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Abstract

An obfuscation device for use in cable television systems includes a memory for storing a plurality of channel status bits. The state of each channel status bit corresponds to the authorization or non-authorization of a particular channel. The obfuscation device includes a circuit for selecting a number representing a frequency and a circuit for generating an obfuscation signal that randomly varies about the selected frequency. The obfuscation device uses the selected number to address a location of the memory to fetch the channel status bits corresponding to the respective residences for the channel in which the selected obfuscation frequency lies. The fetched status bits are applied at random time in a predetermined gating period to gating circuits that enable the generated obfuscation signal to be superimposed randomly, with respect to timing, on the program signal of the channel in which the obfuscation frequency lies to obfuscate the television picture received by viewers of television sets in the residences not authorized to receive the channel in which the obfuscation frequency lies.

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First Claim