| 摘要 |
PURPOSE:To attain information exchange with ease for the concerned personnel of communication by synthesizing ciphering picture control information and a TV signal at the transmission side to form a ciphering picture, adding ciphering picture control information at the outside of picture transmission band of a ciphering picture to change content of ciphering. CONSTITUTION:The TV signal inputted to a terminal 1 and a signal of a disturbing signal generator 5 being ciphering control information are coupled by a synthesis circuit 3 to form a ciphering picture. On the other hand, a part of a signal of the disturbing signal generator 5 is led to an FM modulator 6 to form an FM wave at the outside of the picture band of the same signal as the disturbing signal applied to the synthesis circuit 3. Then the FM wave inputted to an input terminal 11 is separated into a ciphering picture and the FM wave at a separation circuit 7 at the reception side. Then the FM wave is demodulated by a demodulator 8, the disturbing signal being an output of the demodulator 8 is inverted and the disturbing signal is cancelled by a synthesis circuit 10 and a reproducing signal is obtained from a terminal 12. |
