| 摘要 |
A communication station such as a hand-held telephone quickly identifies a desired carrier signal or time slot of a carrier signal and synchronizes itself in time and frequency to that carrier or slot. Synchronization is achieved even when frequency and time reference signals in the communication station are offset, e.g., due to drift, with respect to the carrier signal or slot by averaging successions of signal measurements that occur at times when corresponding signal values are expected. In one method, a plurality of measurements of the received signal taken at a group of predetermined time points where corresponding values are expected are averaged together, in order to enhance the signal to noise ratio. Averaging is carried out several times using different groups of time points, the groups corresponding to respective, different expected clock frequency errors. The results of the averaging steps are used in determining a best hypothesis for the received signal. Dynamic programming is used to test synchronization hypotheses based on different hypotheses of timing drift rate and to discriminate between different hypotheses of timing and timing drift rate in order to maximize sums of correlations.
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