Specifications

Section-1 Introduction
October 17, 2013
1‐6
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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.