Simrad EK80 - Ambient Noise

52
394149/C
(CD010203_300_010)
ATurbulentow
BLaminarow
CAirbubbles
Theboundarylayerincreasesinthicknesswhenitbecomesturbulent.Theboundarylayer
isthinintheforwardpartofthevesselhull,andincreasesasitmovesaft.Thethickness
dependsonshipsspeedandontheroughnessofthehull.Allobjectsstickingoutfrom
thehull,ordentsinthehull,willdisturbtheowandwillincreasethethicknessofthe
boundarylayer.Whentheowspeedishigh,theturbulencecanbeviolentenoughto
destroytheintegrityofthewater.Smallvoidsorcavitiesinthewaterwilloccurandthis
iscalledcavitation.
Rattlenoises
Rattlenoisemaybecausedbylooseobjectsinthevicinityofthetransducer,likexing
bolts.Therattlemayalsocomefromlooseobjectsinsidethehull.
Interference
Interferencefromotherhydroacousticequipmentonboardthesamevesselmaybean
annoyingsourceofdisturbance.Unlessthesamefrequencyisusedformorethanonepiece
ofequipmentonlythetransmittedpulsewillcontributetotheinterference.
Ambientnoise
Ambientnoiseisusuallynotalimitingfactortotheperformanceofsonarsandecho
sounders.
Theambientnoisemaybesplitupasfollows:
•Seanoise:Airbubbles,seismicdisturbances,waves,boundaryturbulence,etc.
•Biologicalnoise:Fish,mammals,etc.
•Manmadenoise:Othervessels,interference
SimradEK80