Re: [PSUBS-MAILIST] sonar research progress report.

["Jens Laland" <laland@artematrix.org>]

David

It is always of great interest to me whenever you have news about your
various projects. This has been, and still is an inspiration for me in my
own attempt to learn more about the fascinating sonar technology.

In connection with your test, you stated:

** Both transmitter and hydrophone were at three feet depth.

My feeling is that you should have gone a bit deeper. Allow myself to
quote from J.W. Horton's book 'Fundamentals of Sonar' when he speaks about
direct listening:

"One requirement which must be met if the interference, as it exists in
the water, is not to exceed the the minimum water noise level is that the
listening operation shall be carried out in deep water far from shore. It
is further necessary that the hydrophone be submerged to at least 20 ft.
below the surface,

[... that it be motionless in the water, and that there shall be, in its
immediate vicinity, no ships or other bodies floating on the surface  and
no submerged machinery or other primary sources of sound.]"

I wish you good luck with your ongoing projects.

Best regards,
Jens Laland





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