[mrgriscomredux] over on [Reddit] was interested in re-creating the nostalgia that was scrambled analog television from the 90s. To do this he captured an NTSC analog video signal using an RSP1 SDR and demodulated that into composite video using GNU Radio to process everything.
The methods that were originally used to scramble analog television are not well documented, however [mrgriscomredux] has done a fine job re-creating it himself in his own way.
He then uses a Python script to modify the “Gated Sync Suppression” within GNU Radio and then transmits that back on to the air using a low cost FL2K VGA adapter we’ve featured on the blog in the past.
These FL2K VGA adapters can be abused as crude software-defined transmitters and we’ve seen people do everything from video transmission to GPS spoofing with them. [Check out the FL2K article here]