Simrad ST90 - Controlling the Gain and Range Settings; Adjusting the Gain (Echo Sensitivity)

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Controllingthegainandrangesettings
Topics
Adjustingthegain(echosensitivity),page61
AdjustingtheTVG(TimeVariableGain)setting,page63
Adjustingthesonarrange,page63
Adjustingtheintensityoftheechopresentations,page65
Changingthetilt,page65
Adjustingthebearing,page67
Adjustingthegain(echosensitivity)
Someechoesareweakwhileothersarestronger.Tocompensateforthisitisoftennecessary
toadjustthesensitivityoftheST90.Thisadjustmentiscommonlyreferredtoasgain.
Context
Youcancomparethisgainsettingwiththevolumecontrolonyourcarradio.Whenthegain
isincreased,theechoeswillappearstronger.Weakechoeswillbeeasiertosee.However,
sinceyoualsoincreasetheacousticnoiseinthereception,theST90presentationswillalso
showthisnoise.Toomuchgainmaytherefore"distort"thepresentation.
Comparingthegainfunctionwiththevolumecontrolonyourcarradioisnotveryaccurate.
Infact,thegainintheST90isconstant.TheGainfunctionisusedtoadjustthesensitivity
.
Thisdonebycontrollingtheminimumlevelofdetection.Whenyouincreasethegainlevel
(morepositivenumber),youreducetheminimumlevel,andthusincreasethesensitivity.
Theechostrength(A)changeswithtime.Theminimumlevelofdetection(B)isadjustedup
ordownwiththeGainfunction.IncreasingtheGainwithamorepositivenumberreduces
Operatingprocedures