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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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