I have three I can spare come to think of it!
David Bartsch
From: alanjames@xtra.co.nz
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Passive sonar research
Date: Sat, 20 Feb 2010 07:36:42 +1300
David,
You could take a cat down. I know they only have half the range of a sea lion
but they're a lot smaller & readily available.
Alan
----- Original Message -----
Sent: Saturday, February 20, 2010 5:51 AM
Subject: [PSUBS-MAILIST] Passive sonar research
To all:
I will of course continue to assist those that wish to obtain broadband underwater communications capabilities however...
I will be attempting to restart my research into directional passive sonar which is and has been my first true passion.
I am at the present researching what if anything I could use to detect 200k for use as an collision avoidance tool. The reason this frequency is of such importance is that most shallow water depth sounders and fish finders transmit at this distinct frequency.
I was able to locate a kids toy that could detect and allow the listening to bats. Perhaps if I took this simple device apart, I could modify it to detect slightly higher frequencies I so desire.
Here is some interesting points of interest...
This is the range by scientific study to these various animals by Ramsey William L. (1986):
Human 20hz to 20Khz
Cats 100hz to 32Khz
Dogs 40hz to 46Khz
Horses 31hz to 40Khz
Elephants 16hz to 12Khz
Cattle 16hz to 40Khz
Bats 1Khz to 150Khz
Mice or rodents 1Khz to 100Khz
Whales and Dolphins 70hz to 150Khz
Seals and Sea Lions 200hz to 55Khz
Has anyone a suggestion as to what if anything I could use or obtain to detect and draw this very high frequency down to what we as humans can hear? Any schematic sources known of? Perhaps the return electronics within a fish finder itself could be used in some way?
David Bartsch
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