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Section-1 Introduction

October 17, 2013

1‐6

WARNING:Disconnectprimarypower priortoservicing. 888‐2693‐004

1.5.1 LowPowerUnit

Figure 1-4 LPU (Low Power Unit)

TheLPUperf

ormsthreedistinctfunctionsintheUAXtransmittersystem:

1. TransmittercontrolviatheLPUfrontpanel

2. SignalgenerationintheLPUmodulatorsection

3. RFpoweramplificationupto100WintheLPUamplifiersection

1.5.1.1 LPUFrontPanelandTransmitterControl

ThelocalcontrolinterfaceforthetransmittersystemisviaafrontpanelLCDscreenandaccompanyingpushbuttons

onthefrontfaceoftheLPUchassis.AverticalcolumnofsevenLEDsprovidesummarystatusinformationformajor

subsystemssuchasTSInput,DriveChain,PowerAmp,PowerSupply,Output,System,an

dMute

Themainco

ntrollerintheLPUcommunicateswithanyexternalpoweramplifiersblocks(PAB)viaanRS‐485

communicationbuss.CommandsoriginatingintheLPUtraveltothePABsviaRS‐485.Amplifierstatusandtelemetry

informationfromthePABsreturnstotheLPUthroughthesameRS‐485connection.

Therear

etwoRJ45EthernetconnectorsontheLPU:onelocatednexttotheLCDscreenbehindtheLPUfrontpanel

andoneontherearpanel.ThefrontpanelconnectorhasastaticIPaddressandactsasaDHCPserver.Therear

panelconnectorcanbeconfiguredasaDHC

Pclient.

Therear

enoroutineinternaladjustmentsinsidetheLPUchassis.

Allsy

steminterconnectionsandanRS232diagnosticportareprovidedontherearpanel.Detailedpinout

informationontherearpanelremotecontrolconnectionstotheLPUandcabinetcanbefoundinSection2ofthis

manual.

1.5.1.2 LPUModulatorSection

TheLPUmodulatorsectionisthesignalsourceforthetransmitterandoccupiestheupperhalfoftheLPUchassis.It

receivestheprogrammaterialtobetransmittedintheformofadigitaltransportstream(oranalogvideoinputin

thecaseofanalogtelevision)andgeneratesalow‐levelon‐ch

annelRFsignal.Multipleinputconnectorsontherear

panelallowfortheswitchovertoredundanttransportstreams.

Speciali

nputadapterboardsarerequiredforeitheranalogtelevision(PAL,NTSC,SECAM).Theseoptionalboards

providetheappropriateinputconnectionsfortheirrespectiveformatsattheLPUrearpanel.

TheLPUca

nbeoperatedwithmultiplemodulationplatformsthroughasoftwarechangeandfeaturekeyupdate.

Themodulationprocessisfullydigital,withanalogcircuitsusedonlyafterthemodulationtoup‐converttheIFsignal

tothedesiredRFchannel.

TheLP

Ucanacceptanexternal10MHzor1pps(pulsepersecond)frequencyreferenceviarearpanelconnectors.A

GPSantennainputandinternalGPSreceiveroptionis alsoavailable.Anexternalstandardiscommonlyusedin

singlefrequencynetworkorprecisecarrierfrequencyoffsetapplications.

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