| 摘要 |
PURPOSE: To obtain a firm decision reference of carrier reproducing, even with respect to a large distortion or noise. CONSTITUTION: This method calculates the centroid of a received three- dimensional configuration in each quadrant of a reproduced plane and introduces the demodulated three-dimensional configuration into the single-frequency range of an ST meter, and precise reproduction is performed by this decision reference. First, speeds Hx and Hg are reproduced to find out an optimum sampling point of time. Samples of an in-phase signal channel X and an orthogonal phase channel Y are obtained on the output side of ADCs 11 and 12. Next calculation is performed in ROMs 13 and 14 to determine their positions in relation to centroids |X| moy and |Y| moy. These two formed ST meters realize the automatic gain control of channels X and Y, and as a result, availability of prediction of displacement of centroids is secured. Since a noise level is compared with the weight of the centroid of the three-dimensional configuration in one quadrant, the three-dimensional configuration is locked correctly, even if a large noise is received. |
