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Jon, The second significant discovery was that by removing the hard mounting bolts and using stretched "o" rings to hold one of these units together, virtually all side sound detections are also removed. Only those sound waves that strike the front surface on which these piezo's are firmly mounted will be able to detect sound and the farther straight out from this plane, the better it is heard. Only testing will determine exactly how directional this set up will be. I will produce such a hydrophone and supply it to you for the in-water testing and evaluations in June. David Bartsch > Date: Thu, 12 Nov 2009 08:53:42 -0500 > From: jonw@psubs.org > To: personal_submersibles@psubs.org > Subject: Re: [PSUBS-MAILIST] guide to hydrophone construction > > > Thanks for that Jens. For towing a unit relatively quickly, the > streamlined shape is important to reduce noise from moving through the > water. The units David developed are very sensitive to this and one way > I used to make sure the electronics were working after encapsulating the > piezo element in a PVC container was to hold it under running water from > the house faucet. If the electronics were working you could hear the > water running over the housing. > > Jon > > > Jens Laland wrote: > > David & co > > > > I just found this document which contains interesting information on > > construction of hydrophones: > > > > http://www.otago.ac.nz/marinescience/downloads/Barlow%20et%20al%202008%20HydrophoneConstruction_TM-417.pdf > > > > Best regards, > > Jens Laland > > > > > > ************************************************************************ > ************************************************************************ > ************************************************************************ > 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 > ************************************************************************ > ************************************************************************ > ************************************************************************ > Hotmail: Powerful Free email with security by Microsoft. Get it now. |