Simrad EK15 - Output Power

Echosoundertheory
(CD010217-004)
20logR
40logR
A A
Theillustrationshowshow
thegainclosetothebottom
(B)islargerthanjustbelow
thetransducer(A).Theechoes
fromtheshclosetothe
bottomwillthenbeshownwith
thesamestrength(colour)as
echoesfrompelagicsh.
Theleftvesselusesthe20log
Rsetting.Duetotheincreasing
beamwidth(C),singleshes
areshownlargerandlarger
withincreasingdepth,even
thoughtheymaybeofidentical
size.
Therightvesselusesthe40log
Rsetting.Thesizeoftheshwillstillappeartogrowlargerastherangeincreases,
buttheechoiscompensateddifferentlytoofferamoreuniformechostrength(colour
intheechogram).
Whenyouarelookingforschoolsthesewilllltheentirebeam,justasthebottom
normallydoes.Alotofgainisthennotnecessary.The20logRsettingwillprovidean
acceptableechostrength.
Relatedtopics
•Echogramdialogboxonpage206
•TVGfunctiononpage215
Outputpower
Theechosounder'stransducerconvertstheelectricalinputpowertoasoundtransmitted
intothewater.InthemajorityofthetransducersmanufacturedbySimradthetransducer's
powerefciencyisbetween50and75%.Thismeansthatbetween50and75%ofthe
inputpoweristransmittedassound.Transducersfromothermanufacturersmayhaveas
lowas5%powerefciency.Naturally,itisveryimportantthatyoucheckthisparameter
whenyouwishtopurchaseatransducer.
Theechosounder'soutputpowerisameasurementonhowmuchelectricalenergy
theampliercansenddowntothetransducer.Themaximumpowerislimitedby
thetransduceryouhave,andhowmuchpoweritmayacceptfromthetransmitterfor
conversiontoacousticenergy.Ifyousendtoomuchpowerintothetransducer,youmay
inictpermanentandunrepairabledamage.
Thesourcelevel(SL)isameasurementonhowmuchacousticenergythatisinfactsent
outbythetransducer,howhigh“volume”itwillemit.Thesourcelevelismeasuredas
“soundpressure”onemeterbelowthetransducerface,anditisgivenidBre.1µPaat
1m.
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