Simrad ST90 - Page 164

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•TVG(TimeVariableGain)
Whenanacousticpulseissentthroughthewater,itwillgraduallyloseitsenergy.The
greaterthedistancebetweenthetransducerandthetarget(s),thegreaterthelossof
energy.TVG(TimeV ariableGain)compensatesforthelossofacousticenergydueto
geometricspreadandabsorption.
•Ping-PingFilter
ThePing-PingFilteranalysesthehistoricalinformationfrompreviousconsecutivepings
inordertoremoveunwantednoiseandfalseechoesfromtheST90presentation.
•PulseType
ThePulseTypefunctionallowsyoutoselectthe"shape"ofthetransmittedpulses
("pings").Differentshapeshavedifferentqualities.Whichpulsetypetousedepends
onthecurrentenvironmentalconditions,yourrangetothetarget(s)andthetypeand
speedofthetarget(s)youareobserving.
•Bandwidth
TheBandwidthfunctionallowsyoutoselectthefrequencyrangeintheHyperbolic
FrequencyModulated(HFM)transmissions.
•Frequency
TheFrequencyfunctionallowsyousetthecentrefrequencyfortheHyperbolicFrequency
Modulated(HFM)andLinearFrequencyModulated(LFM)transmissions(pings),and
theoperatingfrequencyfortheContinuousWave(CW)pings.
•HorizontalTXSector
TheST90transmitsinaswathwithmaximumhorizontalopeningangle360°
omnidirectional.BymeansoftheHorizontalTxSectorfunction,youcanchangethis
openingangleto180,120,90,60or30°.ThefunctionisonlyavailableintheHorizontal,
PlaneandInspectionviews.
•VerticalTXSector
TheST90transmitsinaswathwithmaximumverticalopeningangle94°.Bymeansof
theVerticalTxSectorfunction,youcanchangethisopeningangletoN/A.Thefunctionis
onlyavailableintheVerticalandNavigationviews.
•RangeProjection
Thedistancetoatargetlocatedanywhereinthewatercolumncanbemeasuredintwo
ways.Thiscaneitherbethehorizontaldistancetothetarget(True),oralongthetiltangle
(Slant).TheRangeProjectionfunctiondeneshowthisdistanceismeasured.
•AGC(AutomaticGainControl)
TheAGC(AutomaticGainControl)functionrunsanautomaticanalysisoftheecho
strength.
SimradST90OperatorManual