Importance

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Abstract

An electronically tuned television receiver is provided with a channel lockout feature to control viewer program selection. The television receiver has a tuner local oscillator (101), the frequency of which is controlled by a phase lock loop (12) having a programmable frequency divider (122,123). A microprocessor receives a user input from a keyboard (14) or remote transmitter (15) indicating a desired channel. In response to this input, the microprocessor normally loads a programmable constant in the programmable frequency divider to cause the tuner (10) to be tuned to the desired channel. However, the microprocessor is programmed to respond to a user entered lockout code sequence to store in a non-volatile memory (19) one or more channels to be inhibited for a predetermined period of time. Should a user input indicate one of the inhibited channels, the microprocessor does not load the corresponding programmable constant in the programmable frequency divider with the result that the television receiver continues to receive the last valid channel selected. Once the predetermined period of time has elapsed, the non-volatile memory is cleared of the inhibited channels, and the television receiver reverts to normal tuning operation for all channels. The microprocessor is further programmed to respond to a security code to permit viewing of an inhibited channel during the time that channel is locked out. In addition, the microprocessor is programmed to respond to a master key code to permit clearing of all inhibited channels stored in the non-volatile memory.

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First Claim