Installation manual

SimradSH90
WhatisRCG?
RCGmeansReverberationControlledGain.Thisisa
two-dimensionallteringofthereceivedechoesinorderto
suppressunwantedsurfaceandbottomreverberation.
IfyouselectStrong,thebottomechoeswilldisappearaltogether
ifthebottomisat,whileschoolsofshclosetothebottom
willbeeasiertosee.
NotethatscatteredshmaybemoredifculttospotiftheRCG
functionisactive,asthesecanbemisinterpretedasreverberation.
ItisthereforeimportantthatyouusetheRCGwithgreatcareif
youraresearchingforscatteredsh.
Abouttilt
Thesonarbeamcanbetiltedverticallyinstepsof1degree,and
thechosentiltisshownonthesonarpicture.At0degreestilt
youwilltransmitthesonarbeaminparallelwiththeseasurface,
while60degreestiltwilldirectitalmoststraightdown.
Figure15Tilt
(CD015005D)
C
B
A
Thechallengewillalwaysbetondatiltthatpreventsthesh
echoestobeburiedinreverberationandbottomechoes.
Ifyouuseahightiltvalue(A)theshwilleasilybedisguised
bythebottomechoes,butastrongRCGsettingwillhelp.As
thedistancefromthebottomtotheshincreases,theshwill
beeasiertoseewhentheRCGremovesthebottomechoes.
However,thisassumesthattheshechoesareconsiderably
strongerthanthebottomechoes.
Ifyouuseaverysmalltilt(C)youwillnotbebotheredbybottom
echoes.Iftheseasurfaceisgusty,youwillhowevereasilysee
echoesfromthewaves.Theseechoeswillnormallyberather
weak,andwillhardlymoveinrelationtoyourvessel.
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