Abstract: A universal decoder for scrambled television signals in which the signals are processed in a circuit by converting them to other frequencies and then removing the scrambling signal. One method uses one or more narrow filters at a fixed frequency with the television signal being heterodyned down to the frequency of the filters to place the scrambling signals in the rejection band of one of the filters. A second method eliminates scrambling signals by filters at video frequencies. In this method, the frequency in phase with the television signal carrier of a television channel is regenerated by filtering it with a narrow crystal filter and by means of an automatic phase comparison (APC) loop. The regenerated carrier is then used to synchronously demodulate the television signal. A third method for removing the scrambling signals is by use of one or more comb filters.

Abstract: A master decoder for scrambled television signals in which the signals are processed in a circuit by converting them to other frequencies and then removing the scrambling signal. One method uses one or more narrow filters at a fixed frequency with the television signal being heterodyned down to the frequency of the filters to place the scrambling signals in the rejection band of one of the filters. A second method eliminates scrambling signals by filters at video frequencies. In this method, the frequency in phase with the television signal carrier of a television channel is regenerated by filtering it with a narrow crystal filter and by means of an automatic phase comparison (APC) loop. The regenerated carrier is then used to synchronously demodulate the television signal. A third method for removing the scrambling signals is by use of one or more comb filters.

Abstract: A Television Signal Transmission Security System which provides a higher degree of security then previously possible by utilizing encoding and decoding technology which effectively prevents pirating by amateurs or experimenters. The television signal transmitted is encoded by injecting one or more modulated interfering signals in specific frequency slots in close proximity to the video carrier. Continuous or alternating interfering signals can be injected either above or below the video carrier between harmonics of the horizontal frequencies. Combinations of interfering signals provide coding techniques making the system virtually pirate proof. The interfering signal is removed by very narrow band rejection filters having a rejection band attenuation greater than about 40 dB over a bandwidth equal to the bandwidth between adjacent harmonics of the horizontal sweep frequency. The filters are constructed using advanced technology to produce the quartz crystal bulk resonators or surface acoustic wave filters.

Abstract: A Television Signal Transmission Security System which provides a higher degree of security then previously possible by utilizing encoding and decoding technology which effectively prevents pirating by amateurs or experimenters. The television signal transmitted is encoded by injecting one or more interfering carriers in specific frequency slots in close proximity to the video carrier. Interfering carriers can be injected either above or below the video carrier between harmonics of the horizontal frequencies. Combinations of interfering carriers provide coding techniques making the system virtually pirate proof. The interfering carrier is removed by very narrow band rejection filters having a rejection band attenuation greater than about 40 db over bandwidth of up to 4000 Hz and a 3 dB bandwidth of approximately 5 kHz. The filters are constructed using advanced technology to produce the quartz crystal bulk resonators or surface acoustic wave filters.