Design and application of an underwater acoustic parametric source

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Author
Khosla, Ranvir C.
Date
1973-12Advisor
Eller, Anthony I.
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Show full item recordAbstract
Parametric sound generation has been an active area of
applied research for the last ten years. The acoustic parametric
source takes advantage of the non-linearity of the
medium to generate energy at the difference of two high frequencies.
The principal advantage of a parametric source over
a conventional transducer is its high resolution capability.
The characteristic is a result of its narrow beam width (with
no attendant side lobes) and broad bandwidth.
The parametric source was designed and tested in the laboratory
and also at sea. Laboratory studies showed severe
broadening of the parametric beam and reduction of difference-tone
pressure on reflection from a smooth air-water surface.
This is attributed to the phase reversal that occurs on
reflection.
The coefficient of amplitude variation at sea was found
to be less than 31 at the depth of 20 and 40 ft. and was much
higher at 10 ft. depth. The coefficient of amplitude variation
was higher for the parametric beam as compared to that of
a conventional sound beam at the depths of 20 and 40 ft. The parametric
beam had lower coefficient of variation as compared
to that of a conventional beam at the depth of 10 ft.
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