From: dal3@cbnewsg.cb.att.com (dale.e.parson)
Subject: VHF FM radio observation project, advice needed
Followup-To: sci.astro,rec.radio.shortwave,rec.radio.amateur.misc
Keywords: meteor VHF FM ionization skip bounce
Organization: AT&T
Distribution: na
Date: Wed, 29 Jul 1992 16:44:44 GMT



I apologize for the cross-posts if inappropriate, but I don't usually
read the radio groups & I'm sure some experience is out there. This
continues a sporadic discussion of meteor shower observation using
FM VHF radio, especially for the Perseid shower that peaks around Aug. 11,
that has been going on in sci.astro. My radio questions come at the end.

I signed up to help with a middle school summer science program here at
Bell Labs the week of 8/10, will conduct an experiment with 1 or 2 students,
and decided that because of timing it would be more fun to do VHF FM
observation of the Perseid meteor shower than to do some canned project.
I have never tried this, so the chances for failure are unknown-to-great.

I went to Radio Shack last night & bought an antenna, mast, tripod,
300 ohm twin lead & misc. supplies, so the project budget comes in at around
$55. I have a tuner. If the FM noise-to-meteor signal bounce proves to
be clear & unamiguous, I hope to catch the sessions on cassette tape,
run them through  a Sun Sparc workstation audio input, and crunch them
to at least show the occurance of meteor bounces (which we'll correlate
with our ear observations), maybe even things like attack & decay rate
if they're discernable.

The seeing was excellent last night (July 29 A.M.), so I decided to
do visual observation of meteors along with trying out radio for
first time. Andromeda galaxy was clearly visible to the naked eye, nice
& big. Also it was the first time I found the Cassini division in
Saturn's rings since I got my C8 last fall (12.5 mm eyepiece, 160X),
so things were pretty good.

I was hoping for Delta Aquarids, saw 4 between 00:20 and 01:00 E.D.T.
(I'm at 75 deg. 45 min. W long., 40 deg. 25 min. N lat.). First two were
fast, bright, and thin, dropped about 10 deg. from western Aquarius
straight down into Capricorn. Next one was a nice fireball, same speed
but shorter path (5 deg.), flared twice, second time brighter, ended
straight above Fomalhaut. Last one high in eastern Aqaurius, very short
and dim, but headed parallel to others.

After 40 mins. some Perseids started coming so I switched my attention &
may have missed a few Aquarids. First one blazed across the Great Square
of Pegasus from berfore Alpheratz to Markab, brighter than the
non-fireball Aquarids. That was about 1 AM. During the next 45 min. I 
saw one parallel to first in Pisces, slightly longer (15 deg.) & bright
(around 1st mag.). One faint one near horizon/Perseus, harder to see,
and another parallel one in Cassiopeia, so they came in at about same
rate as Aquarids.

The concurrent nightime radio observations were ambiguous at best. I
pointed the antenna to the respective radiants for Aquarids and Perseids
as I watched. It was almost impossible to find good clean hiss at night,
so I settled for mixes of stations. There were a few occasions where
other stations would fade in briefly for a second or two, other times
when there would be long, slow fades from one dominant station to another,
but nothing bursty or loud. There was no correlation with the visual
meteors, but I expect that radio meteors will be over the horizon.

I tried again between 9 and 10 AM EDT, pointing the antenna NW for
Perseids, & got some results that I don't understand. I was able to find
some clean white noise/constant hiss below 91 MHZ. (August Sky &
Telescope recommends 88 to 91 MHZ for this), but occasionally the hiss'
amplitude would start to pulse, starting out around 10-20 times a second,
taking up to 10 seconds to drop to a period of 1-2 seconds. ALWAYS at
this point I would hear a radio station for a fraction of a second to
a few seconds, usually faint, but some times booming. The vanilla hiss
would return. At 10 AM a station came on & I quit.

There were about 25 of these from 9 to 10 EDT (I was eating & didn't
keep accurate count, my 6 yr. old daughter was VERY interested &
stayed by the radio). I couldn't account for the leading noise amplitude
pulsations, & when I first heard them I figured that they were cars
coming to a stop somewhere. But the pulsing was lower frequency than
car ignition noises I've heard, slowed in frequency very gradually,
and was ALWAYS followed by reception of a radio station for a short time.
IS THIS IT? I'd deparately like to do this experiment with these
students, but I have to be careful not to do something that bombs &
leaves them with a bad impression. I'd appreciate any advice.
Please email me direct as well as posting a response, since I don't
get to the radio groups regularly. Despite being KB3AB, I've never
gotten a ham station, and my radio theory is about 15 yrs. old & rusty.
Thanks.

I also found the following title in the Bell Labs library system, haven't
got the book yet, but it should be useful for anybody trying this out:

Meteor burst   communications / Jacob Z. Schanker
Boston : Artech House, c1990. xii, 169 p.
Radio, Short wave.; Meteor trails
isbn 0-89006-444-X
Chapter 1 - Meteor Burst Basics: An Introduction     1
Chapter 2 - Meteor Burst Systems: Applications     23
[...]
Chapter 10 - Computer Analysis of Meteor Burst Systems     105
Chapter 11 - Meteor   Burst Trends     115



Dale Parson, Bell Labs, dale@mhcnet.att.com

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|    "These words are too solid, they don't move fast enough           |
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|     Suzanne Vega                                                     |
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