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Re: (meteorobs) Radar equipment to monitor meteors
At 03:14 PM 12/13/97 +0100, you wrote:
>Hi everybody from Milano,Italy.
>A simple question.Is somebody using a radar equipment to monitor meteors?I
>mean,is it possible for an amateur to build and use a radar easily?
It is illegal for amateurs to use unmodulated pulse transmissions (which is
what most radar transmissions are called) on the frequency bands where
meteor reflections are common; 6 meters, 2 meters, 220 MHz, and 70 cm bands.
But it IS allowable for amateurs to operate on those bands with extremely
high speed morse code; I have daily schedules at speeds to 1600 words per
minute. So practically, I can actually use high speed morse code, sending
only the letters like "E" or "T", and monitor reflections on a
specially-designed receiver for my own meteor reflections.
It is also illegal to transmit on any frequency without a license, of
course. But most classes of amateur radio operator and station licenses
throughout the world would allow this type of operation.
Is is easy to build such a receiver and transmitter system? Well, it's
technically not at all difficult, although several of the circuit details
are not used in other amateur operations and so will be unfamiliar to most
amateurs. The parts are also readily available. One can obtain very good and
strong reflections using amateur power levels from one hundred watts to 1500
watts, and one can obtain good reflections with standard high-performance
yagi antennas. The only real fly in the ointment is the data collection. But
even there, there are several software programs available which are probably
useful; they were designed for continuous monitoring at automated meteor
receiving stations and might need some modification to work well in this
application.
So the short answer to your question is yes, it is practical for an amateur
to build and operate a propagation "monitoring" radar-emulation station. It
does not require unusually-expensive equipment, but does require
considerable technical know-how. Several amateurs in Europe have built and
operated such stations for some years to monitor all kinds of reflecting
atmospheric propagation conditions including meteor trails, aurora,
sporadic-E, and even to find tropo ducts lying low in the atmosphere. A web
page where you can read of at least one person's experments in this area is:
http://ham.te.hik.se/homepage/sm5bsz/aurora.htm
I've seen at least two other such pages by others in northern Europe and
will look for them if there is any interest. I have never heard of an
amateur in North America building and operating such a station over any long
period of time, although I know a few have built a station and played with it.
Also, the type of equipment and displays for this application are very
similar in principle to that used for weather radar; I know that a few North
American amateurs have built and operated weather radars for the 10 GHz
band, where pulse operation is permitted by the licensing authorities. It
would be possible to combine the basic receiver demodulation and display
circuitry used for either a meteor radar or a weather radar into one unit,
even to the point where the hardware is identical, only the software display
would change (you would be a little confused, for example, to see a meteor
trail displayed as a possible wind shear event!).
Personally, I would like to build such a system which could operate
simultaneously on a number of amateur bands from 50 MHz through 432 MHz, in
addition to having a video camera available; it would be very interesting to
see what kinds of visual meteor trails produce radio reflections at the
higher frequencies. What I lack is the time; I estimate it will take about a
half year minimum for me to have more than two bands running simultaneously.
SteveH
Amateur Radio Meteor Scatter Station Ko0U/1
Shrewsbury MA, Grid locator FN42dg