| 摘要 |
<p>A television system having sync suppression scrambling and descrambling which includes in band and out of band signaling methods. The in band signaling method modulates the IF sound carrier of a premium video channel with timing and data pulses (Figs. 2A, 2B) while the out of band signaling method modulates the previously modulated IF sound on a separate carrier onto a separate out of band data carrier (Figs. 3A, 3B). The in band signaling method uses a descrambler which tunes a channel before demodulating the timing and data pulses from the sound carrier while the out of band signaling method tunes a selected data carrier to demodulate the timing and data pulses. In both methods, the timing pulses are used to restore the levels of the synchronization pulses in the sync suppressed video signal, and thus descramble the signal, while the data pulses are used for addressable messaging to the descrambler including authorization. The out of band descrambler provides broadband sync restoration for a particular channel and thus does not need a broadband tuner for the video signal.</p> |
