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Re: (meteorobs) Radio Observation of Meteors

Steve Harrison wrote:
> 
> At 12:04 AM 1999-08-21 -0700, you wrote:
> >
> >       On the subject of radio observations, I was wondering if amateurs had
> >tried radar detection of meteors themselves.  Perhaps using a beacon
> >with a directional antenna pointing upward, and a receiver with an
> >upward facing antenna a few kilometres distant but out of the ground
> >wave of the transmitter?

	An advantage of doing it this way is that a common beacon may be shared
with multiple receiving sites.  If everything was synchronized from a
common source, such as a LORAN station, once the different propagational
delays are corrected for at the individual receiving sites, multiple
receiving sites are practical.
> 
 it's quite easy for the ordinary amateur to
> build an antenna switch using PIN diodes that will allow antenna switching
> in plenty of time to receive echos from meteor scatter in a backscatter
> system.

	I'd looked into PIN diode switching methods, but I've had problems
getting data on the higher power devices, and finding a supplier.  On
the high speed low power end I've begun experimenting with the Philips
SA630, (1GHZ, 1 dB insertion loss, 50 MHz switching speed, 50 ohm SPDT
switch, unfortunately its only linear up to about 100 mW).  I was
looking into using it for the simple time difference of arrival type of
direction finding for transmitter hunting.

The main problem will be having to design and build a receiver that
> will recover quickly enough; but even that is not a major undertaking.

 In
> fact, one Swedish ham, Leif Asbrink, SM5BSZ, has designed and built his own
> system that he uses not only for meteor detection but also for detection
> and evaluation of aurora conditions; see this URL, near the bottom of the
> page:
> http://ham.te.hik.se/homepage/sm5bsz/index.htm

	I'm going to check it out, thanks.
> 
> I've built and tested my own PIN diode antenna switch which I've tested at
> 500 watts CW power, much more than sufficient, combined with a
> moderate-sized yagi antenna, for detection of meteors, so can attest to the
> practicality of this approach. I haven't had the time to complete a
> receiver, however.

	Would it be practical to adapt something, perhaps from one of the kits
for amateurs to complete the receiver side and try it out?

 But Asbrink also details a receiver system based on a
> fast PC (Pentium II+ required) which can perform all kinds of data
> processing including filtering of received signals, etc.

	
> 
> As for the type of modulation: software to generate phase-shifted audio
> tones with which to drive a standard SSB VHF/UHF transmitter can be easily
> generated using a PC equipped with a standard sound board.

	This last year I've been looking at modifying some of the courses I
teach, so I was looking into various microcontrollers.  I'm thinking
that the newer microcontrollers may have potential, for a dedicated job,
to replace the computer and sound board.

 In point of
> fact, computer-based high-speed morse code meteor scatter (HSMS) has been
> growing amongst North American hams over the past three years,

	I wanted to try that mode, I have the PK 232 with the high speed MS
software, but the software is probably 5 years old now, I doubt that it
would handle 3300 WPM.  And when I started meteor scatter there was more
interest in radio telephony.

 The
> one caveat is that to date, there are no beacon stations in North America
> transmitting with high-speed CW (HSCW) although I believe there have been
> plans for at least one such temporary manned beacon station located in the
> Canadian maritime provinces during last year's Leonids shower. I haven't
> heard of any such plans for 1999 Leonids as yet. The idea of the station
> was to perform the first-ever cross-Atlantic meteor scatter contact between
> North America and Europe using double-hop, or two simultaneous, Leonids
> meteors which could extend the possible distance between the transmitter
> and receiver stations to beyond 3000 km, spanning the Atlantic ocean.

	I was thinking about that a couple of years ago, I'd even posted the
question, as to whether or not a double MS hop was possible, on another
list.  Well, apart from St. John's, NF, there isn't a much better
location to do it from than where I am now.
> 
 Due to the special fast-recovery requirements
> of the receiver, however, a home-built receiver would probably prove as
> easy to implement as modifying something bought off the shelf.
> 
	Maybe its a matter of time then before a few people carry the idea
through to where at least schematics, software, and PC boards are
available for experimenters.  It looks like its unlikely before this
years Leonids.

			Ron (in Gander)
-- 
R & L Thompson, 9 Medcalf St., Gander, NF, Canada A1V 1R9
Tel (709) 256-1179, Fax (709) 256-8638, e-mail rlthompson@thezonedot net

Amateur Radio Station call VO1AV, FP5EK, VE1KM   Grid Square GN28qw
Location 48 57'08" N  054 36'43" W, 
Local time UTC - 2.5 hrs Summer, UTC - 3.5 hrs Winter

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