| 摘要 |
PURPOSE:To secure voice security by changing continuously a carrier frequency and sending data while frequency variable information relating to the change is added to the data. CONSTITUTION:A frequency variable command section 13 outputs present carrier frequency, carrier frequency moving direction and frequency moving quantity as data and outputs them to a frequency variable audio carrier generating section 15, in which an audio carrier is generated based on the received data and given to an audio FM modulation section 9. In this case, the frequency variable audio carrier generating section 15 changes the audio carrier continuously for a period based on the data from the frequency variable command section 13. The audio FM modulation section 9 applies FM modulation to the carrier received from the frequency variable audio carrier generating section 15 by an audio signal whose scrambling is descrambled and provides an output of it to a video and audio mixing section 11, in which a video signal and an audio signal are mixed and the result is outputted to a CATV cable. |
