| 摘要 |
PURPOSE:To prevent illegal viewing by using a received clock so as to improve in the unit of time of the paper viewing system onto a viewer. CONSTITUTION:Illegal viewing for a time longer than the specified time cannot be prevented since the time for the imposition in the unit of the time slows down when a clock frequency slows down in a conventional system that a clock from a crystal vibrator mounted externally is used and the charging in the unit of time by the paper view system is implemented. Then, a received bit stream in 2.048MHz supplied to a PN generating section 1 is supplied to a frequency divider 7, in which the frequency is divided, the frequency division signal is counted by a counter 3 to implement the charging in the unit of the time by the paper viewing system. Thus, the externally mounted crystal vibrator in a conventional system is replaced to prevent illegal viewing for a time longer than the specified time and even when the received clock is changed into other clock, since the PN generating section 1 is not in operation, scrambling cannot be decoded and the illegal viewing is prevented also in this case. |
