| 摘要 |
PURPOSE:To prevent topping and furtive viewing by nonsubscriber even when an address of a terminal equipment is copied. CONSTITUTION:A microcomputer 2 obtains an exclusive OR between a random number x1 from a random number generator 10 and an individual address A and stores the result into a nonvolatile memory 8. An output from the nonvolatile memory 8 is subject to exclusive OR with the random value x1 at an exclusive OR circuit 12, from which the individual address A is decoded. A processing 6 compares an address included in an output of an FSK detector 5 with the individual address A from the exclusive OR circuit 12 to output contract information. The microcomputer 2 controls a tuner 1 based on the contract information to decide the acceptability of viewing. The random value x1 is required to decode the individual address A and even when the content of the nonvolatile memory 8 is copied to the other terminal equipment, the other terminal equipment cannot decode the individual address A and the topping and furtive viewing by nonsubscriber is prevented. |
