| 摘要 |
<p>PURPOSE:To suppress the reduction of a envelop to the minimum and to make the degradation of a picture minimum by making a phase giving the largest value among phases to be the tracking phase while looking at the smallest dimension among dimensions of each envelop in each phase. CONSTITUTION:Dimensions of envelops at every detection point are detected by an envelop detecting means 102 to be outputted as a signal. the signal is stored in the address of a memory 126 specified by a write address generating circuit 124 according to the write command from a microcomputer 101 after being passed through a switch 119 and an A/D converter 125. Next, after the tracking phase is shifted by a prescribed quantity, dimensions of envelops at every detection points are stored in the memory 126 by the same operation. Thereafter, values of dimensions of stored envelops are compared by a comparator 127 to be transferred to the computer 101, which detects changes of envelops at every detection point. By this method, the tracking phase is made to be the most suitable phase.</p> |
