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."

Have you tried...

[Usquebaugh]

The SARA [bambi.net], ARRL [arrl.org] or DX zone [dxzone.com]. You've probably done the google search for "amateur radio telescope" [google.com]
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 /. 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.

Re:Have you tried...

[Vrallis]

....your local ham or astrology club....

I really do hope you meant astronomy club. I don't think Miss Cleo will be of much help with a radio telescope.

Re:Have you tried...

[Hillman]

OH NO! I'm sure he meant astrology! He doesn't want some fancy computer to "interpret" the data! Oh no! He want the real deal! Because miss Cleo gives you the real deal! It might hurt but it's the truth!

Ok, i'll shut up now

Lockergnome

[kruczkowski]

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.

Phasing

[Detritus]

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.

Bandwidth

[Technician]

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)

Moon bounce receive, Weather imaging, Microwave

[QuietRiot]

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 [uiuc.edu] 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...

Re:Moon bounce receive, Weather imaging, Microwave

[billn]

With enough antennae, you could built a (albeit spectrum limited) Very Long Baseline Array by sprinkling the dishes among geographically disparate users and tying it all together via internet links and controller software designed to handle it.

I recall seeing some use of those style dishes for directional wavelan antennae, you could try stringing a transcontinental wavelan backbone. (http://www.personaltelco.net/index.cgi/WirelessLi nks#line166 for a collection of links)

Just a few thoughts.

Re:Moon bounce receive, Weather imaging, Microwave

[Sean Clifford]

Cool - I hadn't considered using them as a poor man's doppler radar! :) One other project I've considered is to build an extensive wireless network, but our business is installing satellite television for <<the_major_brand>> and I really don't want to get into the ISP business. I'd like to do something creative and useful, especially something that can interest the high school students down the block in science.

As several posters in the know have pointed out, I don't really have the equipment (or the know-how) to do SETI, but thought I might be able to do a bit of amateur radio astronomy (with research and help). We do have a few large dishes (about 5 meters in diameter). I did some google and other search engine searches before turning to /. - and I appreciate all the feedback, folks. If we get something interesting off the ground, I'll definitely let y'all know.

sensor integration

[Dr. Tom]

Check this out, too:

Hasas [freshmeat.net]

It's for sonar, but the beamforming technique is applicable to phased arrays.

AIPS++

[Kludge]

AIPS++ is what professionals use.

http://aips2.nrao.edu/docs/aips++.html

Radio Telescope Array in Concord, CA

["Zow"]

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"

802.11b

[Stavr0]

How about some 802.11b relays? Neighborhood ISP for hardcore gamers ....

Re:802.11b

[Sean Clifford]

We're using some of them for 802.11b projects [slashdot.org], but I've got a couple of hundred of them laying around - thus the proposed radio telescope project. I have a lot more to learn about this stuff than I initially thought, but if I can recruit enough local talent and bug some ham and amateur astronomer gurus from time to time, I'm sure I can get something cool running.

Even if all I can do is poor-man's doppler radar, survey the moon, or look at stuff in orbit the project will be enough to keep me occupied in my "spare time".

Thanks, fellow slashdotters, for the valuable advice and for pointing me in the right direction. I'll set up a web site about this project once we get off the ground and keep y'all posted.