Data slice circuit separating data added to a signal superposed on a video signal based on slice level

摘要

A data slice circuit capable of generating an optimal data slice level and separating data for VBI signals of different specifications, provided with a line detection circuit for detecting any line on which a VBI signal having a CRI signal is superposed and outputting a line detection pulse only during the period and detecting any line on which a VBI signal having a reference signal is superposed and outputting another line detection pulse only during that period, a window pulse generation circuit for outputting pulses changing a period of averaging the VBI signal in accordance with the detection pulses, a data slice reference voltage detection circuit for sampling and holding an average voltage of the clamped VBI signal only while the output pulses are at a high level “H”, and a data slice level generation circuit for adding a direct current voltage changed in accordance with the detection pulsed to the output voltage.