From: "David Bartsch" <dbartsch2236@hotmail.com>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Hydrophone systems
Date: Fri, 11 May 2007 17:26:29 -0400
Joseph,
The initial sonar array being constructed is not very ambitious. It will
contain six of these "Dolphin ear" style hydrophones configured in a
hexigon configuration. Just as you would cup your ear with your hands so as
to better hear a specific noise source (You are using the difference in
medium between water(your hand) and air to accomplish this concentrating)
We will isolate these hydrophones one from another using air. The
hydrophone that is most closely aligned with the sound source will recieve
it the loudest. The hydrophone selection is being accomplished by a
handwheel driven cam that makes and breaks small microswitches. These
hydrophones use the basic electronic rule that states that a complete path
is required for current to flow. The ground connection is common to all of
the hydrophones...only the other hydrophone connection is isolated for each
hydrophone by individually assigned microswitches. A small overlap exist to
ensure constant coverage as you transition from one hydrophone or area of
coverage to another.
Once the initial passive sonar is up and running, A modification of
either a larger cam assembly that would accomodate a full 12 switches, or
two same diameter cams mounted one above the other will provide for 30
degree in much the same way.
As to the final degree of accuracy that can be obtained...who knows.
Even with but six hydrophones, sixty degrees is far more acceptable than
360 or none at all.
Also...the use of sound dampening barriers or bulkheads could increase
the bearing accuracy a great deal sorta like moving your ear near a cracked
door to listen in on a conversation. by changing your boats heading and
listening with a known reception window, you could almost certainly
pinpoint a targets exact bearing.
It is my intention to utilize a 12 hydrophone array to aquire a rough
bearing to a detected contact, then use a large lower frequency hydrophone
properly baffled to better pinpoint its location.
I should point out that once the amplifier is adjusted to a confortable
listening level, one need only turn the handwheel to the dirrection desired
in order to listen for boat activity. (This is not going to take away from
a dive as to complexity to operate!)
This is an area still under investigation and of ongoing research...any
findings or research on anyones part can only enhance or improve everones
final passive sonar result.
Also, by having purchased the real mcCoy as to a dolphin ear, some
comparisons could be made between a commercially available hydrophones and
any you can produce yourself and will in the long run ensure that your
final product will be the best that you can obtain.(So don't feel too bad)
From: "Joseph Perkel" <joeperkel@hotmail.com>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Hydrophone systems
Date: Fri, 11 May 2007 11:57:43 +0000
David,
Free is always the "right price"! I cannot be there but, look forward to
seeing the results.
Let me ask you this,... what can a homebuilder expect in terms of
narrowing the bearings to prop sounds to say... within 5 deg? Is that a
reasonable expectation?
Joe
From: "David Bartsch" <dbartsch2236@hotmail.com>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Hydrophone systems
Date: Thu, 10 May 2007 23:32:25 -0400
>Joseph Perkel,
> Nice hydrophones...my plans are free and will be available at the
>upcomming convention!
>
>
>>From: "Joseph Perkel" <joeperkel@hotmail.com>
>>Reply-To: personal_submersibles@psubs.org
>>To: personal_submersibles@psubs.org
>>Subject: [PSUBS-MAILIST] Hydrophone systems
>>Date: Thu, 10 May 2007 18:44:20 +0000
>>
>>
>>Peter and others,
>> >>When I was considering a war-boat replica, I had gone as far a
>>acquiring plans for a homemade directional hydrophone.
>>http://www.digitalmarketingusa.com/hydrophone.html
>> >>There are a number of commercial, albeit expensive units that are
>>off the shelf such as
>>http://www.sonotronics.com/html/products/receivers/mantrak.html
>> >>The idea being that one could mount such a device atop a short
>>shaft through a simple rotating thru hull. One could have a fixed
>>compass rose on the inside with the bow of course aligned
>>@ 360 deg, in order for the operator to determine and call out
>>bearings.
>> >>When I was diving, I was fairly certain within.... I would guess a
>>90 deg swath of the direction of props to try to keep myself from
>>being blended. This is
with human ears so I am quite sure these
>>units will get that down to the degree.
>> >>If you really want to get fancy, there are software programs
>>available that will determine range based upon density and sound
>>wave propagation. This could be run on a Panasonic "Toughbook".
>> >>Joe
>>
>>
>>
>>
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>
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