back to article Spotted the ISS in the sky yet? How about pulling out some spare kit and giving it a listen?

Got plans for the weekend? No? How about pulling that Pi out of the drawer or dusting off an old laptop and getting ready to grab some images from the ISS, courtesy of locked-down European Space Agency (ESA) boffins. Test image from the ISS (no transmissions until late July/August) Decoded image of a test transmission using …

  1. This post has been deleted by its author

  2. DJO Silver badge


    I was going to post a snarcy comment along the lines of so they've hooked a fax to an acoustic coupler and invented Radio-Fax but thought I should perhaps do 5 or 6 seconds of research first.

    It seems from the 1930's to 1970's there was a system called "Radio-Fax" which was indeed the precursor of SSTV.

    Anyway always good to see stuff from space anybody can access.

    1. harmjschoonhoven

      Re: Anyway always good to see stuff from space anybody can access.

      Oh, just some stars. Download free from gaia DR-2.

    2. agurney

      Re: Rats

      Radiofax (aka WEFAX) is still alive and kicking, and is used to transmit weather charts.

      1. logicalextreme

        Re: Rats

        Doing a lot better than Ceefax, then.

    3. werdsmith Silver badge

      Re: Rats

      “ Anyway always good to see stuff from space anybody can access.”

      ISS has been doing amateur radio packet and voice for years. There are numerous other satellites that anyone can take a downlink from, starting with NOAA and on up from there. Two way space comes is also available through AMSAT work and these are all examples of direct downlink and in the case of AMSAT uplink (even images). Not through the receiving equipment at the WebSDR sites. If You want to work space, it’s all there ready and has been all along. If you look at YouTube there are videos of people working Sats using £20 Chinese transceivers.

      The WebSDR software out of the Netherlands is absolutely brilliant, I do hope the various sites, which are volunteer operated are not swamped.

      1. Dave Honess
        Thumb Up

        Re: Rats

        I checked with the folks who operate the Goonhilly Web SDR and that one should be able to take it.

  3. Pascal Monett Silver badge

    I watched the Win7 tutorial

    It would have been nice if the guy had a bit of training in doing tutorials. As it is, it was as painful to watch as it was obviously painful for him to do.

    On top of that, at no point did he explain why he had switched the RX options from PD 120 to ML240 when he stated that it was working.

    I have been teaching people about Windows, Office, VBA and programming for over two decades and I can guarantee you that you quickly come to understand that anything you do without explaining why you do it is going to create confusion in the minds of the students.

    I haven't gotten any image yet, because the ISS was not in range when I tried, but I will persevere.

    1. John Brown (no body) Silver badge

      Re: I watched the Win7 tutorial

      In my job, we get told to do online training a couple of times per year. As someone who used to teach many years ago, 99% of online training makes me cringe. Almost none of them are created by people who know how to teach. Many of them just run through a sequence or machine gun spray a load of facts and you're expected to actually learn something from it. Worse, many seem to bounce around topics and rarely are created with lesson progress and building on experience or the previous lesson.

      1. MrBanana

        Re: I watched the Win7 tutorial

        I haven't seen the Win7 tutorial but I did look at the Android, Ubuntu and MacOS ones. I don't think that the idea is to teach you how to use all the software to its full capability. It's just enough information to get the apps installed, and get you viewing a test picture. The Ubuntu guy did actually explain some of the settings he changed, like increasing the filter to 15Khz to take account of the Doppler effect as the ISS goes overhead. I gave up with MacOS when I needed to download a kernel extension to mess around with the audio settings. Ubuntu looked straight forward enough, but I haven't yet tried it. The Android video is half the length of the others, and was by far the simplest to get working. Just download one app, and put your phone near the speaker of your computer, or another phone, while accessing the Goonhilly WebSDR site. Crude, but it worked first time with the test transmission. Now I just need to wait for the right time for the ISS to fly over.

        1. John Brown (no body) Silver badge

          Re: I watched the Win7 tutorial

          "It's just enough information to get the apps installed, and get you viewing a test picture."

          Agreed, in this case. I was just expanding on my general perception of so much online training, even from so-called reputable;e sources, but in particular large IT businesses with apparently well funded training and education departments.

        2. Dave Honess

          Re: I watched the Win7 tutorial

          Re the Mac OS video. We used Soundflower because it's free and doesn't capture any personal information from you. It's also reccomended on the Web SDR faq page: (see the question about decoding digital modes). There are a couple of alternatives though, if the install process is too complicated, have a look at Blackhole and Loopback.

    2. Dave Honess

      Re: I watched the Win7 tutorial

      The PD 120 to ML240 mode switch was automatic, well spotted though, after the soundcloud test audio finishes playing it starts automatically playing some other piece of music. The auto-detect feature of RX-SSTV then, for some reason, thought that image mode was being used. When you use Virtual Audio Cable you don't actually hear the audio playback from your speakers or headphones so it's easy to miss things like that.

      Regarding the images, the ISS does not transmit SSTV all the time, they post the times when it will transmit on this website:

      Currently there hasn't been an event since January. We were hoping for one this week but because of the COVID situation in Russia they may not be able to get on console to upload the images.

  4. arctic_haze

    Not where I live

    I live North enough to have ISS over the horizon only for a few minutes every third day (or so). So in fact I have not yet seen it, even as I tried to.

    1. MrBanana

      Re: Not where I live

      You will be listening to the output from the receiving station, not from where you are located. Try plugging Goonhilly into the ISS tracker on Heavens Above.

    2. Dave Honess

      Re: Not where I live

      This is precisely the beauty of using a Web SDR. You're using a receiver in a remote location and, with Goonhilly for example, you can get 90 degree overhead passes at its location. Make sure you put the Web SDR location into

  5. Anonymous Coward
    Anonymous Coward

    This looked like it would be a good thing to play with, but it very quickly turned into another lesson in why I hate personal computers.

    How are you supposed to pipe the audio output from the browser to the input of the sstv decoder?

    All I get is an error message from RX-SSTV saying 'can't open sound card', and when I peer into the internals it's asking for device numbers and FIFO's.

    I guess Win 10 is too new for any of this to work with.

    1. ThatOne Silver badge

      > How are you supposed to pipe the audio output

      Well, they do state in the article that the Win10 sound configuration requires a careful RTFM (or "watch video" as it were).

      1. werdsmith Silver badge

        Check out virtual audio cable.

    2. Dave Honess

      Ah yes, if you do not see Stereo Mix come up under the Control Panel > Sound > Recording tab then I suggest to use Virtual Audio Cable. You can basically follow the video for Windows 7 to get it installed.

  6. ThatOne Silver badge

    Slow scan TV through Internet?

    Getting slow scan TV from the web seems a little pointless to me: If you're going to use the web, you can as well go straight to NASA TV...

    IMHO slow scan TV only makes any sense if you want to use your ham radio receiver for something it wasn't actually built for (images). If you remove the "radio receiver" part, the whole thing becomes just a convoluted case of "download picture from Internet"...

    The really captivating part is (IMHO) the tuning in to the ISS zooming over your head and getting something to remember this by. That would actually interest me a lot more, but I guess it's completely overkill getting a ham radio license and buying a receiver and all the stuff required, just to get an electronic postcard from the ISS.

    1. I.S.

      Re: Slow scan TV through Internet?

      For a few dollars you can get a SDR receiver dongle that will pick up the ISS from a very simple home made antenna. No HAM license required in most western countries.

      1. ThatOne Silver badge
        Thumb Up

        Re: Slow scan TV through Internet?

        > you can get a SDR receiver dongle

        Even for VHF frequencies? Cool! Any brand/model suggestions anyone?

        1. phuzz Silver badge

          Re: Slow scan TV through Internet?

          Especially VHF frequencies. The cheap SDR dongles come from some clever type realising that some of the cheap USB TV receivers were capable of receiving a wide range of frequencies (20-1500MHz, depending on the model of dongle) with the right antenna. Of course, you had to pick the right models. (More info here)

          These day's you can get ones that are purpose made for SDR which can cost over £100, but you can also pick up a cheap one for about £20. (Oh, and you'll still be able to use them to pick up DVB and )

          Anyway, stick "RTL SDR" into your search engine of choice for all the information you could want.

          If it helps, I picked up a NESDR Smart and it's well made, although it turns out I live in a proper radio blackspot, and RF electronics is not something I'm very good with.

        2. I.S.

          Re: Slow scan TV through Internet?

          Even the simple ones work up to about 1.7GHz.

          RTL-SDR (currently v3) is one of the most common, very well made and supported.

          Airspy (currently v2) is a step up, with more features for hardcore HAM's.

          You need software to process the output of either one. Airspy provide SDR# and it is pretty much the standard for windows, and there is GQRX for Linux.

          1. ThatOne Silver badge
            Thumb Up

            Re: Slow scan TV through Internet?

            Thanks guys!

    2. werdsmith Silver badge

      Re: Slow scan TV through Internet?

      No ham license necessary if you are receive only.

      btw, SSTV as part of amateur activity, for both send and receive, is decades old.

    3. Dave Honess

      Re: Slow scan TV through Internet?

      Hmm, I get your point. But by using a Web SDR we are potentially including many more people in the activity who would otherwise never even know about it. Some people don't have space to, or can't afford to, set up a proper receiver with a deployed antenna. The videos do explain the SSTV tones concept, the orbit of the ISS and Doppler shift. So there is a lot of opportunity for learning there.

      In fact I actually have a Python script which will do the Doppler tuning of the Web SDR. However for beginners we have been suggesting to increase the filter bandwidth to accommodate the drift or use the allow keyboard function and use the cursor keys to manually track the centre of the transmission as the ISS flies over.

      1. ThatOne Silver badge

        Re: Slow scan TV through Internet?

        > we are potentially including many more people in the activity

        Sure, but SSTV is (AFAIK, IMHO, YMMV) more a byproduct of ham radio, rather than a full-fledged independent activity, isn't it?

        I've spent weeks alone in the middle of the ocean with only a SSB shortwave radio to connect me with the rest of the world, so I understand the fascination of being able to speak to somebody on another continent because of some freak ionospheric configuration, and the urge to explore what you can do with that box in front of you, your (only) link to the rest of the world.

        On the other hand, in 2020 SSTV technology has lost a lot of the usefulness it had back when it was first invented (Hellschreiber, etc.). Nowadays anyone can send still pictures with email, and mobile phones made it even easier: shoot a picture, send it instantly with MMS.

        The big thing in this case is the fascination of receiving something directly from the ISS, making the ISS more real (the same reason people like to watch it fly overhead). But this is diluted if this contact is make through some web site. It loses part of the face-to-face aspect where you get something directly from the ISS.

        Of course, as I stressed all through my post, that's just my own 2 cent's worth, anyone else's mileage will vary, and I can understand that other people will be delighted with this opportunity. So keep up the good work, and big thanks to all who spent their time setting this up!

        1. Dave Honess

          Re: Slow scan TV through Internet?

          Yeah totally right about it being about receiving something directly from the ISS. You can actually claim a certificate from after having received even a bad picture with only a few clear lines in it. Something which I think is really great for the young ones.

          But I agree that the Web SDR does dilute it - it's much more fun with your own ground station - but we wanted people to be able to participate as easily as possible (especially considering COVID times). I hope people will progress onto that way of doing it if they enjoy via Web SDR.

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