| 摘要 |
<p>A method and apparatus for encoding and decoding of standard television signals are disclosed for enabling reception thereof in an intelligible manner only by authorized subscribers. The scrambling of the audio signals is effected by conversion of analog audio signals to coded digital audio signals. There is provided a subscription television transmitter which can transmit separately a plurality of unique pulse coded control signals consisting of 32-bit binary pulse trains to identify individual authorized subscribers and to provide information needed to unscramble the scrambled video and audio signals. The transmitter generates television signals having a program video portion and a program aural portion in a non-standard format to enable reception of both program video and program audio portions in an intelligible manner only by authorized subscribers. It includes: an encryption code signal generating means; a carrier signal generating means; means for digitizing the program audio signal; means responsive to the encryption code signal for digitally encrypting the digitized program audio signal from the digitizing means; and means for combining the encryption codes signal, the digitized and encrypted audio program signal and a video program signal, with the carrier signals whereby the encryption codes signal, the digitized and encrypted audio signal and the video signal can be individually separated at a receiver.</p> |
