Unrecordable Video
Andrew Lippman, Tareq Hoque · IEEE Transactions on Broadcasting · 1987
Proposed in this paper is a scheme to modify NTSC video signals to render the signal unrecordable by video recorders, yet viewable on standard television displays. This method is based on continually varying timing characteristics in the transmitted video signal. Protection of copywrited broadcast material from casual consumer or illicit professional recording would be possible with this implementation. A means of neutralizing this protection scheme would require extensive signal buffering and analysis hardware currently beyond the reach of nearly all unauthorized parties.