Specifications

Section-4 Theory
October 17, 2013
4‐8
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Figure 4-5 LPU Modulator Section Block Diagram
Thepr
ograminputsignals(upperrightofFigure4‐5)entertheLPUviaoneofthreemeans:
• viaananaloginputboardforNTSC/PAL/SECAMsignals
• viaanASIoverIPIinputboardfordigitalmodulation(notshown)
• viaasatellitereceiverinputboard
• viaadirectinputtothesignalprocessingboardforallotherformats
4.3.2 AnalogInputBoard(option)
Theanaloginputboard(AIB)isanoptionintheLPUandservesasanalogfront‐endformain/auxvideoandmain/
auxaudiosignals.Inaddition,itprovidesacompositeaudioinput(BTSCsystem)andavideosyncoutput(back
porchpulses).
Videosignalsar
econditionedanddigitizedwith12bitresolutionata36.4MHzsamplerate.Audiodataare
providedby24bitstereoaudioADCs,andtheBTSCinputsignalisdigitizedwitha16bitADC.Theclocksignalforthe
audioADCsisprovidedbyaPLLlockedtothesy
stemclockof36.4MHz,whichitselfislockedtotheLPU’s10MHz
reference.
TRANSPORT
STREAM
SWITCH
ASI HPA
ASI LPA
SMPTE HPB
SMPTE LPB
FPGA
MODULATOR
DIGITAL
PRECORRECTOR
OPTIONAL
ANALOG INPUT
BOARD
VIDEO
VIDEO AUX
BP SYNC
AUDIO 1(L+R)
AUDIO 2(L+R)
COMP AUDIO
ANALOG
LOOPBACK
SIGNAL PROCESSING BOARD
ADC
DAC
DIVIDE
BY 4
PART OF FPGA
MODULATOR
1st
L.O.
2nd
L.O.
1PPS
GPS
RECEIVER
LOCAL OSC DAC CLOCK
FREQUENCY
EXCITER
RF OUTPUT
UP CONVERTER
AND RF AMPLIFIER
LOCAL OSC
DISTRIBUTION
INPUT- SAMPLE
INPUT- SPARE
INPUT- PA SAMPLE
INPUT- HPF SAMPLE
MULTIPLE
INPUT
RF
SWITCH
DOWN CONVERTER
UP/DOWN
CONVERTER
BOARD
DOWN CONVERTER
J15
140MHz
IF INPUT
EXCITER
GPS
ANTENNA
10MHz
REF
CONTROL
10MHz TUNE 1 PPS INT 10MHz CONTROL
140MHz IF SIGNAL
PRECISE FREQUENCY
REFERENCE BOARD
54MHz CLOCK
LPU MODULATOR SECTION
CONTROL
uC
TX I/O
INTERFACE
USER REMOTE
TX INTERFACE