Simrad SU90 - Page 34

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381291/C
Thechallengeistondatiltthatpreventstheshechoestobe"buried"inreverberation
andbottomechoes.
•Ifyouuseahightiltvalue(A)theshareeasilydisguisedbybottomechoes.A
strongRCG(ReverberationControlledGain)settingwillremovethebottomechoes.
Asthedistancefromthebottomtotheshincreases,theshechoesbecomeclearer.
However,thisassumesthattheshechoesareconsiderablystrongerthanthebottom
echoes.
•Ifyouuseaverysmalltilt(C)youarenotbotheredbybottomechoes.However,ifthe
seasurfaceisgustyyouwillseeechoesfromthewaves.Theseechoesarenormally
ratherweak,andtheyhardlymoveinrelationtoyourvessel.
•Bymeansofamediumtiltangle(B)youareabletopickupscatteredshorschools
ifthesearelocatedatsomedistanceabovethebottom.Theupperschoolinthe
illustrationappearsonthesonarpicturebeforethebottomecho,whilethelower
schoolwilleasilybedisguisedbythebottomechoes.Onceagainyoucanactivatethe
RCGfunctiontoimprovethereading.
Tip
WiththevariousbeamsprovidedbytheSU90,itmaybedifculttounderstand
theconcept.Howdothesebeams"behave"inthewater?Bymeansofagraphic
presentation,theBeamVisualizationdialogboxattemptstogiveyouabetter
understandingofhowtheacousticbeamsaretransmittedintothewater .OpentheBeam
VisualizationdialogboxfromtheSetupmenu.
Procedure
1Clickinanyviewtomakeitactive.
Theactiveviewisidentiedwithathickerborder.UnlessyouusetheApplytoall
function,allchangesyoumakewillonlybeappliedtothisview.
2InaV erticalview,clickonthetiltline,keepthemousebuttondepressed,anddrag
thelineupordown.
Optionally:
3ObservetheMainmenu.
ItsdefaultlocationisontherightsideoftheSU90presentation.
SimradSU90OperatorManual