Specifications

Maxiva UAX
October 17, 2013
5‐15
888‐2693‐004 WARNING:Disconnectprimarypower priortoservicing.
Copyright©2013,HarrisBroadcast
Note
An alternate to the PAB reflected power calibration is possible if a signal generator is available on site.
The generator can be connected directly to the REF IN connector on the PAB rear and simply apply (on
frequency) the two signal levels noted above to that port to calibrate the reflected levels. That simplifies
the reflected calibration procedure by eliminating the need for a directional coupler.
STEP 11 Endofprocedure.
5.5 Pre‐correctionforDigitalTV
Digitaltransmittersaretypicallyoperatedinadaptivenonlinearpredistortionandlinearequalizationmode.The
precorrectionandequalizationareappliedintheLPUmodulatorsection(exciter).Theproceduredescribedbelow
willautomaticallycalculatetheprecorrectionforaninstalledsystem.Oncetheprecorrectionhasbeencalculated,it
canbestoredinthesetupmemoryoftheLPUfo
rlateruseinStoredmode.Theprecorrectionisnormallyappliedby
settingboththeLinearandNonlinearRTACmodetoADAPT.
Assumptions:
• Transmitteraveragepowerlevelisknown
• A signalsampleisavailablefromaforwardcoupleraftertheamplifierandpriortothemask
bandpassfilter.
• Asignalsampleisavailablefromaforwardcouplerafterthemaskbandpassfilter.
EquipmentandTo
olsRequired:
• SpectrumorTVanalyzer
5.5.1 PrecorrectionSetupProcedure
NonlinearPredistortion:
STEP 1
Withthetransmitteroperatingatthedesiredpowerlevel,setthenonlinear
RTACmodetoADAPTviathePOWERmenuontheLPUfrontpanelLCD
displayorbyusingtheLPUwebbrowsertonavigatetoExciterHome>Setup
>DUC/RTACscreen.
STEP 2 VerifythatthenonlinearRTACattemptandsuccesscountersincrement
aboutevery20secondsontheExciterHome>Setup>DUC/RTACscreen.
STEP 3 Useaspectrumanalyzertomeasuretheadjacent‐channelIMDshoulder
levels.Verifycompliancewithanyprevailingspectrummaskrequirements. 
STEP 4 Savethiscurrentnonlinearcorrectioninoneofthefourslots(seeStoring
PrecorrectionSection5.5.2onpa
ge5‐16).
Note
If the Linear RTAC section is in BYPASS at this time, linear correction will not be stored.
LinearEqualizer:
STEP 5
SetthelinearRTACmodetoADAPTviathePOWERmenuontheLPUfront
panelLCDdisplayorbyusingtheLPUwebbrowsertonavigatetoExciter
Home>Setup>DUC/RTACscreen.
STEP 6 VerifythatthelinearRTACattemptandsuccesscountersincrementabout
everytwentyseconds.
STEP 7 UseaTVanalyzertomeasuretheMER(DVBT,DVB‐T2,ISDB‐T)orEVM
(ATSC).
STEP 8 Savethiscurrentlinearcorrectioninoneofthefourslots(SeeStoring
PrecorrectionSection5.5.2onpa
ge5‐16).
STEP 9 Procedurecomplete.