In the seventies I worked for Muirhead on press fax machines that used to transmit pictures over radio and landline as I recall two FM systems were used a carrier 800 Hz modulated +- 150 Hz and 1900Hz +- 400 Hz.

I have recently found software to get my old ICOM PCR1000 communication receiver going again on windows 10 and am picking up a strong signal on 162.800 kHz that appears to be the former system .

Is there any software available that would demodulate it and can anyone identify it?

  • $\begingroup$ The only thing related to ICOM that I can find is this: sigidwiki.com/wiki/Next_Generation_Digital_Narrowband_(NXDN) There might be some useful pointers there. $\endgroup$ – MBaz Apr 4 '19 at 16:41
  • $\begingroup$ I can't say that it rings any bells apart from something like this. In the sense that probably the image is unfolded row-major and then sent over with suitable markers. If you could capture a "session", it might help with decoding it. $\endgroup$ – A_A Apr 5 '19 at 10:23
  • $\begingroup$ I notice with a better antenna there are similar signals on 164 kH, it is definitely not pictures I know what pictures sound like!, I believe it may well be text connected with the internet over phone line service (I get my internet via optical cable much better) $\endgroup$ – syhprum Apr 6 '19 at 14:47

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