Radio Astronomy - Setting up A Radio Observatory

As you may know from a thread in the "Wanted" section, I'm in the process of setting up a radio observatory for purposes of pursuing astronomy from a slightly different perspective. The last three years have been pretty dire from a visual perspective due to the weather and I thought it was time to try a different approach. So, for starters, I'm going to try and set up a meteor detection observatory using radio signal reflection. Unfortunately, my knowledge of all this radio stuff is very limited, but I will explain it as best I can and update this thread from time to time as I learn more.

The equipment required:
1. Radio Receiver
2. Antenna
3. Computer
4. Transmitter
5. Software

1. The Radio Receiver
First, one needs a radio receiver. The one I got was a secondhand radio receiver called an ICOM PCR-1000 which covers a very large range of frequencies (from 0.01 to 1300 MHz to be exact). From reading various sources, this particular model is highly recommended for this type of work. Compare this to an FM radio which covers the frequencies of approx. 87.5 - 108.0 MHz. So, straight off, I can tune in to many more frequencies than an ordinary FM radio.
The second reason for using this piece of equipment is the bandwidth of the frequencies to listen to. With an FM radio, if we tune to say 100 MHZ for Today FM, we are also listening to quite a chunk of data either side of 100MHz. A radio station needs to work this way in order to get decent quality audio to you. With a computer controlled radio receiver such as the PCR1000, one can tune in to a tiny segement/bandwidth of data very precisely.
Third reason is that you can connect the radio receiver directly to the computer via an RS232 or USB cable. In my case, the receiver is an old model so it has a serial cable and then I use a serial-USB device to connect it into my computer. One can adjust the controls of the radio receiver with the computer very precisely and let the computer analyse the data 24/7 using software.

2. Antenna
This is the part I am in the process of purchasing right now. There seem to be loads of different types of aerials/antennas out there and to be prefectly honest, I don't know exactly the difference between many of them. What I do know is that the shape of the antenna will determine the frequency one can listen to. Basially, to tune to certain frequencies, you need to optimise the length of the antenna. One example is the dipole antenna which is a realtively popular antenna. To put it simply, if you want to tune to a particular frequency, the antenna should be bought (or made by you!) so that you can pick up that particular frequency.

3. Computer.
This is the easy bit. Most of us have one of these!

4. Transmitter
The beauty here is that this is the most expensive device and you don't even have to buy it! Basically, its a TV station! For the reflection of radio frequencies from meteors, it is recommended to aim for about 50 MHz. Why? It is around this frequency which many TV stations broadcast on. The lower the frequency, the more effective the radio scatter becomes. Basically, the lower the frequency the more meteors you hear and the same meteor will produce longer duration and stronger reflections. To only get reflection, the transmitter must be below the horizon. If it's only a small distance below the horizon, you may get reflections from aircraft. However, it can't be so far below the horizon that the radio waves miss the meteor altogether (e.g. Australia!). Generally, a transmitter should be approx. 600 - 800km away from the receiver.

5. Software
The PCR-1000 comes with software which allows full control of the radio via the computer. The other software you need is called Spectrum Lab . This software is free and seems easy enough to operate. Generates a graphic result of the data.

So, at this stage, I have the radio receiver. I just ordered the antenna , cable and connectors. Hope to have that kit on the next week or so. I'll let you know how I get on.

Some links with more info:
www.tvcomm.co.uk/radio/
www.imo.net/radio
www.ramfihaz.com/index.htm

Regards,

Michael.

Frequency around 21mhz would be best according to those that know
Antenna, would suggest a 2 element yagi beaming south or a Moxon beam
www.mydarc.de/dk7zb/start1.htm

Some gain and good noise rejection form the sides

Hmmm, that's intersting. A couple of sites I've read (for example: www.meteorobs.org/maillist/msg14637.html )have said to avoid going below 30 MHz due to interference from solar activity. Although we are at solar miniumum I guess...

Michael.

Jupiter tansmits at 20Mhz and I believe its outbursts during radio storms can be more powerful than solar activity due to cyclotron maser processes - which I beleive just means laser but in radio instead of optical.

However, I read that these outbursts aren't continuous as it is transmitted as a large hollow cone and only when the earth clips the wall of the cone - and a storm is inprocess - do we detect the outburst.

But for meteor detection it would appear to me (and in the light of very limited knowledge) that straying away from the 20Mz might be prudent.

You're heading into a fascinating area there Michael - best of luck - and please do keep us updated.

Mark

Best of luck with your project Mike. I am also in the game of setting up a Radio Telescope at home here. I'm going the old fashioned route of antennae >> Bearcat scanner >> DC 'smoother' circuit >> pen recorder (I don't leave my PC on all the time). The scanner covers all frequencies and with the different antennae designs I'll have finished, I'll be able to pick up a heap of things.
Using the scanner's headphones-out jack, I'll split it - 1 part for an audio recorder and the other to pass through the DC circuit and into the pen recorder, which will record my findings graphically. I can then correlate the audio 'over' the graph paper for comparisons.

Later, once I see how you get on with the software, I might try that route with the laptop. I'll let you be the guinea pig first!

Seanie.

So Michael, this is what the crap weather has driven you to :lol:
to be honest, this is also something that I had/have been considering getting into, let us know how it works out.

Imagine the neighbours reactions, first a white dome, and now these ariels start popping up in the back garden, they might think an alien is living back there trying the phone home. :silly: