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.
