Walt is right about the frogloggers getting started in Georgia. The
original press release from the Univ. of Georgia is found at:
http://www.uga.edu/srel/logger.htm
(Some of the emails in the press release are no longer valid.)
The original froglogger was ideal because of the low cost and are most ofte=
n
placed in the field in large numbers to cover large areas that could not
normally be covered in person. Over the years I have shipped batches of 20
or more to many biologists all over the globe. First the stereo cassette
recorders became unavailable then Sony stopped shipping the less expensive
Hi-MD recorders. The only froglogger I build right now uses the Marantz
PMD660 which really makes it too expensive to deploy in large numbers. One
biologist using my frogloggers was responsible for monitoring a 200 mile
stretch of the Mississippi River. Frogloggers are now also being used to
monitor bird and wolf populations.
Therefore, I am developing a much less expensive model that records to a
Flash thumb-drive. I am also adding a very low-noise preamp using an op-am=
p
with a noise density of 0.85 nV/rt.HZ. I believe this is the quietest in
the industry. I'm thinking of using the audible time stamp used in the 1st
generation of frogloggers.
The term "froglogger" has become public domain and is used by many who buil=
d
their own units. My original schematics published in 1995 are still posted
on the US Geological Survey's (USGS) web-site at:
http://www.pwrc.usgs.gov/monmanual/techniques/froglogger.htm
And, BTW, my son Mike (Dr. Dorcas) has written two books on frogs which are
to be in print in a few weeks. Many thanks go to Walt for contributing frog
calls that will be included on CD with one of the books.
Gene
_____
From:
On Behalf Of Walter Knapp
Sent: Wednesday, April 11, 2007 1:21 PM
To:
Subject: [Nature Recordists] Re: MD timers
Actually there is one other "feature" that's missing for using the SD7XX
recorders as frogloggers, that one is cost. Froglogging goes on for a
long time, the froglogger may be in place for months. It's attended only
enough to bring new batteries (usually a car battery) and change the
recording media as necessary. You want the service interval to be long,
these things might be at a site that's hundreds of miles away from your
base. And you really want to have multiples of them to cover more than
one site. The GA DNR right now has a half dozen frogloggers out that I
know of, that would be quite a cost using the SD recorders. (and there
is the risk of theft)
The Portadisc has VOX, I've used it a few times, but it's not as
valuable as it might seem. It does not get the initial increase in
sound. It could probably be set up as a froglogger but that's a
expensive thing to tie up.
And, yes, we are talking multiple times for a froglogger. Cassette
recorders have the advantage that turning them to record is a mechanical
locking switch, so by simply turning the power on and off to them you
can do record intervals. The newer machines that are software controlled
have a problem with this. For a simple build you want either a set of
relay contacts and/or supplying power to be all it takes to both start
and stop recording for each interval.
In one way the newer equipment is a little easier, it can timestamp each
interval easily. With the cassette usually a audio announced time is
recorded on one channel and the other records the site in mono. The time
announcements are extra equipment in that design.
Walt
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