VOICE PRIVATE TRANSMISSION SYSTEM AND EQUIPMENT FOR TELEVISION SIGNAL

PROBLEM TO BE SOLVED: To attain simple audio scrambling at a low cost for a CATV system. SOLUTION: A multiplex control signal not superimposed on an audio private signal is outputted at a head end of a CATV system. Furthermore, the audio signal is sent as a sub channel signal and a meaningless tone is sent as a main channel signal. A home terminal 200 uses a tuner 21 to select a reception signal and an FSK data demodulator 29 demodulates control data. A CPU 30 decodes control data and allows a multiplex control signal generator 31 to generate a multiplex control signal when confirming it that the demodulation is allowed. A multiplex demodulator 32 demodulates the reception signal into a dual audio signal by using the multiplex control signal. The signal demodulated by the multiplex demodulator 32 is amplified by low frequency amplifiers 28, 33 and outputted from speakers 35, 36. When the demodulation is not permitted, since the main channel signal is demodulated and the meaningless tone is outputted, the audio signal is scrambled.