Synchronizing signal recovery circuit

Abstract

Abstract PURPOSE:To recover a horizontal synchronizing signal whose tip levels are arranged to a uniform level stably by slicing the horizontal synchronizing signal expanded once at a prescribed DC level. CONSTITUTION:A video scramble signal is inputted to a terminal IN and a synchronizing separator circuit 10 separates a horizontal and a vertical synchronizing signal. A data superimposed during the vertical blanking period by a data extracting circuit 11 is fed to a data recovery circuit 9 to generate a timing pulse for offset processing and polarity inversion processing, a video inversion circuit 1 restores the polarity of the video signal and a synchronizing offset circuit 3 outputs a signal whose offset level is recovered. The horizontal synchronizing signal expanded by the synchronizing offset circuit 3 and a synchronizing signal expansion circuit 5 is sliced by a slice circuit 6 by using the tip level of a vertical synchronizing signal sampled by a sample holding circuit 7, and a descramble video signal whose pedestal level and tip level are arranged to a prescribed value is obtained at the output terminal OUT of an output circuit 12 to recover the horizontal synchronizing signal.

Inventors

• 👤 Akinobu Masuko
• 👤 昭宣 増子

Bibliographic Details