| 摘要 |
PURPOSE:To obtain a constant duty ratio under controlling, by picking up a DC level through the pulse shaping of a clock pulse signal with a prescribed duty ratio and controlling a slice level with a difference output through the comparison between the preset reference level and the DC level. CONSTITUTION:The DC reproduction is made from a character multiplex broadcast signal inputted via a television broadcast transmission system at a pedestal clamp circuit 1 and the signal is inputted to a slice amplifier 2. From a rectangular wave signal shaped, a clock run-in signal only is picked up at a clock pulse gate circuit 3 and inputted to a low pass filter 4. From the low pass filter 4, a DC signal is detected and it is compared with a prescribed reference level Er at a DC amplifier 5 and the difference output is obtained. The comparison output is fed back to the slice amplifier 2 to control the slice level. |
