 (10 kHz),• wow & flutter CCIR and unweighted

(3150 Hz),• pitch error (3150 Hz),• channel selection (mono)• channel selection (channels 1+2)• channel selection (channels 3+4)• distortion d3 (1 kHz) at nominal

level +3 dB• erasure attenuation + output level at

1 kHz.

After the selection of mode and se-quence the measurement is started au-tomatically. If the recorder is remotelycontrolled, no further action is required.Without remote control the operator isrequested to rewind the tape and pressPlay or Rec+Play. Measurement resultscan be stored together with the test report information for documentation

(FIG 2), postprocessing or comparison.Results can also be subjected to an automatic tolerance check with the aid of a user-defined tolerance mask.Values within the tolerances aremarked and will not be shown in theprintout. This allows a very fast go/nogo test or a short test report to bemade.

The test program considerably simpli-fies the maintenance of tape recordersand therefore improves performancereliability while at the same time reduc-ing workload. Users of UPD may obtain the respective Application Note(1GPAN19) together with the programfree of charge from their local Rohde &Schwarz representative.

Tilman Betz

REFERENCES

[1] Kernchen, W.: Audio Analyzer UPD gener-ates and measures analog and digital audiosignals. News from Rohde & Schwarz(1992) No. 139, pp 13 –15

[2] Hempel, J.: Automatic audio measurementswith user-friendly control system of Audio Analyzer UPD. News from Rohde & Schwarz(1993) No. 143, pp 29 –30


Application notes

FIG 2 Result of frequency-response measure-ment

DVTS – video sequence for assessing MPEG encoders

every detail. And this future has al-ready started. For Rohde & Schwarz asa manufacturer of TV test and measur-ing instruments the question is: how canthe quality of TV pictures be assessedunder these new conditions? To tacklethis question a number of problemshave to be defined and solved first.

allowed reliable conclusions to bedrawn. That was the world of analogTV.

The TV pictures of the future will be dig-itally coded. They will be data-reducedand compressed and show character-istics that cannot yet be assessed in

What is picture quality? How do youdefine TV picture quality? Up to nowthings were relatively simple. The pic-ture quality determined in subjectivetests with large groups of viewers onrepresentative examples was closelycorrelated with a number of measure-ment results, the assessment of which


An initial step towards finding an answer is to assess the influence of theencoder on the picture components.

The type of coding entailed by MPEG-2[1] is mainly based on the reduction ofredundant and irrelevant informationcontained in consecutive TV pictures,for instance, on the minimum resolutionrequired for the human eye to discernmoving elements on the screen. By elim-inating these redundant and irrelevantcomponents, and particularly by an intelligent combination of differentdata-reduction methods, compressionfactors of the order of 50:1 to 100:1are obtained depending on the sourcematerial and the desired picture qualityof the coded signal. This means, for example, that a TV signal to CCIR 601of 216 Mbit/s is compressed to around4 to 2 Mbit/s. Since different reductionand compression methods are com-bined in this case, greatly varying results are obtained after encoding depending on the individual parame-ters selected.

The tools that can be used in the en-coder are described in detail in theMPEG-2 standard. The efficiency of thecombined tools for the source materialcan be globally assessed by visually examining the encoded signal, but adifferentiated evaluation was so fardoomed to failure because of the con-siderable effort involved in a statistical-ly sound, subjective quality assessment.For this reason Rohde & Schwarz has

developed a product in close coopera-tion with the communications institute ofBraunschweig Technical University as afirst attempt to solve these problems.

The Encoder Test Sequence DVTS (FIG)consists of stationary and moving picture elements that stringently test the various capabilities of an encoder.It allows assessment with the aid of theartefacts typical for this kind of hybridcoding. The test sequence in line withCCIR 601 is stored on tape in the D1 orBetacam SP format. The test sequenceis used as an input signal to the en-coder. The encoded signal is then de-coded and displayed on a monitor. Byusing the same decoder the differencesbetween different encoders can be determined. Theoretically the decodershould have no influence on signalquality, so even different decoders maybe used.

The following parameters can be as-sessed in this way: • global quantization factor (for JPEG,

MPEG-1 [2], MPEG-2) indicated as a relative quantity (0 to 31) on ascaled bar display,

• quantization error at grey-scaled,neutral wedges; the block artefactsexamined in this case permit conclu-sions to be drawn on DCT (digitalcosine transform) parameters,

• quantization error at edges; this error is to be assessed separately for the luminance and chrominancecomponents,

• quantization error for moving ob-jects; at high compression factors, inparticular the artefacts moving infront of a background which corre-sponds to a noise signal can beclearly distinguished,

• prediction errors; they allow conclu-sions to be drawn on the sequenceof I, P and B frames (intracoded, pre-dicted and bidirectionally predictedpicture elements).

Information on preprocessing is pro-vided in addition:• subsampling of luminance and/or

chrominance components in thevertical direction,

• subsampling of luminance and/orchrominance components with pre-filtering with/without separation of picture elements,

• discarding of luminance and/orchrominance components.

With the Encoder Test Sequence DVTSthe first of many steps has been taken towards objective assessment of picturequality for heavily compressed videosignals. Updates will be regularly issued to include the latest findings of experts and users alike. Throughcooperation with its customers Rohde &Schwarz would like to find a solution to the problem of objective assessmentof TV picture quality.

Dr. Jürgen Lauterjung

REFERENCES

[1] ISO/IEC 13818-2: Information Technology– Generic coding of moving pictures and as-sociated audio information, Part 2: Video

[2] ISO/IEC 11172-2: Information Technology– Coding of moving pictures and associatedaudio for digital storage media at up toabout 1.5 Mbit/s, Part 2: Video


Application notes

DVTS test pattern


A variety of measurements are stipu-lated for type-approval tests of mobileradios and base stations. The specifi-cations of the European Telecommuni-cation Standards Institute (ETSI) definemeasurements of RF parameters andmeasurements at different layers. Thesecan be carried out fully automaticallyby systems for mobile-radio type-ap-proval testing from Rohde & Schwarz.FIG 1 shows a configuration based onTest System TS8510 for base stations[1]. The DUT is integrated into the testprocedure via three different interfaces:a digital interface with 2.048 Mbit/s (Abis) and two RF interfaces for DUTtransmitter and receiver. The two RFinterfaces and the digital interface areoperated by separate units – in TS8510by Digital Radiocommunication Test SetCRTP04 from Rohde & Schwarz [2] for the RF interfaces and a Siemens pro-tocol tester for the Abis interface. Thisconfiguration meets all the require-ments for RF tests with standard accu-racy and for classic protocol tests.

In addition to protocol tests, ETSI specifications also stipulate paramet-rical RF measurements with partly veryhigh demands on DUT and test system.These parametrical RF measurementscomprise:• receiver dynamic range from –104

to –15 dBm,• susceptibility of receiver:

intermodulation suppression,adjacent-channel suppression,co-channel suppression,blocking,spurious response,

• spurious emission of transmitter,• intermodulation attenuation of trans-

mitter.

In many of these cases, RF signals fromdifferent sources are to be applied to the DUT very accurately or the testsignal or sections of it have to be mea-sured and detected precisely. This will

be illustrated by two typical tasks oftype-approval test systems: measure-ment of receiver RFI immunity andtransmitter spurious emissions.

of 200 kHz a signal/noise ratio of >170 dBc is obtained. Even given thebest generators, this is only possiblewith the use of filters. Three filters are re-quired for the large frequency rangefrom 100 kHz to 12.75 GHz: a low-pass filter and a highpass filter for fre-quencies outside the receiving rangeand a notch filter for frequencies withinthe receiving range. As the receive fre-quency of the DUT has to be variable,a tunable notch filter is used for measur-ing blocking signals in its vicinity. To en-sure accurate stimulation of the wantedsignal to within ±1 dB, it is adjusted at a high level with a precision powermeter and then reduced to the requiredlevel of –104 dBm via an attenuator.

The spurious emissions of base sta-tions have to be measured in the fre-quency range 100 kHz to 12.75 GHz.Their level must not exceed –36 dBm in this range (–30 dBm from 1 GHz).The base stations are operated at fullpower level – for TS8510 this meansoutput power up to +43 dBm, whichcorresponds to a dynamic range of 79 dB. Testing is made difficult (as faras the spectrum analyzer is concerned)by the fact that ETSI standards stipulatetest bandwidths of up to 3 MHz. This

Application notes

RF switch units simplify type-approval tests for mobile radio

In testing the RFI immunity of base stations a wanted signal of very lowlevel (eg –104 dBm) is applied to theDUT and at the same time an unwantedsignal of very high level (eg +8 dBm) in the range 100 kHz to 12.75 GHz.With a receiver input bandwidth

Protocol tester Base station(DUT)

RF switch unit

Fadingsimulator

Filter bank

Filter bank

Blocking adjust uplink signal

Downlink signal

Uplink signal( -104 dBm)

RF switch unit

Basestation

Signalgenerator

FIG 1 Block diagram of Test System TS8510for base stations

FIG 2 Block diagram of RF switch unit for type-approval test systems


cannot be managed by the spectrumanalyzer without filters, which is whythree filters are required for each re-ceiving range (a lowpass and highpassfilter each as well as a notch filter), ie a total of six filters for GSM and PCN.As GSM and PCN signals have thesame coding apart from the frequency,the spurious emissions of GSM stationsin the PCN band and those of PCNbase stations in the GSM band mustnot exceed –98 dBm at full output power. The required dynamic range of>140 dB can only be produced using a special duplex filter and an amplifier.

For manual switching, all these mea-surements require a lot of hardware for the test setup, measurement and

compensation of the individual paths.Moreover, the setups have to be docu-mented very precisely for type-approv-al testing so that measurements may berepeated under the same conditionsany time. An RF switch unit offers an alternative: measurements are carriedout fully automatically and can be repeated and verified any time underexactly the same conditions – even inother labs. FIG 2 illustrates the principleof such a switch unit used by Rohde &Schwarz in its GSM Simulator, ITA Test System TS8910, PCN SimulatorsTS8920 and TS8925, DECT TestSystem TS8930 as well as in TestSystem TS8510 for base stations men-tioned above.

Michael Manert

REFERENCES

[1] Tiwald, W.: Type-approval tests on GSM/PCN base stations with Test System TS8510.News from Rohde & Schwarz (1993) No. 143, p 28

[2] Schubert, W.: Digital RadiocommunicationTest Set CRTP04 – Test set for base stations to new PCN/DCS1800 mobile-phone standard. News from Rohde & Schwarz(1993) No. 143, pp 8–10


Application notes

Test hint

Rohde & Schwarz offers a narrowband RF spec-trum analyzer (option CMD-K43) for the GSM/PCN/PCS test sets of the CMD family. With a frequency span of ±130 kHz and selectable reso-lution filters, spectral lines can be measured in adynamic range of up to 60 dB. This analyzer is especially suitable for the alignment of I/Q mod-ulators. For a GSM modulator, for example, the RFsignal to be tested is modulated with +67.7 kHzfrequency offset. By adjusting the gain, offset andquadrature, signal components at –67.7 kHz andat the carrier center can be reduced to minimum.

For this purpose Digital Radiocommunication TesterCMD has three additional markers that also oper-ate as difference markers. The quality of alignmentcan thus be checked very easily.

Werner Mittermaier

After alignment compli-ance with specificationsof I/Q modulator can be verified using twomeasured values andtwo difference markers.

Alignment of I/Q modulatorsby narrowband RF spectrum analysis

Reader service card 151/14 for further information onCMD-K43

DUT CMD

I/Q modulator


2 Basic modulation techniques

The amplitude, frequency and/or phaseof the RF or baseband signal describedby equations (2) to (6) are modified bythe data signal so that the information itrepresent is impressed on the RF signal.The terms M-ary amplitude, frequencyor phase modulation are used to indi-cate which parameter is varied to rep-resent the information. The term keyingis used for digital modulation. The abbreviations ASK for amplitude-shiftkeying, FSK for frequency-shift keyingand PSK for phase-shift keying arewidely used internationally.

Straight ASK has ceased to have anysignificance in practice, but FSK andPSK are widely used in their binary andM-ary forms. With M-ary PSK, theupper limit for M is 8 because noise sus-ceptibility rises disproportionally as Mincreases. A combination of ASK andPSK is used for M >8. This leads to M-ary quadrature amplitude modula-tion (QAM). In this case the carrier canassume M states or, as has alreadybeen explained, there exists a set of M time-domain signals, each of whichrepresents a digital word ld(M) bits inlength (ld = logs to base 2).

The actual modulation process involvesmultiplying an RF carrier of the form A · cos[(2πfct + ϕ(t)] , which can also be expressed in complex form asA · exp(j2πfct) · exp[jϕ (t)] , by thebaseband signal. A simple ring mixercan be used to perform straightforwardtypes of modulation like binary ASK orPSK. The data sequence is convertedinto a unipolar (ASK) or bipolar (binaryPSK) NRZ signal. With M-ary PSK andQAM, the signal to be modulated mustbe split into its I and Q components.Both components are modulated bytwo different time-domain signals cI(t)and cQ(t), which are derived from thedata sequence a(n). However, it turns

out that these two time-domain signalsare identical to the real and imaginaryparts of the complex, equivalent base-band signal to within the sign of the imaginary part. Modulation is thenessentially a process of mapping thedata sequence a(n) to be transmittedonto the complex envelope of the mod-ulated RF signal.

2.1 Amplitude-shift keying

Amplitude-shift keying (ASK) is the simplest way of modulating digital information onto a carrier. Eventhough on/off keying (OOK), the original version of ASK, is no longercommonly used, it is the key to under-standing the fundamentals of digitalmodulation.

To simplify the discussion, we shall assume that the data stream whichmodulates the (real) carrier A · cos(2πfct)is a sequence a(n) with a ∈ 0, 1 com-prising an alternating sequence of 1sand 0s, ie a(n) = 1, 0, 1, 0, 1, 0, .......This sequence is converted into a uni-polar NRZ signal by a digital interpo-lation filter with

1––T

for – T––2

≤ t ≤ T––2h(t) =H

0 elsewhere

After D/A conversion, a signal with theFourier series

1 2 1 u(t) = -– A ·31+ -– · cos[2π[-– fbit]t]2 π 2

2 3– ––– · cos[2π[-– fbit]t]+…4 (7)3π 2

is obtained.

The DC component is half the ampli-tude (A/2) and there are spectral linesat odd half-integer multiples of the bitrate, ie (2n +1) fbit/2. There are nospectral lines at whole integer multiplesof the bit rate n · fbit (n ≠ 0). If the

data sequence is a random, uniformlydistributed sequence of 1s and 0s, agood assumption for actual data trans-missions, the discrete spectrum tends to a continuous spectrum in the limit.Again there is a DC component of A/2and zeroes at multiples of the bit rate.This signal is fed to the modulator.

It is easy to see that the carrier is, in ef-fect, turned on and off when it is multi-plied by the unipolar NRZ signal. Ifmodulation is taken to be the assign-ment of a symbol ai from an alphabetcomprising N symbols to a signal si from a set of N signals (in this case N = 2), the signal s1 = cos(2πfct) is assigned to the symbol 1 and the signal s2 = 0 to the symbol 0.

As the carrier signal and the basebandsignal are multiplied together, it followsfrom the shift theorem for Fourier trans-forms that the spectrum of the modulat-ed RF signal is

1 s(t) = -– A ·3cos(2πfc t)2

1 1 + -– ·cos[2π[fc ± -– fbit]t]π 2

1 3– ––– · cos[2π[fc ± -– fbit]t]+…4 (8)3π 2

for the sequence a(n) = 1, 0, 1, 0, 1, 0...... and a continuous spectrum in theform of a symmetrical mapping of thebaseband spectrum into the RF bandfor a random sequence a(n). In bothcases the carrier frequency is present in the spectrum but at half its originalamplitude. The spectrum has zeroes atthe frequencies fc ± nfbit (FIG 3).

Equation (8) shows that both halves ofthe spectrum centered on the carrier frequency would, in theory, be infinitelywide. Therefore, to ensure efficient use of the RF band, the spectrum mustbe bandlimited. This is best done in the

Refresher topic

Digital modulation and mobile radio (II)


baseband. Specifically, all frequenciesin the baseband signal up to at leastfbit/2 must be allowed through. This isequivalent to limiting the bandwidth ofthe RF signal to fc ± fbit/2, in otherwords to fbit .

Abrupt limiting of the baseband atfbit/2 is counterproductive becauselarge signal delays are introduced. Thefilter that is used should, therefore, havea continuous transition from the pass-band to the stopband which follows acosine function for example.

be transmitted. The theoretical upperlimit for ASK is 1 bit/s/Hz, but in practice efficiencies between 0.65 and0.8 bit/s/Hz are encountered.

2.2 Binary phase-shift keying

If the data sequence a(n) is mapped to a sequence of delta functions a(n) · δ (nT) ∈ +1;–1, an NRZ signal is output by the sin x/x lowpass. Thissignal, unlike the modulation signal

for ASK, is bipolar (binary phase-shiftkeying, BPSK). If the NRZ signal is used to modulate a carrier of the formA · cos(2πfct), an RF signal which is phase-shifted by 180° as comparedto the modulating signal is obtained.This means that s1(t) = –s2(t) and this type of modulation is called antipodal.

The (real) spectrum of the basebandsignal is given by

4 1 u(t) = A ·3-– · cos[2π[-– fbit]t]π 2

4 3– -—––·cos[2π[-– fbit]t]+…4. (10)3π 2

and has no DC component.

The spectrum of the modulated carrier

2 1 s(t)= A ·3-– · cos[2π[fc ± -– fbit]t]π 2

2 3– -—–·cos[2π[fc ± -– fbit]t]+…4, (11)3π 2

is obtained by multiplying the base-band signal and the carrier together.The spectrum does not contain the car-rier frequency (FIG 4). The occupiedbandwidth is the same as that for ASKand has been limited by passing thebaseband signal through a lowpass fil-ter with a cos roll-off before modulation.Consequently, ASK and BPSK have thesame theoretical maximum bandwidthefficiency of 1 bit/s/Hz and a band-width efficiency between 0.65 and 0.8 bit/s/Hz in practice.

Refresher topic

FIG 4 Time-domain signals and spectra withbinary phase-shift keying

FIG 3 Time functions and spectra with amplitude-shift keying

(1– α )1 for 0 ≤ f ≤ ————2T

1 π(2fT –1) (1– α ) (1– α )H(f) = H—H1– sin3——————4 for ————< f ≤ ———— (9)2 2α 2T 2T

(1– α )0 for ————< f2T

Baseband signal

RF signal

0.5 f bit

f bit

Baseband signal

RF signal

0.5 f bit

f bit

This filter replaces the sin x/x lowpasswhich was mentioned previously. TheRF signal now has a bandwidth Bwhich is a function of the roll-off factorα and in fact when α = 0, B = fbit andwhen α = 1, B = 2fbit. In practice roll-off factors between 0.35 and 0.5are widely used; this corresponds to RF bandwidths between 1.35fbit and1.5fbit. It is then possible to define abandwidth efficiency which indicateswhat bit rate per Hz of bandwidth can


2.3 M-ary quadrature amplitude modulation

To increase bandwidth efficiency, two,three or in general k consecutive bitsfrom a data sequence a(n) can be com-bined to form a new symbol b(m) bymeans of serial/parallel conversion. Asa result, the symbol rate is reduced tofbit/k. The new symbols are referredto as dibits, tribits, quadbits or k-bitwords in general. The modulation pro-cess requires M = 2k RF signals, eachwith a different phase and/or ampli-tude. The M = 2k possible symbols b(m)are mapped onto these signals.

An I/Q modulator is the best type ofmodulator to use. First of all, it splits theunmodulated RF signal into two compo-nents. The quadrature or Q componentis phase-shifted by 90° with respect to the in-phase or I component. There-fore the unmodulated I component is described by cos(2πfct) and the unmodulated Q component by–sin(2πfct). Both components are fedto mixers, where they are multipliedwith the modulating signals cI(t) andcQ(t); cI(t) and cQ(t) are derived fromthe symbol sequence b(m) and to within the sign of the Q component areidentical to the real and imaginaryparts of the complex envelope of themodulated RF signal. The products cI(t) · cos(2πfct) and cQ(t) · [–sin(2πfct)]are added together to give the mod-ulated RF signal. The modulation pro-cess is reduced to mapping the symbolsequence b(m) onto the two basebandcomponents. In the case of unfilteredquadrature amplitude modulation (QAM), staircase signals in the time domain with M/2 possible values areproduced (FIG 5).

By passing the baseband signalthrough a filter with a cutoff frequencyequal to half the symbol rate, the band-width of the RF signal is limited to thesymbol rate = bit rate/k, which meansthat the bandwidth efficiency is k timesbetter than for BPSK. Quadraturephase-shift keying (QPSK) is the firststep in this direction. Two consecutive

bits are combined to form a dibit which can represent one out of M = 22 = 4 symbols. These symbols are mapped onto the phases ϕ i ∈ 45°,135°, 225°, 315° of the RF signal or onto the four time-domain signals si(t) = A · cos[2πfct + (2i + 1) · π/4]with i ∈ 0, 1, 2, 3. TABLE 1 showshow the bit sequences, the dibits, themodulation signals and the phases ofthe RF signal are related. FIG 6 showsthe signals in the time domain, in thefrequency domain and by means of aphase state diagram. It should be notedthat in this case too there is no carrier-frequency component in the spectrum.

TABLE 1 Modulation parameter assignments

Theoretically, the bandwidth efficiencycan be increased to 2 bit/s/Hz and sois twice the maximum bandwidth effi-ciency for ASK and BPSK. In practice,values between 1 and 1.5 bit/s/Hzcan be obtained.To be continued Peter Hatzold

Refresher topic

Bit Dibit cI(t) cQ(t) ϕsequence

00 I 1 1 45°10 II –1 1 135°11 III –1 –1 225°01 IV 1 –1 315°

FIG 6 Quadrature phase-shift keying

Pulse shaping

Digitalfilter

Digitalfilter

16 QAM

Bit sequence

Time-domain signal in baseband

RF time-domain signal

RF spectrum

Unmodulatedcarrier

Modulatedcarrier

I/Q modulator Phase statediagram

0.5 f bit

FIG 5 M-ary quadrature amplitude modulation


The automation of EMC measurementsin development and production has become a topic of interest since the coming into force of the electromag-netic compatibility law (European EMCDirective 89/336/EEC) this year. Labelling electrical and electronic prod-ucts with the CE mark is now stipulatedby law to indicate compliance with inter-national standards for electromagneticinterference and susceptibility. Rohde &Schwarz, a leading enterprise in thefield of EMC, offers – in addition to advanced EMI/EMS Software PackageES-K1 [1] with modular, flexible and ex-tendable architecture under Windows –a budget-priced EMI software intendedin the first place for small and medium-sized enterprises to provide fast, reliableand reproducible EMC measurements.

Software Package ESxS-K1 supportsboth Rohde & Schwarz compliance-class Test Receivers ESHS/ESVS/ESSand Test Receivers ESVD/ESVB/ESN/ESVN, which measure useful signals in line with the EN standard [2]. The dialogs and masks for defining test setups, scan modes, measurements,evaluation and report generation arestraightforward and simple, making iteasy to get acquainted with the pro-gram even for those working with it for the first time. In addition, EMI Soft-ware ESxS-K1 offers measurementand evaluation functions frequentlyneeded by experienced EMC users including:• measurements at a keystroke (con-

figuration and loading of setups,scan start),

• graphic display of results and scandata,

• comparison of limit lines with peakand average detection,

• standard-conforming evaluation withquasi-peak and average detector,

• data reduction by subranging and/or acceptance margin selection,

• peak-list edit function, peak list canbe modified for automatic and semi-automatic measurements,

• marker functions and zoom func-tion.

Frequency sweeps can be stopped, afacility that is often needed in prac-tice. Sweeps can be restarted at themarker frequency, the current receivefrequency or at the point they werestopped.

Software

ESxS-K1 – attractively priced Windows softwarefor EMC measurements

FIG 1 Fully auto-matic RFI test systemwith Test Receiver ESHS, V-NetworkESH3-Z5 and com-puter with EMI Software ESxS-K1Photo 42 219


After completion of a frequency sweep,selected subranges can be examined indetail using the zoom function. For this,the Find Worst Case function offers thecurrent and the maximum level values,while the user performs fine-tuning ofthe receiver, determines the EUT posi-tion for the Worst Case mode and, at akeystroke, initiates final measurementwith quasi-peak and average detec-tion. The final result is automaticallyadded to the frequency list.

Three options are available for finalmeasurement:• automatic measurement; this means

cycling with a defined test setupthrough the frequency list obtainedfrom peak measurements,

• semiautomatic measurement; sameas automatic measurement but withFind Worst Case function activated,

• manual measurement; maximum level indication is obtained throughfine-tuning of receiver and position-ing of EUT.

ESxS-K1 of course allows complete set-ups to be loaded into the receiver andcurrent setups to be stored in the PCunder ’Receiver Setup‘. Using editablelimit lines and tables with correction values for frequency-dependent trans-ducer factors, reproducible, standard-conforming measurements can bemade. It is also possible to integrate V-Networks ESH3-Z5 (two-line) andESH2-Z5 (four-line), which are con-

trolled by R&S receivers via the userport, allowing the phase and PE wiresetting to be recorded along with thefrequency and level information.

The reports generated have the samelayout as receiver reports, including all settings relevant to measurement re-producibility. Reports can be displayedbefore they are printed using the PrintPreview function. Reports can be outputto any printer or plotter supported byWindows™ 3.1. Individual report fields

can be transferred via DDE (dynamicdata exchange) to other Windows applications such as Winword or Excel, allowing the user to generate reports in any desired form. Moreover,detailed online help is available in English and German for all softwarefunctions.

EMI Software ESxS-K1 can be installedon any Windows-compatible computerwith 80386 processor or higher withIEC/IEEE -Bus Interface Card PS -B4 from Rohde & Schwarz or PCII/IIA orAT-GPIB from National Instruments.

The software package is available for precertification Test Receiver ESPC (9 kHz to 2.5 GHz) [3] under the designation EMI Software ESPC-K1(supplied as accessory with ESPC). Thefunctions and features of this softwareare identical to those of ESxS-K1, butESPC-K1 only supports Test ReceiverESPC.

Volker Janssen

REFERENCES

[1] Wolle, J.: EMI Software ES-K1 – Windowsfor EMI measurements. News from Rohde &Schwarz (1993) No. 142, pp 22–23

[2] Rohde & Schwarz: Test & MeasurementProducts (Catalog 96/97)

[3] Janssen, V.: EMI Test Receiver ESPC – EMCprecertification measurements for every-one. News from Rohde & Schwarz (1995) No. 149, pp 16 –18


Software

FIG 3 Final measurement with Find Worst Casefunction activated and measurement using quasi-peak and average detectors

FIG 2 Curvesmeasured with peakand average detec-tors, with limit linesconforming toEN55022 and asso-ciated frequency list


It is a popular fallacy that data trans-mission by shortwave is unreliable,complicated and out of date. With theaid of Message-Handling SoftwarePackages ALADIN (Automatic Link And Data Interchange Network) andARAMIS (Automatic Radio MessageInterchange System), shortwave be-comes increasingly attractive in themodern communications world. ALADINand ARAMIS provide reliable, loss-freeand free-of-charge data transmission no matter whether in a building or overthousands of kilometers. Besides con-ventional text files, fax messages andvideo stills can be produced and trans-mitted. The menu-controlled user inter-face makes it easy to get familiarizedwith the system (FIG 1).

example, many foreign ministries com-municate with their representations allover the world via shortwave, indepen-dent of service providers [1], and re-search institutes use this medium tokeep in touch with their remote fieldbases [2].

ALADIN and ARAMIS automaticallytransmit and receive messages so thatthe user requires no in-depth knowl-edge of the shortwave medium. Whenthe user issues an addressed message,link setup and data transmission to thecounterstation will be performed auto-matically. The two software packagesprovide a modern workstation (FIG 2)with a clear-cut, menu-controlled userinterface for the generation, editing

To prevent data losses during trans-mission, ALADIN and ARAMIS use thesoftware-implemented Z-modem proto-col in addition to data-link protocolsFEC (forward error correction) andARQ (automatic repeat request) imple-mented in the hardware components. Ifa link breaks down or is disturbed, datatransmission will be continued from the point of disturbance. Successfullytransmitted data will not be sent again.Encryption algorithms are available to provide increased security againstthe interception of sensitive data.

The two software packages ALADINand ARAMIS make it possible to imple-ment communication networks whereeach station can communicate with anyother station. Alternatively, any user-defined organization structure, eg astar configuration, can be implemented(FIG 2).

ARAMIS was designed especially for therequirements of small and medium-sized networks. It is the simpler of the two systems and restricted to theshortwave medium. In an ARAMIS station, the antenna is automaticallyaligned in the direction of the stationcalled to make the maximum use oftransmitted and received power.

ALADIN was designed for the imple-mentation of worldwide communica-tion networks. In addition to short-wave, it allows alternative transmissionmedia to be integrated such as Satcomterminals [3], telephone networks orLANs. If a communication link is dis-turbed, switchover can be made to an-other medium without interrupting thetransmission – a unique and so far unri-valled feature of ALADIN. Successfullytransmitted data will not be sent again.In addition, for each medium, alterna-tive communication paths between thesender and the addressee (eg via a relay station) are offered to which

Software

ALADIN and ARAMIS message-handling software –convenient data transmission by shortwave

If no cable connection exists betweenparties located at a large distance fromeach other or if communication inde-pendent of a network operator or tele-phone company is desired, this iswhere shortwave comes into its own. Inthe frequency range 1.5 to 30 MHz,communication links can be set upworldwide at low operating costs. For

and transmission of ASCII texts, fax filesand video stills. Basically any binaryfiles can be transmitted. The user is sup-ported especially in the management,storage and archiving of large quan-tities of incoming and outgoing mes-sages. Possible I/O devices includecamcorders, fax machines, printersand teletypewriters.

Message Handling Software

Version 3.1 26.3.96

ARAMISARAMISFIG 1 User interface of ARAMIS software


switchover is made automatically in theevent of a failure.

For shortwave transmission, the core ofthe system is formed by a special HFdata modem [4]. The 2700-bit/s mo-dem provides an effective throughputrate of up to 2150 bit/s at 100% datatransmission reliability (correspondingto 2690 bit/s at an asynchronous PCinterface with a start and a stop bit).

ALADIN and ARAMIS are based on anoperating system with multitaskingcapability. This means that a largenumber of automatic processes can be performed simultaneously. For ex-ample, while a received message is out-put to a fax machine, a text file can betransmitted to another station and at the same time a picture recorded with a camcorder. The software packagesrun on System Processor MERLIN [5] or a standard PC meeting specific environmental requirements (shock andvibration resistance, EMC).

Message-Handling Software PackagesALADIN and ARAMIS make long-dis-tance shortwave links as reliable aswired phone and fax connections butare far more economical.

Thomas Kneidel

REFERENCES

[1] Ofer, K. H.: Crisis-proof communication byshortwave in German diplomatic service.News from Rohde & Schwarz (1991) No. 135, pp 18–21

[2] Kohnen, H.: Reliable shortwave commu-nications – a matter of life and death in the Antarctic winter. News from Rohde &Schwarz (1993) No. 141, pp 41–43

[3] Böhler, U.: Shortwave radio or satellitecommunication? News from Rohde &Schwarz (1995) No. 149, pp 57– 59

[4] Hackl, H.: Secure data transmission with2700 bit/s on shortwave links. News from Rohde & Schwarz (1994) No. 146,pp 29–31

[5] Maurer, P.; Völker, K.: Multimedia com-munication with MERLIN system processor.News from Rohde & Schwarz (1993) No. 142, pp 27–28


Software

FIG 3 Typical structure of shortwave network

FIG 2 Modern shortwave workstationPhoto 42 295


Object-oriented software developmentis in part based on concepts alreadyknown for some time; it is however only in the past five years that it has become a topic of general interest.There are various definitions as to whenan approach can be regarded as ob-ject-oriented. In contrast to the common-ly employed function- or data-orientedapproaches, object-oriented softwaredevelopment combines data and func-tions in such a way that they reflect as closely as possible the concrete andabstract objects of the real world.

Rohde & Schwarz has, for a customer-specific project, systematically andconsistently implemented an object-oriented concept. The result is a flex-ible, easy-to-service ship communica-tion system for the exchange of radardata, electronic mail and files of virtu-ally any size [1]. The whole system isextremely immune to interference fortwo reasons:

1. use of high-quality Tx/Rx compo-nents such as VHF-UHF TransceiverXT452 and HF Transceiver XK855 withintegrated FSK modem and ALIS pro-cessor [2],

2. use of reliable system software thatautomatically responds to disturbanceor interference from the environmentnot only by changing the frequency butalso by effecting handover between the HF and VHF Tx/Rx components.The software design is based on object-oriented software engineering accord-ing to Jacobson [3], since this methodenables a smooth transition from de-sign to implementation.

Design steps

Object-oriented software developmentis implemented in several steps.

Step 1: Definition of functionsBased on the customer’s requirementsand the resulting specifications, all de-sired system functions – referred to asuse cases – are recorded. The objectiveis to describe as completely as possibleall functions required in a system. Fol-

lowing are four examples from the shipcommunication system:“StartSupercycle” starts the super cycle,ie the central sequencing control for radio data transmission.“StopSupercycle” stops the super cycleand allows radiotelephone communi-cation.“MakeLink” starts the procedure for aX.25 link setup.“SendMessage” starts radio data trans-mission.

Step 2: Finding objectsIn this step you determine what objectsare necessary for system operation andwhat relationships exist between theseobjects. As a result the software archi-tecture is obtained, ie the organizationof the software into tasks and compo-nents (FIG 1). For example, the mes-sage dispatcher developed by Rohde &Schwarz plays an important role in thesystem because it extends the multitask-ing capability of the operating system(multi-user DOS) by simulated multitask-ing at the application level. While themajor tasks are handled by the multi-tasking function of the operatingsystem, the message dispatcher man-ages the objects within the tasks. Forthis the objects must register with alltheir methods (messages) at the mes-sage dispatcher during runtime. Thisprocedure is employed not only for in-ter- but also for intra-task communica-tion and for communication with devicedrivers (FIG 2).

Step 3: Description of interactionbetween objectsObject-oriented programs are based onthe exchange of messages between ob-

Software

Object-oriented software developmentfor computer-aided, mobile data transmission

FIG 2 Typical inter-task communicationvia message dis-patcher (O2 sendsmessage to O4)

FIG 1 Software architecture for com-munication system


jects. A commonly employed method ofillustrating the message flow is by meansof message sequence charts (interac-tion diagrams). The message sequencecharts enable the functional interfacesof the objects to be defined (FIG 3).

Step 4: Specification of objectsThe majority of the objects used in theship communication system were imple-mented in the form of status automatonsas is common practice in communi-cations engineering. State transition diagrams are used for the specificationof the objects. The diagrams allow asmooth transition from design to imple-mentation (FIG 4).

Coding and quality

About 20 new objects (classes) weredefined for the above communicationsystem. Part of the objects was later im-plemented from C++ using inheritance.Most of the objects can be re-used, egthe message dispatcher, as well asclasses employed for system configu-ration and a timer class for time moni-toring, to name just the most importantones. But not only have new classesbeen generated, old ones were used aswell. The latter mainly included con-tainer classes and classes for the con-figuration of the user interface andwere taken from the Borland library ofclasses.

High-quality software is characterized,among other features, by stability,maintainability and testability. Rohde &Schwarz created high quality in its shipcommunication system by following astrategy based on three mainstays:

Precondition and postconditionchecksEach object ensures as far as possiblethat its data are consistent by checkingthem during runtime. Checking is per-formed twice, ie on entering a method(precondition check) and on leaving a method (postcondition check). Theconcept is simple [4] but it markedly enhances quality and productivity as itrequires developers to specify classesaccurately to be able to define the conditions (invariants) for these checks.This makes codes maintainable and also extends component testing, whichsubstantially reduces the probability ofruntime errors.

Exception handlingException handling causes the pro-gram to go to a recovery routine in the event of an error. This feature ofC++ is another powerful tool for the determination of runtime errors. It isused for cushioning protocol errors,for example.

Trace mechanismEach object of a task writes messagesinto a file during runtime. The messagesare classified according to contentsand can be filtered as required. Systemoperation is recorded in this way, andany malfunctions are traceable. Thisfeature can be disabled for reasons ofsystem performance.

Through the use of object-oriented tech-niques in conjunction with measuresaimed at the improvement of softwarequality, Rohde & Schwarz has devel-oped a product that meets even themost exacting requirements. Not with-

out reason is the object-oriented ap-proach regarded as a quantum leap in terms of productivity and maintain-ability in professional software devel-opment. Exception handling as well aspre- and postcondition checks havebeen incorporated into modern pro-gramming languages [5] and make for considerably increased reliability,stability and testability.

Jürgen Rauch; Karl Scalet

REFERENCES

[1] Jungherz, M.; Maurer, P.: Radiocommunica-tion system helps Italian customs authoritiesin coastal monitoring. News from Rohde &Schwarz (1996) No. 150, pp 46 –47

[2] Greiner, G.: Reliable shortwave with ALIS.News from Rohde & Schwarz (1988) No. 116, pp 47– 50

[3] Jacobson, I.: Object-Oriented Software En-gineering – A Use Case Driven Approach.Addison-Wesley (1993)

[4] Porat, S.; Fertig, P.: Class Assertions in C++.Journal of Object-Oriented Programming.SIGS Publications (May 1995) volume 8,No. 2, pp 30–37

[5] Meyer, B.: Eiffel: The Language. PrenticeHall (1992)


Software

FIG 4 Detail of state transition diagram (object:RSX25Group; state transition: linking → init)

FIG 3 Message sequence chart for MakeLink systemfunction


Airsense 500 (FIG 1) is an extremelyfast, selective and highly sensitive gas-analysis system for use in the automo-bile industry. Modern motorcar enginesshould have low fuel consumption andminimum exhaust emission. Moreover,drivers expect their cars to have a longservice life and adequate engine per-formance. These requirements can bemet by optimizing the combustion pro-cesses in the engine and by the use of acatalytic converter. For this, appropriategeometry of the combustion chamber,correct ignition timing and the rightcombustion mixture are required. Com-bustion processes today are micro-computer-controlled, which necessitatesa thorough knowledge of the complexchemical and physical processes takingplace in the engine and in the catalyticconverter.

Any variation of engine load has an immediate effect on the composition ofthe exhaust gases. For example, in adiesel engine more benzene can beproduced with than without a catalyticconverter if the engine is idling. As thecomposition of gases is highly complexand the processes take place at highspeeds, just a few exhaust-gas com-ponents (eg NOx, CO, SO2, total hydrocarbons) have been analyzed so far. The processes taking place in the engine can be optimized through

detailed analysis of the composition ofexhaust gases and its variation withtime. Mass Spectrometer Airsense 500meets the exacting requirements as to selectivity, speed and sensitivity involved in an analysis of this kind.

A mass spectrometer is an analysissystem that identifies substances bytheir mass. To this end, gaseous ions

are generated in an ion source from asample gas. The ions are separated inan analyzer according to their massand charge and recorded by means ofa detector. In classical mass spectrome-try, ions are generated through the col-lision of fast electrons with the sample.This takes place in small chambers inwhich electrons emitted from a cathodeare accelerated towards the anode,ionizing gas particles on their way. Often, more energy is transmitted in thisprocess than required for ionization,with the result that the ions break upinto smaller, likewise charged particles(fragmentation). A large number of different ions of equal mass is thus obtained in a mixture of gases, whichmakes qualitative and quantitativeanalysis impossible, ie the process isnot very selective.

Airsense 500 avoids fragmentation byemploying a special ionization method.A gas sample is ionized through the

Panorama

Mass Spectrometer Airsense 500 –fast gas analyzer for automobile industry

FIG 1 Multicompo-nent gas analyzer

Airsense 500: sturdy,turnkey system con-

figurable to customerrequirements

Photo 42 459

FIG 2 Basic designof Mass SpectrometerAirsense 500


exchange of charges between chargedsource-gas ions (eg Xe+) and the mole-cules under examination (secondary-ion mass spectrometer). Each type ofsource-gas ion has its characteristic energy. Using suitable source gases,the ionization energy can be exactlydetermined and fragmentation avoided.Airsense 500 in this way provides inter-ference-free analysis of complex gasmixtures.

The source-gas ion current is focussedin the first octopole (FIG 2) using high-frequency fields in an ultra-high vacuumand transported to a chamber wherecharge exchange takes place, ie the gassample is ionized. The ions obtainedare focussed in a second octopole. Theion streams are separated according totheir masses in a quadrupole filter usingcrystal-stabilized high-frequency fields.The particle detector consists of a sec-

ondary-ion multiplier (Channeltron), afast preamplifier and an electronicGHz counter. This special system affords detection limits far below oneppb (part per billion) and measurementtimes below 100 ms. This allows evenextremely small changes in the concen-tration of a substance to be detected on-line (FIG 3). Using different ionizationgases in rapid succession, it is possibleto extend the spectrum of measurablecomponents.

The gas-analysis system Airsense 500has proved its value under adverse conditions such as exist on engine test stands as well as in garbage-incin-erating plants, coal-fired power stationsand in the food-processing industry.

Dr. Andreas Waßerburger


Panorama

FIG 3Exhaust-gas concen-tration as function ofengine load

The “lifeline” to rescuers in the airIn summer 1995 Rohde & Schwarz wonthe order to supply a blanket radio net-work for the SAR service (search andrescue) of the German Air Force. Thisorganization of the Federal ArmedForces is primarily a service to supportmilitary operations. And as part of the national search and rescue serviceof the Federal Republic of Germany, ithelps any aircraft and – in cooperationwith Deutsche Gesellschaft zur RettungSchiffbrüchiger (German society for rescuing shipwrecked persons) – anyvessel in an emergency situation. In addition to these tasks it supports thecivil rescue service in case of acuteemergencies (FIG 1), provided there isno conflict of interest with the militarytasks and requirements of the SAR service [1].

Holstein. This belongs to the SAR areaof Glücksburg and comes under the jurisdiction of the German Navy, whichhas its own radio network.

More than 30 air-control radio stationsare set up to ensure blanket VHF-UHF

The Federal Republic of Germany is di-vided into SAR areas (FIG 2). Searchand rescue activities are managed by the rescue coordination center. Thiscenter of the German Air Force is responsible for the whole of Germanyexcept for its northern state Schleswig-

FIG 1SAR helicopter

of German Air Forceon duty

Photo: Armed Forces Office


radio coverage for the operation areaof the German Air Force. These stationscomprise two radio systems based onequipment of series 400 (FIG 3) [2].They can be operated in the VHF orUHF aeronautics band and allow datatransmission in both frequency bandsfrom an air-control radio station. Sta-tions already operating VHF-UHF radioservices are provided with separatetransmitters and receivers with asso-ciated antennas. This is usually the case with local military ATC centersand air-defense radar stations. Stationsof the German Air Force AutomatedCommunications System are normallyequipped with transceivers only. The

rescue coordination center operates,monitors and controls the radio networkvia a central system.

One of the radios of the air-control radio stations is linked to the monitoringand control system in the rescue coor-dination center via a semipermanentline. Communication with such radios is thus always possible on the set fre-quency. The second radio is elected asan ADS (automatic direct subscriber)via the German Air Force AutomatedCommunications System so that a sec-ond frequency in the VHF-UHF bandcan be used at the same time. The operational equipment (primary units)

of all the air-control radio stations are normally operated on a commonfrequency. However, the frequency canbe changed by remote control to dealwith major incidents.

The semipermanent lines of all the air-control radio stations are linked to therescue coordination center. Moreover,ADS links are set up between the rescuecoordination center and the nearestswitching center. The control of radiosincluding all the required device set-tings as well as the output of devicemessages is via three independentdata-processing workstations. The wholeradio system can be accessed from any of these workstations. The radionetwork can be divided into subnet-works. Access to the primary unit of an air-control radio station is computer-controlled, ie access is possible byclicking the selected air-control radiostation on the graphic display of the radio network. The secondary unit is selected by means of the direct accesskey.

Project planning provides for step-by-step implementation and startup of theradio network. The complete system isintended to be available in 1998. Thus,SAR will receive a tool that consider-ably facilitates and speeds up operat-ing routines in radiocommunication, im-proves availability and last but not leastreduces operating costs.

Franz Ketterle

REFERENCES

[1] Günther, H.-J.; Ketterle, F.: Funk – das Fern-meldemittel der dritten Dimension. ElektronikReport 95, pp 20–24

[2] Krüger, G.: Communication equipment forair-traffic control and airports. News fromRohde & Schwarz (1991) No. 134, pp 4–7


Panorama

FIG 2 SAR areasof German ArmedForces (asterisk = rescue coordinationcenter, triangle =SAR helicopter, red circle = SAR helicopter with doctor on call)

FIG 3 Transceiverof Rohde & Schwarzradio equipment series 400Photo 40 903


It can hardly be overlooked, the 300-mhigh tower in a rural area aroundLeeuw-Saint-Pierre, directly located onthe route to Pepingen in the heartlandof Flemish Brabant (FIG). Extremelypowerful sound-broadcast and TV trans-mitters from Rohde & Schwarz are operated in this tower. The whole storybegan because of an accident. In autumn 1983 a heavy storm destroyedthe antenna mast of BRTN (Belgian TVand broadcasting company of theFlemish community) and RTBF (BelgianTV and broadcasting company of theFrench community) at the Wavre broad-cast station. BRTN chose Leeuw-Saint-Pierre to set up a new mast now pro-viding Greater Brussels with the FMprograms Radio 1, Radio 2, Radio 3,Studio Brussels and Radio Donna andwith the two TV programs TV1 andTV2.

The transmitters are located in a hugehall on the second platform of the tower at the base of the antenna mast.The FM transmitters have a power of 10 kW each and a common standbytransmitter. Radio Donna, the fifth pro-gram, transmits with 2.5 kW and has astandby transmitter of the same power.The different radio programs are takenvia a transmitter-combining filter andemitted from a common antenna. TheFM transmitters are solid-state through-out, which keeps operating costs at a minimum. The transmitters are air-cooled and the recovered heat is usedto warm the rooms in winter.

The transmitter for TV1, the most modernin Europe according to Paul Desmet,advisor to the head of program ser-vices, consists of two 10-kW solid-statetransmitters that are used together. Thesystem thus corresponds to a 20-kWtransmitter operating with integratedactive standby. The system for TV2 con-sists of two identical transmitters yield-ing a total power of 40 kW. These are

operated in turns, ie in passive standby.In contrast to the transmitters for TV1,those for TV2 have klystron tubes andare extremely reliable.

Rohde & Schwarz, which is firmly established in Belgium’s FM network,won the order in the face of competitionfrom four other well-known Europeantransmitter producers. “It was the mostfavourable offer for BRTN”, confirms

Reader service card 151/20 for further informa-tion on FM and TV transmitters

Panorama

Rohde & Schwarz FM and TV transmitters provideGreater Brussels with entertainment

Paul Desmond. The high-quality systemsare in compliance with all standardspecifications and completely meet userrequirements, especially with regard toprice, ease of maintenance and repairas well as safety regulations.

Leo Terneven (BRTN)

Broadcasting tower of Belgium’s BRTN at Leeuw-

Saint-Pierre in Flemish Brabant and view of hallwith TV transmitters from

Rohde & SchwarzPhotos: BRTN


The United Arab Emirates (UAE) withapprox. 2.2 million inhabitants are a federation of seven emirates (Abu Dhabi, Dubai, Sharjah, Ras Al Khai-mah, Fujairah, Um Al Qaiwain, Ajman)that were united in a common state in 1971. The Emirates stretch over anarea of 90,600 km2. Since the foun-dation of the state, Sheikh Zayed binSultan Al Nahyan (head of state, presi-dent and also sovereign of Abu Dhabi)has been transforming the country at abreathtaking speed together with theheads of all the other emirates from a barren desert landscape into a pros-perous, modern state thanks to im-mense technological and infrastructuralinvestments.

Current investments include the updat-ing of telecommunication facilities. Inearly 1990 it was recognized that investment spent on different, incom-patible radio systems with limitedcoverage and of different performancedata for daily use coupled with the special demands in emergency situa-tions would be absolutely unsuitable.Trunked-radio systems were winningthrough more and more and finallyturned out to be the ideal solution forthe realization of the vision of one radiosystem for all parties concerned.

At the end of 1993 Rohde & Schwarzreceived an order to install a national,blanket turnkey trunked-radio systembased on ACCESSNET® [1]. The firstplanning stage was successfully im-plemented in close cooperation withthe UAE Ministry of the Interior withinsix months. Another stage was com-pleted half a year later so that com-plete coverage of all the important re-gions/cities stretching from Abu Dhabi,Ras Al Khaimah to Fujairah, where90% of the people live, was ensured (FIG 1).

The graduated, modular and hierarchi-cal switching concept of ACCESSNET®

with its outstanding software functions(signalling standard MPT 1327/1343)is the ideal key technology to meet all the operational requirements of se-curity organizations, coastguard, civildefence, police, customs, immigrationauthorities, fire brigades, ambulances,etc. Thanks to ACCESSNET® these user groups can now effectively carryout their specific tasks independentlyor, if required, together for the benefitof the inhabitants or maintaining inter-nal security.

An optimum, decentralized switchingconcept was implemented by the instal-

lation of a master system controllerwhich, as a central switching unit, isnetworked with five regional trunkedsite controllers via wired lines. Twenty“dislocated” radio base stations (FIG 2)controlled by the trunked site controllersvia terrestrial lines ensure full cellularcoverage and provide excellent gradeof service and high traffic capacity with a large number of radio channels.The whole network infrastructure can ofcourse be monitored by a central main-tenance computer system or by region-al maintenance terminals. 100% avail-ability is thus guaranteed.

The users have powerful trunked-radiosets, which are installed in vehicles andships (FIG 3) and can also be used asdesktop units in local centers of oper-ation. Hand-held radios with special accessories are for use in and outsidevehicles. About 2000 trunked-radiosets are currently used by the differentorganizations and are not only used for speech communication but also for data transmission. A sophisticatedscheme for call numbers and task-oriented release of certain functions for

Panorama

A vision comes true – trunked radio for United Arab Emirates

FIG 1System design oftrunked-radio net-work ACCESSNET®

in United Arab Emirates (red: locations of phase 1, blue: phase 2)

FIG 2 Example of ACCESSNET® radio basestation in United Arab Emirates Photo: Author


particular subscribers/subscriber groupsoptimize the deployment of people andmaterial in day-to-day and emergencysituations. Dispatcher terminals in re-gional centers allow rapid task allo-cation to operational units.

ACCESSNET® is in operation aroundthe clock and the network will be extended successively. The tactical demands of coastguards and other security organizations will thus be met by equipping all the present andadditional sites along the coast and onthe islands with digital switching andradio technology to allow encrypted, ie absolutely intercept-proof, end-to-endcommunication. A new generation ofdigital shipboard radios with inte-grated encryption is also part of the extension. ACCESSNET® thus followsthe trend from purely analog to fullydigital technology with application-tailored speech and data encryption[2]: an indispensable precondition fororganizations with security tasks.

ACCESSNET® fulfills the vision of theUnited Arab Emirates: this powerful

trunked-radio system will not only master today’s needs but also those of tomorrow and the day after. As theoperator of ACCESSNET® the UAEMinistry of the Interior has undoubtedlyset a notable example and received attention and won recognition. Con-sequently, the trunked-radio system ACCESSNET® is offered at low cost toall national organizations with a viewto becoming independent user groups.A large number of these organizationsare expected to take advantage of theattractive offer in the near future.

Karl-Heinz Wagner

REFERENCES

[1] Wagner, K.-H.: Trunked-radio systems suc-cessful all along the line. News from Rohde& Schwarz (1994) No. 146, p 55

[2] Schinke, U.; Klier, W.: RadiocommunicationSystem ACCESSNET®-D – Trunked radiogoes digital. News from Rohde & Schwarz(1995) No. 149, pp 28–31

Reader service card 151/21 for further informa-tion on ACCESSNET®

Panorama

FIG 3 Patrol boatsof coastguard of

United Arab EmiratesPhoto: Gulf News

R& S signal generators at Finnish Institute of Technology

setup with Signal Generator SMT [1]and Spectrum Analyzer FSEA [2] forgeneral measurement tasks. But it wasfound that the more favourably pricedSignal Generators SMX and SMY [3; 4] also maintain their specificationseven in harsh environments, are well -protected against accidentallyapplied external voltages and ex-tremely rugged thanks to their sturdymetal cabinets.

mechanical and electrical stability at anadequate price, as the instruments mustfrequently be transported between labsand test sites and students often lack experience on how to deal with mea-suring equipment.

The Kotka Institute of Technology inFinland decided to use Rohde &Schwarz equipment for many of theirmeasurements. FIG 1 shows a test

In the field of RF design, manufacture or maintenance, talented and well-educated engineers are the most valu-able resource of any company or publicinstitution. For creating such resources,extensive laboratory exercises havebeen included in the training programof technical institutes and universities.The teaching environment sets specificdemands on the laboratory equipmentin terms of RF specifications as well as


Another advantage of R&S signalgenerators is their simple operation –an important aspect in university appli-cations, as many students are afraid ofmaking operating errors and, after all,the main focus of learning is some-where else. If the student must first readand learn for several hours about howto tune the instrument to the right fre-quency, he will be distracted. Happilyenough, there is test gear with a betterdesign approach. Take Signal Genera-tor SMY: via a large spinwheel the stu-dent has immediate control of carrierfrequency and level. Changing steps orunits is performed by hardkeys belowthe display, and activating modulationis also very easy. And if, according toMurphy’s law, the student pushes thewrong button anyhow, he simply gets a clearly indicated error message. Theplastic guide card below Signal Gen-erators SMX and SMY is a valuable aid for the average student (FIG 2) and normally no handbook is neededbecause IEC/IEEE-bus commands arealso included.

Test equipment used for teachingshould be of a high quality standard.Many facts of modern telecommuni-cations and RF engineering cannot be demonstrated or tested with simpleinstruments because power level, fre-quency and modulation tolerances, eg

of hand-held phones, are very tight. Onthe other hand it is not advisable to pur-chase the most expensive and luxuriousinstruments for a teaching lab. Besidesthe financial risks in maintenance, cali-bration and repair, there is the fact thatthese devices are simply overspecifiedand have a lot of features which arenever used. When dealing with RF, oneway to save is to set a suitable frequen-cy limit. The benefit is felt in costs, andmost of the phenomena encountered inradio engineering can be still demon-strated and measured. For many pur-poses Signal Generator SMY is a suit-able choice with its upper frequency of 2 GHz instead of a microwave unit,which would cost at least three times asmuch. In a normal teaching environmentbasic specifications should be main-

tained within reasonably tight limits if financial limits demand, and instrumentsbe chosen that can be upgraded at alater date.

All the mentioned aspects demonstratethat Signal Generator SMY is a goodsolution for measurements in training institutes. Its excellent features and mod-ulation variety show that the instrumentis intended for the professional market,but it is nevertheless within the means ofthe not-so-wealthy customer – like mostof the academic teaching branch tendto be nowadays.

Dr. Pekka Eskelinen (Kotka Institute of Technology, Finland)

REFERENCES

[1] Lüttich, F.; Klier, J.: Signal Generator SMT –The signal source for receiver and EMSmeasurements up to 3 GHz. News fromRohde & Schwarz (1993) No. 142, pp 13 –15

[2] Wolf, J.: Spectrum Analyzer FSEA/FSEB –New dimensions in spectral analysis. Newsfrom Rohde & Schwarz (1995) No. 148,pp 4–8

[3] Lüttich, F.: SMX, a cost-effective signal generator for 100 kHz to 1000 MHz.News from Rohde & Schwarz (1986) No. 115, pp 13–15

[4] Klier, J.: Signal Generator SMY – The signalsource within everybody’s means. Newsfrom Rohde & Schwarz (1994) No. 144,pp 8–10

Reader service card 151/22 for further informa-tion on SMY

Panorama

FIG 1 High-qualitytest setup comprising

Signal GeneratorSMT and Spectrum

Analyzer FSEA usedfor measuring anten-na radiation patterns

Photo: Huurrekorpi

FIG 2 Signal Generator SMX withplastic guide card –so normally no handbook is neededPhoto 42 445


The new radio stations installed byRohde & Schwarz onboard the Belgian ships Zinnia and Godetia areused to ensure a permanent linkbetween national authorities and naval forces as well as other vessels,search and rescue organizations, air-craft and helicopters. These two command vessels of the Belgian naval forces, which also perform logistic tasks, are named after the two escort planes of the British FlowerClass. The two giant vessels that were used to transport the Belgiantroops of the British Royal Navy and offered to Belgium at the end of WW2 are also in operation as minehunters and minesweepers andproved to be very successful duringthe Iraq-Iran conflict, the Gulf War and during a mission in Somalia. “Thanks to the excellent technicalequipment and a very competent crew we succeeded in finding and destroying about 270 mines withoutany accidents or casualties,” says the Belgian Navy.

It is obvious that an extremely high-performance radio station is a pre-requisite for such missions. Rohde &Schwarz was thus asked to replace alarge part of the outdated equipmentinstalled at the end of the 60s. Thenew radio station (FIG 1) comprisessix receivers and four transceivers as well as a number of radio sets spe-cially designed for mobile land andmaritime radio services. It also con-tains a microprocessor for controllingdata exchange between the modules.The most powerful transceiver onboardthe vessels (1 kW) allows long-distancelinks over continents and also auto-matic setup of shortwave links andmaintains them in case of interference.The other three transceivers are mainlyused for vessel-to-vessel or vessel-to-land links. All the transceivers operatein the frequency range from 1.5 to 30 MHz. The six receivers cover therange 10 kHz to 30 MHz. The asso-

ciated transmitting/receiving anten-na is installed on the vessel platform (FIG 2).

Teletype signals from a receiver arerouted through a matrix in one of thethree MERLIN system processors, high-end terminals for RTTY networks toNATO standard, and then output on aprinter or teleprinter. In the other direc-tion, the messages coded by MERLINare sent via the transmitters. It is alsopossible to pass on messages receivedfrom another vessel via MERLIN.

The system has plenty more to offer.Thanks to an automatic alarm receivingsystem operating on the internationalfrequency 2.182 kHz, Godetia has an automatic distress signal. PSTNhookup is also possible so that mem-bers of the crew can ring home. Ves-sel-to-vessel communication by meansof this system is carried out by three-member teams taking turns every sixhours. The communication systemproved its reliability during an exer-cise in the Mediterranean in which Italian, Spanish, English, French andGerman units participated. Second

radio operator Guy Corvelijn con-firms: “With this installation, we havea very fast and reliable system. This in-vestment in a communication systemthat is extremely secure and thus indis-pensable for navigation is completelyjustified.”

Jean-Paul Hosdain(Capitaine de Corvette,

Force Navale Zeebruges)

Reader service card 151/23 for further informa-tion on maritime radio systems

Panorama

New radio stations for Belgian Navy

FIG 2 Antenna system of maritime radio stationPhotos: Force Navale

FIG 1 Communication system onboard Belgianvessel Godetia

Photo: Müller

5th international EMCtrade fair and congressThis three-day event at the Karlsruhecongress center in February 1996was the biggest trade fair staged todate on electromagnetic compatibil-ity. With 246 exhibitors attending,some 50 more than in 1994, the4554 registered visitors (approx.3900 in 1994) were offered a wideview of the market, new products,the latest research results, new or changed standards. Rohde &Schwarz attended sporting a mottoof “The Sure Way to CE”, ie the EU’sconformity mark, and informed thenumerous visitors to its stand (photobelow) about test equipment to


Newsgrams

CeBIT 96 with extremelysatisfied exhibitorsAt the world’s biggest showgroundsin Hanover, information and com-munication technology was againthe order of the day from 14 through20 March this year. There were twomajor differences compared to oneyear earlier. First of all the show wasshortened by one day and did notcommence until the Thursday. Andsecondly the number of visitorsdropped from 755,300 to about600,000. The number of exhibitorson the other hand rose from 6111 to 6507.

The decrease in the number of visi-tors was planned because, accord-ing to the show’s organizers, its ca-pacity had more than been reachedthe year before. The new concept ofa “profi CeBIT”, accompanied by adrastic increase in entrance pricesand consequently one third fewerprivate visitors than a year earlier,was seen by show committee mem-ber Hubert-H. Lange as a “precisionlanding en route to professionalism”.As far as shifting the opening day toa Thursday is concerned, this creat-ed enormous scheduling programsfor the trade and business press, because there were countless pressconferences to be attended in justtwo days, and so visits to the standsof the exhibitors had to be neglected.The federal information technologyassociation would like the show torun from Monday through Saturday,and we shall have to wait and seehow the organizers respond.

Rohde & Schwarz was present asusual in hall 17 with an exhibitionarea of 192 sqm. The motto this yearwas “Rohde & Schwarz – Com-petence in Radiocommunication”(photo above). In relation to the

shortness of the show there weremore customer contacts, also spreadacross the weekend. At the focus ofinterest were mobile radio and EMCengineering, followed by trunked radio. Overall, corporate sales ratesthe results of CeBIT 96 as very posi-tive, which is in tune with the ma-jority of exhibitors. 89.7% have already announced their intention to attend CeBIT 97. C. Rockrohr

Rohde & Schwarz equips mobile-radio laboratory of Munich Technical UniversityIn a special laboratory of the facultyof communications engineering atMunich Technical University (Prof. J. Hagenauer), a development andtest facility is being set up for mobileradio. Rohde & Schwarz, as theworld’s leading company in the fieldof digital radiocommunication test-ing, was awarded an order to equipthe laboratory. The facility is beingfinanced by Munich Technical Uni-versity itself, the Free State of Ba-

varia, the German government andRohde & Schwarz. It will enable in-vestigations of the quality of digitalradiocommunication when influencedby different kinds of interference,and the possibilities for correctionoffered by various coding systems.The laboratory will be equipped withseveral differently configured trans-mitters with digital modulation, afading simulator and a number ofunits for analyzing the spectral widthof signals, the impulse response oftransmission channels and trans-mission errors. Beside high-speeddigital signal processors, six SUN-Sparc and Ultra workstations will bein use for coding and decoding.There is sufficient capacity in the laboratory for six academic theses to be worked on at the same time.This makes it a highly specializedtraining facility for engineers in what is the fastest growing field ofcommunications technology. The laboratory will also conduct joint research with industry and networkoperators. PI

accompany product development,compliance test sets and what Rohde& Schwarz offers in the way of train-ing. Particular interest focused on thecompact S-LINE test cell for measur-ing susceptibility to interference (seealso page 7 in this issue). There werePC information terminals on thestand to present a diskette demon-strating Rohde & Schwarz’s compe-tence in EMI and EMS solutions, andalso giving new customers an over-view of CE certification, standards,accredited offices and R&S refer-ence customers. (If you are interest-ed, ask your local R&S represen-tative for the diskette.) As in previousyears, Rohde & Schwarz invited visitors to its traditional weisswurstparty with beer and pretzels on thesecond day of the event. This wasagain very popular, and 350 guestsenjoyed the Bavarian specialitieswhile consulting the company’s teamof EMC experts.

Because of the increased number ofexhibitors and visitors, the 6th EMCfair and congress in two years’ timeis moving to Düsseldorf. Rohde &Schwarz will again be attending.

V. Janssen

Rohde & Schwarz faculty prize 1995 in JenaThe faculty prize for excellent scien-tific achievement at Jena University –donated by Rohde & Schwarz – wasawarded at the beginning of theyear as part of a colloquium con-vened by Prof. Wolfgang Richter, the dean of the physico-astronomyfaculty. Wolf-Rüdiger Lange, Execu-tive Vice President of Rohde &Schwarz, presented the prize for the best dissertation in 1995 to Dr Andreas Kleinwächter and for the best thesis to Jens Stäbe, Dipl.-Ing. (in the photo from left: Richter, Lange, Kleinwächter, Stäbe).

Photo: Holthaus

Photo: Janssen


Newsgrams

Whereas Andreas Kleinwächter’ssubject “ Investigation of rotatingdisks in the general theory of relativity” was expressly theoreticalin nature, Jens Stäbe’s work “Inves-tigation of the effect of vehicle pitch oscillations on the distribu-tion of dip beams”, carried out for automobile producer BMW, is of immediate practical benefit. Inawarding the prize for 1995, Rohde& Schwarz continued a five-yeartradition. Company co-founder Dr Hermann Schwarz instituted theprize to honour the university thatboth he and Dr Lothar Rohde at-tended, and to demonstrate thecompany’s interest in high stan-dards of education for engineersand physicists.

K.-O. Müller

CTD55 – go/nogo tester forGSM, PCN and PCS phonesBeside Go/Nogo tester CTD52 forGSM mobile phones, Rohde &Schwarz is now offering a small,lightweight and low-cost unit –CTD55 – that can test PCN (DCS1800) and PCS (DCS1900)phones in addition (photo above).The tests, with a clear go/nogo re-sult, run automatically, and the userneeds no knowledge at all of radio-communications testing. OptionallyCTD55 will allow more in-depth teststhat it logs on a connected printer.The functions include call setup and cleardown in both directions,change of power and channel,measurement of power ramping, anecho test and checking of receiversensitivity. W. Mittermaier


RSE success continuesRohde & Schwarz Engineering andSales GmbH (RSE) was able to re-port a 30% leap in orders received,compared to one year earlier, at its third international sales meetingin autumn 1995. In addition to allEuropean representatives, the coun-tries Russia, Turkey, Egypt, SaudiArabia and the United Arab Emir-ates attended the annual meeting for the first time, held in Schwangauat the foot of Neuschwanstein Castleto mark the 150th birthday ofBavaria’s King Ludwig II. Similarly to King Ludwig in his day, who wasvery open to innovative engineering,the participants were presented withthe latest RSE product lines duringtheir three-day stay. At this meetingtoo there were trophies for the

representatives with the biggestgrowth and the biggest order book.The highest turnover in Europe wasachieved by England, in Germanyfor the third time by Cologne, and inthe Middle East by Saudi Arabia.Cups for the biggest percent growthwent to the representatives fromDenmark and Russia as well as to theNuremberg office. To conclude themeeting, as a small thankyou for thegood results in the past businessyear, the group undertook a white-water trip in five dinghies throughImster Gorge. This was masteredwith great bravura thanks to thesplendid team spirit, most of the participants managing to avoid contact with the 6°C cold water(photo below).

W. Schmittseifer

Feedback

In the chapter “History” a meeting between thesenior engineer of HESCHO at that time, HansHandrek, and Dr Rohde and Dr Schwarz is described. We already mentioned this event in “News from Rohde & Schwarz” about 13 yearsago in our jubilee issue on the 50th anniversary ofthe company (issue 103). We take this opportunityto thank Mr. Knaf and Mr. Kerbe for their letter. Allreaders who require further information or wish tosee the technical monument in Hermsdorf maycontact Mr. Knaf or Mr. Kerbe under the followingaddress and phone number:

Verein für Regional- und Technikgeschichte e.V.Hermsdorf, Industriegelände PF 2153 D-07621 Hermsdorf=: (+49 03 66 01) 6 23 72/6 49 08

The following is taken from this brochure: “The association for regional and technical history succeeded in adding the 40-kW high-power signal generator of the ceramics company as atechnical monument to the list of protected objects.The signal generator was last operated in 1989for product testing. One of the aims of the asso-ciation is to maintain the generator operationaland to provide the public at large access to it. Theinstallation was developed by the Munich-basedcompany Rohde & Schwarz and put into opera-tion at HESCHO in July 1941, the result of aninteresting technical development accompaniedby many personal contacts.”

Karl-Eduard Knaf, president, and Friedmar Kerbe,vice-president of the association for regional and technical history in the Thuringian town ofHermsdorf wrote to us: “As regular readers ofyour magazine “News from Rohde & Schwarz”and especially after seeing your report “100 yearsof radiocommunications – Rohde & Schwarz hasbeen shaping it for more than 60 years” we wouldlike to draw your attention to a monument inHermsdorf: our 40-kW high-power signal gener-ator developed by Rohde & Schwarz and put intooperation at HESCHO (Hermsdorf-Schomburg Insulator Company) in 1941. For more detailed information refer to the enclosed brochure.”

40-kW high-power signal generator from Rohde & Schwarz,a “technical monument”

Photo: Leonardi


Digital Radio Analyzer PCSD is adapted by software options either for channel impulse re-sponse (CIR) analysis in radio networks or for general interference analysis and C/I analysis; 8-inch colour display (VGA), for external monitors1024 x 768 pixels; PCMIA interface.

Data sheet PD 757.2150.21 enter 151/24

Digital Radiocommunication Testers CMD50,CMD53 (GSM, PCN/PCS) are equivalent toCMD52 and CMD55 when equipped with options,but are intended for service purposes.


Vector Signal Analyzer Option FSE-B7 demod-ulates, analyzes and documents all digital mobile-radio signals with Spectrum Analyzers FSEA and FSEB.


Antenna Preamplifier ESMI-Z7 (20 MHz to 7 GHz)reduces the noise figure of systems by 8 dB; 50 Ω, VSWR (> 60 MHz): < 1.7; power supply(115 or 230 V) included.


Calibration System Family TS9000 for measuringinstruments is of modular design to allow cali-bration to various standards and offers fully auto-matic operation in dialog; complete system con-figurations are available for specific tasks.


Spectrum Analyzers FSEA, FSEB, FSEM The datasheet now also covers models FSEM20 (9 kHz to26.5 GHz) and FSEM30 (20 Hz to 26.5 GHz)


Digital Monitoring Direction Finders DDF0xM(0.3 to 3000 MHz) feature digital correlative operation according to Watson-Watt; monopulseprocessing and direction finding of GSM signals;DF error < 1 ° RMS, minimum signal duration HF ≤ 5 ms, VHF/UHF ≤ 500 µs; AC and DC supply; antennas for stationary and mobile use, internalPC with colour LCD available.


Multichannel Communications System 400U(100 to 163/225 to 400 MHz) is based on the successful Series 400 from R&S, but features enhanced flexibility and serviceability.


Multichannel Communications System 400U(100 to 163/225 to 400 MHz) Information leafletgiving an overview of standard models of this triedand tested modular program.

Info PD 757.1383.21 enter 151/31

Log-Periodic Dipole Antenna HL040 (400 to3000 MHz) for transmission and reception in mobile and stationary use, linearly polarizedbroadband field-strength and EMI measurements;50 Ω, VSWR typ. < 2, gain 5 to 7 dBi; input powermax. 50 W (cw).


Container Location System COLOS, based onGPS, enables three-dimensional positioning ofcontainers with a pinpoint accuracy to within 1 m,thus optimizing container management and transport.


Spectrum Display EPZ513 The updated data sheet describes the RF panoramic display (max.650 MHz) when EPZ513 is used together withCompact Receiver ESMC.


Base station antennas for GSM and PCN networks (860 to 960/1710 to 1889 MHz) areavailable as omnidirectional and directional an-tennas with different gain levels, MTBF 40 millionhours thanks to completely new stripline technique,electrical and mechanical main-lobe down tilt,easy-to-use snap-in connections.

Info PD 757.1931.21 enter 151/07

TACAN Receiver ETS200 Specifications have beenredefined (R&S Cologne Plant).


New application notes

C/I EMI analysis in digital radio networks

Appl. 1CMAN26E enter 151/35

Test signals for DAB and DVB

Appl. 1GPAN27E enter 151/36

Frequency hopping for GSM base station testswith Signal Generator SME

Appl. 1GPAN28E enter 151/37

Measurement of clicking noise on audio lines using Audio Analyzer UPD

Appl. 1GPAN31E enter 151/38Schz

Information in print

The Test & Measurement Products Catalog 96/97,just published in German and English, replaces theMeasuring Equipment Catalog 93/94 as well as theNew Products Supplement 94/95. On 360 pagesthis catalog provides a comprehensive overview ofRohde & Schwarz activities in the field of mobile radio, EMC, spectrum and network analysis, signalgenerators and analyzers, voltage and powermeasurements as well as general laboratory mea-surements. In line with business developments atRohde & Schwarz, the fields of mobile radio, EMCand test systems are given the main emphasis.

The new catalog no longer covers sound and TVbroadcasting since a separate catalog is availablefor this. New additions to the catalog include opti-cal measurements as well as a number of spectrumand network analyzers from Advantest, for whomRohde & Schwarz is the representative in Europe,Africa, Australia and Brazil. For reasons of salesrights, there is also an English version of the catalogwithout the Advantest products.

The new Test & Measurement Products Catalog hasbeen completely revised and is a compact referencemedium containing all essential information.

Test & Measurement Products Catalog 96/97PD 756.3501.25 enter 151/39

There is another new publication: the EMC Test &Measurement Products Catalog. Since the begin-ning of this year it has become mandatory for allmanufacturers and importers of electrical equip-ment to ensure the electromagnetic compatibility oftheir products. On 64 pages the catalog presentsthe whole range of EMC test and measurementproducts available from Rohde & Schwarz andgives some EMC background information.

EMC Test & Measurement Products CatalogPD 757.2350.21 enter 151/40

Kr

New catalogs


Press comments

The French magazine “Electronique”, no. 54/95,showed a few examples from the wide selectionof systems and aids that Rohde & Schwarz offersfor measuring emission of and susceptibility toelectromagnetic interference.

Digitally monitoredEdition 6/95 of the defence magazine “armadainternational”, published in Switzerland, lookedat modern surveillance direction finding from HFthrough UHF and highlighted Digital DirectionFinder DDF0xM:

The growing spread of time compression and frequency hopping makes it increasingly difficult to intercept an opponent’s radiocommunications.Realizing that the necessary search and DF receiver performance exceeds the capabilities ofmost military surveillance receivers in use, Rohde& Schwarz has developed a new surveillancesystem working with digital signal processing for fast Fourier transform, linear filtering, etc.One result of this development activity is the recently presented compact DF receivers of theDDF0xM series.

Where Bavaria is topsUnder this headline “Bayernkurier” presentedRohde & Schwarz of Munich in its edition of 21 October 1995:

One of the outstanding companies in Bavaria isundoubtedly Rohde & Schwarz of Munich, a producer of equipment for radiocommunications,test and measurement, and an enterprise true to the motto “Where Bavaria is tops”. There is hardlya TV transmitter or radio station that can managewithout its products. In many sectors Rohde &Schwarz is the market leader in Germany, in Europe and even in the world. … At Rohde &Schwarz the manufacturing depth is characteristic.A whole number of pace-setting machine tools andproduction systems have been designed and builtto the company’s specifications. “We vouch foreach of our services with our good name”.

Plain-clothes man“Highly recommended” was the judgement of a plain-clothes participant in courses on thesubject of GSM/PCN at the Rohde & Schwarz training center in Munich. The editor of “Mobil-funk News” in issue 1/96:

The courses last three days, two days for “GSM/PCN – digital mobile telephones” andone day on “GSM/PCN – testing mobile sta-tions”. The material is put over in a pleasantly relaxed and interesting way. Whether retailer ordesign engineer, everyone gets their money’sworth. The presenter gives you basic and back-ground knowledge in masterly fashion, and hisobservations of the scene make you sit up. Eventhough the price of 1790 and 920 DM may seemhigh, the participant can be sure straight after-wards that the investment will soon pay off.

Journey to the heartof the chartThis was the headline chosen in edition 7/96 of “Markt & Technik”, the Munich weekly for electronics and information technology, for its report on the presentation of Vector Network Analyzer ZVR at a press conference during theProductronica 95 show:

Rohde & Schwarz is trying to put a new family oftest instruments in place on the booming tele-communications market. The ZVR line stands forextremely fast, highly precise and yet user-friendlyvector network analysis, one of the company’sshowpiece activities. … Modular design, Rohde &Schwarz has realized this too, is increasingly im-portant at a time when the unbounded investmentof earlier years is giving way to modest restraintand customers have to work with strictly limitedbudgets.

Top Products of 1995 andThe Best in TestAs Top Product of October 1995 the editors of the US magazine “Microwave & RF” choseDigital Radiocommunication Tester CMD80 inedition 12/95, and the jury of “Test & Measure-ment World”, issue 12/95, was also unanimousin placing this Rohde & Schwarz instrumentamong the Top 11 Test Products.

Vector Network Analyzer ZVR drew a lot of interest in the press, nationally and internationally. Edition 206 of France’s “Electronique International” awardedthis top product from Rohde & Schwarz space on its title page. “Elektronik Praxis” (issue 3/96), “hf-praxis” (1-2/96) and “ntz” (2/96) also gave ZVR the pole position on their cover spreads.


Final article

Microwave Generator SMP – top-class performance to customer’s benefit

They have been on the market for about two years now – the microwavegenerators of the SMP family for the frequency range up to 40 GHz.Thanks to their excellent technicalcharacteristics such as high outputpower, extremely high spectral purity,an intelligent operating concept and,last but not least, an especially attrac-tive purchase price, the generators established themselves in this criticalmarket segment straight away.

The qualities of SMP are reflected by itsexternal design (FIG 1): a large-sizeLCD display normally provided only on high-grade notebook computers issimply an invitation for you to make anentry. Next you discover that operationis just as easy as it looks: all settingscan be made with a few keystrokes.

No need to consult a manual. It is ob-vious that designers were at work herewho knew all about practical opera-tion. All functions have been packedinto clear-cut, straightforward menus.Multifunction keys and cryptic specialfunctions are really a thing of the past.And should the user some time or otherwish additional information: help textsare available at a keystroke. The bene-fits for the user are evident. The feelingwhen working with SMP can best bedescribed by the – slightly modified –slogan of a Bavarian automobile man-ufacturer: measure with pleasure.

But the merits of SMP are not restrictedto its outside. Just take a look at FIG 2,which shows the typical output powerversus frequency for the various SMPmodels. Levels of +16 dBm at 27 GHz(SMP03) and +11 dBm at 40 GHz (SMP04) are unparalleled on the mar-ket. Not to forget SMP22, which withabout +29 dBm at 2 GHz and notable+23 dBm at 20 GHz puts quite a fewcompetitors in their places. The advan-tages for the customer are obvious heretoo: the high output power makes allSMP models ideal for use in automatictest systems. “Power killers” such aslong connecting cables, waveguideadapters, power dividers or relay matrices become harmless even at 40 GHz. In short, SMP users have

got it made. They need no expensivebooster amplifiers. The modules shownin FIG 3 guarantee high output powerand a wide frequency range.

And yet, what would the user-friend-liest and most powerful signal genera-tor be without a high-quality frequencysynthesizer? SMP users need not worryabout this. The state-of-the-art conceptof SMP based on direct digital synthe-sis with a resolution of 0.1 Hz up intothe 40-GHz range, excellent frequencystability, fast settling and extremely lowSSB phase noise (FIG 4) leaves nothingto be desired.

Naturally, the modulation characteris-tics are every bit as good as the otherdata offered by generators of the SMPfamily. For example, AM ranges fromDC to 100 kHz. Scan modulation witha wide dynamic range is possible forsimulating antenna rotation in radarapplications and for similar effects. FMranges from DC to 5 MHz (typ. 7 MHz)for max. 10 MHz deviation and carrierfrequencies up to 20 GHz (or max. 20 MHz deviation for frequenciesabove 20 GHz). On top of this, SMP is the first microwave generator world-wide to provide phase modulation fromDC to 100 kHz. And not to forget pulsemodulation, the classic type of modula-tion performed by microwave genera-

FIG 1 Microwave Generator SMP, successfulsymbiosis of superb microwave technology andergonomic computer design Photo 42 447

FIG 2 Typical maximum output

power of MicrowaveGenerators SMP


Final article

At this point the inclined reader may be wondering if so much high tech is affordable. Well, the SMP family wasdesigned not only for excellent techni-cal performance but for high economyand future-proofness too. The result is an instrument the user can tailor to his requirements by choosing from a wide range of options the componentshe really needs. Should a subsequent extension or adaptation be necessaryto handle new measurement tasks – noproblem, SMP can easily be retrofittedas required. Built-in diagnostic func-tions and computer-aided measurementfunctions ensure fast and uncompli-cated servicing. Calibration is requiredevery three years at the earliest. Theunit need not be opened for calibra-tion, nor do any mechanical adjust-ments have to be made.

Which member of the SMP family is theright one for you? Take your choicefrom the versions listed in the blue box.

Wilhelm Kraemer


1. User correction to obtain a user-selectable frequency-response charac-teristic of the RF level. Correction valuescan be entered manually or via theIEC/IEEE bus. With an external powermeter (NRVS or NRVD) connected, SMPdetermines correction values automati-cally at a keystroke.2. Memory sequence, programmablesequence with complete instrument setups.3. List mode, programmable se-quence with up to 2003 frequencyand level pairs.4. External level control using exter-nal level meter.

tors, where SMP features rise and falltimes typically shorter than 5ns, pulsewidths below 10 ns and an on/off ratiobetter than 80 dB.

One problem frequently encounteredin microwave measurements is thatsignal sources and EUTs have to beconnected to one another via cablesthat are long compared with the wave-length, which means high attenuationas well as high frequency response.So it is difficult to feed the EUT with de-fined RF power. The signal generatorsof the SMP family offer four functionsto solve this problem:

FIG 4 SSB phase noise of Microwave Genera-tors SMP at 10 GHz

FIG 3 The YFO (YIG filter oscillator),the core of SMP(background), fea-tures space-testedtechnology for highoutput power, ex-tremely high spectralpurity and reliability.In the 40-GHz frequency doubler (front), patented thin-film technology does the trick: output power thatsets new standards worldwide.Photo 42 444

Model Frequency range Output power

SMP02 10 MHz/2 to 20 GHz >+11.5 dBm

SMP22 10 MHz/2 to 20 GHz >+20 dBm



ROHDE& SCHWARZ GmbH & Co. KG · Mühldorfstraße 15 · D-81671 MünchenP. O. B. 8014 69 · D-81614 München · Tel. (+49 89) 41 29-0 · Fax (+49 89) 41 29-21 64

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News from Rohde & Schwarzcdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_news_from... · News from Rohde & Schwarz Number 151 (1996/II) 5 • waveform function for representing