Carl Reade

Hi you will also need to know where and when the Milky way will pass through the horn. Stellarium  software etc.

Carl

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.

5 hours ago, Ed astro said:

Hi Peter,

I would have expected to see atleast something at this point...

The '"wavy" response is also a bit strange, but it may just be the passband respons of the SDR you are using.

To get an idea of what you should be able to see I quickly put together something similar to your setup. I used a small conical horn antenna (which whas originally intended as a feed antenna for my dish but was rarely used), a nooelec sawbird HI LNA and an RTL SDR. I did not do bandpass correction. The hydrogen line shows up as a small bump in the spectrum that normally would not be there. Note that the aperture of my horn antenna is probably quite a bit smaller than yours, so you should expect to see a somewhat stronger HI signal than me.

 

 

Excellent post. That's how small it is. Software is half the battle. I am also not sure what the humps are Peter on your last post, that is an issue in the receive end.

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 be 2db above the noise very weak. I would also ensure the dB increments on the left are as low as you can set, I think the most it goes down to is 3 dB. If aiming for the sun there will be no humps etc the entire noise level will rise.

Software settings can be half the battle.

Hi yes it can be difficult to know if a H line dedicated LNA is working but you should see a rise in the noise level when switching on. A wideband LNA is much easier to test as you can just test it on any signal in SDRsharp to see if it's working. If your H line Freq is clear of spikes you should get away without a filter.

I found it easier to use SDRsharp with the IF Averager plugin. It can be calibrated flat. As per one of your links. The hump can be easily seen when using it. Then go on to the more complex software. 

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 the ground. The noise from the ground is far higher than cold sky hence would wipe out any readings.

Top tip we have a convenient large orange noisy ball in the sky 😁 your entire noise level should rise when pointed at it. If your system can't see the sun it's unlikely it will see the H line.

Go for the sun first. Keep at it you will get there.

Hi here a link to a really useful site which helped me enormously. http://www.parac.eu/

Take a look in the project section  especially project 3 and 9 in the list.

Regards Carl

Excellent results! Keep posting👏

On 02/01/2021 at 16:46, Victor Boesen said:

Thanks to @Ed astro for the simple solution of just collecting an "empty" sample at a slightly higher or lower frequency I had some time today to brush up my software. I think it turned out nice, but I have some issues to fix when averaging a large number of FFT's and the y-axis which doesn't really contain any useful information as of now.

Here are two images of the hydrogen line between Cygnus and Cassiopeia and one in from around Deneb in Cygnus. I believe I managed to catch two peaks in the first photo(maybe even three but the resolution isn't high enough to confirm I'd say).

Thanks all!

Victor

Yes there are three peaks in there here's what I got a while back. Working well!!

Another way would be to feed the system with a dummy load instead of the antenna for a period of time while recording. Straight into the LNA then reconnect the antenna feed.

Carl

Hi good work! There is a plugin for SDR# called IF Averager which will bring out more detail. There is another which flattens out the spectrum but can't remember what it was.

Carl

On 10/08/2020 at 17:37, gabrielxp46 said:

What is the material of the horn feed? Could it be zinc?

Can be a any type of metal, but needs to be weather resistant.

12 hours ago, gabrielxp46 said:

Do you have a pdf or video that best explains your hydrogen radio telescope project?

Have a look at this link from the PARAC site.

http://parac.eu/projectmk3.htm

10 hours ago, gabrielxp46 said:

What is the minimum distance between the PC and the antenna so that there is no interference between the equipment?

Hi probably around a minimum of 5 meters of distance from radio gear to PC. It would also be beneficial to have the receiver in a metal box.

I have had the receiver beside the PC without any problems but depends on your rf environment. You won't know what interference, if any, until you look at the band.

Regards Carl

9 hours ago, gabrielxp46 said:

What materials do I need to build a radio telescope for hydrogen line? What program do I use to obtain and analyze the data?

Hi if you have a read through the thread most of what you are asking is in there.

Hi not sure who the youngest would be. Not too many magazines on the subject it's a small sport. SARA group is very good to join.

This site has been invaluable for me the CFRAD software works great. Have a read at the projects section particularly 3 and 9 to see what is achievable with the basics.

http://parac.eu/

On 17/03/2020 at 17:25, Kaffeedor said:

So now, two months later, I still haven't made first light. Software (I use Cotos VIRGO) is ready, feed is beside LNA done and I think I have a place to put it now.

My problem now is, I think I have destroyed my LNA... 

Does anyone here know a good and cheap(<30€) LNA that I has a USB plug onboard!! and doesn't need to be soldered anywhere? 

Thank you all,

Fedor

Hi there are quite a few options on eBay at that price. Wideband LNAs with a bias tee circuit or screw terminals for power. Why do you think yo destroyed your current one?

 Carl

22 hours ago, Macavity said:

Great stuff @wxsatuser. Since we last spoke, I have been able to resolve
(various HF band) FT8 transmissions that make no "waterfall" trace at all! 😎

As a random thought regarding VNA, my "tuned" longwire (via 4:1 Unun)
gives great SWRs on the (traditional) HF bands: 



UNfortunately, when I add the COAX feeder: "All h*ll breaks loose" ROFL!
I suspect the Coax outer functions as a counterpose / part of the antenna?
Who Knows? I suspect that's why most HAMS favour tuned antennas!  😛

Things seem to be much easier at VHF/UHF where the feeder is "several"
wavelengths long? At the moment I am thinking of doing a survey of all
signals received locally on VHF/UHF, with the SIRIO (to 3Gz!) Discone! 😉

Looks like SUCH THINGS  are a thing of active / serious research! 😉

Who knows? Will I be the oldest ever candidate for the RAE... Will I try
do genuine "Radio Astronomy"... Or just receive satellite weather pics. 🤔

As another GENERAL question, I am thinking of adding a G8FEK BBA3
50MHz-2GHz <1dB noise LNA to my kit of parts! Is the vendor active?
Has anyone tried these LNA's (or similar)? Will a 30dB LNA completely
overload my RSP1A/SDRUno? I sense another ASTRO "Money Pit". lol 🤣

Hi I can vouch for G8FEK LNAs. Very professional and solid. I have the 1300 -1700 and has easily allowed me to observe the hydrogen line. I would definitely add the wideband LNA to your gear if using an SDR as they are not the most sensitive devices and won't overload it at all.

Without going deep into the dark art of antenas my favourites for HF are the Cobweb or the doublet which is fed with ladder line to an MFJ tuner. 

A lot of long wire users tend to use a 9:1balun to match

Carl

It will work fine. I think what UR is saying is the plate on the feed is a reflector which it is but not the main reflector.

Copper will need sprayed with a coating to protect it from the weather. Keep us updated on the build.👍

Love to see some spectrum guys results here. It does look dim to the naked eye. Are we in for a big bang?

3 hours ago, Kaffeedor said:

Hello everyone! 

@Carl Reade

Does this ⬇️ (on the bi quad feed) need to be exactly 90° or can it be like that? 

 

 

Thanks in Advance, 

Fedor

As long as the sides are 90 deg to eachother I'm sure you can have a small curve.

Looks like you will be up and running soon. What size of dish are you using?

Carl

14 hours ago, Kaffeedor said:

Oh sorry I meant this:

@Carl Reade

Ahh it is thin so was able to bend it into shape.

On 17/12/2019 at 18:01, Kaffeedor said:

Hello everyone!

@Carl Reade

How did you attach the 'Sides' of the bi quad, to the main Plate? 

Did you bend it, or did you glue it, (if yes, with what did you glue it?).? 

Bcs I can't find any Conductive Glue for Metall! 

Greetings from Austria 

Fedor (aka. Kaffeedor)

22 hours ago, Kaffeedor said:

Hello everyone!

@Carl Reade

How did you attach the 'Sides' of the bi quad, to the main Plate? 

Did you bend it, or did you glue it, (if yes, with what did you glue it?).? 

Bcs I can't find any Conductive Glue for Metall! 

Greetings from Austria 

Fedor (aka. Kaffeedor) 

Hi Fedor basically I had to cut a hole in the centre of the plate and screw a small price of copper circuit board to a female N connector. So the screws go through the plate and N connector. The. I soldered a small price f hard coax to the copper plate using the correct spacing from the plate. Then I soldered the "bow to the coax. The top middle of the bow to the centre core and the bottom centre to the outer coax. As I used hard coax its outer is like copper tube and was enough to support the bow. It is far easier if you can get a piece of copper plate and solder a small copper pipe to it and then you just feed coax though it. The second pic is an easier way. I would also mention that you need to solder with a blowtorch to get enough heat and plumbing solder. Hope this makes sense. Carl.

Have a read through the thread there are lots of links and diagrams to get you started.

Carl