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Surplus PrimeStar Dishes => Radio Telescope Array?
Sean Clifford asks: "Anyone
have suggestions on how to get started setting up an amateur radio
telescope array using a ton of old PrimeStar dishes? I've read a
couple of articles like this
one, that makes this idea seem good in theory. Adapting some gear
for RVs to steer the dishes should be simple, but does anyone know of
good open source software for controlling them? And *nix software
for collecting, filtering, and analyzing the data would be sweet
too. I've got a couple of hundred dishes in the back yard at work
that are screaming for some type of use other than recycling. I'm
already adapting a couple for a wireless network, but would like to
see what I can do with the rest."
Personally I think it is WAYYYYY too much trouble to set them up as a radio telescope type array.. Do you really have enough time to spare for that type of thing?
Maybe consider turning them into a collection of nice woks. Chop suey anybody?
i hate pansy republicans
The SARA, ARRL or DX zone. You've probably done the google search for "amateur radio telescope" /. should post, I doubt there will be many posts but who cares. I want thought provoking or interesting questions. In short I want questions that make me go and hunt down some ideas.
Given that you have the hardware it would seem you need to find someone who has the skills to design the thing. My guess is that your local ham or astrology club would have people who have the knowledge and desire to help. Do you have a university close by, prehaps they might want to take it on as a grad project. But my first port of call would be SARA.
IMHO this is the sort of question that
The guy that runs the Linux newsletter on lockergnome.com builds telescopes. He was saying on one of his newsletters that he uses Red Hat 6.2 to power his telescopes. He also said that he was selling them to Japan, so it soulds like he knows what he is doing.
hmm... for fun I enjoy launching DDoS attacks against 127.87.42.5
I'm not an RF guy, but I work around microwave antennas and receivers. Combining multiple feeds, from one antenna or multiple antennas, is tricky, esp. at microwave frequencies. For the frequency of interest, the feeds must be in phase with each other. You need to be able to adjust the phasing for maximum output from the combiner. If you want to do interferometry, it gets a lot more complicated.
Mea navis aericumbens anguillis abundat
Being a licensed radio amateur (holding a General ticket), this post interested me in that respect.
A quick google search for "dish array" took me here which explains some of the basics of dealing with dish arrays.
One thing I was considering is not using the dishes to look randomly to space hoping to sniff some martian communications, but to somehow extract some known low level signal from somewhere - how about the moon? Amateurs sometimes bounce signals off the moon for communication. Really! Do a search for moon bounce, find out the frequencies often used, and see if you can construct an array.
I know I made that sound _really_ simple, but I'm sure it wouldn't be. I think the frequencies involved would significantly complicate using those small dishes and the supplied LNBs (or whatever the receiving elements they use these days are called). Anyway, it's something to look into.
I'd also suggest looking into ways in which you could turn an array into some sort of radar receiver. Lay them out correctly pointing to the sky and bathe some clouds with radar signals. Try to image the cloud densities, determine their height, etc.
Put them on the wall of a high building for weak-signal microwave receive.
Just some ideas...
Bandwidth of the dishes is going to be a problem. Much of the search is in the 150 MHZ and up spectrum. The smaller dishes can not focus a signal much larger than 10 cM. They are limited mostly to the microwave band above 1GHZ. They will not work well in the 100 Mhz to 1GHZ band. Phasing an array for a large effective apature is not childs play at these frequencies. Temprature changes change the geometry of the feedlines. Microwaves have a very high attenuation in coax. To get past just these limitations would almost require downconverting. To maintain signal phase, the downconversion would have to be done with very low jitter phase locked downconverters tied to a master clock. Last time I checked a phase locked downconverter was >$1200.00 US. (I installed one for a radio station to receive a subscription CANA feed on C-band)
The truth shall set you free!
Check this out, too:
Hasas
It's for sonar, but the beamforming technique is applicable to phased arrays.
AIPS++ is what professionals use.
http://aips2.nrao.edu/docs/aips++.html
I'm pulling this from deep in my memory, so I may be completely off here, but I seem to recall that the University of Califoria, Berkeley had a large array of radio telescopes in Concord, CA - I saw a picture once and they didn't look to be that big - maybe 1 meter radius tops, but the picture wasn't that good so my sense of scale could have been completely off. In any case, it's probably worth digging around the department of astronomy pages at Berkeley and see what you can dig up - chances are that it's affiliated with SETI.
Good luck & have fun!
-"Zow"
How about some 802.11b relays? Neighborhood ISP for hardcore gamers ....