| 摘要 |
PURPOSE:To reduce the deterioration of video quality produced for cryptograph, by providing the code generation section which additionally selects and outputs the code corresponding to the predetermined mode, with the normal code generating section producing random codes. CONSTITUTION:Newly and additionally, an oscillator 21, gate logic circuit 22, binary decimal counter 23, mode generating circuit 24, 4-bit latch circuit 25, 4-bit parallel serial shift register 26, coincidence circuit for group A 27, and coincidence circuit for group B 28 are connected. Thus, the coding system for radio type charged television broadcast is constituted and the mode selection period of encode control signal is made longer while maintaining random nature, and the code signal only corresponding to this mode is selected and controlled. Thus, the deterioration of video quality is less and the confidentiality is increased. |
