| 摘要 |
PURPOSE:To obtain an accurate, high-precision measuring device of simple constitution by sampling and holding a signal generated by clipping the peak of a luminance signal of video at a constant voltage, and measuring a frequency after frequency modulation by said output through a counter. CONSTITUTION:The peak of the horizontal synchronizing signal of an input video luminance signal 18 is clamped by a clamping circuit 11 to the constant voltage, and the clamped luminance signal is processed by high-frequency emphasis 12. A spike pulse generated at this time is suppressed by a white clip/ dark clip circuit 13 and inpt the resulting signal 22 to a sample holding circuit 14. When a switch 20 is placed on the side of measurement of a sink chip level SCL, a sampling pulse SP generating circuit 17 outputs an SP signal 24A which synchronizes the horizontal synchronizing signal of the signal 18 except in a vertical blanking period to a circuit 14, which holds the SL of the signal 22. The SCL is converted 15 into a frequency, which is measured 16. Then, the switch 20 is placed at the side of measurement of a white peak level and an SP signal 25B is outputted from the circuit 17 to take a measurement 16 of a white peak carrier frequency. |
