Simrad SU90 - Adjusting the TVG (Time Variable Gain) Setting; Adjusting the Sonar Range

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AdjustingtheTVG(TimeVariableGain)setting
Whenanacousticpulseissentthroughthewater,itwillgraduallyloseitsenergy.The
greaterthedistancebetweenthetransducerandthetarget(s),thegreaterthelossof
energy.TVG(TimeV ariableGain)compensatesforthelossofacousticenergydueto
geometricspreadandabsorption.
Context
TheTVG(TimeV aribleGain)compensationisdesignedtocounteractthenatural
phenomenaofgeometricspreadandabsorptionloss.IntheSU90,theTVG
compensationismadeusingdigitalsignalprocessingsoftware.TheTVGcompensation
isexpressedasalogarithmiccurve.Eachcurvehasadifferentslopecreatingadifferent
gaincompensation.EachcurveisidentiedwiththeequationXlogTVG.Thecoefcient
"X"isaninteger.Typicalvaluesfor"X"are10to40.
Procedure
1Clickintheviewyouwanttoactivate.
Thesettingyouchoosewillonlybevalidfortheactiveview.Theactiveviewis
identiedwithathickerborder.
2OpentheActivemenu.
3LocatetheTVGbutton.
4Select[+]or[-]tochoosetherequestedsetting.
Relatedtopics
Controllingthegainandrangesettings,page56
Adjustingthesonarrange
Someechoesareclose,othersarefurtheraway.Itisoftennecessarytoadjusttheradius
ofthesearcharea.OntheSU90,thisisreferredtoasrange.
Context
TheRangesettingdeneshow"far"youwishtheSU90todetectechoes.Inother
words,youspecifythehorizontalorverticaldistancefromthevesseltotheouteredge
ofthesearcharea.
SimradSU90OperatorManual