From: "Jay K. Jeffries" <bottomgun@mindspring.com>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: RE: [PSUBS-MAILIST] Hydrophone systems
Date: Fri, 11 May 2007 18:45:52 -0400
Joe,
The easy part is telling whether the target is approaching or departing.
The hard part is getting a converging solution as to which side of the lobe
the target is on. By remaining motionless you will not be able to do this.
Using Target Motion Analysis (TMA), it is possible to determine which side
of the lobe the target is on over a ten minute period if the target
maintains a constant heading. To complete TMA and arrive at a solution
(with a range), you have to run a straight course while taking bearings
(and
plotting the azimuths) to the target and then alter your course again
plotting bearings to the target. If you have a solid sound contact, the
solution should become evident. I don't picture this being done in a K-350
sized submersible. None of this holds true for sailboats or other slow
moving electric boats.insufficient sound signature.
Aboard today's modern subs with conformal sonar arrays down their sides, a
long towed array, and fast computers the solution is rapidly arrived at
without having to run much of a course and no heading changes.
R/Jay
Respectfully,
Jay K. Jeffries
Andros Is., Bahamas
A skimmer afloat is but a submarine, so poorly built it will not plunge.
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Joseph Perkel
Sent: Friday, May 11, 2007 12:35 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Hydrophone systems
Jay,
Interesting,...explains what I see mounted on the old fleet boats with that
funny shaped array.
In that scenario regarding the lobes, if I understand you correctly, the
problematic determination of direction is for a sound source that is
maintaining a fixed bearing, is this correct??...which would be bad news if
it's getting louder!
So if you have a prop sound that is in fact changing bearings, could you
reasonably determine if it were P or S, converging or not?
Joe