Specifications

Gettingstarted

thesonar’smaximumrange.Asshowinthemenu,theAGChasfourdifferentsettings.

Thesesettingsdenethedifferencebetweenthemaximumandminimumecholevelfor

theltertotakeeffect.

Note

Whenthisparameterischangedonahorizontalmenu,thechosensettingisonlyput

touseonthehorizontalsonarpresentation.Ifyouchangetheparameteronavertical

menu,itisonlyappliedtotheverticalsonarslicepresentation.

Tip

ThemostpracticalwaytousetheAGC(AutomaticGainControl)istorstswitchit

off.Adjusttheechopresentationusingthegainuntilyouhavethebestpossibleresult,

thenactivatetheAGC.

TheAGCworksbestwithevenbackground(homogenousnoiseconditions)and

pronouncedtargets.WithuniformsonarconditionsyoumaybenetfromstrongAGC

compensation.However,ifyouarelookingatscatteredsh,reducetheAGC,andtry

toaddgaininstead.

Ifyouworkclosetoothervessels,thenoisefromtheirpropellersmaybemisinterpreted

asechoes.Thiswillalsoreducethevisibilityofotherechoes.ReducetheAGC.The

sameappliesifthebottomconditionsplaceyourvesselwithdecreasingdepthonone

sideofthevesselandyourtargetsontheotherside.

Ifyouhaveverystrongechoesfromalargeschoollocatedclosetoyourvessel(typically

closerthan150meters),werecommendthatyoureduceorswitchofftheAGC.Thisis

becausetheAGCltermisinterpretstheschoolfornoise.

KeepinmindthattheltersintheSH90areimplementedin“series”.Thegain

compensationsaremadebeforetheAGC.Forthisreason,yourgainsettingwillalways

haveaneffectontheAGC.

Relatedtopics

•WhatisAGC?onpage102

Procedure

1ClickeithertheHorizontalorVerticaltabtoopentherespectivemenu.

2ObservetheAGCbutton.

3Clickeithersideofthebuttontoleafthroughtheoptions,orthemiddleofthebutton

toopentheparameterdialog.

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