Voice descrambler for GQRX
A perl script from here http://www.windytan.com/2013/05/descrambling-voice-inversion.html
Changed to work with GQRX udp output
Scrambled voice used in some ham radios to secure communication.
Enconding method is "voice inversion" and the sound reminds Donald Duck.
https://en.wikipedia.org/wiki/Voice_inversion
Change $fc = 3333; # carrier frequency to tune voice decoding.