Abstract: Television signal scrambling is effected by combining moderate level trap-attenuation of the visual carrier frequency with an injected fm-modulated interfering signal to effect, by adjustment of amplitude and fm-modulation levels, satisfactory picture scrambling and overpowering audio distortion in the user's television receiver.

Abstract: Television or similar picture scrambling or the like wherein narrow trapping of the visual carrier is effected with one-direction FSK-FM modulated wobbulation of the visual carrier, preferably alternately at different multiples of the horizontal synchronizing frequency.

Abstract: This disclosure is concerned with an improved special program addressable subscription decoding technique in accordance with which ordinary program subscribing decoders continue to receive and decode the scrambled flat rate programs to which they are entitled while being disabled from receiving any of a plurality of special scrambled programs associated with a different control signal that will only enable decoding after pre-set unique address verification has been transmitted, checked and introduced into memory indicative of subscription to particular of such special programs, whereby the special program decoding will be effected compatibly with the continued flat rate program decoding by ordinary program subscribers.

Abstract: This disclosure is concerned with simplification of customer TV decoders for scrambled television signals fed from a master antenna system or the like, by novel head-end decoding and simultaneous scrambled STV transmission along the distribution cable to the user TV sets.

Abstract: This disclosure is concerned with simplified decoder apparatus for use with depressed horizontal sync scrambled television transmissions, embodying intercarrier detection of picture and sound carriers and FM demodulation of audio information including a pilot tone used to restore the video sync signal by controlling an RF gating amplifier.