Importance

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Abstract

A scrambling and descrambling system and method for the video and/or audio portions of a broadcast TV signal, for example, broadcast by cable, microwave or communication satellite, includes a telephone modem at the descrambling receiver decoder box which is periodically, for example once per month for a few seconds, connected to a central computer of the head end operator. The decsrambling decoder box is enabled to receive the telephone call by a digital identification code broadcast periodically and associated with each decoder box. Each decoder box has a digital serial number in its Read-Only Memory (ROM) portion of its CPU (central processing unit) and an Electrically Alterable Read-Only Memory (EAROM) containing an alterable look-up table having for each program code a corresponding descrabling code to enable the descrambler. The central computer calls the descrambler box, receives its temporary serial number code and then, by digital code translated into electrical signals, changes the look-up table to provide a new temporary identification code, unique to that box, for the nex period. Simultaneously, the central computer polls the EAROM to record, by program number, those pay-per-view programs which had been viewed, for billing purposes.

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First Claim