Register online at www.ATIcourses.com or call ATI at 888.501.2100 or 410.956.8805 Vol. 95 – 43

InstructorScott R. Bullock, P.E., MSEE, specializes in Wirelss

Communications including Spread Spectrum Systemsand Broadband Communication Systems for bothgovernment and commercial. He holds numerouspatents in communications and published severalarticles in various trade magazines. He was active inestablishing the data link standard for GPS SCAT-Ilanding systems and developed spread spectrumlanding systems for the government. He is the author oftwo books, Transceiver and System Design for DigitalCommunications & Broadband Communications andHome Networking, Noble Publishing. He has publishednumerous technical articles, is an adjunct professor atITT and a guest lecturer for Polytechnic University onDirect Sequence Spread Spectrum and Multiple AccessTechnologies.

What You Will Learn• How to perform link budgets for types of spread

spectrum communications?• How to evaluate different types of wireless

communication transceivers?• What methods are used for spread spectrum

modems, multiple access, OFDM, error detection/ correction for digital communication systems?

• What is multipath and how to reduce multipathand jammers?

• What is a Global Positioning System? • How to solve a 3 dimension Direction Finding

system using interferometry?From this course you will obtain the knowledge

and ability to evaluate and develop the systemdesign for wireless communication digitaltransceivers including spread spectrum systems.

March 24-26, 2009Beltsville, Maryland

$1490 (8:30am - 4:00pm)

"Register 3 or More & Receive $10000 eachOff The Course Tuition."

Course Outline1. Transceiver Design. dB power, link budgets,

system design tradeoffs, gains/losses, Signal-to-Noise,Probability of Error, Bit Error Rate, Eb/No, link margin,tracking noise and signal level through a completesystem, effects and advantages of using spreadspectrum techniques.

2. Transmitter Design. Various types and systemdesigns of spread spectrum transmitters, PSK, MSK,QAM, OFDM, Other, Pseudo-Random code generator,multiple access TDMA/CDMA/FDMA, antenna sizing,transmit/receive, local oscillator, upconverters,sideband elimination, power amplifiers, standing waveratios.

3. Receiver Design. Dynamic range, imagerejection, limiters, minimum discernable signal,superheterodyne receivers, importance of low noiseamplifiers, 3rd order intercept point for intermodulationproducts, two tone dynamic range, tangentialsensitivity, phase noise, mixers, spurious signals,filters, A/D converters, aliasing and anti-aliasing filters,digital signal processors DSPs.

4. Automatic Gain Control Design & Phase LockLoop Comparison. AGCs, linearizer, detector, loopfilter, integrator, using control theory and feedbacksystems to analyze AGCs, PLL and AGC comparison.

5. Demodulation. Demodulation and despreadingtechniques for spread spectrum systems, pulsedmatched filters, sliding correlators, pulse positionmodulation, CDMA, coherent demod, despreading,carrier recovery, squaring loops, Costas and modifiedCostas loops, symbol synch, eye pattern, inter-symbolinterference, phase detection, Shannon' s limit.

6. Basic Probability and Pulse Theory. Simpleapproach to understanding Probability, Gaussianprocess, quantization error, probability of error, bit errorrate, probability of detection vs probability of falsealarm, error detection and correction, digital pulsedsystems, pseudo-random codes for spread spectrumsystems.

7. Multipath. Specular and diffuse reflections,Rayleigh criteria, earth curvature, pulse systems,vector and power analysis.

8. Improving the System Against Jammers. Burstjammers, digital filters, adaptive filters simulations andactual design results, quadrature method to eliminateunwanted sidebands, orthogonal methods to reducejammers, types of intercept receivers.

9. Global Navigation Satellite Systems. Basicunderstand of the Global Positioning System GPS andthe spread spectrum BPSK modulated signal fromspace, Satellite transmission, signal structure, GPSreceiver, errors, narrow correlator, selective availabilitySA, carrier smoothed code, Differential DGPS, RelativeGPS, widelane/narrowlane, carrier phase trackingKCPT, double difference.10. DF & Interferometer Analysis. Positioning and

direction finding using a simpified interferometeranalysis, direction cosines, basic interferometerequation, three dimensional approach, antennaposition matrix, coordinate conversion for movingbaseline.

Wireless Communications & Spread Spectrum Design

SummaryThis three-day course is designed for wireless

communication engineers involved with spreadspectrum systems, and managers who wish to enhancetheir understanding of the wireless techniques that arebeing used in all types of communication systems andproducts. It provides an overalllook at many types andadvantages of spreadspectrum systems that aredesigned in wireless systemstoday. This course covers anintuitive approach that providesa real feel for the technology,with applications that apply toboth the government andcommercial sectors. Studentswill receive a copy of theinstructor's textbook, Transceiver and Systems Designfor Digital Communications.

www.ATIcourses.com

Boost Your Skills with On-Site Courses Tailored to Your Needs The Applied Technology Institute specializes in training programs for technical professionals. Our courses keep you current in the state-of-the-art technology that is essential to keep your company on the cutting edge in today’s highly competitive marketplace. Since 1984, ATI has earned the trust of training departments nationwide, and has presented on-site training at the major Navy, Air Force and NASA centers, and for a large number of contractors. Our training increases effectiveness and productivity. Learn from the proven best. For a Free On-Site Quote Visit Us At: http://www.ATIcourses.com/free_onsite_quote.asp For Our Current Public Course Schedule Go To: http://www.ATIcourses.com/schedule.htm

Bullock Engineering Research Copyright 2008

1

Digital vs. Analog Comms

A/D

5V analog = Digital 101

5V

Mod Demod

Digital 101 = 5V analog

5V

D/A

LO LO

Sampler

Analog + Noise

Digital

Mod Demod

LO LO

Analog System

Digital System

Perfect Reconstruction of the Digital Waveform Assuming No Bit Errors

Analog

PSK, FH, etc.

AM/FM etc

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2

Digital Modulation

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3

FSK and MSK Spectrums

Reduce Frequency Separation or Increase the Frequency Minimum Shift Key Rate - MSK

MSK

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4

Continuous Phase - Phase Shift Keying CP-PSK

• Sinusoidal transitions from one phase state to another• No zero crossing, No AM• Remains at a phase state for a period of time• Used for packet radio and other burst type systems• Minimum Spectral Re-growth due to non-linearities

+45

-45

+135

-135

0,0

+90

-90

180 I Channel

Q Channel

Q

1

R

RR

R1,0

1,10,1

0

0

1

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5

Spectral Re-growth

Output ofModulator

FilteredOutput SidelobesReduced

SpectralRe-growth(SidelobeRegeneration)

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6

Practical Digital Waveform Impulse Response

MSKGaussian Filter

Ideal filter is the Sinx/x which is impossible to build These filters approx. this ideal filter

Sinx/x

Raised Cosine

Raised cosinesquared

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7

Direct Sequence Spread Spectrum

SpreadSpectrumSpreader

Signal

SpreadSpectrum Signal

Jammer

Signal

Jammer

SpreadSpectrum

despreader

Jammer

Signal

SpreadSpectrumReceiver

Signal

Jammer

Fast PNCode

Fast PNCode

Filter

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FH Spread Spectrum

Spread Spectrum JammerSignal

SpreadSpectrumSpreader

Signal

Jammer

SpreadSpectrum

despreader

SpreadSpectrumReceiver

PN HoppingSynthesizer

PNDehoppingSynthesizer

Jammer

Jammer

Filter

Spread Spectrum Signal

Spread Spectrum Signal

Spread Spectrum Signal

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9

Multiple User Techniques

Code 1

Code 2

Code 3

System 1

System 2

System 3

time1 2 3 1 2 3

System 1 System 2 System 3

a. Time division multiple access

b. Code division multiple access.

.

FrequencySystem 1 System 2 System 3

c. Frequency division multiple access.

f2 f3f1

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Costas Loop

Signal 1

Signal 2

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OFDM Spectrum

0

0.2

0.4

0.6

0.8

1

1.2

-10 -5 0 5 10

Frequency

Ampl

itude Channel 2

Channel 3Channel 1

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Chapter 3 The Receiver

PowerDivider

LO

IF BPFImageRejectFilter

T/RSwitch Limiter LNA IFAmp

AGC LO

LPF A/DConverter

ToDigitalProcessor

Transmitter

Superheterodyne

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13

Phase Noise, Log-Log Scale

white noise fFlicker noise 1/fwhite FM 1/(f*f)

Flicker FM 1/(f*f*f)

Random walk FM 1/(f*f*f*f)dBc

10 kHz1 kHz100101

So(f)

Frequency

So(f) = power spectral density(radians2/Hz) dBc/Hz

1/(f*f*f*f) = close to carrier, difficult to measure, vibration, shock, temperature, environmental.

1/(f*f*f) =, observable in high quality oscillators, masked in low quality oscillators, not fully understood, physical resonance mechanism or actual parts in the oscillator.

1/(f*f) = common in passive-resonator like cesium and rubidium standards.

1/(f) = transistors, amplifiers, etc., noisy electronics, LNA helps.

f = produced like the 1/f noise, stages of amplification is mainly responsible, broadband noise.

Short term frequency/phase instability

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Group Delay

LinearReceiver

Constant Group Delay

Non-Linear

Receiver

ISI Dispersion

Non-Constant Group Delay

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Group Delay Compensator

Filter Response ______

Filter Group _______Delay

Constant Group Delay

Group Delay ______Compensator

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AliasingAliasing

Sample points in time

Waveform is sampled at the Nyquist rateEstimated FrequencyWaveform does not meet Nyquist criteriaAlias frequency produced by under-sampling the high frequency

tststststs

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Control Theory Analysis and Root Locus Plot

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AGC/PLL Comparison

Kd F(s) Threshold = 0 Kc Ko/S

a. AGC control system analysis block diagram.

b. PLL control system analysis block diagram.

+

-

Kd F(s) Threshold Integrator Ko+

-

V/dB 1/S dB/V

dB

dBmdBmDC offset

Kc

filter gain

phase

phase

phase error

V/phase filter no offset gain phase/V

VCO control curve

Amp control curve

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Bode Plot for NegativeFeedback Systems

+20dB

0dB

Instability & oscillation criteria for negative feedback systems, 0dB Gain, -1800 phase shift

Gain

Phase

Frequency (log scale)

-1800

-2700

-10 dB

Gain Margin (-1800 phase shift) = 0dB – (-10dB) = 10 dB

-1000

Phase Margin(0dB gain) = -1000 – (-1800) = 800

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Cascaded PN-code Matched Filters for Increased Process Gain and Margin

1 delay 1 delay 1 delay 1 delay

sum

1 -1 1 1Additional PN- Code(Or retrieve data direct)

444

44 4 4

4444

16

-4

Position of Pulse outputprovides data information

1 delay 1 delay 1 delay 1 delay

sum

1 -1 1 1PN- Code 111

11 1 1

4

-1

4 4

-4

1 1 1-1

1 1 1-1 -1-1 -1

1 1 1 1-1

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Comparison between Absolute and Differential PPM

TOA Pulse 1Dead Time

TOA Pulse 2 TOA Pulse 3

Time Slots of PPM

Data output 011

Dead Time

Data output 000

Time Slots of PPM

. .

t0 t1 t2 t3 t4 t5 t6 t7

Dead Time

Absolute PPM

No Pulse detectedin Time Slots

No Data Output

Reference Pulse

Differential PPM

Reference Pulse

Dead Time

t0 t1

TOA Pulse 1

t2 t3 t4 t5 t6 t7 t0 t1

TOA Pulse 2

t2 t3 t4 t5 t6 t7

No Time Slots of PPMNo Dead Time

Received Pulse ok butNo time reference

No Data outputBut Provides reference

For next pulse

No Pulse detectedin Time Slots

No Data Output

Dead Time TOA Pulse 3

Time Slots of PPMData output 000

t0 t1 t2 t3

t0 t1 t2 t3t0 t1 t2 t3 t4 t5 t6 t7

Data Lost

Data Lost Data Lost

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Coherent vs Differential Bit Errors

Coherent System

1 1 0 1 0 1 1 0 1 1 1 0 0 0 1 0 1 0

Bit error

Differential System

1 0 1 1 1 1 0 1 1 0 0 1 0 0 1 1 1 1

Sent digital data

Sent digital data

Bit error

1 1 0 1 0 1 1 1 1 1 1 0 0 0 1 0 1 0

1 0 1 1 1 1 0 0 0 0 0 1 0 0 1 1 1 1

Received digital data

Received digital dataTwo Received data errors

One Received data error

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Sliding Correlator

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Intersymbol Interference (ISI)• One received symbol interfering with adjacent received symbols• Caused by Dispersion

– Pulse stream/pulse consists of many frequencies – Fourier Series/Transform

– Frequencies propagate at different delays – non-constant group delay

Non-Linear

Receiver

ISIDispersion

Non-Constant Group Delay

ISI = -20log(Vh/Vl)

Vl = lowest Vpeak center of the eye.

Vh = highest Vpeak center of the eye.

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CDF Equation For Gaussian Distribution

• Fx(x) = 1/2[1+erf(x/( ))], mean = 0• Fx(x) = 1/2[1+erf(-2/( ))]

– =1/2[1+erf(- )]– erf(-x) = -erf(x), -erf(1.414) = -.954– Fx(x) = 1/2[1- .954] = .023– Probability +/- 2 = 2*.023 =.0456– Probability inside curve = 1-.0456 = .954 = 95.4%.

2

22

Probability of Occurrence

Value x

Probability Density Function for Gaussian Distribution

x = - 2 x = +2

x = +1 x = -1 Fx(x) CDF

f

Cumulative Distribution Function for Gaussian Distribution

1 or 100%

.023

fx (x) for x = -2

fx (x) for x = -1

.15995.4%.

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Probability of Error Curves

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Eb/No (dB)

Pe

Coherent BPSKCoherent QPSKDPSKCoherent FSKNonCoherent FSK

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Probability of Detection and False Alarms Curves

• Cumulative distribution function determines probabilities of one sided noise and S+N gaussian probability density functions

– CDF from the right – sum probabilities from the right.0 1.00E+00 0.00102259 #NAME? #NAME? 1 5 6.99 7.78

0.1 9.97E-01 1.34E-03 #NAME? #NAME? 1 5 6.99 7.780.2 9.89E-01 1.75E-03 #NAME? #NAME? 1 5 6.99 7.780.3 9.76E-01 2.28E-03 #NAME? #NAME? 1 5 6.99 7.780.4 9.57E-01 2.94E-03 #NAME? #NAME? 1 5 6.99 7.780.5 9.33E-01 3.78E-03 #NAME? #NAME? 1 5 6.99 7.780.6 9.06E-01 4.83E-03 #NAME? #NAME? 1 5 6.99 7.780.7 8.74E-01 6.14E-03 #NAME? #NAME? 1 5 6.99 7.780.8 8.38E-01 7.76E-03 #NAME? #NAME? 1 5 6.99 7.780.9 8.00E-01 9.76E-03 #NAME? #NAME? 1 5 6.99 7.78

1 7.59E-01 1.22E-02 #NAME? #NAME? 1 5 6.99 7.781.1 7.17E-01 1.52E-02 #NAME? #NAME? 1 5 6.99 7.781.2 6.73E-01 1.87E-02 #NAME? #NAME? 1 5 6.99 7.781.3 6.28E-01 2.30E-02 #NAME? #NAME? 1 5 6.99 7.781.4 5.83E-01 2.82E-02 #NAME? #NAME? 1 5 6.99 7.781.5 5.38E-01 3.43E-02 #NAME? #NAME? 1 5 6.99 7.781.6 4.94E-01 4.14E-02 #NAME? #NAME? 1 5 6.99 7.781.7 4.51E-01 4.98E-02 #NAME? #NAME? 1 5 6.99 7.78

0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00

1.20E+00

0

0.6

1.2

1.8

2.4 3

3.6

4.2

4.8

5.4 6

6.6

7.2

7.8

8.4 9

9.6

10.2

10.8

11.4 12

12.6

13.2

13.8

Energy

Pro

babi

lity

of O

ccur

ance

NoiseSignal + Noise

PdPfa Threshold

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FEC Code GenerationBlock

Encoder

Figure 6.7.2.2a Block Codes (Hamming, Cyclic, RS Codes)

Figure 6.7.2.2b Rate 1/2 Convolutional Encoder

Information Input Bits

switch

Tapped Delay LineOutput Symbols Two times the

Input Rate

k Information Bits n bit code word n = Block Length

Maps k information bits into an n-symbol output block

XOR

XOR

•Convolutional code, rate ½, constraint length 7

Block Codes (Hamming, Cyclic, Reed Solomon Codes)

7-bit shift Register

1 2 3 4 5 6 7

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Example of Generating a Linear Systematic Block Code (7,4)

Generator Matrix Message Modulo-2(1000011) 1 (1000011)(0100110) 0(0010111) 1 (0010111)(0001101) 0

Systematic Code Word =(1010100)Identity MatrixMessages Codewords (7,4)(0000) (0000000)(0001) (0001101)(0010) (0010111)(0011) (0011010)(0100) (0100110)(0101) (0101011)(0110) (0110001)(0111) (0111100)(1000) (1000011)(1001) (1001110)(1010) (1010100)(1011) (1011001)(1100) (1100101)(1101) (1101000)(1110) (1110010)(1111) (1111111)

–4 bits of data–3 parity bits

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Error CorrectionError Vector H-T Coset, error vectorse6,e5,e4,e3,e2,e1,e0 * 0 1 1 0 e6 e6 1 0 0 0 0 0 0

1 1 0 e5 e5 0 0 1 0 0 0 0 01 1 1 = e4 e4 e4 0 0 1 0 0 0 01 0 1 e3 0 e3 0 0 0 1 0 0 01 0 0 e2 0 0 0 0 0 0 1 0 00 1 0 0 e1 0 0 0 0 0 0 1 00 0 1 0 0 e0 0 0 0 0 0 0 1

e5+e4+e3+e2 = 0e6+e5+e4+e1 = 0

e6+e4+e3+e0 = 10 0 1

3 equations, 7 unknowns (7-3=4), possible solutions = 24

Solve for a solution with the most zeros = all zeros except for e0 = 0000001 e6=e5=e4=e3=e2=e1=0 and e0 = 0000001 satisfies the three above equations with most zerosCorrect Code sent = 1010100

Vc = r+e = 1010101+ 0000001 = 1010100 Corrected bit in code word

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Trellis Diagrams

Constant Mod hi = 1/4

Multi-h [1,2/4], [hi] = [1/4,2/4]

1st merge, need to make a decision2 possible paths

1st merge

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Turbo CodesInformation Bits PAD

Interleaver

Encoder 1

Encoder 2

Mux Parallel/SerialPuncturing

+ Z-1 Z-1Z-1 Z-1

+

Turbo Encoder

Turbo Decoder

Turbo Encoded Output

Recursive Systematic Code Generator

Input

Decoder 1 Decoder 2Interleaver

De-Interleaver

De-InterleaverDe-MuxSerial/Parallel Insertion

Estimated Sequence

Turbo Encoded Input

PAD appends n – k tail bitsfor all zeros state, x0

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Diffuse Reflection over a Glistening Surface

R

GlisteningSurface

hr

ht

Transmitter

Receiver

Reflected raysOff Glistening Surface

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Antenna Diversity

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Quadrature GSO System

PD

PD

-+

PD

LO

PD

PD

-+

PD

LO

0

90

0

90

I

Q

wi

error i

error q

wq

int

int

I signal out

Q signal out

OMNI Antenna(Jammer only)

Directional Antenna(Signal + Jammer)

Jammer Only

Jammer Only

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Wideband Adaptive Filter

LMS

Q-channel

WidebandSignal Only

High FreqWideband + NarrowbandSignal

DigitalFilter

DigitalFilter

LPF LPF LPF

LO

LPF

LPF

BPFBPFBPF

BPF

BPF

Synthesizer

-10 dB-10 dB

10 dB

10 dB

10 dB-10 dB

15 dB

30 dB30 dB

30 dB

10 dB

15 dB15 dB15 dB

-90o

I-channel

0o

4-portPD

10 dB

Update shared weights

ResidualNarrowbandSignal

NarrowbandSignal Estimate

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GPS Landing Systems

D8PSK LPI/Anti-jam Data LinkSends GPS Corrections

Relative GPS for moving platforms (Aircraft Carriers)Kinematic Carrier Phase Tracking KCPT for CATIII landing systems

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MILCOM

Need to Provide a Military Communications Network

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Interferometer

Baseline

Antenna 1

Antenna 2

INTERFEROMETER

Phase 1

Phase 2

Measures the phase difference between two antennas