Specifications

Section-4 Theory
October 17, 2013
4‐14
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4.4 LPUAmplifierSection
TheLPUamplifiersectionoccupiesthelowerhalfoftheLPUchassisandisequippedwithtwopowersuppliesand
twopoweramplifiermodulestoamplifytheRFoutputsignal oftheLPUmodulatorsectiontoalevelof
approximately1to150watts,dependingonmodulationformat.ThetwoPAmodule
sareconnectedinseriesto
increasetheamountofgainavailabletoapproximately40dB.
Note
The 10 W transmitter is an LPU which has only one PS and one modified PA module that has two FETs
operating in series (see
Section 4.5.1 on page 4-15).
TheLPUa
mplifiersectionsharesthefollowingboardsormoduleswiththeexternalpoweramplifierblocks.
• PAmodule
• PSmodule
• PAbackplaneboard
Thefunctiona
lityoftheseitemsisdescribedinSection4.5onpage4‐15addressingtheexternalpoweramplifier
block.
4.4.1 AmpController(901‐0223‐071G)
TheUAXAmpControllerhastwomaindevicesthatmanagetheamplifierinterface.ThefirstdeviceisaCPLD
(ComplexProgrammableLogicDevice).TheCPLDmanagesthecontrolcommandsthatarebeingdistributed
betweentheinternalandexternalampl ifiers.TheseconddeviceisaTexasInstrumentsMSP430microcontroller.
Themicroc
ontrollermanagesthedataacquisitionandreporting.TheAmpControllerisalsoequippedwithRF
detectorsthatareusedtomeasuresystempowerorlocaloutputpowerdependingonthetypeofunititisinstalled
in.
TheCon
trollerCPLDmanagesallofthecommandsignalsbyroutingtheI/Otothecorrectlocationdependingonthe
mode.Wheninstalledina100WLPU,theControllercanfunctionasthe“Master”or“Slave.”Inthemastermode,
theCPLDwillroutetheONcommandandRestrikecommandsfromtheFr
ontPaneldirectlytotheexternalinterface
whichisfunctioningasanoutput.TheCPLDwillalsoroutetheONcommandtotheinternalsuppliesandamplifiers.
TheCPLDappliestheONcommandtothepowersupplies500mSbeforeapplyingtheONcommandtothe
amplifiers.OncetheONcommand totheampl
ifiershasbeenasserted,theRestrikecommandisissued.TheRestrike
commandclearsanylatchedfaultsandenablesthebiastotheFETs.
WhenaTC
Uisinstalledinthesystem,theampcontrollersintheLPUsautomaticallyrecognizeitspresenceandrun
inslavemode.ThisistheonlywaytogetanampcontrollerlocatedinaPABtoruninslavemode.IftheTCUis
disconnectedandthetwoLPUsr
emainbussedtogether,bothLPUswilltrytofunctioninmastermodeandtherewill
besignalcontention.
Ina50
0WHPU,theCPLDalwaysfunctionsinslavemode.InthismodetheCPLD’sexternalinterfaceareinputs.The
PABcontrollersreceivetheircommandsviatheexternalinterfaceandbegintheirONcommandsequencing.Allof
theslaveampcontrollersinthesystemreportfaultsbacktothemasteram
pcontrollerviatheexternalparallelfault
I/O.
Theampco
ntrollermicroalsohastwodifferentmodes.However,themicro’smodesarecompletelyindependentof
theCPLD’smodes.ThemicrocontrollermodescontrolhowtheRS485bussesaremanaged.InanLPU,theexternal
RS485busisturnedonoroffbasedontheMaster/Slavesignalthatispassedfr
omthefrontpanel.TheLPUthatis
functioningasthemasterechoesthecommandsthatarebeingsentfromitsfrontpanelRS485totheexternal
RS485.ThePAB’s,dependingontheiraddress,respondtothecommandsthatarebeingsentbythemasterLPU.In
thesamemannerastheCPLD
,themicrocontrollersonlyfunctioninslavemodewhentheyareinstalledina500W
HPU.
Themicr
ocontrolleralsomanagestheinternaldataacquisitionfromthepoweramplifiers,faninterface,and
detectorsaswellascontrollingthePABLEDpanel.Themicrocontrollermultiplexesfouranaloginputsandfour
digitalinputsthatarecontrolledbyeightchipselectoutputstoacquirethedata.Thedatathatisg
atheredviathe
microcontrollermultiplexingisthenpassedtothemasterLPUfordisplaythroughtheexternalRS485.Themicro
controlleralso multiplexesthreeLEDoutputstocontrolthesixLEDsthatarelocatedatthefrontofthePAB.