Simrad EK15 - Bottom Slopes

SimradEK15
Thismeansthatthesoundercanreceivebothverystrongandveryweakechoes.
Actually,theEK15willdetectechoesfromplanktontowhales,bottomonmostdepths,
andpresenttheinformationfreefromdistortion.Asacomparison,ouroldechosounders
ES380andET100had-usinganalogueTVG-adynamicrangecorrespondingto
approximately65dB.
Naturally,wecannotpresentalltheseechoesonthedisplaysimultaneously,asthis
wouldcreateamessofcolours.
DynamicrangeinEK15
(CD010217-001)
-25dB/W
-165dB/W
140dB
36dB
70
ColourScale
When12coloursareused,wecreate
a36dBsectionandgiveeachcolour
a3dBstrength.Everycolour(3dB)
therepresentadoubling
oftheecho
strength.With12coloursinusethis
willbea36dBcolourrangefromgrey
tobrown.Greyisusedfortheweakest
echoes,whilethestrongestechoesare
brown.Allechoesstrongerthanbrown
willstillbebrown,whileechoesweaker
thangreywillnotbeshown.
With64coloursinuse,eachcolour
representsapproximately0.5dBecho
strength.
Theoldpapersoundershadadynamic
rangeof12dBintheirprintoutsusing
the“colours”fromlightgreytoblack.
ThedynamicrangeintheEK15colour
presentationisthusalotlarger;24dB
or250times.
Alongthedynamicrangewetakethe36dBsectionand“movesit”upanddownwith
thesettingsintheGainbuttonontheMainmenu.
UsetheColourScaleinformationpanetomonitorthecoloursincurrentuse.Tochange
thecolourscale,usetheColourSetupfunctionontheDisplaymenu.
Relatedtopics
•ColourScaleinformationpaneonpage126
•Gainfunctiononpage147
•ColourSetupdialogboxonpage160
Bottomslopes
“Bottomslopes”isawellknownphenomenonwithechosounders.Thishappenswhen
thebottomrisessuddenly,andthestartedgeofthetransducerbeamdetectsthebottom
beforetheoppositeedge.
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