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Neutral Hydrogen Detection - sigh.....


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23 hours ago, Ed astro said:

 

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Ed that is a really cool setup, would be good for outreach. 

Jim 

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Hi, if you have the software running, when you turn on the amp the noise level should jump up. Will give you an indication things are connected. The last thing you want to use in calibration is t

Hi all yes I would recommend using the sdr Averager plugin to start with and take a calibration about an hour before the galaxy comes into view of the scope. Bear in mind the H line will usually only

Hi, I agree with Carl Reade, with my 3 metre dish the hydrogen line is at most around 2dB above the noise floor. I also use IF average and it works fine for me. I would like to add that the

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Yes, I'm none the wiser about those bumps in the output.  I tried to get a reading on Saturday and it took me 4 hrs in the morning to capture the background, then I managed to get 1 reading in the afternoon, which was completely flat.  This is most likely because it took so long.  I'm not currently hooking SDRSharp up outside to the received, but using spyserver in the middle with a PI (as PI's are more portable to the garden and easier to waterproof!).  In other words, I have a desktop PC running SDRSharp doing a TCP/IP connection over WIFI to a PI running spyserver, which has the SDR and antenna etc connected.  The WIFI is good and I don't think it is responsible for the 4hr delay, but my next test will be to hook the sdr directly up to my PC and see if that works better.  It might account for the 4 hr delay, the bumps or whatever.  There isn't much in terms of guides on IF Average plugin - does changing the level/gain invalidate a (background) capture if its in progress?

Anyway, at the moment, based on the last couple of replies, I was having better success with the original VIRGO software, as I at least had a graph matching Ed's with the 3 peaks (tho no hydrogen bump).  At this rate, I'm expecting someone to show me they can pick it up with a milk bottle top, but that was a good graph, thank you!  I think you're right and that this is software - I can pick up other things like FM radio, the antenna etc fundamentally works and I have to assume it is getting at least reasonable gain on it (more than just the waveguide horn shown above anyway).  

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9 hours ago, Peter Masters said:

Yes, I'm none the wiser about those bumps in the output.  I tried to get a reading on Saturday and it took me 4 hrs in the morning to capture the background, then I managed to get 1 reading in the afternoon, which was completely flat.  This is most likely because it took so long.  I'm not currently hooking SDRSharp up outside to the received, but using spyserver in the middle with a PI (as PI's are more portable to the garden and easier to waterproof!).  In other words, I have a desktop PC running SDRSharp doing a TCP/IP connection over WIFI to a PI running spyserver, which has the SDR and antenna etc connected.  The WIFI is good and I don't think it is responsible for the 4hr delay, but my next test will be to hook the sdr directly up to my PC and see if that works better.  It might account for the 4 hr delay, the bumps or whatever.  There isn't much in terms of guides on IF Average plugin - does changing the level/gain invalidate a (background) capture if its in progress?

Anyway, at the moment, based on the last couple of replies, I was having better success with the original VIRGO software, as I at least had a graph matching Ed's with the 3 peaks (tho no hydrogen bump).  At this rate, I'm expecting someone to show me they can pick it up with a milk bottle top, but that was a good graph, thank you!  I think you're right and that this is software - I can pick up other things like FM radio, the antenna etc fundamentally works and I have to assume it is getting at least reasonable gain on it (more than just the waveguide horn shown above anyway).  

Hi maybe a factor maybe not I had read that the PI itself like most computers can cause interference via RF and needs to be a good distance from the LNA and antenna. Maybe the bump issue especially if it's using WiFi as well.

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Yeah it does actually cause a lot of interference, so I had moved it 5m away (using USB extension cables between it and the SDR) and I also wrapped it in tin foil (clingfilm first to ensure the tin foil didn't cause connections on the PI).  I don't think that is the issue still because I'd be seeing spikes on particular frequencies.

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