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Subject: Which is more approperiate either 200kHz or 50kHz to detect plankton?
From: musse <[log in to unmask]>
Reply-To:Academic forum on fisheries ecology and related topics <[log in to unmask]>
Date:Tue, 29 Apr 1997 12:33:04 +0800
Content-Type:TEXT/PLAIN
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TEXT/PLAIN (30 lines)


         According to the literature, if the intention is to detect fish, the
echoes from plankton are part of reverberation. So as if the intention
is  to study plankton, there are still likely to be unwanted signals from
solid particles in suspension and of course the large echoes from fish
are no longer wanted. However, the sonar frequency is important in this
context.

        If the intention is to detect large targets (fish) in background of
smaller echoes, a lower frequency should reduce the reverberation.
Conversely, if the small targets are of primary interest, then higher
frequency might give better results. But in other development, an other
suggestion has arose which bears the concept of a lower operating frequency


        If the intention is to detect large targets (fish) in background of
smaller echoes, a lower frequency should reduce the reverberation.
Conversely, if the small targets are of primary interest, then higher
frequency might give better results. But in other development, an other
suggestion has arose which bears the concept of a lower operating frequency
can detect  plankton layers (smaller targets) better than higher frequency.

        Therefore, I would rather like if anyone clarifies which is  good
for either detection of plankton?

        Your help is greatly appreciated.

        Thanks in advance


        M. G. Hassan

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