Decoding SSB OM recorded files

I need to restore/decode some transmissions made by OMs in SSB modulation (i.e., I have to make the recorded files correctly understable), because the person who recorded the files forgot to activate the BFO function on its radio. Can it be done in Audacity? If yes, how?
Many, many thanks in advance!

How have you recorded the transmissions? What format are they?
(for the benefit clarity it would be helpful if you used less abbreviations - this is a forum for audio software not ham radio)

Single Side Band, Suppressed Carrier transmission. AM radio takes up a lot of room on the dial and if you do the math, most of it is duplicated or wasted. HAM radio operators aren’t bothered by messy broadcast standards, so they quickly figured out how to suppress the parts that “weren’t needed” before the transmit signal hits the antenna.

Hams have a fixed (low) amount of radio power and the more efficient they can make the transmission, the better.

Unfortunately, the parts left out have to be reinserted at the receiver before natural voices are produced. That’s what the BFO does. The sound track is almost completely unintelligible garbage without that. (you should post a sample so we can chew on it.)

You may be out of luck. You have to do this in the receiver. You might try the vocoder effect. That’s basically a linear multiplier in a friendly box.

Past that…


Isn’t the solution the same as demodulating the “subliminal” stuff on an ultrasonic carrier …

That could do it. You have to put the carrier back in for successful demodulation. Unfortunately, when you do that with the the audio, the carrier would be battery voltage or DC. The “real” voice is the difference between the carrier and the “stuff” we got.

So yes, if you beat or push our “funny audio” up far enough, you can Generate > Tone and put that in where the carrier would have been, it might give understandable voice.

We’ll know more when the poster puts some of the show on-line for us.


Proof of concept …

Yes. That should do it. It will never be perfect because you’re actually missing one one of the two sidebands as well, but if you need to derive useful intelligence, that should be enough.


1st of all, thanks to all for precious replies! I’m sorry if I wasn’t so clear in asking, using technical terms. Anyway, I’ll give a try to your suggestions! Basically, I have a bunch of MP3 recorded files from Single Side Band transmissions, made by Ham. I have to re-create (if possible) the messages in it. So, I repeat, I’ll try yuor suggestions; a result similar to “Shannon” one would be acceptable. I’ll let you informed about my progress. In the meantime, if anyone has other suggestions, they are welcome, obviously!
Thanks again!