Abstract: Augmenting pulses are added to the horizontal sync pulse intervals of a video signal to prevent a copy of the thus modified video signal from being satisfactorily displayed. The magnitude of the augmenting pulses is chosen so that the modified signal containing these pulses can be displayed without distortion. When the modified video signal is recorded and then reproduced by a typical VCR (i.e., when the modified video signal is copied), attenuation of the augmenting pulses and the remaining portions of the horizontal sync pulse occurs so that a television receiver cannot properly detect horizontal sync in the copied modified video signal, resulting in an unsatisfactory display.

Abstract: A system and method for encoding an optional video disc to inhibit unauthorized recording of played back signals by conventional videotape recorders is provided. A source program is mounted on a video signal generating means. The video signal is modified by increasing and decreasing time durations from a standard horizontal line duration of pre-established maximums and minimums. The modified video signal is recorded on a previously blank optical video disc.

Abstract: A method of controlling the operation of slave decoders in a cable television distribution system having a central control computer; in which each subscriber location having a slave decoder also has a master decoder; in which there is a control message connection between each master decoder and its associated slave decoder(s); and in which the central control computer can individually address each master decoder and each slave decoder. The method includes the steps of transmitting control messages for the slave decoders at the control message frequency for the master decoders. In response thereto, each master decoder will retransmit the control message to its associated slave decoders.

Abstract: A means for coding and decoding video signals by the application of one of a plurality of available scrambling signals includes means for comparing the brightness level during a predetermined time period of the video signal with the brightness level of the video signal over the succeeding predetermined time period. There are means for changing from one scrambling signal to another if the difference between brightness levels in successive predetermined time periods exceeds a given value.

Abstract: A method and means for coding and decoding video signals by repetitive video signal polarity reversal includes the steps of comparing the brightness level of a predetermined time period of the video signal with the brightness level of the video signal over the previous predetermined time period. The polarity of the video signal is inverted or reversed if the difference in brightness level between successive predetermined time periods exceeds a given value.

Abstract: An audio and video signal coding system in which the normal sync pulses in the horizontal and vertical blanking intervals are suppressed, and clock and control data as well as digital audio data is inserted therein. The data, both audio information and clock data in the horizontal blanking interval is further distorted by the application of a periodic waveform and/or voltage level enhancement of certain portions of the horizontal blanking interval.

Abstract: A converter/decoder for use in subscription television includes means for converting any input TV channel to a predetermined output channel. Decoding means are connected to the converter at its output for decoding the selected output channel. The decoder is enabled in response to data carried on the TV signal which describes the program level of the particular selected channel. The means for enabling the decoder includes a comparison circuit which compares the television signal program level data with authorization data and performs an enabling function when there is correspondence between the two data entries. The authorization data may be received by the converter/decoder simultaneously with the program level data, but at a frequency other than that of the television signal, for example, at a frequency in the FM band.