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313
Tip
Youmaywishtoadjustthegainonalltheechogramsofthesametype.Todothis,click
themiddleoftheGainbuttontoopenit,andselectApplytoall.
ToselectwhichechogramtypesyouwishtoseeintheES80presentations,usethe
Echogramdialogbox.
DonotconfusethisGainsettingwiththeTVG(TimeV ariedGain)setting.
Howitreallyworks:Dynamicrange
Comparingthegainfunctionwiththevolumecontrolonyourcarradioisnotvery
accurate.Infact,thegainintheES80isconstant.TheGainfunctionisusedtoadjust
thesensitivity
.Thisdonebycontrollingtheminimumlevelofdetection.Whenyou
increasethegainlevel(morepositivenumber),youreducetheminimumlevel,andthus
increasethesensitivity.
Theechostrength(A)changeswithtime.Theminimumlevelofdetection(B)isadjusted
upordownwiththeGainfunction.IncreasingtheGainwithamorepositivenumber
reducestheminimumlevel,andthisincreasesthesensitivity.Onlyechoesoverthe
minimumlevelareshownintheechogram(C).
TheES80hasadynamicrangeof
140dB.ThismeansthattheES80
canreceivebothverystrongandvery
weakechoes.Actually,theES80will
detectechoesfromplanktontowhales,
bottomonmostdepths,andpresentthe
informationfreefromdistortion.Asa
comparison,ouroldechosounders
ES380andET100had-usinganalogue
TVG-adynamicrangecorresponding
toapproximately65dB.
Naturally,wecannotpresentallthese
echoesonthedisplaysimultaneously,as
thiswouldcreateamessofcolours.
When12coloursareused,wecreatea36dBtotalrange,andleteachcolourpresenta3
dBstrength.Everycolour(3dB)therepresentadoubling
oftheechostrength.With12
Functionsanddialogboxes
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