Simrad ES80 - Page 434

432
406273/C
MinimumDepth
Thebottomdetectorstartsthesearchforthebottomechoatthisdepth.The
detectorwillfailinshallowwaterifyouselectatoolargedepthvalue,andthetail
ofthetransmittingpulsemaycauseproblemsifatoosmallvalueisset.
Note
Ifyousetmaximumdepthtoavalueidenticalorsmallerthantheminimumvalue,
thebottomdetectionalgorithmwillbedisabled.TheES80willnotdetectthe
bottomatall,andthedisplayeddepthwillbe0.00m.
BottomBackstep
Thisparameterallowsyoutomanuallymodifywhereonthebottompulsethe
depthshallbedetected.Thesettingdoesnothaveaneffectontheabilitytodetect
andtrackthebottom.
AThepeakofthebottompulse
BDefaultbottombacksteplevel
CApproximatebottombacksteplevelfor
atshdetection
DApproximatebottombacksteplevelfor
seagrassdetection
Thebottompulsebasicallyidentiesthebottom
depthjustpriortothepeakofthepulse(A).
However,thismaynotbethetruebottom.Forexample,ifthebottompulseis
generatedbyarockbottomunderathicklayerofmud,theactualdepthisslightly
shallower.Forthisreason,theES80isbydefaultsetuptogiveyouadepthreading
afewmillisecondsbeforethepeakofthepulse.Thisisdonebysettingthebottom
backstepleveltoadefaultvalueof-50dB(B).
Theactualbottomwillneverappearatthepeakofthebottompulse(A),itwill
alwaysbeslightlybeforethepeak.BychangingtheBottomBackstepparameter
youcandetectthebottomearlier.Thisfeaturecanforexamplebeusedwhenyou
shforatsh,orwhenyouareharvestingseagrass.
Example
Ifyoushforsole,ounderorsimilarspecies,youcanusetheBottom
Backstepparametertoenhancethedetectionofthesh.Increasethe
bottombackstepvalue(makeitmorepositive)sothatthebottomis
detectedslightlydeeperthanthecorrectdepth.TheES80willthen
"pushthrough"theshbetter,andtheatshwillbeshownasthey
arelocated"above"thebottom.
SimradES80ReferenceManual