| 摘要 |
PROBLEM TO BE SOLVED: To synchronize the frequency of the receiving carrier of orthogonal amplitude modulated signals having a large multilevel value to that of a reproduced carrier in a short time. SOLUTION: In order to synchronize the frequency of the receiving carrier of orthogonal amplitude modulated signals having a large multilevel value to that of a reproduced carrier, a symbol point which is to be utilized for frequency discrimination is defined in advance out of symbol points a-j in an I-Q plane and, when the signal point corresponding to the defined symbol point is received, the frequency synchronization is established in a short time by rotating I-Q orthogonal coordinate axes by moving the signal points on the straight line L connecting an origin O to an ideal symbol point having the largest amplitude value. In addition, by repeating the synchronizing process by switching the receiving symbol point utilized for discrimination in accordance with the synchronous state, the phase error which occurs when the frequencies are synchronized to each other is reduced. |
