From: "Joseph Perkel" <joeperkel@hotmail.com>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Sound contact ! ( Dolphinear hydrophones )
Date: Thu, 24 May 2007 01:06:17 +0000
Peter,
If I understood correctly, you suspended the cable in "mid air" from the
sensor to the control room to negate mechanical contact (rubbing).
If so, It will be interesting to see what a permanent installation will
look like, what kind of insulating material is used.
This is good news.....and yes...sounds like fun!
Joe
From: "Peter Madsen" <peter@submarines.dk>
Reply-To: personal_submersibles@psubs.org
To: "support" <support@doyle-renney.com>
CC: <personal_submersibles@psubs.org>
Subject: [PSUBS-MAILIST] Sound contact ! ( Dolphinear hydrophones )
Date: Wed, 23 May 2007 01:08:03 +0200
Ken,
I asked a scientist at the Technical University of Denmark who is a friend
of mine to take a closer look at your hydrophone - and I received my self
#2 hydrophone.
During a test over the side of a boat It did exactly the same as the first
- ergo - no ( likely ) error in the amplifier or hydrophone.
Then tonight - my scientist called me with his conclusions:
Result 1: I know to little of how to use highly sensitive instrumentation
like this.
Result 2: Given instructions on how to install and use the hydrophone - it
turned out to be a very usefull sensor - especially in combination with a
submarine.
My friend concluded the DolphinEar is a good and very sesitive hydrophone
at its cost - yet he recommended a better cable, or the amplifier to be
build into the hydrophone itself.
He explained that the cable must be handled with extreme care not to
produce noise, since it itself has a pieco electric effect - hence makes
noise when
mechanically stimulated.
He also explained that the polymer and epoxy parts would not have
unlimited life in a marine environment. This is not a problem for the
DolphinEars normal use
but when installed permanently submerged on the sub it would become a
problem over time. Polymers simply are not impenetrable by water.
Tonight the first hydrophone was therefore installed like this...in
Kraka´s bow we have two flat acrylic viewports. The sensor was placed on
the INSIDE of the one viewport,
and in very intimate contact with it. The cable was pulled back to the
controlroom and secured so that its not mechanically disturbed.
Then our black u-boat sailed into the indeed very black harbor and
submerged. The boat leveled out at 18 foot of water and the device was
turned on...WOILA...very low noise...I can hear
any sound generated in the boat - a relay clicking - if I scratch the
paint - the sound of a minute HP air leakin the sea outside...any sound in
the boat is heard very magnified. At this point a challup form our
Royal Yacht "Dannebrog" - moored at in the harbor started its propeller -
and Kraka´s new listening gear immediately detected the sound
contact...long before I could hear it the "normal" way.
Once it got so close I could hear it directly - the hydrophone was
overwhelmed and made the noise I have complained about.
Conclusion:
DolphinEar hydrophone are useful in submarines - but must be installed
with care. They are exceptionally sensitive to solid and liquid
transferred sound - and this was mis interpreted by me.
We now have to find out how its directional characteristic is in this
mounting - or perhaps improve it. Initially I will place the other
hydrophone in the starboard window and see what that does to us...
In my opnion - there is a lot more to be learned and lot more potential
for these hydrophones in combination with underwater recreational vessels.
The sound dive was really fun.
Best regards,
Peter Madsen / Submarines.Dk
--
Jeg beskyttes af den gratis SPAMfighter til privatbrugere.
Den har indtil videre sparet mig for at få 14729 spam-mails.
Betalende brugere får ikke denne besked i deres e-mails.
Hent gratis SPAMfighter her: http://www.spamfighter.com/lda
************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003. Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.
If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
removeme-personal_submersibles@psubs.org
Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of
our server receiving your request.
PSUBS.ORG
PO Box 53
Weare, NH 03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************