Simrad SU90 User Manual

58
381291/C
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

Simrad SU90 Specifications

General

Brand	Simrad
Model	SU90
Category	Sonar
Language	English