| 摘要 |
PURPOSE: To provide a method and device for encryption of digital multi-sound in television broadcast and its decoding. CONSTITUTION: A transmission source 1 applies a digital signal including sound information to an NICAM generator 2, which formats the signal and gives the result to an encryption unit 4, in which the resulting signal before it is sent to a receiver. The receiver is provided with a decoding unit 5. A transmitter side adds a pseudo random sequence to a digital signal to encrypt the signal. The receiver side reproduces the original signal through similar processing. A pseudo random sequence generator generates the pseudo random sequence. The sequence is controlled by a control word, generated at random at the transmitter side and changed at a proper time interval. The control word is encrypted and sent to the receiver and decoded thereat and fed to a pseudo random sequence generator of the receiver. |
