| 摘要 |
PURPOSE:To obtain a stable data by providing the 2nd clamp circuit operated digitally to the post-stage of the 1st clamp section in a clamp circuit used for an A/D converting section of a time axis correcting device of a VTR. CONSTITUTION:A video amplifier 2 amplifies an input video signal 1 and given to an A/D converter 6. In order to eliminate a DC change of the video signal inputted to the A/D converter 6, the pedestal of the video signal is sampled by a clamp circuit 3, fed back and the pedestal part is clamped finally to a desired DC potential. A digital data 7 outputted from the A/D converter 6 is subject to sampling and averaging at least at three parts by a sampling circuit 9. The averaged data 10 is inputted to an error detection circuit 13, compared with an absolute data of the predetermined pedestal part, an error output 12 controls an error correction circuit 11 so as to correct the output data 7 of the A/D converter 6. |
