Victor Boesen

Thanks!! I would watch out increasing the median smoothing too high as that could hide some of the faint/weak details of the hydrogen line such as individual peaks and etc. But other than that, I'd say it looks great

That's excellent Steve!!! May I ask what parameters you used? The spectrum is very good looking, far better than what I've managed! Victor

Excellent!!! That's a great observation

Did you try installing the following? sudo apt-get install libatlas-base-dev

Some lunar action tonight. A rather short session as the seeing wasn't great and not many features were visible due to the almost fully illuminated disk. And a quick snap with my OnePlus 7 Pro resulted in the following, rather soft in my opinion, image: This was with a 10mm Baader Classic Ortho and my rather new Baader Zeiss prism which I like very much. Anyone else out? Victor

For RTL-TCP each sample is streamed to the client computer immediately, so the entire observation is the same length as it takes from start to plot of data. So trailing can still be an issue The duration of observations through RTL-TCP will be limited to your wifi transfer speeds. That is why USB will be faster since it doesn't need to remain a connection between two TCP sockets.

Hydroxyl is definitely on my TO-DO list because of the reason you also mention, required equipment/software is somewhat similar between the two. I have a filtered LNA with 30dB gain centered at 1688MHz and a pass band of 80MHz. This should perform nicely for at least three of the two of the frequencies you mention. Have you tried observing OH masers? Victor

Yes, I am using both the Nooelec H1 SAWbird LNA and RTL-SDR V3. Adding another LNA will increase system noise floor as you say, and I would advice against it. After all, it's not certain the spikes are due to the SDR. Often spikes from the SDR only occur at harmonic frequencies of the local oscillator in the SDR for example. I would stick to n=10k for the reasons your mentioning yourself. Running observations locally on a device (without RTL-TCP), however, will be a lot faster than the 8.5 minutes (closer to 2 minutes from my testing). I would try to get a couple ferrite clamps since they can be found quite cheap and would be an easy fix. If that doesn't help, then there are only a couple options left to explore: Either try to locate the source of the noise spikes or move the antenna to a place less affected by this noise. Victor

Could be many things unfortunately!! PC noise, power supply noise, LEDs, flourescent lamps, the list goes on. A quick fix can sometimes be adding some ferrite clamps around the coax- and USB cable. It's not guaranteed to work, but sometimes it does if the noise is coming from USB or the PC.

Looks great Steve!! Glad you found the problem;) To increase the resolution of the observation, I would try increasing n to 10000 (10k). Each observation will take longer, but it should look even nicer Look forward seeing your 24h observations! Victor

Just turn off the bias T, remove the LNA from the receiving line and then try to have a look around the FM band in a software like SDR++ or SDR#. Try something like this instead: python3 H-line.py -s 2400000 -r 11 -n 10000 -l 51 -g 0 -z 0 -a 90 -e 192.168.1.116 -m 3 -i 0 It will make the spectrum look cleaner but not fix your problem, if your SDR isn't receiving anything from the antenna, hence my suggestion with the FM band. Victor

How many samples ("n" option) are you collecting? And also, have you tried listening to regular FM broadcast with your antenna feed? That could quickly conclude whether the SDR is even receiving any signal. Note you should try this without the H1 SAWbird in-line of course Victor

This will fix the "importing numpy c-extensions failed" error sudo apt-get install libatlas-base-dev Victor

Oh no... This can turn out dangerous Let us know how you get along with it along with your 102mm frac;) Victor

I believe jocular uses KivyMD for its UI. Try installing the following: sudo apt-get install libsdl2-2.0-0 libsdl2-image-2.0-0 libsdl2-mixer-2.0-0 libsdl2-ttf-2.0-0 That should fix it. EDIT: Getting the packages above may actually not fix it. In that case, try using a python version older than 3.8

Thank you Ed, very useful! I don't think I'll be done with hydrogen line in the near future, but would also like to play with new stuff. I just started on university the summer last year and have yet to play with the 3m dish available on campus Should be nice for hydrogen line, although for higher frequencies in X-band, Ku, K band and etc there are also a couple of solid 1m dishes available. Plenty to observe out there!! Victor

Thanks Steve, appreciate it! The re-write is mostly for my own sake I made some sneaky solutions back then that I would like to fix/tidy up, before I would go ahead and advance to new features. I would also like to increase performance slightly. I know the duration of observation is mostly due to the actual sampling by the SDR itself, but when performing digital signal processing on a Raspberry pi I am quite confident I can reduce the execution time by a significant amount. Please get in touch if you experience any major issues or have a great idea I should try to implement I may not be able to fix/add it immediately, but I will add it to my TODO-list. Victor

This is excellent!! I've never heard of radio emissions at these frequencies from water masers. What type of software did you use to receive the emission? I suppose you must have done a lot of oversampling and smoothing to receive it judging by the y-axis interval on your frequency domain plots? This is most definitely I would be looking forward doing at some point! Victor

I'm surprised I haven't seen this thread before now! Your build looks excellent I'm glad you got my software working! I'm currently in the proces of rewriting a lot of the code structure to make future improvements easier. Unfortunately an unexpected faulty PC has set back my work by quite a bit, and I haven't had the opportunity to work on the code for some time. I will hopefully have the ability to do so soon! With regards to your question, the software is only able to compute the signal to noise ratio of the hydrogen line peak in dB. If you want to create a map from this signal intensity, you could take each signal to noise ratio and plot it together with the right ascension and declination of the observation. Unfortunately, there is currently no simple way to do this yet, but from the beginning of the project, it has been my intention to add a feature in the software that will do this automatically. However, due to life's circumstances I have not found the time to implement this yet, but I hope to do so at some point I think you would find the following article quite interesting if you haven't seen it already. It's basically the same procedure as I explained above: https://www.rtl-sdr.com/jobs-radio-telescope-hydrogen-line-northern-sky-survey-with-rtl-sdr/ I hope I understood your question correctly? If not, feel free to ask again!! Victor

Might get home and have a look at this. Thanks for the heads up Stu! Been ages since the weather and time has been cooperative.

Beautiful first scope!! Mine wasn't that long ago actually, back in 2016 to be exact. It was a Bresser Pollux as shown below but without the solar film: Unfortunately I can't find a photo of my exact one. I believe this might be due to my experience with it being rather disappointing. I didn't know much about telescopes and eventually learned the hard way about Bird Jones type telescopes. Yes, I did see Jupiter and some cloud bands, a fuzzy ring around Saturn, the Orion nebula and etc. but at a focal length of 1400mm and a 25mm eyepiece in a 150mm scope I wasn't in for any particularly impressive deep sky views. The moon looked great though.... as with almost any other telescope! This scope stayed in my possession for about 9 months until I eventually switched it out for a Skywatcher 250PX which I enjoyed way more!! I treated myself some lovely ES 82 degree eyepieces which I still own and love today, and I learned a lot more about which scope, eyepieces or even filters are best suited for a particular target at a particular location! Shown here is me (far right) sharing views of the moon at an outreach at the Planetarium of Copenhagen. Now I'm a happy owner of two fracs and no shaving mirrors wait, how did that happen Victor

I've thought about getting some of these since the barrel of my TV 2X Barlow is too long to use in my Baader prism without hitting the surface of the prism. I think it would be a simple and easy fix.

Wait??? Someone has more eyes than Stu?

I agree Compared to my 102mm APO the extra 28mm certainly make quite a difference judging from these shots. I can only imagine the view through the scope under excellent seeing.

I'm utterly impressed Stu!! I can even seem to pick out a couple craterlets in Plato in the second pic. I must've forgotten, but do you use a smartphone mount for these shots? Victor