Installation and Operation Manual for Compact Tower-Top Amplifier System Models 429-83H-01-M/T and 429-83H-01-M-48

8/20/2019 Installation and Operation Manual for Compact Tower-Top Amplifier System Models 429-83H-01-M/T and 429-83H-…

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YOU'RE HEARD, LOUD AND CLEAR.

8625 Industrial Parkway, Angola, NY 14006 Tel: 716-549-4700 Fax: 716-549-4772 [email protected] www.bird-technologies.com

Installation and Operation Manual for

Compact Tower-Top Amplifier System

Models 429-83H-01-M/T

and 429-83H-01-M-48

Manual Part Number

7-9439


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Warranty

This warranty applies for one year from shipping date.

TX RX Systems Inc. warrants its products to be free from defect in material and workmanship at the time of shipment.

Our obligation under warranty is limited to replacement or repair, at our option, of any such products that shall have

been defective at the time of manufacture. TX RX Systems Inc. reserves the right to replace with merchandise of

equal performance although not identical in every way to that originally sold. TX RX Systems Inc. is not liable for dam-

age caused by lightning or other natural disasters. No product will be accepted for repair or replacement without our

prior written approval. The purchaser must prepay all shipping charges on returned products. TX RX Systems Inc.

shall in no event be liable for consequential damages, installation costs or expense of any nature resulting from the

purchase or use of products, whether or not they are used in accordance with instructions. This warranty is in lieu of all

other warranties, either expressed or implied, including any implied warranty or merchantability of fitness. No repre-

sentative is authorized to assume for TX RX Systems Inc. any other liability or warranty than set forth above in con-

nection with our products or services.

TERMS AND CONDITIONS OF SALE

PRICES AND TERMS:

Prices are FOB seller’s plant in Angola, NY domestic packaging only, and are subject to change without notice. Fed-eral, State and local sales or excise taxes are not included in prices. When Net 30 terms are applicable, payment isdue within 30 days of invoice date. All orders are subject to a $100.00 net minimum.

QUOTATIONS:

Only written quotations are valid.

ACCEPTANCE OF ORDERS:

Acceptance of orders is valid only when so acknowledged in writing by the seller.

SHIPPING:

Unless otherwise agreed at the time the order is placed, seller reserves the right to make partial shipments for whichpayment shall be made in accordance with seller’s stated terms. Shipments are made with transportation charges col-lect unless otherwise specified by the buyer. Seller’s best judgement will be used in routing, except that buyer’s routingis used where practicable. The seller is not responsible for selection of most economical or timeliest routing.

CLAIMS:

All claims for damage or loss in transit must be made promptly by the buyer against the carrier. All claims for shortagesmust be made within 30 days after date of shipment of material from the seller’s plant.

SPECIFICATION CHANGES OR MODIFICATIONS:

All designs and specifications of seller’s products are subject to change without notice provided the changes or modifi-cations do not affect performance.

RETURN MATERIAL:

Product or material may be returned for credit only after written authorization from the seller, as to which seller shallhave sole discretion. In the event of such authorization, credit given shall not exceed 80 percent of the original pur-chase. In no case will Seller authorize return of material more than 90 days after shipment from Seller’s plant. Creditfor returned material is issued by the Seller only to the original purchaser.

ORDER CANCELLATION OR ALTERATION:

Cancellation or alteration of acknowledged orders by the buyer will be accepted only on terms that protect the selleragainst loss.

NON WARRANTY REPAIRS AND RETURN WORK:

Consult seller’s plant for pricing. Buyer must prepay all transportation charges to seller’s plant. Standard shipping pol-icy set forth above shall apply with respect to return shipment from TX RX Systems Inc. to buyer.

DISCLAIMERProduct part numbering in photographs and drawings is accurate at time of printing. Part number labels on TX RXproducts supersede part numbers given within this manual. Information is subject to change without notice.

Bird Technologies Group TX RX Systems Inc.


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Symbols Commonly Used

WARNING

ESD Electrostatic Discharge

Hot Surface

Electrical Shock Hazard

Important Information

CAUTION or ATTENTION

High Voltage

Heavy Lifting


NOTE

Manual Part Number 7-9439

Copyright © 2009 TX RX Systems, Inc.First Printing: June 2007

Version Number Version Date

1 06/08/07

2 08/17/07

3 10/10/07

4 02/08/08

5 10/24/08

6 09/03/09


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Contact Information

Changes to this Manual


Sales Support at 716-217-3113

Customer Service at 716-217-3144

Technical Publications at 716-549-4700 extension 5019

We have made every effort to ensure this manual is accurate. If you discover any

errors, or if you have suggestions for improving this manual, please send your

comments to our Angola, New York facility to the attention of the Technical Publications

Department. This manual may be periodically updated. When inquiring about updates tothis manual refer to the manual part number and revision number on the revision page

following the front cover.


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Table of Contents Manual 7-9439-6 09/03/09

Table of Contents

General Description ............................................................................................1Unpacking ............................................................................................................4

Pre-Installation Checkout ...................................................................................4Mechanical Inspection ....................................................................................... 4

Initial Power-up Test ........................................................................................... 5

Bench Testing.....................................................................................................6Installation............................................................................................................8

Base to Tower-Top Communications ................................................................. 8 Test Transmission Line ......................................................................................9

Installing the System .................................................... ...................................... 9Installing the Tower-Top Box ............................................................................. 9

In-building Lightning Arresters ...................................... ...................................... 9Installing the MCU ............................................................................................12Interference and IM Considerations..................................................................14

Feedline Data .....................................................................................................14Optimizing The System.....................................................................................15

Attenuation Settings .........................................................................................15 TTA Net Gain.....................................................................................................15

Receiver Multicoupler Distribution.....................................................................15 Setting the TTA NET GAIN Attenuation ............................................................16 Determining Needed Attenuation ............. ....................................................... 16

Setting Distribution Attenuation .........................................................................17Spectrum Analysis ............................................................................................17

Procedure for Spectral Analysis......................................................................19Operational Tests (Sensitivity and Degradation) ...........................................19

Front Panel Test Port ........................................................................................19 Tower Top Amplifier Inputs................................................................................19 Static System Sensitivity ................................................................................... 19

Measuring Static Sensitivity (Load Connected)............. .................................... 19 Effective System Sensitivity...............................................................................21

Measuring Effective Sensitivity (Antenna Connected)....................................... 22Degradation.......................................................................................................23

Routine Operation .............................................................................................23 Amplifier Monitoring...........................................................................................23 LCD Display.......................................................................................................23

Current Draw ...................................................................................................23 Test Cable Connection ....................................................................................23

TTA Temperature ............................................................................................23 Software Version .............................................................................................23

Front Panel LEDs ..............................................................................................24 Form-C Contacts ...............................................................................................24Alarms ................................................................................................................24

The Test Mode ...................................................................................................24

Set LNA X Active ...............................................................................................24 Terminate LNA X ...............................................................................................25 Un-Terminate LNA X .........................................................................................25

System Troubleshooting ..................................................................................25 Performance Degradation ................................................................................ 25

Hardware Problems ..........................................................................................25 Lightning and Lightning Arresters ...................................................................26 Vandalism .......................................................................................................26

AC Line Fuse (Model 429-83H-01-M)...............................................................26


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Disconnected Cables ........................................................................................26

Periodic Maintenance........................................................................................27Recommended Spare Parts..............................................................................27Optional Equipment ..........................................................................................27

Narrowband Filter ..............................................................................................27 Multicoupler Expansion Deck ............................................................................28

Figures and TablesFigure 1: Front view of the tower-top box ............................................................ 1Figure 2A: Top view of the multicoupler unit (MCU) ............................................ 2Figure 2B: Front view of the MCU .......................................................................2

Figure 2C: Back view of the MCU .......................................................................2Figure 3: Cable connections for system components .......................................... 4

Figure 4: Initial power-up test ...............................................................................5Figure 5: Boot-up sequence ................................................................................. 6

Figure 6: Default display.......................................................................................6Figure 7: Menu selections ....................................................................................7

Figure 8: Test equipment interconnection for “bench testing” ............................. 8Figure 9A: System installation guidelines ..........................................................10Figure 9B: System installation guideline notes...................................................11

Figure 10: Tower-top box mechanical details ...................................................... 9Figure 11: Application of rubber splicing tape ...................................................12

Figure 12: Lightning Arrester..............................................................................12Figure 13: Optional Data Network Protector.......................................................13Figure 14: Alarm terminals ................................................................................14

Figure 15: Testing the output spectrum ............................................................. 18Figure 16: Maximum signal level mask ............................................................. 18

Figure 17: Calculating actual sensitivity .............................................................20Figure 18: Measuring sensitivity through the test port .......................................21

Figure 19: Optional filter interconnect diagram ..................................................28

Figure 20: Optional multicoupler expansion deck ..............................................28

Table 1: System Specifications .............................................................................1Table 2: Tower Box Specifications......................................................................... 3

Table 3: Multicoupling Unit Specifications.............................................................3Table 4: Bench Test Results.................................................................................. 6

Table 5: Optimum Total TTA NET GAIN..............................................................16Table 6: Distribution Attenuation Settings ...........................................................17Table 7: Amplifier Status Troubleshooting Guide ................................................22

Table 8: Typical Current Readings ......................................................................23Table 9: Loss of Sensitivity Troubleshooting Guide ............................................26

Table 10: Disconnected Cables ..........................................................................27Table 11: Optional Narrowband Filters................................................................27


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Appendixes

Appendix A: Front Panel Ethernet Connectivity.................................................29

Ethernet Connectivity ..........................................................................................29 Direct Connection ..............................................................................................29

Required Equipment........................................................................................29 Procedure ........................................................................................................29

Networked Connection ...................................................................................... 30 Required Equipment........................................................................................32

Procedure ........................................................................................................32 TTA Network Port Security ................................................................................ 34 Data Encryption ...............................................................................................34

SNMP Support Disabled..................................................................................34

Telnet Security.................................................................................................34

Changing the Telnet Port Password................................................................... 35

Appendix B: Changing your Service Computer IP Address...............................36


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TX RX Systems Inc. Manual 7-9439-6 09/03/09 Page 1

GENERAL DESCRIPTION

Your TXRX Systems Inc. Tower Top Amplifier Sys-tem provides the highest degree of reliability avail-able in a Tower Top Amplifier (TTA). The system

uses quadrature-coupled amplifiers (also calledbalanced amplifiers) to create a redundant ampli-

fier configuration in both the tower box and thereceiver multicoupling unit (MCU). Each quad-

amplifier provides two simultaneously used, essen-tially parallel paths of amplification. Failure of oneof these paths of amplification results in an overall

gain reduction of only 6 dB.

The system also supplies automatic backup-ampli-fier switching in the tower top box. Fault detection

circuitry continuously monitors the DC power oper-ation of the primary quad-amplifier and automati-cally switches to the identical secondary quad-

amplifier if conditions indicate a primary malfunc-

tion. If the secondary quad-amplifier malfunctions,operation switches to whichever quad-amplifier isstill providing some gain due to operation of one of

its amplification paths. Fault detection circuitry also

provides at-a-glance status reporting, with front-

panel LED’s and an LCD display. The systemspecifications for the tower top amplifier are listedin Table 1.

Figure 1: Front view of the tower-top box (door removed for clarity).

Amplifier / Filter

Assembly3-21548

SurgeSuppressor

8-21514

Door

Clamp

SurgeSuppressor

8-21183

SurgeSuppressor

8-21549

Tuning Screw

DO NOT ADJUST

Parameter Specification

Bandwidth 792 - 824 MHz

Noise Figure 2.9 dB typ, 3.5 dB max

3rd order IIP > 15.0 dBm

TTA Net Gain Fully settable by

electronic attenuator

Rejection 110 dB Min, 120 db Nom

@776 and 851 MHz

AC Current

(model 429-83H-01-M) 340 mA (typ) @120 VAC

DC Current

(model 429-83H-01-M-48) 780 mA (typ) @ 48 VDC

Table 1: System specifications.13 dB TTA Net Gain and

maximum 6 dB transmission line loss assumed


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Figure 2C: Back view of the MCU. Model 429-83H-01-M shown.

Ground

Test

cableTransmission

cable

To additional 8-way dividers

on optional expansion deck.

Terminate when unused.

CAT-5

Cable

here

AC or DC Cord(model dependent)

Alarm

Terminals To station receivers

Unused ports do not

require termination

To station receivers

Unused ports do not

require termination

Figure 2B: Front view of the MCU. Model 429-83H-01-M shown.

LAN Port Status LED’sContrast

AdjustUp

ButtonCancel

Button

Amplifier Select

Buttons

Down

ButtonEnter

Button

Test

Port

Display

Figure 2A: Top view of the Multicoupling Unit (MCU). Model 429-83H-01-M shown.

8-21515 Power Supply (model 429-83H-01-M)

3-21516 DC-DC Converter (model 429-83H-01-M-48)3-21476

Front Ethernet Board

(under shroud)

3-21453

Front Panel Board

(under shroud)

3-21450

Distribution Amp

3-21496

Rear Panel

Board

3-18173

4-Way Divider3-18171

8-Way Divider3-18171

8-Way Divider


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The quad-amplifier in the tower top box amplifies

the weak received signal before the signal enters along and lossy transmission line, thus preventingthe line loss from degrading the signal-to-noise

ratio. The quadrature amplifiers have a separatepower circuit for each half of the amplifier which

provides component redundancy as well as unsur-passed IM performance. Microprocessor controlled

fault detection circuitry in the tower top box pro-vides continuous monitoring and switching of each

quad amplifier while sending operational data tothe base unit front panel for at-a-glance statusreporting and form-C contact switching for alarm

integration. Included in the tower top box is a pre-

selector filter, amplifier “A” and amplifier “B,”

switching circuitry, control board and PolyPhasersurge suppressors (see Figure 1). The specifica-tions for the tower box are listed in Table 2.

The ground-mounted MCU shown in Figures 2A

through 2C is intended for 19-inch rack mounting.It houses amplifier and signal distribution assem-

blies, alarm indicators, a power supply or DC-DC

Electrical Specifications

Frequency Range 792 to 824 MHz

Net Gain 23 dB

Noise Figure (typ /max) 2.7 / 3.0 dB

Backup Amplifier Switching Solid State RF Switch

Integrated Test Port

Isolation

45 dB

Preselector Type

Loss

Rejection

7-pole TEM Bandpass

with cross-couplings

60 dB @ 776 and 851 MHz

LNA Type

Gain

Noise Figure

3rd Order Input IP

2-stage Quadrature

integrated into filter

26 dB

1.2 dB

18 dBmImpedance 50 Ohms

Antenna Port VSWR 2 : 1

Power Requirements 12 VDC @ 1.25 A

Lightning Protection Impulse Suppressor on all

external connectors

Operating Temp Range -30°C to +60°C

Mechanical Specifications

Enclosure Modified NEMA 4x:

Stainless steel

weather resistant

Connectors N -female

Dimensions (HWD)

not including mounting tabs

and connectors

18” x 6” x 6”

(457 x 152 x 152 mm)

Net Weight 20 lbs (9.1 kg)

Table 2: Tower box specifications. Values are typical unless

noted otherwise.

Electrical Specifications

Frequency Range 792 to 824 MHz

Multicoupler Net Gain +1 dB typ; 0 dB min

Distribution Amp Type

Gain

Noise Figure

1 dB compression point

3rd Order Output IP

Quad-Coupled dual stage

23 dB

4 dB

27 dBm

46 dBm

Number of Outputs

Split Loss

16 or 32

18 dB

Impedance 50 Ohms

VSWR


12/48


converter, and a display panel to provide visual

feedback on the system’s operating status. Thespecifications for the MCU are listed in Table 3.Also included in the system is a webpage user

interface for controlling and monitoring of amplifiercurrents, alarms, and attenuators. The webpage

user interface is accessed through the front panelLAN connector. Refer to Appendix A for instruc-

tions on accessing this feature.

UNPACKING

Each major component of the TTA system is indi-vidually packaged and shipped via motor freight or

UPS. It is important to report any visible damage tothe carrier immediately. It is the customer's respon-

sibility to file damage claims with the carrier withina short period of time after delivery (1 to 5 days).

PRE-INSTALLATION CHECKOUT

The following pre-installation tests should be per-formed after unpacking the system to verify nothinghas loosened during transit. Additionally, the sys-

tem should be made operational on the bench withall components at ground level to verify proper

electrical performance. Figure 3 illustrates all ofthe cable connection points for both the tower top

box and the MCU.

The tower top box should NOT be

installed on the tower until all of thepre-installation tests are successfully

completed.

Mechanical Inspection

Open the tower top box by loosening all the door-

clamp locking screws and rotating the clamps to

NOTE

TestPort Trans

ToStation Receivers

ToStation Receivers

To120VAC

CAT-5e Cable

TestPort

MainTransmission

Main

Main

Test

Antenna

MCU

Tower Top Box

Lightning ArresterTX RX part no.8-21550

Figure 3: Cable connections for system components. Model 429-83H-01-M shown.


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release the door. Make sure that all of the connec-

tors are tight. In addition, it is advisable to checkthe tightness of the hold-down screws for the vari-ous assemblies to insure nothing loosened duringshipment. Likewise, check all of the cable connec-

tions on the MCU to insure they are all properlymated to their associated plugs.

CAUTION: The wide band filter in

the tower top box is factory tunedand must not be field adjusted. Field

tuning of this filter is not required. Donot adjust the tuning slugs of theamplifier/filter assembly.

Initial Power-Up Test

To perform the initial power-up test the systemshould be temporarily interconnected at groundlevel using short cables. Figure 4 shows the tem-

porary equipment hookup for initial power-up test-

ing.

Once the equipment is temporarily interconnectedthen power is applied to the system by plugging the

MCU’s AC cord into a suitable AC outlet (model429-83H-01-M) or connecting the DC power cable

to a suitable -48 VDC supply (model 429-83H-01-M-48). The following start-up sequence occurs.

1) At turn-on, the three front panel status LED’s

will all glow a steady red while the display panelshows a row of solid boxes on the top displayline. This will last for about 10 seconds while

the systems micro-controllers boot-up.

2) During the next 5 seconds the base unit (MCU)will establish communications with the tower

box. The front panel status LED’s will occasion-ally flash green. The display panel will presentthe message “Connecting to Tower Controller”

and then will briefly flash the MCU’s currentsoftware version. See Figure 5.

Tower Top Box

MCU

Lightning ArresterTX RX part no. 8-21550

CAT-5e

Cable

FrontPanelTestPort

Test Ant Main

Figure 4: Initial power-up test.


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3) After the power-up sequencing is complete the

screen should show the default display asshown in Figure 6. The status LED for each

active amplifier will glow a steady green and thestatus LED for the inactive (stand-by) LNA willbe dark.

The tower top amplifier system is software directed

so control of the system is accomplished via userinterface with the front panel using the display

screen and the four menu selection buttons. A flowchart showing all of the possible user menu selec-

tions is shown in Figure 7.

Bench Testing

The purpose of the bench test is to verify that all ofthe system components are working correctly and

to measure the systems sensitivity before climbingthe tower to mount the tower top box. One station

receiver is selected and the test is performed atthis frequency. Short temporary cables are used tointerconnect all components. A SINAD meter is

used for the test (or a bit error rate meter ifrequired) along with a signal generator.

1) The stand-alone receiver sensitivity is mea-sured and recorded first. Record the value inTable 4.

2) Connect the equipment as shown in Figure 8.Be sure that the signal generator is setup for a 3

KHz deviation with a 1000 Hz tone (analog) orproper pattern for BER testing.

3) Measure and record the systems bench test

static sensitivity in table 4. The sensitivity valuewill vary depending on the amount of internalprogrammable attenuation selected via soft-

ware interface. The bench test measurementshould be taken with the default values selected

for “TTA NET GAIN” attenuation (3.0 dB) and“DISTRIBUTION” attenuation (1.0 dB). These

are the factory default settings that are pro-grammed into your system when you first turn iton.

4) Select the other tower top amplifier and check

that the bench test static sensitivity valueremains nearly the same. This will insure that

both amplifiers in the tower top box are func-tioning properly. To select an alternate tower-top amplifier press the associated amplifier

select button on the front panel, the status LEDwill begin to flash, then press the ENTER button

to finalize the selection.

5) If the tower box door is opened during theinstallation it is important to re-tighten the door-

clamp locking screws uniformly so that the doorgasket seal is maintained. Tighten each clampabout half-way, then start back at the first clamp

and fully tighten each one in the same order.Tighten with a hand tool only. Insure that the

moisture vent holes at the bottom of the box areunobstructed.

Test Performed Result

Stand Alone

ReceiverSensitivity

dBm

* Bench TestStatic

Sensitivity dBm

Model Number

(Tower Top Box)

Serial Number

(Tower Top Box)

Table 4: Bench Test Results.

* Default “TTA NET GAIN“ Attenuation (3.0 dB)* Default “DISTRIBUTION” Attenuation (1.0 dB)

Figure 6: Default display.

Figure 5: MCU software version is displayed briefly

during the boot-up sequence.


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TTA NET GAIN

DISTRIBUTION

MAIN LINE LOSS

TEST LINE LOSS

STATIC W/LOAD

REFERENCE W/ANT

AS AN EASY REFERENCE

RECORD VALUES HERE

NOTE: Use arrow to adjust






429-83H-01-M

TX RX SYSTEMS INC

DEFAULT

DISPLAY

PRESS CANCEL KEY

LNA X ACTIVE

A CURRENT XXXmA

B CURRENT XXXmA

BASE CURRENT

XXXX mA

TEST CABLE

CONNECTEDNOT CONNECTED

TTA TEMPERATURE

+/- XX DEGREES C

BASE V X.XX

TOWER V X.XX

INITIALIZE

ENTER TO RESTART

TESTENTER TO SELECT

ATTENUATORS

ENTER TO SELECT

FEEDLINE DATA

ENTER TO SELECT

SENSITIVITY

ENTER TO SELECT

TTA NET GAIN

ENTER TO ADJUST

MAIN LINE LOSS

ENTER TO ADJUST

STATIC W/LOAD

ENTER TO ADJUST

Manual Mode

TTA NET GAIN

X.X dB

Automatic Mode

TTA NET GAIN

AUTO MODE

MAIN LINE LOSSX.X dB

STATIC W/LOAD

-XX.X dB

DISTRIBUTION

ENTER TO ADJUST

TEST LINE LOSS

ENTER TO ADJUST

REFERENCE W/ANT

ENTER TO ADJUST

DISTRIBUTION

X.X dB

TEST LINE LOSSXX.X dB

REFERENCE W/ANT

-XX.X dB

SET LNA A ACTIVE

ENTER TO CONFIRM

SET LNA B ACTIVE

ENTER TO CONFIRM

TERMINATE LNA A

ENTER TO CONFIRM

TERMINATE LNA B

ENTER TO CONFIRM

UNTERM LNA A

ENTER TO CONFIRM

UNTERM LNA B

ENTER TO CONFIRM

Return to

DefaultDisplay

NOTE:

After pressing the ENTER Button the MCU

will re-boot, then return to the Default Display.

PRESS ENTER KEY

PRESS UP-ARROW KEY

PRESS DOWN-ARROW KEY

PRESS EITHER ARROW KEY

YELLOW INDICATES

RECORDABLE VALUE

KEY

429-83H-01-M Menu System

C

E

EE E

E E

E E

E

E

C

E

C

E

C

C

C

C

C

C

C

E

C

E

C

E E

E

E

C

E

C

Figure 7: 429-83H-01-M menu selections.


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INSTALLATION

The following sub-sections of the manual discussgeneral considerations for installing the system. All

work should be performed by qualified personal.TXRX Systems provides the base MCU, tower top

amplifier box, and the mainline lightning arrester.All additional parts required for installation must be

supplied by the customer. Before mounting thetower top box we recommend that you record the

model number and serial number of the unit forfuture reference (table 4 is a convenient place torecord them). The numbers are located on a tag

attached to the inside of the door and mayberequired in the future if you call the factory for cus-

tomer support.

Base to Tower-Top Communications

A special lightning arrester (TXRX part # 8-21550)is provided with this TTA for installation at the main

transmission line entry bulkhead/grounding plate.This unit not only passes the DC current required

to operate the TTA, but also generates the low fre-quency subcarrier used for the standard AISG/EIA-

485 data communications between the base unitand the tower top box. A standard CAT-5e data

cable (double shielded) must be installed betweenthe base unit (MCU) and the lightning arrester forcarriage of the EIA-485 data. The TTA will operate

normally with all backup functionality intact if thisdata cable is not installed, is damaged or removed,

but status and alarms will not be available at thebase.

Minimum length cables

Best possible sensitivity

Default "TTA NET GAIN" Attenuation (3.0 dB)

Default Distribution Attenuation (1.0 dB)

Signal Generator

MCU

FrontPanelTest

Port

Tower Top Box


12 dB SINAD Receiver

CAT-5e

Cable

Diagnostic CableTest Ant Main

Figure 8: Test equipment interconnection for “bench testing” of system components.Connection to an appropriate power source is assumed.


17/48


Test Transmission Line

Proper installation of this system requires theinstallation of a test transmission line in addition tothe main transmission line for system testing and

diagnostics. The system will operate normally if thetest transmission line is not installed or becomes

damaged, except the base status LED will continu-ously display an alarm (red) condition. In addition,

one of the display sub-menu’s will show a testcable not connected message.

Installing the System

Installation of the TTA system should follow theinstallation standards listed in Figure 9A and 9B

on pages 10 and 11. Lightning arresters are incor-

porated throughout the system; refer to items 6, 7,and 11 listed in figure 9. In addition, surge suppres-

sion is also provided for all cable connectionswithin the tower top box. Proper grounding tech-

niques MUST BE observed for these devices toperform properly. See the following sections forspecific installation instructions.

Installing the Tower Top Box

Figure 10 shows some of the mechanical featuresof the tower top box. Four mounting tabs are

welded to the back of the box to allow for fasteningto the tower. Because of the varied tower types,the customer must fabricate the interface brackets

between the tower frame and the box . To install thetower top box perform the following steps.

1) Mount a receiving antenna on the tower.

2) Run the main transmission cable as well as thetest transmission cable up the tower.

3) Mount the tower top box on the tower and con-

nect the antenna feedline, main transmissionline and test line to the box.

4) Connect the tower top box ground lug to a good

solid ground on the tower.

To insure stability, it is important to

fasten the box to the tower using all

mounting tabs. The box must be

mounted with the connectors andmoisture openings facing downward

to prevent water entry. After connecting the main

transmission line, test line, and the antenna feed-

line, we recommend that the connections be tightlywrapped with rubber splicing tape (see Figure 11).This will help prevent water entry into the cables.

Start the wraps on the cable several inches awayfrom the connector and wrap towards the connec-tor, this will prevent water from seeping in between

the wraps of tape. Cover the connectors com-pletely with tape.

5) If the tower box door is opened during the

installation it is important to re-tighten the door-clamp locking screws uniformly so that the doorgasket seal is maintained. Tighten each clamp

about half-way, then start back at the first clampand fully tighten each one in the same order.

Tighten with a hand tool only. Insure that themoisture vent holes at the bottom of the box are

unobstructed.

In-building Lightning Arresters

Two lightning surge suppressors must be installed

in the equipment room one each for the main andtest transmission lines, refer to Figure 9. The fol-lowing steps are required for proper installation.

1) For the test line install a lightning arrester.PolyPhaser part # DC50LNZ15MA (N-M/N-Fconnectors) or DC50LNZ15 (N-F/N-F connec-

tors). The chassis of the lightning arrestershould be connected to the master ground buswith a pigtail.

2) For the main transmission line install a lightning

arrester TXRX part # 8-21550. This device is

NOTE

Mounting Tabs

.312 Dia Thru

Mount Holes

4 Places

6.69"

12.00"

Figure 10: Tower-top box mechanical details.


18/48


Lightning Arresters 7 and 11 must be groundedto the Master Ground Buss.

MCU ground stud must be connected to theEquipment Rack Master Ground Bar.

Building entry-point ground plate andEquipment Rack Master Ground Barmust be grounded to Master Ground Buss.

GROUNDING REQUIREMENTSGROUNDING REQUIREMENTS

WARNING

Failure to ground the TTA System properly can result

in equipment failure caused by electrical surges.

1

1

1

1

1

1

6

11

7

5

13

Optional

BNCTestPort

To

Base

StationBuildingEntry-Point

Ground

Plate

Copper

Ground

Strap

FromRepeaters

10

5

12

1

8

1

2

2

2

2

2 2

2

4

4

4

2

TransmitCombiner

MCU

Master Ground Buss

Internal Perimeter Ground (Halo)

Tower TopAmplifier

Test MainAnt

RX TX

Entry-PointGround Buss

To Electrical

Service Ground

Equipment Rack

Master Ground Bar

NOTE

*

**

*

*

**

Figure 9A: System installation guidelines.


19/48


Main transmission and test line grounded at top, base, shelter entrance and every 75 feet.

All external cable connections weatherproofed.

Hoisting grips used every 200 feet per mainline.

1/2" LDF 10 foot jumper cable from each antenna to its mainline and tower top amplifier.

1/2" Superflex for all internal RF runs.

Lightning Arrester on TX lines.

Lightning Arrester on test port line.

Polyphaser part number DC50LNZ15MA (N-M / N-F ).

Polyphaser part number DC50LNZ15 (N-F / N-F ).

3/8" LDF test port mainline.

We recommend that you follow a good industry standard as a guideline for communicationssite installations such as Motorola's R56 Standard. This standard depicts grounding methods

which will help to ensure expected system performance, reliability and longevity.

1/4" Superflex, N male to N male.

Lightning Arrester with RS485 communication interface.

TX RX part number 8-21550.

Data Cable - CAT-5e patch cord (Double Shielded).

L-Com part number TRD855DSZ-XX or equivalent.

Additional Protection (Optional):

If additional protection of the data communication line is desired, a data network protector canbe installed. For this, use Polyphaser Model NX3-05.

This data network protector must be located as close as possible to

the MCU rear data port and grounded to the Equipment Rack Master

Ground Bar. Refer to Figure 13.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

INSTALLATION STANDARDS

SYSTEM ENGINEER RESPONSIBLE FOR

All mounting hardware

Wall feed-through hardware

TX RX Systems Inc. 8625 Industrial Parkway, Angola, NY 14006

716-549-4700 bird-technologies.com [email protected]

Figure 9B: System installation guideline notes.


20/48


shipped from the factory along with thetower top box. Refer to Figure 12. The chas-

sis of the lightning arrester should be connectedto the master ground bus with a pigtail.

Installing the MCU

The MCU is designed for indoor mounting in acommon 19-inch relay rack or cabinet. The follow-ing steps are required for proper installation.

1) Install the MCU into the rack or cabinet with four

mounting screws from the hardware kit (part #3-16509) which is included with your shipment.

Make sure you use a nylon washer under thehead of the screws in order to protect the frontpanel. Torque the mounting screws to no more

than 15 in/lbs. Over tightening the mounting

screws may damage the front panel.

2) Connect the MCU ground lug to the Equipment

Rack Master Ground Bar with a pigtail.

3) Connect the main and test transmission cablesto the appropriate connectors at the back of theunit.

Figure 11: Application of rubber splicing tape. Note: Additional waterproofing protection can be realized by

covering the rubber tape with either “Scotch Kote” or Vinyl Plastic Electrical Tape (“Scotch” brand 33+).

TestLine

Antenna

Feedline

Main

TransmissionLine

Ground Lug

Moisture

Vent

Figure 12: Lightning arrester TXRX part # 8-21550.

This device must be connected to the master ground

buss with a pigtail.

RF In

from

Tower Top

RF Out

to MCU

CAT-5e

Cable

Here


21/48


4) Connect a double-shielded CAT-5e cable from

the RJ45 plug on the rear panel of the MCU tothe RJ45 connector on the lightning arrester atthe building entry ground plate. We recommend

using a pre-built cable from L-Com (part #TRD855DSZ-XX). The -XX suffix represents

the cables length in feet. An equivalent cablefrom another manufacturer is acceptable.

5) If optional additional protection of the data com-

munications line is desired a Data Network Pro-tector can be installed. Use PolyPhaser part #NX3-05. The data network protector must be

grounded to the equipment rack master ground

bar. Keep this ground wire as short as possible.

See Figure 13.

6) Connect the optional data network protector to

the lightning arrester with the cable from step 4.

Then connect the rear panel MCU data port tothe data network protector with a short length ofdouble-shielded CAT-5e cable. We recommend

using a pre-built cable from L-Com (part #

TRD855DSZ-XX). An equivalent cable from

another manufacturer is acceptable.

7) If you have a supervisory alarm system, con-

nect its wiring harness to the terminal screws atthe back of the MCU. Refer to Figure 14.

8) Connect the station receivers and optional 16-

port receiver multicoupler expansion deck to theoutput ports on the back of the MCU with high-

quality 50-ohm coaxial cable such as 1/4-inchsuperflexible transmission line. Some flexibilityin the jumper cables will prevent strain and pos-

sible damage to the connections. We also rec-

ommend the use of quality BNC connectors.

Unused receiver outputs need not be termi-nated. However, unused expansion ports (the 2left-most ports) should be terminated with 50

ohms until connected to an expansion panel

(refer to Figure 2C).

Master Ground Buss

Equipment Rack

Master Ground Bar

Internal Perimeter Ground (Halo)

MCU Rear Panel

ground stud

Ground Wire

Keep as shortas possible

RJ45

RJ45

RJ45

RJ45

Short CAT 5epatch cable

(double shielded)

NX3-05

Locate Data

Network Protector

as close to MCU

Data Port as possible

Lightning Arrester

TX RX part number 8-21550

RS 485 Data Line

CAT 5e patch cable(double shielded)

Figure 13: For optional additional protection install the data network protector.


22/48


Interference and IM Considerations

Although TX RX Systems, Inc. TTA systems aredesigned for maximum interference immunity,there are many factors that can lead to harmful

interference when using a tower-mounted ampli-fier. It is highly recommended that the receiving

and transmitting antennas be vertically separatedto maximize antenna isolation.

Although most 700/800 MHz transmitters are con-nected to their antenna through a combiner, it is

quite likely that the combiner does not haveenough transmitter noise filtering to prevent desen-

sitization of the receivers unless there is significantantenna space isolation. Large values of antenna

isolation are most easily realized when the anten-nas are separated vertically. This antenna isolationalso helps reduce the possibility of intermodulation

interference in the receiving system.

One other important factor that can strongly con-tribute to interference problems is excessive gain,

ahead of the receiver. Excessive gain can causeoverdrive to the station receivers when strong sig-nals are present, making them more prone to inter-

modulation or carrier desensitization problems.Receiver preampli f iers should not be used

because the receiver multicoupler, which is incor-porated in the MCU, serves this purpose.

FEEDLINE DATA

As part of the installation process you will need todetermine the cable losses for your main and testtransmission lines. These loss values can be deter-

mined by sweeping the cables or they can belooked up from the cable manufactures specifica-

tions. For your system these values will be fixedonce the cable type is chosen and cut to length.

Once you have determined the main and test linecable loss for your system this information can be

recorded in system memory for future reference inthe Feedline Data menu selection. To save the

cable loss values in memory perform the followingsteps.

1) From the default display press the DOWNARROW button on the front panel to scroll

through the menu choices until you reach theFEEDLINE DATA menu.

2) With the FEEDLINE DATA menu displayed

press the ENTER button to step down to theMAIN LINE LOSS sub-menu.

3) Use the UP and DOWN ARROW buttons to setthe main line loss to the desired value. This

storage register works in a forward loop fash-ion, starting at 0.0 and increasing to 9.9. A but-

ton press after 9.9 returns the setting back to 0.

Figure 14: Alarm terminals. Normally open or normally closed screw terminals are available.Model 429-83H-01-M-48 shown.

DC Power Cord used in model 429-83H-01-M-48

(Red is -48 Volts and Black is common)

AC Cord used in model 429-83H-01-M

Test Cable

connects hereMain Cable

connects here

Ground

(double-shielded)

CAT-5e Cable

connects here

Alarm Terminals

The ground lug

must be connected

to the equipment

rack master ground

bar with a pigtail.


23/48


4) After setting the main line loss value press the

ENTER button to return back to the FEEDLINEDATA menu. This will save your setting choice.

5) With the FEEDLINE DATA menu displayedpress the ENTER button to step down to the

MAIN LINE LOSS sub-menu. Press the UPARROW button to move to the TEST LINE

LOSS sub-menu.

6) Use the UP and DOWN ARROW buttons to setthe test line loss to the desired value. This stor-age register works in a forward loop fashion,

starting at 0.0 and increasing to 9.9. A button

press after 9.9 returns the setting back to 0.

7) After setting the test line loss value press theENTER button to return back to the FEEDLINE

DATA menu. This will save your setting choice.

Then pressing the CANCEL button while at theFEEDLINE DATA menu will return you to thedefault display.

OPTIMIZING THE SYSTEM

In the TTA system the first stage of amplification isin the tower top box which is used to overcome themain line loss, develop the noise figure, and the

TTA Net Gain. The second amplifier, located onthe multicoupler deck (base unit), is used to over-

come the losses associated with distribution.

When the tower top amplifier system is installed

there are detailed adjustments and test procedureswhich must be followed in order to insure optimum

performance of the system. The process includes:

Attenuation SettingsSpectrum Analysis

Operational Tests Sensitivity with Load Connected Sensitivity with Antenna Connected

Operational testing must be performed in a

methodical manner to provide the correct perfor-mance evaluation and ensure that the information

obtained is correct. For each procedure it is impor-tant that the data be recorded accurately and isavailable anytime assistance is required or when

performance is in question. Before a receive sys-tem problem is suspected, the appropriate opera-

tional tests must be performed. Before operationaltests for sensitivity can be verified, the programma-

ble attenuation settings and spectrum analysismust be performed. If these are not correct, the

sensitivity and degradation may appear out of tol-

erance.

ATTENUATION SETTINGS

The system contains programmable attenuators foroptimizing both the TTA Net Gain and receiver

multicoupler distribution. Both of these attenuatorsmust be adjusted as part of the system installation.

The attenuation adjustments allow the system tomaintain maximum protection of the receivers,while obtaining the best sensitivity possible.

TTA Net Gain

TTA Net Gain is defined as the net gain betweenthe input of the tower top LNA and the input of the

base LNA. The amount of programmable attenua-tion that your system requires in order to reach anideal amount of TTA Net Gain will vary depending

on the length of your main transmission line.

The value of the TTA Net Gain programmableattenuator can be adjusted either manually by the

customer or automatically by the microprocessor inthe MCU. The choice of manual or automatic is

determined by a menu choice in the WebpageUser Interface which is accessible via the MCU’sLAN connector using a separate PC. For a com-

plete description of the Webpage User Interfacesoftware refer to the TXRX Systems Inc. technical

manual 7-9440.

When automatic has been selected the message

“AUTO MODE” will be shown on the MCU frontpanel display when you scroll down the menu

choices to the TTA Net Gain value, refer to themenu selections chart shown in figure 7. Manual

changes to the attenuator value using the frontpanel ARROW buttons are not allowed when in the

automatic mode.

Receiver Multicoupler Distribution

Receiver Multicoupler Distribution is defined as thegain between the input of the base LNA and the

input of the station receiver. The receiver multicou-pler distribution adjustment allows for proper com-

pensation of the MCU to receiver cable/distributionlosses and should ideally be set to unity. Theamount of attenuation that your system will require

in order to reach an ideal amount of receiver multi-coupler distribution will vary depending on the

length of the cables from the multicoupler outputsat the rear of the MCU to your receivers. Distribu-

tion attenuation is always adjusted manually usingthe front panel ARROW buttons. There is no auto-


24/48


matic mode for distribution attenuation adjust-

ments.

The factory default setting for TTA Net Gain is 3.0

dB of attenuation and the factory default setting forreceiver multicoupler Distribution is 1.0 dB of atten-

uation. These are the initial settings that are pro-grammed into your system when you first turn it on.

You will need to adjust these values to optimizeyour system. This is done through software inter-

face via the menu select keys. Your settings will bestored in system memory until you change themagain even if the equipment is powered down.

Setting the TTA NET GAIN Attenuation

The total amount of TTA Net Gain attenuation foryour system is composed of two parts, the main

line cable loss (which is fixed, based on cable typeand length) as well as the TTA Net Gain attenua-

tion setting (which is variable, depending on soft-ware selection). This is illustrated in the formulabelow.

Main Line Loss + Software Setting = Total

It has been found in practice that different levels oftotal TTA Net Gain attenuation are required for dif-

ferent types of modulated signals to obtain the bestperformance. Table 5 lists the optimum total TTA

Net Gain attenuation value for various signal types.

It should be kept in mind that these values are notextremely critical. Systems that depart from these

values can still give reasonably good performance,but may degrade somewhat when extremely strongand very weak signals are present, as compared

with an optimized system.

The TTA Net Gain attenuation is programmableand needs to be adjusted to optimum levels for thetype of signals being processed. The default fac-

tory setting is 3 dB. Further reduction may only be

necessary when the main transmission line loss is

low; that is, when line loss does not reduce theTTA gain enough to obtain the desired total TTANet Gain attenuation level.

DETERMINING NEEDED ATTENUATION

To calculate how much attenuation is needed tooptimize the TTA Net Gain of your system use the

following formula;

TTA Net Gain(dB) = Gain TTA(dB) - Line loss(dB)

For example, if the TTA gain is 24 dB and the main

transmission line loss is 3 dB:

TTA Net Gain = 24 dB - 3 dB = 21 dB

If your system uses FM Voice, you would like a

TTA Net Gain as close to 13 dB as possible. The

amount of TTA Net Gain attenuation required iscalculated with the following formula;

Attenuation(dB) = Actual(dB) - Desired(dB)

Attenuation = 21 - 13 = 8 dB

So in this example the TTA Net Gain attenuation

setting should be 8 dB. If the sign of the calculatedattenuation had been negative it would indicate

that we could actually use more gain! No attenua-tion would be required.

The programmable attenuation for optimizing yourTTA Net Gain attenuation is adjustable from 0 to

15.5 dB in 0.5 dB increments. To adjust the valueperform the following steps.

1) Press the DOWN ARROW button on the front

panel to scroll through the menu choices untilyou reach the ATTENUATORS menu.

2) With the ATTENUATORS menu displayedpress the ENTER button to step down to the

TTA Net Gain sub-menu.

3) Press the ENTER button again to advance tothe TTA Net Gain adjustment screen. The cur-rent TTA Net Gain setting will now be displayed.

Use the UP and DOWN ARROW buttons to setthe TTA Net Gain to the desired value. The

attenuation setting works in a forward loop fash-ion, starting at 0 and increasing to 15.5, a but-

ton press after 15.5 returns the setting back to0.

Type of Signal The optimum total

amount of TTA NET GAIN

FM Voice 13 dB

Digital 10 dB

Table 5: Optimum total TTA NET GAIN.


25/48


4) After setting the TTA Net Gain press the

ENTER button to return back to the ATTENUA-TORS menu. This will save your setting choice.

Then pressing the CANCEL button while at theATTENUATORS menu will return you to the

default display.

Setting Distribution Attenuation

The MCU to receiver cable loss can be determinedfrom the cable manufacturers specifications. For

your system these values will be fixed once thecable type is chosen and cut to length. Typically 2

to 3 dB of Distribution attenuation is usuallyrequired to achieve unity gain. Use the attenuationvalues shown in Table 6 to set the Distribution

attenuation to the correct value.

The DISTRIBUTION attenuation is adjustable from

0.0 to 15.5 dB in 0.5 dB increments. To adjust themulticoupler attenuation perform the following

steps.

1) Press the DOWN ARROW button on the front

panel to scroll through the menu choices untilyou reach the ATTENUATORS menu.

2) With the ATTENUATORS menu displayed

press the ENTER button to step down to theTTA Net Gain sub-menu.

3) Press the UP ARROW button to move to theDistribution sub-menu.

4) Press the ENTER button again to advance to

the Distribution adjustment screen. The currentdistribution value will now be displayed. Use the

UP and DOWN ARROW buttons to set the dis-tribution to the desired value. The attenuation

setting works in a forward loop fashion, starting

at 0.0 and increasing to 15.5, a button pressafter 15.5 returns the setting back to 0.

5) After setting the distribution value press the

ENTER button to return back to the ATTENUA-TORS menu. This will save your setting choice.

Then pressing the CANCEL button while at theATTENUATORS menu will return you to thedefault display.

SPECTRUM ANALYSIS

Obtaining good sensitivity requires an understand-ing of the levels applied to the receiver. A receiver,like any electronic device, has a dynamic range of

operation. As long as this dynamic range is main-tained, the specifications of the receiver are main-

tained. When the levels applied to the receiverexceed this range, the sensitivity, intermodulation

rejection, as well as the adjacent channel selectiv-ity will deteriorate. To properly perform a SpectrumAnalysis, a spectrum analyzer must be connected

to the output of the multicoupler as if it were areceiver, essentially monitoring what the receiver

sees.

Figure 15 shows the equipment interconnection forthis measurement while Figure 16 is a graph which

indicates the maximum desired measured-signallevels both inside and outside of the transmit andreceive bands. TTA filter selectivity and antenna

space isolation are the dominant factors that deter-

mine the signal levels observed. Excessivelystrong receive signals indicate the need for addi-tional attenuation in the MCU. There are three

areas of the spectrum that must be evaluated:

1) Receive Band - The spectrum where the

receive frequencies reside must not have carri-ers above -35 dBm. These are the carriers that

are intended to enter the receiver. If subscribersor control stations are near the infrastructure

the levels can be very high. If the levels areabove -35 dBm, the gain of the system must bereduced or the source of the high level carrier

must be reduced.

2) Transmit Band - The highest carrier that thereceive system will consistently see is its owntransmitter. The preselector of the receive sys-

tem must adequately remove these carriers toprevent over-drive. The goal of the preselector

is to reduce all transmit carriers below -55 dBm.If the level of a transmitter is above -55 dBm the

Set DISTRIBUTION

attenuation to

for cable / distribu-

tion losses of

3 dB 1 dB

2 dB 2 dB

1 dB * 3 dB

0 dB more than 3 dB

* factory default setting

Table 6: Distribution attenuation settings.


26/48


-30

-35

-40

-45

-50

-55

-60

-65

-70

-75

-80

dBmReceive Band

Less than -35 dBm

Transmit BandLess than -55 dBm

Remaining SpectrumLess than -75 dBm

Transmit BandReceive Band

Frequency (MHz)

Maximum Signal Level Mask

Figure 16: Maximum permissible signal levels at receiver output of TTA MCU.

MCU

FrontPanelTestPort

Tower Top Box


CAT-5e

Cable

Test Ant

Antenna

Main

Spectrum AnalyzerBird SignalHawk

Figure 15: Testing the output spectrum of the TTA system.


27/48


preselector is not adequately performing its job

and must be changed.

3) All Other Frequencies - The receiver is

designed to monitor very low signals and theremust be a minimum amount of undesired

energy exposure. The preselector has verysharp selectivity and must reduce all carriers

outside the bandwidth below -75 dBm except asindicated above.

Procedure for Spectral AnalysisSpectral analysis will verify the signals arriving at

the receiver as well as validate the TTA Net Gain

adjustment. To perform a spectral analysis of the

site follow the steps listed below.

1) Make sure programmable attenuators are prop-

erly adjusted.

2) Connect the spectrum analyzer to one of theoutput ports of the multicoupler.

3) Setup the spectrum analyzer as follows;

Span = 700 to 800 MHzResolution = 50 KHz

RF Attenuation = 0 dBmReference Level = -20 dBm

Peak (Max) Hold = ON

4) Monitor the spectrum for 5 minutes (during

peak hours).

OPERATIONAL TESTS

(SENSITIVITY AND DEGRADATION)

Before sensitivity and degradation can be verified,attenuation adjustments and spectrum analysis

must be performed. If these are not correct, thesensitivity and degradation may appear out of tol-erance.

The sensitivity tests will measure the full range of

performance from the maximum achievable to real-world performance in the presence of RF noise.

These tests are absolutely necessary, not only toinsure proper performance, but also to serve as abench mark for future evaluations and trouble-

shooting.

Two types of sensitivity measurements will need tobe made, Static and Effective. Static sensitivity is

measured without the presence of site noise whilethe Effective sensitivity measurement includes site

noise. The difference between the two is the sys-

tem degradation.

Front Panel Test Port

The front panel BNC test port is connected to thetower box through the test line allowing signals

generated at ground level to be injected into an iso-lated 45 dB port at the input of each tower top

amplifier circuit board. The test port feature pro-vides a convenient means of performing static sen-

sitivity tests of the system.

Tower Top Amplifier Inputs

Under normal operating conditions RF signals pass

from the antenna to the inputs of the tower top

amplifier. In addition, the input of each tower topamplifier can also be switched to an internal 50Ohm load for testing purposes. The front panel test

port remains connected (through its isolated 45 dB

input) to the tower top amplifiers regardless ofwhether the amplifiers input is connected to theantenna or the internal load. This allows system

sensitivity testing to be done with and without sitenoise being coupled into the system through theantenna.

Static System Sensitivity

Static sensitivity is the maximum sensitivity achiev-able because any possible interfering signals are

blocked from entering the LNA while static sensitiv-ity is measured. To determine the Static systemsensitivity the signal level into the first amplifier

must be known. The easiest way to achieve this isto inject a test signal into the Test Port (located on

the front panel of the base unit) and measure theBER or SINAD of the test receiver. The static sys-

tem sensitivity can only be measured while theactive tower-top LNA is connected to the internalload. Once you have made the measurement the

actual static system sensitivity can be calculated.Figure 17 shows the formula for calculating the

actual static system sensitivity as well as a workedthrough example.

Measuring Static Sensitivity(Load Connected)To test the static system sensitivity through the test

port with the internal load connected to the ampli-fier perform the following steps;


28/48


Caution: During this test on-air sig-nals will NOT pass through to the

station receivers.

1) The signal generator and SINAD meter (or biterror rate meter if appropriate) should be con-

nected to the system as shown in Figure 18.

2) Be sure the signal generator is setup for a 3

KHz deviation with a 1000 Hz tone (analog) orproper pattern for BER testing.

3) From the default display, use the ARROW but-tons to scroll to the TEST menu choice then

press the ENTER button to bring up the test submenu’s.

4) Use the ARROW buttons to scroll over to the

TERMINATE LNA “A (or) B” menu choice

(depending on which amplifier is currentlyactive) and press the ENTER button to switch

the amplifiers input from the antenna to theload. The “TEST TTA OFFLINE” message will

appear. The RF signal path through the towertop box will be interrupted and on-air signals will

not be passed to the station receivers.

5) Adjust the signal strength from the signal gener-ator until the 12 dB SINAD or required BER

point is acquired. This determines the systemsstatic sensitivity without the presence of site

noise. This value should be recorded in theMCU’s memory for future use.

It is very important that sensitivity

always be measured to a recog-nized benchmark such as bit rateerror (BER) or SINAD. Do not use

your ear or other subjective tech-niques.

6) Press the front panel CANCEL button. This willswitch the amplifier input back to the antenna

and will return you to the default display.

If left unattended, after about 9minutes the input of the active

amplifier will automatically switch

back to the antenna and on-air sig-nals will again pass through to the

station receivers.

7) From the default display, use the ARROW but-tons to scroll to the SENSITIVITY menu choice

then press the ENTER button.

NOTE

NOTE

Actual Sensitivity is calculated using the following formula:

Actual Sensitivity (dBm) = IS (dBm) + TC (dB) + TP (dB)

Where:

is the Injected Signal Level

is the Test Cable Loss

is the Test Port Loss

IS

TC

TP

LEV

LO

LO

Example:If the Test Cable for the system is 200 ft. long with a loss of 3.6 dB per 100 ft., then the Test

Cable Loss will be 7.2 dB. The Test Port Loss is Fixed at 45 dB. If the Injected Signal acquires

BER or SINAD at a level of -71.8 dBm, then the Actual Sensitivity would be -124 dBm.

LEV LO LO

Figure 17: Calculating actual sensitivity (both static and effective).


29/48



STATIC W/LOAD menu choice and press theENTER button.

9) Use the ARROW buttons to dial in the staticsensitivity value (from the signal generator) and

press the ENTER button to save the informationin memory. By storing the sensitivity value at

the time of installation it can be compared withfuture tests and used as an indication of system

degradation or failure. In general, the sensitivitymeasured with the antenna will be less thanthat measured with the load unless site noise is

at a minimum.

The sensitivity value measured instep 5 is less (45 dB plus Test Lineloss) than the actual sensitivity

value.

Effective System Sensitivity

The Effective System Sensitivity is the sensitivityas seen by the subscriber. This represents theTalk-in coverage component of the infrastructure.

To determine the Effective System Sensitivity thesignal level into the first amplifier must be known.

The easiest way to achieve this is to inject a testsignal into the Test Port (located on the front panel

of the base unit) and measure the BER or SINADof the test receiver. The effective system sensitivity

can only be measured while the active tower-topLNA is connected to the antenna. Once you havemade the measurement the actual effective system

sensitivity can be calculated. Figure 17 shows theformula for calculating the actual effective system

sensitivity as well as a worked through example.

NOTE

Signal Generator

MCU

FrontPanel

TestPort

Tower Top Box


12 dB SINAD Receiver

CAT-5e

Cable

DiagnosticCable

Test Ant

Antenna

Main

Figure 18: Using the test port to measure sensitivity of the TTA system.


30/48


Measuring Effective Sensitivity

(Antenna Connected)The Effective system sensitivity should be taken

under normal conditions as well as with all trans-mitters producing full power. All transmitters keyedwill show the worse case situation. To test the sys-

tems effective sensitivity through the test port withthe antenna connected to the amplifiers perform

the following steps;

1) The signal generator and SINAD meter (or biterror rate meter if appropriate) should be con-nected to the system as shown in Figure 18.

2) Under normal conditions the antenna is con-

nected to the amplifiers so no software interac-tions are required. Be sure the signal generator

is setup for a 3 KHz deviation with a 1000 Hztone (analog) or proper pattern for BER testing.

3) Adjust the signal strength from the signal gener-ator until the 12 dB SINAD or required BER

point is acquired. This determines the systems

sensitivity in the presence of site noise. Record

this value in the MCU’s memory for future use.

4) From the default display, use the ARROW but-

tons to scroll to the SENSITIVITY menu choicethen press the ENTER button.


REFERENCE W/ANT menu choice and pressthe ENTER button.

6) Use the ARROW buttons to dial in the effectivesensitivity value and press the ENTER button to

save the information in memory. By storing the

sensitivity value at the time of installation it can

be compared with future tests and used as anindication of system degradation or failure.

The sensitivity value measured in

step 3 is less (45 dB plus the TestLine loss) than the actual sensitiv-ity value.

NOTE

Status LED Possible Amplifier Status Form-C Contact Status

Tower top Amplifier A

Green Selected; normal current Normal

Off Not selected; normal current Normal

Red Failure: Very abnormal current; can only be selected if amplifier B is

also in Alarm

Alarm contacts change state

Red Failure: Extremely abnormal current; cannot be selected Alarm contacts change state

Tower top Amplifier B

Green Selected: normal current Normal

Off Not selected; normal current Normal

Red Failure: Very abnormal current; can only be selected if amplifier A is

also in Alarm

Alarm contacts change state

Red Failure: Extremely abnormal current; cannot be selected Alarm contacts change state

Base (Distribution) Amplifier

Green Normal current Normal

Red Failure: Very abnormal current Alarm contacts change state

Table 7: Amplifier status troubleshooting guide.


31/48


Degradation

The difference between the static sensitivity (load-connected) and the effective sensitivity (antenna-connected) is the system degradation which can

be caused by noise or interference (such as a useron an active channel). At 800 MHz it is unusual to

have degradation greater than 2 dB (and even thisis rare). The degradation value should be recorded

for future reference. Degradation levels in excessof 1 to 2 dB should be investigated, as this will

decrease the range and performance of the sys-tem.

ROUTINE OPERATION

During normal operation only one of the two tower

top amplifiers (“A” or “B”), along with the MCUampli f ier (“BASE”), are used to ampli fy thereceived RF signals. The LED’s for the two active

amplifiers will illuminate green. The remaining

tower-top amplifier will be in stand-by mode, whichis indicated by its LED being off. The system soft-ware also provides an indication of which tower top

amplifier is active. From the default display use theARROW button to scroll down to the LN A X

ACTIVE menu which will display the currentlyactive tower top amplifier.

Upon power-up, the system defaults to operationon the “A” tower top amplifier (the “BASE” amplifier

in the MCU is always on). Operation can be manu-ally switched to the “B” tower top amplifier by

pressing the “B-SELECT” switch, which is located

below the “B-Status LED” on the MCU front panel.The “B-Status LED” will begin to flash, then press

the ENTER button to finalize the selection.

If necessary the system can be re-ini-tialized via software interaction. From

the default display use the ARROWbutton to scroll to the INITIALIZEmenu then press the ENTER button.

Amplifier Monitoring

The system continuously monitors the current

being drawn by all three amplifiers and reveals thestatus of the amplifiers in three ways: LCD Display,front panel LED’s and Form-C contacts (“screw ter-minals”). Table 7 summarizes the status of the

LED’s and Form-C contacts for various amplifierconditions.

LCD Display

The LCD display provides extensive status infor-mation through the menu system including the cur-

rent draw of all amplifiers, connection of the testtransmission line, the tower top box temperature,and installed software version level.

CURRENT DRAW

Typical displayed values for each of the three sys-tem amplifiers is listed in Table 8. The current

value for any amplifier can be read from the displayby using the ARROW buttons to scroll down fromthe default display. The A and B tower top amplifi-

ers current draw are shown on one menu displayand the BASE amplifier current draw on another.

TEST CABLE CONNECTION

The status of the test cable is indicated by a menudisplay. Use the ARROW buttons to scroll down

from the default display. The TEST CABLE sub-menu will show the message Test Cable Con-

nected or Test Cable Not Connected depending on

the status of the test cable connections. The sys-tem will operate normally if the test cable has a badconnection although you will not be able to performany diagnostics with the test port. In addition, the

base status LED will continuously display an alarm(red) condition.

TTA TEMPERATURE

The temperature of the tower top box can be readfrom the display by using the ARROW buttons to

scroll down from the default display to the TEM-PERATURE sub-menu. The recommended normaloperating temperature range for the tower top box

is -30 to +60 degrees Celsius.

SOFTWARE VERSION

There are micro-controllers located in both the

tower top box as well as the base unit so there aretwo software versions in the system. Both the

BASE and TOWER software version can be readfrom the display by using the ARROW buttons to

NOTE

Amplifier Displayed Value

TTA Amp A ~ 600 ma

TTA Amp B ~ 600 ma

Base Amp ~ 850 ma

Table 8: Typical current readings.


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scroll down from the default display to the SOFT-

WARE VERSION sub-menu.

Front Panel LEDs

Status indicator LED’s for all three amplifiers illumi-nate in one of two colors. The meaning of each

color is summarized in table 7. During normal oper-ation, the LED’s for amplifier A and the BASE

amplifier will glow green, indicating normal currentdraw. The LED for amplifier B will be off indicating

this amplifier is in stand-by.

Form-C Contacts

ALARM form-C relay contacts are located at theback of the MCU (see figure 14). These screw ter-

minals are intended for connection to the cus-tomer’s supervisory and data acquisition system.

Both normally open and normally closed contactsare available. There are two sets of screw termi-

nals for customer convenience. Both sets of screwterminals have the same functionality.

ALARMS

The system will alarm when either of two distinct

conditions occur including an abnormal currentflow in any of the systems three amplifier assem-

blies or a loss of serial communications betweenthe base unit and the tower top box.

When the current to any of the three amplifiersdeviates from normal by approximately +/- 55 ma

or greater the specific device LED will glow a solidred. In addition, amplifier switching will take place

in the tower top box if the fault lies with one of thetower top amplifiers. There is no switching provi-sion for the amplifier in the MCU. The ALARM

Form-C contacts located at the back of the unit willalso change state.

Fault detection circuitry continuously monitors the

DC power operation of the primary tower top quad-amplifier and automatically switches to the identicalsecondary quad-amplifier if conditions indicate a

primary malfunction. If the secondary quad-ampli-

fier malfunctions, operation switches to whicheveramplifier is still providing some gain due to opera-tion of one of its amplification paths.

A loss of communications (along the main trans-mission line) between the microprocessors in the

base unit and tower box will cause the front panelA and B indicator LED’s to flash RED. The ALARM

Form-C contacts located at the back of the unit will

also change state.

THE TEST MODE

The TEST sub-menu allows the field engineer tochoose the active tower top amplifier as well as

control the input of each of the tower top amplifiersvia software. The base amplifier is always active.

When you use functions in the TEST sub-menuyou are operating the system in the test mode. Beaware that some of these tests will interrupt the RF

signal path through the tower top box and on-airsignals will not be passed to the station receivers.

We recommend that when you are in the test mode

and you complete your testing use the CANCELbutton to exit back to normal mode and the defaultdisplay. If you exit the test mode without using the

CANCEL button and leave one of the amplifiers in

other than its normal operating condition the mes-sage “NonFunctional” will appear in the LNA XACTIVE sub-menu. As a safety feature the system

will switch out of the test mode and back into thenormal mode of operation after about 9 minutes of

inactivity. Each of the three functions availablethrough the TEST sub-menu is described below.

Set LNA X Active

Allows the selection of the active amplifier via soft-

ware interface.

1) From the TEST sub-menu display use the

ARROW buttons to scroll over to the SET LNA“A (or) B” ACTIVE menu choice, depending on

which amplifier you want to choose as theactive amp, and press the ENTER button.

2) If you choose to make the already active ampli-

fier active again, the system will return you tothe TEST sub-menu. If you choose to make thenon-active amplifier active, then the “Test TTA

Offline” message will appear. The RF signalpath through the tower top box will be inter-

rupted and on-air signals will not be passed to

the station receivers.

3) Pressing the CANCEL button returns you to thedefault display. Whichever amplifier you had

selected to be active in the TEST sub-menu willnow be the active amplifier back in the normal

mode and on-air signals will again pass throughto the station receivers.


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If left unattended, after about 9

minutes the system will switch outof the test mode and back into thenormal mode of operation. The

amplifier selected while in the testmode will now become the active

amp and on-air signals will againpass through to the station receiv-

ers.

Terminate LNA X

Allows you to connect the input of either of thetower top amplifiers to its internal 50 ohm load.

1) From the TEST sub-menu display use the

ARROW buttons to scroll over to the TERMI-NATE LNA “A (or) B” menu choice and press

the ENTER button.

2) If you choose to terminate the input of the non-active amplifier the system will return you to theTEST sub-menu. This is the normal behavior of

the system, having the input of the non-activeamplifier terminated to a 50 Ohm load. If you

choose to terminate the input of the activeamplifier then the “Test TTA Offline” messagewill appear. The RF signal path through the

tower top box will be interrupted and on-air sig-nals will not be passed to the station receivers.

If left unattended, after about 9

minutes the system will switch out

of the test mode and back into thenormal mode of operation. On-air

signals will again pass through tothe station receivers.

3) Pressing

Documents

Installation and Operation Manual for Compact Tower-Top Amplifier System Models 429-83H-01-M/T and 429-83H-01-M-48