HS-Modem and some unknown modes

  • Hello.

    My name is Wilhelm and I am 70 years old. I got my ham radio license as a young man in the 1970th. At that time I had made some experiments using the orbiting Oscar satellites. Image transmission, programming and image processing in different areas of the electro-magnetic spectrum have been my hobbies since that time. Now I would like to start operation via QO-100. On the receiving side I'm already a bit QRV, with a dish in the attic.

    Particularly the HS modem is very interesting. It's a reason for me to get active again via satellite. Many thanks to Kurt for programming it and to everyone who keeps the MultiMedia beacon running.

    However I have problems recognizing some modes. I can distinguish Fax, RTTY, SSTV and KG-STV. But there are some formats on the QO-100 that I can't decode. For example 5) often calls but never gets an answer. My suggestion is that we announce the mode and the baud rate in the waterfall before the broadcast starts, see as an example 3) and 4) in the appendix. A call sign would of course also suffice. Then interested people can google it. A voice announcement only works if one already is listening on the right frequency. In the waterfall, the information would be independent of the correct frequency and, in limits, also of the time.

    What do you think?

    Does anyone know what modes 1), 2), 3) and 5) are?

    I have a further suggestion: The HS modem mutes the sound under Windows11 and it works with a virtual sound cable only. I don't need the cable for the other programs: they work with Windows's internal sound mixer and the sound remains. Maybe that can still be changed.

    Thanks again everyone for the great project,

    have a nice day,

    best regards


  • Hello Wilhelm,

    perhaps I can give some clarification, at least for 5).

    1) is a signal I didn't find any information about and even got no clue here in the forum. It seems to be a kind of ARQ mode as the small FSK bursts look like requests or confirmations for/of the much longer and broader packets.

    2) looks like an MFSK signal. I myself experimented a bit with different MFSK modes like THOR, THROB etc. all done with the Fldigi software package.

    3) perhaps the DRM-TX in the waterfall is a hint to a DRM-like modulation scheme though the bandwidth is much narrower compared to commercial DRM with 4.5 kHz and more.

    5) This is the VARA-SAT scheme of the Winlink-Mailbox maintained by IS0GRB on the frequency shown.

    I hope this helps a bit. I'm very curious about 1) as I haven't found any information of the scheme so far and noone could give me a hint yet. Sometimes I think it may be an intruder using QO-100 as a cheap relay for his data.

    73, Frank/DL6DBN

  • Merry Christmas.

    A lot of time has passed since my last post, but now I am QRV.

    So far I have transferred images with KG-STV via the is0grb Websdr, see images.

    Transferring Christmas greetings via the waterfall also works very well.

    Now I can work on the HS modem.

    Kind regards from Gescher,

    Wilhelm DG2YK

  • I'm currently running some full duplex tests with this setting:

    4410 QPSK BW: 2500 Hz (QO-100 standard)

    The bandwidth is slightly lower than the permitted 2.7 KHz, so that images can be received even with imperfect settings.

    I increased the 100 Hz tone slightly using the transmitter's bass settings. This makes the synchronization of the receiver path work easier.

    Best regards


  • Hello Wilhelm i added the section "Last images decoded on 10489615 (HS-MODEM 4410 QPSK BW:2500Hz - QO-100 Standard)" in my WebSDR, so you can try to test image transmission with the great HS-MODEM.
    I hope to contribute to improve the activity of image transmission with HS-modem
    Roberto IS0GRB