Simrad EK80 - Physical Dimensions Versus Beam Opening

26
394149/C
Physicaldimensionsversusbeamopening
Thephysicaldimensionsofatransducercanbeexplainedasafunctionofthebeamopening
atagivenoperatingfrequency.
Traditionally,a7°openinganglehasbeenthestandardformarinesurveys.However,for
applicationswherethephysicalsizeandweightofthetransducerisimportant,youcan
reducethesizebyallowingalargeropeningangleoftheacousticbeam.
Theeffectivecircularareaofthetransducerfaceiscalculatedfromtheequation:
=
A
l
2b
( )
2
x
p
Where:
•A=effectivetransducercirculararea
•λ=wavelength
•ß=beamwidthinradians(-3dBpoints)
Thetransducerneareldistheregionrightinfrontofthetransducerface,wherethesound
wavesarecomplicatedanddoesnotfalloffsphericallywithrange.Targetswithinthenear
eldwillnotbedetectedcorrectly.Theneareldiscalculatedbytheequation:
=
Nearfield
l
A
Parametersfromtypicalscientictransducersaregiveninthetable.Themaximumand
minimumsourcelevel(SL)iscalculatedfromtheavailablepowersettingsontheSimrad
EK80scienticechosounder.
FrequencyWavelength
BeamwidthMax/MinSLEffective
circulararea
Neareld
18kHz
83mm11°
225/215dB
1479cm²178cm
38kHz
39mm7°
229/219dB
820cm²208cm
70kHz
21mm7°
227/217dB
242cm²113cm
120kHz
13mm7°
222/212dB
82cm²66cm
200kHz
8mm7°
220/212dB
30cm²39cm
333kHz
5mm
7°
212/209dB
11cm²24cm
Relatedtopics
Transducers,page21
SimradEK80