This has been a project a couple yrs dabbling.
Curious if anyone is familiar about the types of scrambling used in
military or private type radios, as I have a vintage tape recording
where 2 stations are transmitting in perhaps a scrambled type of audio....or maybe SSB
or possibly overdriven AM.
At first I thought it was SSB, then was advised that since its on a very old
70's cassette tape, the tape material has degraded, lost its properties and is the reason
why there is this kind of distortion present.
Since then I have had a few audio professionals try to clean it up to no
avail. Then I noticed the cass tape housing was missing the felt pad inside that
presses on the play head when in play mode. I thought that was the entire issue, but after an entire
transplant of the tape into a new housing with the felt pad, the noise and distortion is still
there. A segment of the audio
can be heard in a wave and ogg file here:
https://www.mediafire.com/file/xo8nw1vbyigpbvo/Airstrike.zip/fileCouple weeks ago I played more of the tape and about half way through, the 2 stations
get in touch with another 2 stations
and they are heard perfectly, but anytime the other 2 stations transmit,
they are still distorted and not very readable
which is why I think this is perhaps a secure scrambled channel between them I believe.
Thought maybe some of the older vets around that did radio back then may be
able to know for sure if its a scrambler or maybe a way to clean it up.
I was told is sounds more like overdriven AM, when 2 stations are too close in proximity
and the front ends are overloaded, but then I think they would not be able to converse at all
and they sound like they have a solid qso.