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Re: (meteorobs) Meteor Detection on FM--a new experience.



Don't confuse the sounds of meteors from the NASA satellite tracking radar
with the FM radio detection technique.  They're two different things.

The FM (or TV) method entails tuning your receiver to a station that is
"over the hill" or beyond the horizon for line of sight reception.  The
station should be inaudible except for the moments when a meteor's
ionization trail provides a reflector for the station's signal.  What you'll
hear will be "blips" or short bursts of the station's program as meteors
pass overhead and the signal is reflected briefly.  These burst will usually
be less than a second long so you have to get used to listening almost as
hard as you watch when observing visually.  You'll hear static punctuated by
bursts of music, single syllables of announcer's voices and stacatto bursts
of noise.  Sometimes you find yourself recognizing or attempting to guess
what the one syllable or the single note of music was from.

Here in Palm Bay, Florida, I usually use stations either in Jacksonville,
Florida, Savannah, Georgia or Pensacola, Florida to detect meteors.  I have
five or six stations preset into the memory of a Sangean radio that I use
and I just pick the one that seems to come in the clearest during the burst
of a meteor.  On a typical, off-peak night during the summer, I'll detect
about 10-20 meteors per minute this way.  During the Leonids, (I was clouded
out)  these stations were constantly heard in my receiver because of the
constant bombardment and continuous ionization of the atmosphere.  So, the
radio backscatter technique has it's limits.  With that much activity, I
couldn't find any station that could be heard during a meteor event, that
wasn't constantly "on" due to the massive amount of activity.

I haven't tried any of the tricks using directional antennas or filters but
I haven't really needed any.  I am planning on running the output of my
receiver into the SoundBlaster of a cast off 486 PC and use it to count the
activity 24/7.  Somewhere on the net, you've probably already been sent the
link but I think you can find it from the NASA website, there is software
available that can be set to ignore the static and just pick up the "jumps"
or "bursts" in the audio output from the radio receiver and thus resolve the
meteor activity.  Now all you need is some feel for how this relates to
visual activity.  What would a 700/hr radio rate mean to a visual observer?
This is something that will change with atmospherics and with geography.


----- Original Message -----
From: "Wayne Watson" <mtnviews@earthlinkdot net>
To: <meteorobs@atmob.org>
Sent: Wednesday, December 19, 2001 1:44 AM
Subject: Re: (meteorobs) Meteor Detection on FM--a new experience.


> Hello, I've recently again become interested in detecting meteors by FM. I
tried this in a limited
> way about 2 years ago but didn't have much success. I was somewhat
constrained by the location of my
> FM receiver and an available antenna. I have several FM receivers to play
with: an old Scott FM kit
> rcvr, a Technics FM/AM rcvr, and a C. Crane CC-Radio with AM/FM, TV, and
weather. I also have a
> six-element Radio Shack FM yagi FM antenna. In browsing around the web for
info about meteor obs by
> FM radio, I haven't found too much, frankly, that details this procedure.
What I have found roughly
> says, attach a directional FM antenna to an rcvr, point it upward 20-30
degrees from the horizontal,
> tune to a dead band, and listen. The preferred listening time is from
midnight to 6 AM. In my most
> recent round of browsing, I see someone talk about filters, and some
suggestions that using a TV
> rcvr might be better. I do have a RS digital VM and can use it to convert
analog to digital. That
> may be a possibility for some use of software and a PC.  I'd like to try
listening for meteors by
> FM, but it would be good to start simply. What do you suggest that would
most likely meet with
> success?
>
> I listened to a meteor recording on a NASA site, but I have a feeling the
quality of the recording
> is far superior to anything I might get off of FM. What's the story with
TV? Can one use an old TV
> rcvr or does one have to buy some rcvr that will tune into the TV band? Is
it the same procedure as
> used with FM?


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