Simrad ST90 - Adjusting the Intensity of the Echo Presentations; Changing the Tilt

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Adjustingtheintensityoftheechopresentations
TheeffectoftheGainadjustmentisminimizedifyouapplyRCG(ReverberationControlled
Gain)andAGC(AutomaticGainControl).TheDisplayGainisappliedtowardstheendof
theltersequenceintheST90.ThismeansthatyoucanuseDisplayGainifyouarenot
completelysatisedwiththeresultsoftheautomaticgainfunctionality.
Context
DisplayGaincontrolsthe"amount"ofechothatisdisplayed,inotherwordsthe"strength"or
"intensity"oftheechopresentation.Thefunctionthusincreasesordecreasesthepresentation
oftheechocolours.UsethisparametertogetherwithGaintoadjusttheST90sensitivity.
Forallpracticalpurposes,adjustingDisplayGainhasthesameeffectasadjustingGain.
AdjusttheDisplayGainsothatyoucanseethetargetswithouttoomuchnoiseand
reverberation.Thechosensettingisamatterofpersonalpreferences.
Procedure
1OpentheDisplaymenu.
2SelectDisplayGain.
3Adjustthesettingtotyourrequirements.
Tochangethesetting,movethecursortoeither
sideofthebutton.Selecttheleftsideofthe
buttontodecreasethevalue.Selecttherightsideofthebuttontoincreasethevalue.
Selectthemiddleofthebuttontoopenit.Ifyouhaveakeyboardconnectedtothe
ST90,youcantypetherequestedvalue.
Relatedtopics
Controllingthegainandrangesettings,page61
Improvingtherecognitionofshandschoolsusingreceiverlters,page78
Changingthetilt
Inordertodetectshorschoolsinthewatercolumnyoumayneedtochangetheangleof
thesonarbeams.Thesonarbeamscanbetiltedelectronicallyfrom-10to+84degrees.
Context
ThecurrenttiltisshownwithasolidlineintheV erticalview.IntheHorizontalview,the
currentsettingsforrange,gainandtiltareshowninthetopleftcorneroftheview.
At0°tiltthesonarbeamistransmittedparallelwiththeseasurface,while84degreestilt
willdirectittowardsthebottom.
Operatingprocedures