| 摘要 |
<p>PURPOSE:To convert a video signal into a digital signal and to decide standard/ nonstandard signal by generating a television signal with a prescribed time difference from a television signal from an A/D converter converting a television signal into a digital signal and comparing synchronizing signals of television signals with a prescribed time difference. CONSTITUTION:A video signal inputted from an input terminal 10 is converted into a digital signal by an A/D converter 14. Moreover, a burst PLL clock generating circuit 12 outputs a clock signal of 4fSC to each section. The digital signals is retarded by delay elements 16, 18, 20, and when the input video signal is a standard signal, the signal is delayed by 1H, 1H, 524H respectively at the delay elements 16, 18, 20 and the video signal is converted into 1-bit synchronizing signal by synchronizing separator circuits 40, 42, 44. Two synchronizing signals inputted to a phase difference detection circuit 46 are standard television signals, then the signals are in-phase signals delayed by one frame, and no output is obtained and if any output exists, it is the nonstandard signal. Thus, the decision of the nonstandard is applied independently of the characteristic of an A/D converter or the like.</p> |
