| 摘要 |
A communications management system introduces a low bandwidth phase locked loop (LoBW-PLL) working in tandem with a high bandwidth phase locked loop (HiBW-PLL). The LoBW-PLL only needs to follow the average frequency of the transported clock and not all of the excursions made by the master clock. During periods of downstream outage, the LoBW-PLL opens its loop and free wheels such that disturbances caused by a reacquisition do not impact the concept of time for the LoBW-PLL. After reacquisition, the LoBW-PLL and HiBW-PLL are compared to determine if a timing error has occurred. If a timing error is detected, the magnitude of the timing error is measured upon completion of the reacquistion cycle, and this measurement is used to correct the timing error.
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