| 摘要 |
PURPOSE:To shorten convergent time until a loop becomes stable state by correcting the number of frequency according to the quantity of a mistaken lock. CONSTITUTION:When the state of the mistaken lock occurs, output 'zero' is generated by a mistaken look detection circuit 18 and when the state of the mistaken lock does not occur, the output '1' is generated. As an APC loop is opened by an AND circuit 30 in the state of the mistaken lock, it is essentially cut. Then only a mistaken locked loop works. When the frequency error of a VCO 17 is held down in a controlled range by the APC loop, the output of the mistaken lock detection circuit 18 becomes '1'. As the result, a closed circuit is formed by the APC loop and the operation by the APC loop is obtained. Thus the phase of the output chrominance components from a band filter 21 is controlled to be the frequency (fs).
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