Simrad ST90 User Manual

457420/A
59
Selectingthebestoperatingfrequency
TheFrequencyfunctionisusedtocontrolthecentrefrequencyoftheacoustictransmissions
(pings).Thecentrefrequencycanbechangedfrom14to24kHzinstepsof1kHz.Alltypes
ofnoisematterwhenyouwishtondthebestoperatingfrequency.
Context
Alowerfrequencygivesyouabetterdetectionrangebecausetheattenuationlossissmaller.
Ahigherfrequencygivesyoubetterrangeresolution.Ahigherfrequencyalsogivesyou
narrowerbeamsanda"sharper"image".
Noisefrominternalandexternalsourceshaveanimpactonthechoiceofoperating
frequency.Onespecicfrequencymayperformbetterthantheothersonyourvessel.To
measurethenoiselevel,observethevaluepresentedontheNoisepageintheBITEdialog
box.
Werecommendthatyoudothistesttwice.First,dothetestwithallotherhydroacoustic
systems(echosounders,ADCP,sonars)turnedoff.Second,dothetestwithnormal
operatingconditions.Thisallowsyoutoseehowtheotherhydroacousticsystemsaffect
theST90operation.
Procedure
1OntheMainmenu,selectUserSettings.
aSelectST90FactoryDefault.
bSelectActivateSelectedSetting.
cSelectOKtoapplyyourchangesandclosetheUserSettingsdialogbox.
2OntheMainmenu,setRangeto1000m.
3OpentheOperationmenu.SetTxPowertoOff.
4OpentheActivemenu.SetPulseTypetoCWMedium.
5OpentheSetupmenu.
6SelectBITEtoopenthedialogbox.
aSelectNoisetoopenthepage.
bSelectStartNoiseMeasurements.
cOntheActivemenu,changetheFrequencysettingwhileobservingthenoisevalue.
dNotefrequencieswithhighnoiselevels,andtrytoavoidusingthem.
Operatingprocedures

Simrad ST90 Specifications

General

Brand	Simrad
Model	ST90
Category	Sonar
Language	English