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(meteorobs) Radio Observation of Meteors

Hi John,

Read your message regarding the radar site in Texas being used for meteor
detection and your query about using WWV.

I haven't read all the responses (although it is heartwarming to see so
many--there's hope for the radio detection of meteors yet!), so I'll make
my coments and then read a few more and comment again if necessary. (By the
way, the reason I didn't read them all at once is that I am still
recovering from heart surgery and it takes a lot of effort even to read
e-mail. So hopefully everyone will bear with me.)

Yes you can use WWV. I am the leader of the Ontario DX Association's Meteor
Detection Group and a few years back we did that experiment, but we used
CHU (14.670 MHz) in Ottawa. CHU uses a 5 kW transmitter for 24 hour-a-day
time signal transmission on that frequency. As you suggested, we did
middle-of-the-night experiments, but even during the day, propagation
between our receiving site (near Toronto) and Ottawa is non-existent. The
reflected signals were classic patterns for underdense and overdense
trails.

In fact, the lower you go in frequency, the longer the duration of the
reflection and the higher the reflected-signal amplitude (assuming all
other things being equal). So the lower frequencies should be much better
for meteor detection. However, as Ron noted, the problem is the number of
stations. On vhf TV and the FM broadcast band, there are lots of
high-power, 24 hours-a-day stations to monitor. It's tough to find many
stations below VHF. Commercial meteor scatter networks usually operate
between 40-50 MHz because above 50 MHz, propagation loss rises too rapidly;
below 50 MHz, antenna size increases too rapidly. Ron also mentioned
shortwave stations (I think). The ODXA's Meteor Detection Group also
monitored VOA's early morning transmission to S. America (in the 19-meter
band, I think). The question which we never could answer was whether we
were hearing meteor reflections from the VOA signal off the back of their
antenna or whether the reflections were 'back scatter' from meteors to the
south of the VOA site. (Back scatter isn't an accurate term in the case of
meteors, but it gives the general idea.) The other problem with HF meteor
detection is that noise rises rapidly below 20 MHz and that makes weak
reflections difficult to hear. We did attempt to receive signals from CHU
on 7.335 and 3.330 MHz during the day when propagation was non-existent
between Toronto and Ottawa, but we were unsuccessful. Discussions with Dr.
Oswald Villard, Jr. lead us to the conclusion that it was just too noisy to
hear anything on such low frequencies. (Some of the early work in meteor
detection was done on low frequencies, but they were likely sucessful
because they were using high-power cw radar.

An ideal opportunity for meteor detection should be the 10-meter amateur
radio band, especially during showers. If we could get enough amateurs on
10-meters there should be lots of reflected signals. The ODXA has run two
tests so far on 10-meters. During one we asked for help through
announcements in QST, CQ VHF, TCA (a Canadian amateur radio magazine), etc.
The only contacts we made were with two stations with which we had
pre-arranged schedules. We did also receive a couple of reception reports
from listeners. The second test was a space diversity test in which we
didn't pre-arrange schedules. Again we advertised, and we sent e-mails to
clubs and amateur radio groups. We are going to try again in November
(during the Leonids). We have requested the use of VE3OSC, the amateur
radio station at the Ontario Science Centre here in Toronto and we have
already asked for the assistance of a couple of amateur radio stations at
science museums in the U.S.. I think the 10- and 15-meter amateur radio
bands should provide excellent opportunities for meteor work, but we need
more stations operating. It may even be possible to use the 20 meter band.
There are more than enough 1 kW amateur stations around that have beam
antennas. I think just not enough amateur radio operators are aware that
meteor scatter is possible on the HF bands.

Anyway, John, give WWV a try and let me know how you make out.

(By the way, where do you live?)

Phil Gebhardt, VA3ACK
pgebhardt@compuserve.com
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