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I've downloaded a file encoded in RTTY 45.45 baud (mp3 output of linked video). I'm not sure if the final output should be audio or text.

I've also installed minimodem which I'm reading can convert data into audio with option --tx and out with --rx.

For example converting a picture into audio and back with:

cat pic.jpg | minimodem --tx 9600 -f audio.wave

minimodem --rx 9600 -f audio.wave > pic2.jpg

I tried the following two commands, one expecting audio output and another expecting text:

minimodem --rx rtty -f youtube.mp3 > out.mp3

minimodem --rx rtty -f youtube.mp3 > out.txt

Neither of these seem to work.

Can anyone advise me on how to decode this story?

Philip Kirkbride
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1 Answers1

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I'm not familiar with minimodem, but found the following eventually worked:

minimodem -a --rx rtty --stopbits 1 -f new1ch.wav

which produces output like

### CARRIER 45.45 @ 740.0 Hz ###
SET YOUR DECODER MODE TO RTTY 45
START TRANSMISSION...
HELLO AND WELCOME TO ANOTHER STRANGE BEACONS RTTY STORY.

The command did not seem to like an mp3 file as input, and when I converted that to wave it said input stream must be 1-channel, so I used sox new.mp3 -c1 new1ch.wav to reduce the file to 1 channel. The option -a made the command auto-detect the carrier frequency of 740hz. Initially, the text output was recognisable but with missing letters, so I tried the --stopbits 1 to override the default of 1.5 and that helped a lot.

meuh
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