Automatic frequency control unit which detects a frame pattern in a phase modulation signal

摘要

An automatic frequency controller synchronizes a received carrier signal with a simulated carrier signal to automatically control a center frequency of the simulated carrier signal. The received carrier signal has a first synchronous code pattern inserted into a plurality of frame periods and a second synchronous code pattern inserted into a plurality of multiframe periods. The phase of the received carrier signal is determined by sweeping the center frequency of the simulated carrier signal and mixing the simulated carrier signal with the received carrier signal. The sweep of the center frequency of the simulated carrier signal is reduced when frame synchronization is detected and the sweep of the center frequency is fixed when multiframe synchronization is detected.