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Coto

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About Coto

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  1. PICTOR just surpassed 150 unique users with over 800 observations on the archive!
  2. My suspicion from what I read from the link I gave is that in the box there might be the pre-amplifier. I'm not 100% sure but that's my guess since there's nothing else to be there according to the block diagram given below in the page. I did a few simulations in CST Studio and found that a slightly shorter and thinner wire does the job for me (just by looking at the S-Parameter plot). Is there anything else I should look at to confirm this 50-Ohm impedance match?
  3. Hi Alan, Your concerns are exactly the reason I built PICTOR. Quoting from my previous post, PICTOR is an open-source radio telescope that allows anyone to observe the radio sky using its convenient web platform for free. The goal of this effort is to introduce students, educators, astronomers and others to the majesty of the radio sky, promoting radio astronomy education, without the need of building a large and expensive radio telescope by the user. PICTOR consists of a 1.5-meter parabolic antenna that allows anyone to make continuous and spectral (i.e. hydrogen line) drift-scan observations of the radio sky in the 1300~1700 MHz regime for free. For more information, please take a look at the Website: https://www.pictortelescope.com/, the GitHub repository: https://github.com/0xCoto/PICTOR and/or the PDF guide that includes some introductory information on radio astronomy as well as instructions on how to use the telescope: https://pictortelescope.com/Observing_the_radio_sky_with_PICTOR.pdf This way you will be able to observe the radio sky without having to really worry about lack of knowledge in the field. I will try to shorten the PDF Guide a bit (10 pages might be too much stuff to read through for most people I believe) and change a few things up a bit, but it includes some introductory radio astronomy information and instructions on how to use PICTOR (slightly un-updated but sufficient for the most part). If you don't have the time to read the whole PDF I'd suggest you at least take a look at the resources, it has two interesting short YouTube videos that should give you an idea of what radio astronomy is about. Ideally (for me) if you have something like Discord (see my signature) I'd be more than happy to help you there with absolutely anything you need (I suggest Discord because it is a more direct and efficient way of communicating in my opinion).
  4. Hi all, We're currently working on the 3D Corner Reflector antenna for pulsars. I emailed the creator of the original antenna but I haven't gotten a response in a while (maybe he's been busy). Here are my questions if anyone is able to help: 1) http://iw5bhy.altervista.org/info.php here the creator of the antenna says the monopole is 53 cm long. Why so long? Doesn't theory say that the monopole's length should be around λ/4 = 70/4 = approx. 17.5 cm? 2) Why so thick? 10mm sounds pretty thick to me... On feed designs for the hydrogen line I've seen thicknesses less than 3mm. How does this huge thickness help? 3) Also, how would I manage to solder this huge thick wire onto an N-Type connector? The N-Type connector's pin is far smaller than 10mm... 4) Does the ground side of the N-Type connector have to make electrical contact with the metal grid? Is a simple solder to one of the wires enough, or must I make sure the entire connector makes GREAT contact with the grid (i.e. put a metallic plate for the connector to sit on)? 5) Do the metal panels (each 2x2 side) have be in electric contact with each other (e.g. a wire or two touching between each panel)? 6) Does the antenna's ground need to be in contact with the Earth (at this frequency will good Earth grounding provide any reduction in static/noise)? Thanks a lot!
  5. Hi Carl, I provide an approximate location (very accurate considering the beam of the telescope) in the PDF guide. The telescope is not mounted on a motorized mount, but it’s excellent for drift scan observations! Users can submit observation requests via the /observe page and it will be automatically taken care of by the raspberry pi in the Faraday cage. Once the observation is finished, the user receives an email with the data of their observation. All of the above are mentioned in the PDF guide so perhaps further questions might be answered there as well!
  6. @Carl Reade Just made a post on the Radio Astronomy section of the forum about my radio telescope.
  7. Hi all! Over the past few months, I've been working on PICTOR. PICTOR is an open-source radio telescope that allows anyone to observe the radio sky using its convenient web platform for free. The goal of this effort is to introduce students, educators, astronomers and others to the majesty of the radio sky, promoting radio astronomy education, without the need of building a large and expensive radio telescope by the user. PICTOR consists of a 1.5-meter parabolic antenna that allows anyone to make continuous and spectral (i.e. hydrogen line) drift-scan observations of the radio sky in the 1300~1700 MHz regime for free. For more information, please take a look at the Website: https://www.pictortelescope.com/, the GitHub repository: https://github.com/0xCoto/PICTOR and/or the PDF guide that includes some introductory information on radio astronomy as well as instructions on how to use the telescope: https://pictortelescope.com/Observing_the_radio_sky_with_PICTOR.pdf All feedback is welcome and encouraged!
  8. Just installed G8FEK's L-Band radio astronomy LNA on a fixed 3.2m dish pointing 20 deg below zenith. Here is a first result: (The square-ish blocks are due to data intervention (had to remove some RFI spikes)) Detecting the hydrogen line is nice and all, but what about multiple HI lines in a single observation? You already did this: And it's been done here, by an even smaller dish: http://blog.svenbrauch.de/2014/08/29/14204-mhz-hydrogen-line-there-it-is/ (my feed dimensions are identical too) And these guys with a 3.1m dish seem to get amazing results with similar equipment: http://www.midem-drustvo.si/Journal papers/MIDEM_47(2017)2p113.pdf Firstly, how can I distinguish hydrogen line emissions originating in the spiral arms of our galaxy, from other types of emissions (e.g. nebulae like Cas A, emissions with extragalactic origins etc.)? Secondly, what does it take to see multiple lines in a single (averaged) spectrum? Is pointing an important factor I'm not considering? I've managed to do it with the 1.5m (up to 2 lines though) with little observing time (2 mins in this case): I think it'd be interesting to see more than 1 or 2 hydrogen lines, proving we live in a spiral galaxy by a single plot. P.S.: My chain is Feed -> G8FEK LNA -> 3m LMR-400 coax -> 1m USB extension -> RTL-SDR (without the shield ) -> PC Do you think it'd increase my S/N significantly if I inserted an in-line amp right after the LNA? EDIT: Also, do you think it'd do any difference if I took an OFF measurement and then subtracted the ON data from the OFF data? (I don't believe I could extract anything else from this plot)
  9. Yes... I did a lot of experiments. I think I'll install the Pi under the dish (whose reflecting surface acts as a shield reflecting the Pi's interference away into the Earth's ground). I tried that and the RFI went away (at least sufficiently enough). I think it'll still cover it with aluminum foil or something. P.S.: Do you know if G8FEK's L-Band Radio astronomy LNA is waterproof, or will I need to put it in a project box?
  10. Well, I tried covering the entire box with aluminum foil, making sure it touches the antenna's ground, but I still get RFI... Why is that?
  11. So I guess my question is, where does this energy go? Like the Pi emits radiation, it is picked up by the foil (as an antenna?) and transferred to the feedhorn's ground? Where does the energy go from there? Does it get radiated outwards (into the sky and also into the dish reflector as well)? Where exactly does this energy go?
  12. Separating the Pi out of the box would be quite problematic for me as I had already planned everything to nicely sit in a box... Also, putting it a few meters away would also be susceptible to interfering with my dish. I think I'd still need to make a faraday cage for. Currently planning to try this with my current box, although I'm not so sure how it should be done... Do I just cover the whole box with aluminum foil? Do I then need to connect this aluminum foil anywhere (as a ground/redirecting all the EM energy the Pi emits elsewhere away from the dish)?
  13. So after a bit of investigating, it is indeed the RPI causing all this RFI, and not the power supply I was suspecting. Also, it seems like the in-line amp and the bandpass filter just don't seem to work. I really don't know what I'm doing wrong, but as soon as I insert the in-line amp after the LNA, I see no HI line. Same goes for the hydrogen filter: I insert it after the LNA, no HI line. It's as if the in-line amp and the HI filter are acting as attenuators... I'm not sure. Either way, using the LNA alone works fine for me so I'll go with that (I made a fine observation last night). As for the interfering Pi, I'll try wrapping the project box in aluminum foil (forming a faraday cage) and making sure the aluminum foil makes contact with the feedhorn's ground (the waveguide side = the N-type connector's outer "shell"). If this doesn't help I'll have to get the Pi out of the box and put it away elsewhere, or maybe change it's CPU clock speed (cause it's originally rated at 1.4 GHz...).
  14. Why? The Pi gets pretty hot and you think could make the LNA noisy? (I don't think that's the case - they aren't in contact so it's not like the LNA would feel very warm or something)
  15. Gonna try some troubleshooting soon when I get back to my dish. Just a question that came up to my mind: I installed the LNA a little bit too deep into the box, so the SMA male to male connector wasn't long enough to reach my feed's connector. Is it wrong that I used 2x right-angled SMA connectors before reaching my feed's SMA to N-Type connector? Could the loss of these connectors be significant enough to degrade the signal strength of the hydrogen line that I would otherwise be able to detect without these connectors, or am I just being paranoid?
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