| 摘要 |
<p>PURPOSE:To generate a pulse at always prescribed leading timing by detecting a half value of a peak voltage from an input signal having periodicity, comparing it with the input signal and using the coincident point as the leading point of the pulse. CONSTITUTION:Only a 4.5MHz beat is extracted from an output signal of a video detection circuit 38 by a band pass filter 39, subject to AM detection by an AM detection circuit 40, the one is inputted to a pulse generating circuit 41. The other is inputted to a peak detection circuit 42 and a peak voltage of an output waveform is detected, a half value of the peak voltage is outputted by a half value detection circuit 43 and the result is inputted to a pulse generating circuit 41. The pulse generating circuit 41 compares the AM detection output with a half value of the peak voltage of the AM detection output and when the voltage of the AM detection output is higher, a pulse is generated. The pulse width from the leading time is adjusted in the pulse by a pulse width adjuster 42a and the amplitude is increased by an RF amplifier 35 for a period when the pulse is inputted, the scrambled synchronizing signal is descramble.</p> |
