Kongsberg EA440 - Page 25

392616/B
25
isnecessarytokeepthenoiselevelisaslowaspossibleinordertoobtainlongrange
anddependableinterpretation.
Thenoisethatcontributestothesignaltonoiseratiomaybedividedintothefollowing
typesofnoise:
•Selfnoise
•Ambientnoise
•Electricalnoise
•Reverberation
AThetransducercanpickupnoisefrom
•Biologicaldisturbances
•Interference
•Cavitation
•Propellernoise
•Flownoise
•Acousticnoisefromotherhydroacousticsystems
BThetransducercableislong,andmaypickupelectricnoisefromgenerators,
pumps,coolingsystemsandotherelectricorelectromechanicaldevices.
CThepreampliersareverysensitive,andtheycaneasilypickupelectricalnoise
frominternalandexternalpowersupplies.Thepreampliersarealsovulnerablefor
analoguenoisecreatedbytheirownelectroniccircuitry.Digitalnoisecreatedby
theconverterandprocessingcircuitrycanalsocreateproblems.
DConverterstransformtheanalogueechoestodigitalformat.
ESignalprocessingcircuitrycancreatedigitalnoise.
Preparations