Method and apparatus for detecting timing pulses for scrambled television system

摘要

A method and apparatus for detecting timing pulses for descrambling a scrambled television signal, wherein a video IF signal and a sound IF signal are separated from a scrambled television IF signal by utilizing different filters, a local video carrier wave synchronized with the separated video IF signal is generated and is mixed with the separated sound IF signal for producing a beat signal, the timing pulses are detected by demodulating the main sound IF signal, and then descrambling the received scrambled television IF signal by stretching horizontal synchronizing intervals in accordance with stretch data obtained by decoding compression data contained the detected timing pulses, whereby the main sound IF signal is separated from the beat signal by attenuating the auxiliary sound IF signal with a bandpass filter.