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+--- Thread: What digital mode is this ?? (/thread-957.html)
What digital mode is this ?? - VK4ADC - 30-04-2020
I saw a strange signal on the WSJT-X waterfall this evening and have no idea what mode it is, so I am here to check with others.
Band in use at the time was 30M, (so 10.136.00 MHz,) while on FT8 mode and the strange signal signal occupies about 100Hz of bandwidth starting at 880Hz.
Have a look at the image below and submit your suggestions...
RE: What digital mode is this ?? - OZ2M - 30-04-2020
From the picture it looks like FSK with eight tones. https://www.sigidwiki.com/wiki/Category:Amateur_Radio Perhaps some sort of MFSK-8 or a faster FT8/JT8 variant being tested.
RE: What digital mode is this ?? - VK2CSW - 30-04-2020
Something like this?
https://www.ahrdf.net/forum/thread-685-post-2870.html#pid2870
RE: What digital mode is this ?? - OZ2M - 30-04-2020
Maybe but in the picture the tone spacing looks like using K = 2 and the bandwidth is 150 Hz. The one from Doug looks like K = 1. It could also be the n'th harmonic of a signal.
Unfortunately, I don't know of a any public programs with automatic protocol detection and decoding - it would indeed be nice to have.
RE: What digital mode is this ?? - VK4ADC - 01-05-2020
Bo
I looked through that table and it doesn't match up with anything there. I only have the original screen shot but have done a 250% blow-up of part of it below, with a normal FT8 emission just to the RHS.
The bandwidth is obviously 100 Hz, structure at 8 frequency streams (very obvious in the base spectrum display). The data rate looks to be similar to that of FT8.
So still an "i don't know" .... Maybe it is a new mode being tested - right in the middle of the designated FT8 "band".
RE: What digital mode is this ?? - OZ2M - 01-05-2020
It looks FT8'ty. There seem to be two sync frames. One at the beginning and one at the end. I cannot see if there is anything in the middle.
If you hear it again you may try to log it using Spectrum Lab https://www.qsl.net/dl4yhf/spectra1.html to get a much closer view on things.
Not all modes are in the linked signal wiki.
RE: What digital mode is this ?? - VK5PJ - 03-05-2020
Hello Doug, looks like audio harmonics from someone with audio over-drive on a lower part of the FT8 segment, have seen this a bit on 40mx FT8 when stations get over excited...