| 摘要 |
PURPOSE:To maintain the secretness of a secret communication system on which its transmitter and receiver synchronize each other, even if someone tries to made a wiretap by using a secret communication equipment of the same type, by key-coding synchronous codes with the inverted array of a MLS (maximum period sequence). CONSTITUTION:A signal indicating a synchronous signal transmission is supplied from input terminal 1 to synchronous code generator 3, whose coding output is supplied to inversion control circuit 13, thereby transmitting bit synchronizing code 10 and frame synchronizing code 11, which is expressed by inverting a code of a maximum period sequence MLS code corresponding to a code supplied from terminal 2, from terminal 4. At the reception side, on the other hand, the pattern of synchronizing code 10 inputted to input terminal 6 is supplied via shift register 6 and coincidence circuit 7 to shift register 14, the output of which is then supplied to coincidence circuit 15, where the synchronous pattern outptted from register 14 in parallel is compared and collated, according to a code from terminal 9, thereby outputting it from terminal 8 according to the discrimination result of circuit 15. |
