Opinions needed: Ham radio digital modes -- what's currently being used?

edited November 2023 in Feature requests

While waiting for Kiwi 2 issues to get sorted out I started to take a look at Fldigi (open source ham digital mode decoder) with an eye toward adding a digital mode extension. I started by implementing the RSID function. Works fine.

But then I started listening around the bands. My conclusion is that no one is using RSID. A real shame. Worse, no one seems to be using any (or few) of the modes Fldigi supports. Let's set FT8(4)/JS8CALL/WSPR and RTTY aside for the moment. The rest of the activity seems to be VARA+chat or some version of PACTOR. Both of those are proprietary without any open source implementations I can find.

Now, I haven't listened for more than a few hours. But does this reflect reality? Would I be wasting my time porting more modes from Fldigi? It seems MFSK32/64 is useful (especially image mode) as that shows up in the Shortwave Radiogram transmissions. And I'm probably going to port the Fldigi CW decoder since it seems superior to what we have now.

I'd appreciate your opinions about this.


  • As you mention, MFSK modes (specifically 32 and 64, text and images) would be nice on the Kiwi as that is currently my primary use of Fldigi.

    Not part of Fldigi, and I'm not sure about it's "open source" status, but EasyPal would also be a nice addition to the decoders available on the Kiwi. Hams and shortwave pirates occasionally make use of it to send images. Basically a form of DRM.

    Not a digital mode, but another addition that would be interesting on the Kiwi would be DazMan's "Comb Stereo" decoder, if it doesn't end up using too many resources. A few shortwave radio shows, particularly those on RNEI and WRMI have been using it. I have never personally had the chance to install the software and decode a broadcast for myself, but have heard recordings.

  • Hi John,

    I think you have most of the common modes already covered, perhaps with the exception of ROS.

    I agree about the lack of RSID. It is becoming increasingly difficult to identify some digital modes that are being used on the amateur bands. New ones seem to po up all of the time, and unless you are part of the "clique" that use them, up to date information regarding operational frequencies and specific modes, seems to be very hard to find.

    Outside of the amateur bands

    Winlink and Sailmail seem to be the only others that spring to mind and they use a mixture of Packet, Pactor, ARDOP and VARA, most of which is proprietary




  • A while ago I tried out some not so popular modes such as FSQ, ROS and KG-STV which are interesting technically and work well within certain limitations of course.

    Looking at the spot statistics by PSK reporter for modes such as these they appear hardly used at all or at least not reported and so may not be worth implementing due to low activity.

    In the case of FSQ the original version (FSQCALL v0.42) does not send spots to PSK reporter. The Fldigi version does when enabled.

  • I'd agree that some digital modes seem to disappear almost as quickly as they emerge, so unless it is very easy it probably isn't worth the effort of trying to incorporate them into the KiWi. I had considered mentioning Digital Voice, but as with the others I don't think it gets much use.

    The OpenWebRX+ fork of OpenWebRX has a selection of more slightly obscure data mode decoders, but a lot of these are really only of use on the VHF / UHF bands, so once again probably not worthwhile including in the KiWi

    PI4 is a possibility because it has been mandated by the IARU for use with co-ordinated amateur beacons.


    But it's still a bit niche by the standards of FT4/8, which seems to account for most of the current amateur digital mode activity.



  • I had a few QSOs with the Olivia mode. It's been a while since, but there was regular activity between 14100 and 14150 kHz.

  • Based on PSKreporter.info statistics, especially on weekends, apart from the most popular ones, there are a lot of ROS, PSK31, SIM31 in use, which I use myself.

  • I am a digital audio (FreeDV) user and use KiwiSDR to check propagation. I wish KiwiSDR had the ability to decode FreeDV.

  • In almost 40 years of amateur radio, I have seen many digital operating modes come and go. Basically I just miss the ability to decode PSK31 and some submodes, maybe JT65. For the rest you can use external programs such as Multipsk.

    73s Holger, DF6DBF

  • Pactor - no FOSS decoder AFAIK, but specification is open: https://www.p4dragon.com/downloads.html (under Documents).

    FreeDV - little activity outside activity periods, but there seems to be quite a lot of interest. A UK-based group of FreeDV users has a 5 MHz weekly net and at least one of them uses my Kiwi to check his signal. https://freedv.org/ https://qso.freedv.org/

    Digital SSTV - aka HamDRM among other names - I use QSSTV to decode this. It's Qt-based, cross-platform and GPL 3. https://github.com/ON4QZ/QSSTV

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