초록 ▼

A high security pay television system is provided in which television receivers include a decoder and with periodically changed removable memory modules. The decoder only functions to properly descramble the scrambled broadcase signal when a changeable system-wide code is available in the decoder. T

A high security pay television system is provided in which television receivers include a decoder and with periodically changed removable memory modules. The decoder only functions to properly descramble the scrambled broadcase signal when a changeable system-wide code is available in the decoder. The code can either be carried in the memory module, or an internal code unique to the decoder and resident in the decoder can be combined with an external code in the removable memory module, and also unique to that decoder, to generate the common systemwide system code. Program viewership is written on the removable memory module which is returned to a central facility for later subscriber billing.

대표청구항 ▼

A television receiver adapted for use in a pay television system in which broadcast signals are scrambled comprising turner means for receiving the broadcast signal and for separating the broadcast signal into at least two components; a decoder circuit connected to receive a first one of the compone

A television receiver adapted for use in a pay television system in which broadcast signals are scrambled comprising turner means for receiving the broadcast signal and for separating the broadcast signal into at least two components; a decoder circuit connected to receive a first one of the components from the tuner means; a mixer to combine the output of the decoder circuit with the first component of the output of the tuner means; a television screen and associated driver circuitry to display the output of the mixer; an electrically alterable memory module containing a first memory portion in which at least one pre-written external code is carried and a second memory portion in which program information may be entered; a microprocessor in the decoder circuit programmed to (1) read the external code from the memory module, (2) derive a broadcast code from the video signal, (3) generate a descrambling signal from the external code and output the descrambling signal to the mixer, and (4) to write information about programs actually being descrambled, as determined by the broadcast code, in the memory module so that use of the receiver to view scrambled broadcasts can be billed on a usage basis; and means for descrambling a second of the separated components of the broadcast signal from the tuner means separately from the other components so that full, descrambled composite video signal is not available at any one point in the receiver.