Saturday, January 29, 2022

Text and image reception via MFSK on 31m band


I'm not sure I understand the purpose of it (proof of concept?), but for the next few days, text and image bulletins will be sent on various SWBC frequencies in the 19, 31 and 41 meter bands.

I learned of this via a Tech Minds video posted yesterday to YouTube:

The website referenced in the video, SW Radiogram, provides time and frequency info but very little else of substance. An "About" page would be a very welcome addition to the website.

As I read over the site I noticed that a 30-minute transmission was scheduled to take place on 9265 kHz in about an hour. FLDIGI was already set up on my laptop and configured to interface with the IC-705 so it was simple enough to tune the dipole for maximum noise on the 31m band and then start the software.

The transmission starts out on MFSK32 and then switches to MFSK64 about 15 minutes later. FLDIGI automates mode changes and follows along with what's being received as long as 'RFID' is checked in the upper right-hand corner of the program.

Little did I know that MFSK can be used to send images but, as they were sent, another window opened up within FLDIGI and the images appeared - all with no interaction required on my part.




  1. Hello John, nice post. I've experimented with rx en tx pictures on MFSK in 2010. Even made a tutorial on how to transmit pictures on that mode and published it on my blog. It is nice to see that it is still being used. And it is very interesting for "new" young tech people as well. When I discovered this 12 years ago I was very excited about it. Unfortunately I saw not many stations using this mode. 73, Bas

    1. Hi Bas, I guess I'm about 12 years behind the times! I never knew MFSK had that capability. It's odd to see commercial SW stations using this mode though. On 3 Feb, Radio Northern Europe International will be broadcasting a "radiogram" on various wavelengths using EasyDRF:

      Why - because they can?