Channel searching circuit

Abstract

Abstract PURPOSE:To change a channel faster by preventing the channel from changing at a constant cycle, writing a necessary video signal into a memory after the output of a phase locked loop(PLL) circuit is phase-locked to an input video signal, and thereafter, immediately providing a means to change channel. CONSTITUTION:The video signal from a video amplifier 6 is supplied to a lock signal generator 21. Further, a regenerative horizontal synchronizing signal form a synchronizing circuit 14 to separate the synchronizing signal from the input video signal is supplied to the lock signal generator 21. A regenerative horizontal synchronizing signal PHL consists of a PLL circuit in the synchronizing circuit 14. The horizontal synchronizing signal induced in the video signal from the video amplifier 6 is decided whether or not it is synchronized with the regenerative synchronizing signal PHL inside the lock signal generator. When a lock condition is decided, a decision output J is supplied to a channel change generator 19. When the decision signal J to indicate the lock condition is inputted, the channel change generator 19 applies a next channel searching signal to a tuner 2.

Inventors

• 👤 Yukitomi Fujishima

Bibliographic Details