Oak Industries, Inc.

Pieter J Fondse

Pieter Den Toonder

Johannes C Seltenrijch

Graham S Stubbs

Howard F Jirka

Cornelis A De Jong

Tom De Koningh

A coding and decoding system for video and audio signals includes means at the transmitter for deriving clock and internal timing signals from the video signal. The internal timing signals are utilized at the transmitter to provide digital audio data representative of the program audio signal. The digital audio data is derived by sampling the program audio signal during horizontal lines of the video signal. The synchronizing information in the horizontal and vertical blanking intervals of the video signal is suppressed and the digital audio data and data representative of a decoder clock signal are inserted in the horizontal blanking intervals. Vertical reference signal data is inserted into the vertical blanking intervals of the video signal as it is transmitted. At the decoder there are means for reconstituting the audio signal from the digital audio data. There is an independent sync pulse generator at the decoder which is controlled by the clock data and the vertical reference signal data and which provides the appropriate synchronizing information for the video signal. The video signal, without sync information, is combined with the separately generated sync pulses from the sync pulse generator and with the reconstituted audio to provide a television program signal usable at a conventional receiver.

Coding and decoding system for video and audio signals

A coding and decoding system for video signals includes means at the transmitter for applying sine wave amplitude modulation of approximate line frequency to the aural carrier to prevent the chrominance subcarrier from providing receiver synchronization.

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.

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Papendrecht, Netherlands

Pieter J Fondse