METHOD AND APPARATUS FOR DESCRAMBLING A TELEVISION SIGNAL

摘要

A baseband television signal having a video portion with a suppressed horizontal sync pulse is descrambled by using a variable attenuator. The attenuator shifts the level of predetermined portions of the signal to restore the suppressed horizontal sync pulse to a normal unsuppressed level with respect to the rest of the signal. A reference voltage is derived from a blanking level potential and sync level potential of the signal, and is equal to the zero carrier level of the video portion of the signal. The reference voltage is utilized to maintain the level of the restored sync pulse at a proper value.