Alan,
In in-water tests of the six hydrophone array using a micro switch hydrophone selector in 2007, ranges to small pleasure craft with gas engines with low horse power (<25) was over 1/2 mile and this was in a lake containing many branching outcrops. The lake had underwater trees and mud that absorbed and scattered sound. In open water the detection of similar craft could be several miles.
In this same lake boats with electric drive trolling motors were easily heard 1/4 of a mile.
I'll see if I can retrieve the actual in-water test reports from this outing.
The hydrophones in use today differ little from these very ones used during this test.
David Bartsch
From: alanjames@xtra.co.nz
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] directional passive sonar has arrived!
Date: Wed, 1 Dec 2010 22:50:47 +1300
David,
You previously mentioned tracking a submarine from a boat with this system.
That sounds great, what range do you anticipate it would have ???
I presume if you have your receivers even further apart then the direction would be easier to pick up.
Alan
Sent: Wednesday, December 01, 2010 9:24 PM
Subject: RE: [PSUBS-MAILIST] directional passive sonar has arrived!
Alan,
Before this system (although it has yet to be better refined) a grid search was all that a surface craft could do to locate a disabled submarine equipped with a distress pinger. Now with this system deployed aboard the surface support vessel, no grid search would be required but simply the training of this sonar onto the source of this transmission!
David Bartsch
From: alanjames@xtra.co.nz
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] directional passive sonar has arrived!
Date: Mon, 29 Nov 2010 21:04:45 +1300
David,
You could possibly use this to conduct grid searches.
You could have a surface boat with GPS tracking a certain course, & the sub on the bottom
following sounds emitted from the surface craft.
Alan
----- Original Message -----
Sent: Monday, November 29, 2010 7:20 PM
Subject: RE: [PSUBS-MAILIST] directional passive sonar has arrived!
I was using the Sierra 1 rc Bismarck and the range was 200' at the farthest. Normal boat traffic will no doubt be picked up much farther. It does get flaky when the range is less than 20' but farther out it's great. If I add the analog meter circuit this should get this to within 1 to 3 degrees! The farther out from the array the more accurate the results.
The next logical step is for Jens to come up with a time delay circuit whereby three fix mounted hydrophones at the base of a K250/350 can determine the actual bearing with beam forming as apposed to turning an actual array. This is where we intend to go with this.
There are some bugs to work out. The need for shielding of signal wires came in loud and clear as I once again heard radio stations...when I ran the rc boat I almost went deaf!
It's like when "skunk works" found what shape best evaded radar. Once discovered, they were handed it back and told to find a way to make it fly...
We have a passive sonar that can show the bearings of detected contacts. All we need now is a simple way to install and use on these small submarines. We have our work cut out for us.
I was very impressed with this first in-water test of this system.
David Bartsch
From: alanjames@xtra.co.nz
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] directional passive sonar has arrived!
Date: Mon, 29 Nov 2010 17:40:55 +1300
Keep at it David sounds great.
I guess you now have the added security that you will be able to tell
what direction the crocodiles comming from. (Lake Placid movie)
Alan
----- Original Message -----
Sent: Monday, November 29, 2010 3:09 PM
Subject: [PSUBS-MAILIST] directional passive sonar has arrived!
To all:
I just tested the passive binaural sonar system in the waters of Lake Placid in Chickasaw State Park just East of Henderson, Tn. today. This system can determine the exact bearing to a given detected passive sonar contact within about 5 degrees and should prove even more accurate once an analog meter system is deployed.
There are still a few issues to work out such as proper shielding to avoid radio reception and better sound mounting to avoid self generated noise.
Passive directional sonar has finally arrived!
David Bartsch
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