Sharp SD-AT1000W Spécifications télécharger pdf (Page 170)

Section-4 Theory

October 17, 2013

4‐6

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

Figure 4-4 RF Power Control Block Diagram

AnRFsamplefr

omaforwarddirectionalcoupleratthetransmittersystemoutputisdeliveredtoafrequency‐

compensateddetectorontheampcontrolboardintheLPU.Thedetectorfunctionsinbothrmsmode,forusewith

digitalmodulationformats,andpeakmode,forusewithanalogtelevisionformats.Thepe

akandaveragedetected

voltagesaredeliveredtoananalog‐to‐digitalconverterontheLPUfrontpanelboard.Adigitizedrepre sentationof

theforwardpowerlevelisdeliveredtothecontrolCPUonthesignalprocessingboard,wherethecoreautomatic

gaincontrolfunctionsareperformedinsoftware(dashedlines):thecu

rrentpowerleveliscomparedtoastored

forwardpowerreference(i.e.desiredpowerlevel)andthepowercommandsignaltotheRFattenuatorontheup‐

downconverter(UDC)boardisraisedorloweredaccordinglytomaintainaconstantoutputpowerlevel.The

forwardpowerreferencemaybeseteitherthr

oughthewebremoteinterfaceorthefrontpanelraise/lower

buttons.

4.2.6 TransmitterRFPowerwithM o dulesRemoved

Asmodulesareremovedfromservice,theoutputpowerproducedbytheamplifyingstagedropsaccordingtothe

formula:

Power(d

B)=20*log(modulesstillinservice/totalnumberofmodules)

Thisfo

rmulaisuniversaland maybeappliedtoanytypeofisolatedcombiner,not justthosefoundintheUAX.

Forth

eUAXfamilyoftransmitters,thistranslatestothefollowingoutputpowerlevelswithanysinglemodule

removedfromthetransmitter.

Table4‐1PowerOutputwithSingleModuleRemoved

FailedModule

Model PA PS

UAXPA(LP

U) OFF OFF

UAX2PA ‐6.0dB ‐6.0dB

UAX4PA ‐2.5dB ‐2.5dB

UAX8PA ‐1.2dB ‐1.2dB

DAC

ATTENUATOR

MODULATOR

UDC

LOW POWER UNIT (LPU)

DETECTOR

PAD

FILTER

ANTENNA

PAB

FORWARD

SAMPLE

REVERSE

SAMPLE

WEB

REMOTE

INTERFACE

FORWARD

REFERENCE

POWER

CURRENT

POWER

LEVEL

ETHERNET

SIGNAL PROCESSING

FRONT

PANEL

FPGA

ADC

RAISE

BUTTON

LOWER

BUTTON

LCD

POWER

SET

FRONT PANEL

CONTROL

AMP CONTROL

1 2 ... 165 166 167 168 169 170 171 172 173 174 175 ... 291 292

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