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Old 19-04-2011, 09:51 AM
Shenanigans
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Yagi Recever antena Amplification

Hi ive been looking at how to make a Yagi radio telescope for monitoring solar activity by listening to radiation in the atmosphear. I cant seem to figure out how im supposed to amplify the signal from the antena before feeding to the recording device (which will be my sound card) By how much do i need to amplify and what sort of amplifier do i need.Ive seen somewhere i may need to filter the signal, I realy dont mind making it from scratch if anyone knows of scematics for the amp i need. any help would be usefull. Thankyou
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Old 19-04-2011, 11:08 AM
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ZeroID (Brent)
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You need to be asking this on the Radio Astronomy and Spectroscopic forum
http://www.iceinspace.com.au/forum/f...splay.php?f=40.
There is a good forum over on CloudyNights as well. Plenty of links to the relevant hardware requirements.
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Old 19-04-2011, 11:33 AM
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Quote:
Originally Posted by Shenanigans View Post
Hi ive been looking at how to make a Yagi radio telescope for monitoring solar activity by listening to radiation in the atmosphear. I cant seem to figure out how im supposed to amplify the signal from the antena before feeding to the recording device (which will be my sound card) By how much do i need to amplify and what sort of amplifier do i need.Ive seen somewhere i may need to filter the signal, I realy dont mind making it from scratch if anyone knows of scematics for the amp i need. any help would be usefull. Thankyou

It is not clear from you post what you actually want to achieve..
Sound card of your computer may be a good recording device (it has ADC's) but it also has a limited bandwidth (being an audio device) so you have to include some sort of detector to your project.

There are kits for receiving radio signals from Jupiter, they may be used on Sun as well.

Last edited by bojan; 20-04-2011 at 04:23 PM.
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Old 19-04-2011, 01:54 PM
pjphilli (Peter)
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Hi Shenanigans

I recall assisting in a project for listening to radio noise from space some time ago.
This was in the range 20 to 30Mhz. Some things to keep in mind:
1. The HF bands are jam packed with manmade signals and noise so it
is rather hard to find a quiet spot to listen to extratrerrestrial noise.
2. Rather than go to the expense of building a special receiver see if
you can get a cheap dual band (ie am/high frequency) receiver and listen around on the hf bands that you wish to study. Such small receiver can often be bought very cheaply at garage sales or markets and likely you already have one!
3. In regard to antennas, a yagi will give you more selectivity and sensitivity in a given direction but keep in mind they are rather large for HF band frequencies and providing mechanical means of pointing can be rather challenging.
4. As above, to reduce unwanted signals, a narrow band audio filter
between the output of the receiver and computer recording device
would help. You may find lots of circuits for these on the net. However,
first you need to find what bandwidth the solar signals occupy. A straight out am receiver will give you about 5Khz or so of audio bandwidth.
5. To embark on such a project you will probably need some (or access to
someone with) rf/electronic expertise.
6. Don't want to turn you off but the friend I was assisting eventually gave up this quest will little to show for it mainly because non extraterrestrial noise was too hard to separate from manmade "noise".
(Almost as bad as big city astronomy!)

Cheers Peter
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  #5  
Old 19-04-2011, 02:29 PM
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Brian W (Brian)
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Quote:
Originally Posted by Shenanigans View Post
Hi ive been looking at how to make a Yagi radio telescope for monitoring solar activity by listening to radiation in the atmosphear. I cant seem to figure out how im supposed to amplify the signal from the antena before feeding to the recording device (which will be my sound card) By how much do i need to amplify and what sort of amplifier do i need.Ive seen somewhere i may need to filter the signal, I realy dont mind making it from scratch if anyone knows of scematics for the amp i need. any help would be usefull. Thankyou
Hi if you can find a copy of the AARL ANTENNA BOOK most if not all of your questions will be answered.

Brian
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Old 19-04-2011, 02:37 PM
Barrykgerdes
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Hi

I have listening equipment that covers the broadcast band to 30 MHZ
and 100Khz - 20 GHz (a spectrum analyser).

I have spent a lifetime in radio communications and have listened to the noise in the 20-30Mhz region but never heard anything I could identify as coming from space so it is really not something that I would expect a novice to have much success with.

A highly directive antenna for the 20 - 30 Mhz band will require a few hectares of space and if you want to be able to point it, well that is another story..

A yagi is probably the simplest type of directional aerial to build or a modified version called a cubical quad can reduce the size but they do not have a very wide bandwidth and will need to be built to the correct size. These types have directional properties that become sharper as the size increases.

A wide band directional aerial is the log aperiodic but these will be bigger than a similar performing yagi at a single frequency.

If you have suitable receivers directional aerials for UHF and Microwaves can be built much easier. There is space noise in the 400Ghz region and the Sun gives out a lot of RF in the 1420Mhz Hydrogen radiation. These aerials will be directly pointable to the noise source so you will be able to see where it comes from.

I am in the process of re-commisioning the 1420/400 Mhz dish aerials at Wiruna but have not reached the stage of actually looking for signals. I have made a dipole feed for the 1.5 metre dish and will try that next time I go to Wiruna.

Barry
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Old 19-04-2011, 03:10 PM
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Brian W (Brian)
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Hi, not trying to hijack this thread but perhaps the Jovian antenna set-up that NASA sells might be a good way to begin to get involved in this end of the hobby?

Now I know next to nothing in this area so if someone like Barry might think it was a good idea or not a good idea as a place to start I would put a lot more weight into his opinion than mine.
Brian
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Old 19-04-2011, 04:11 PM
Barrykgerdes
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Hi

There is quite a lot of information on the internet if you google jovian antenna. This site has a number of recordings of the sound bursts fo different events to help you know what to look for.

http://www.radiosky.com/rjcentral.html

The signal level however is only in the vicinty of .25 microvolts so it will not be readily noticeable. A directional dipole will give some gain, perhaps up to 10 db but the signals will still be masked largly by other noise.

Barry
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Old 20-04-2011, 04:19 PM
Shenanigans
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Quote:
Originally Posted by pjphilli View Post
Hi Shenanigans

I recall assisting in a project for listening to radio noise from space some time ago.
This was in the range 20 to 30Mhz. Some things to keep in mind:
1. The HF bands are jam packed with manmade signals and noise so it
is rather hard to find a quiet spot to listen to extratrerrestrial noise.
2. Rather than go to the expense of building a special receiver see if
you can get a cheap dual band (ie am/high frequency) receiver and listen around on the hf bands that you wish to study. Such small receiver can often be bought very cheaply at garage sales or markets and likely you already have one!
3. In regard to antennas, a yagi will give you more selectivity and sensitivity in a given direction but keep in mind they are rather large for HF band frequencies and providing mechanical means of pointing can be rather challenging.
4. As above, to reduce unwanted signals, a narrow band audio filter
between the output of the receiver and computer recording device
would help. You may find lots of circuits for these on the net. However,
first you need to find what bandwidth the solar signals occupy. A straight out am receiver will give you about 5Khz or so of audio bandwidth.
5. To embark on such a project you will probably need some (or access to
someone with) rf/electronic expertise.
6. Don't want to turn you off but the friend I was assisting eventually gave up this quest will little to show for it mainly because non extraterrestrial noise was too hard to separate from manmade "noise".
(Almost as bad as big city astronomy!)

Cheers Peter
Thanks Peter, ive taken what you said onboard, the hardest part of this project is aiming the antena. Im going to spend alot of time on doing just that. If i cant do it i might just buy a goto telescope. thankyou
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Old 20-04-2011, 04:22 PM
Shenanigans
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Quote:
Originally Posted by Barrykgerdes View Post
Hi

There is quite a lot of information on the internet if you google jovian antenna. This site has a number of recordings of the sound bursts fo different events to help you know what to look for.

http://www.radiosky.com/rjcentral.html

The signal level however is only in the vicinty of .25 microvolts so it will not be readily noticeable. A directional dipole will give some gain, perhaps up to 10 db but the signals will still be masked largly by other noise.

Barry
Very good site, with some good examples and software. Thankyou Barry
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  #11  
Old 20-04-2011, 04:24 PM
Shenanigans
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Originally Posted by Brian W View Post
Hi if you can find a copy of the AARL ANTENNA BOOK most if not all of your questions will be answered.

Brian
I found a copy and i should have it soon. thankyou Brian.
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  #12  
Old 20-04-2011, 04:49 PM
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Long time ago I was involved in recording man-made noise and distant thunderstorms, reflected from ionosphere, around 27kHz (yes, kHz.... just above audio band). (Atmospherics)
While this may sound to be trivial, it is actually indirect observation of the Sun's activity, as this noise level was directly affected by Sun (the received signal was properly filtered, rectified and averaged so it represented a slowly changing DC voltage that was easily recorded on the paper tape by mechanical chart-recorder).
Some details on this are available here: http://www.ann-geophys.net/25/2175/2...-2175-2007.pdf

The effect is most prominent just prior to dawn
http://www.sciencedirect.com/science...c&searchtype=a

http://books.google.com.au/books?id=...page&q&f=false

This may be much easier than SW band (as an antenna, you need just a long wire between two trees, 10-20 metres apart).
The receiver is actually an audio amplifier (with 27kHz filter at front), rectifier + LP filter and DC voltage recorder...
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Old 20-04-2011, 05:10 PM
M_Lewis (Mark)
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We used to use quad-matched helicals for moon bounce on the 2m band a ways back. They had a much tighter directional pattern than yagi's did, and higher db gains. I'm not sure why I keep my amatuer licence current, especially when i dont' use it. They like to charge $66 a yr for the piece of paper.
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