| 摘要 |
A clock recovery apparatus provides a digital data stream from an incoming stream of raw data on a ring-type data communications network. The apparatus employs a clock generator having a fixed operating frequency for providing a clock signal, a receiving circuitry for receiving the incoming data stream, a phase comparison circuit for comparing the phase of the incoming data stream with the clock signal, and a phase selection circuit responding to the phase comparison circuit for discretely changing the relative phase difference of the data stream and the clock when the phase difference between them exceeds a predetermined phase tracking criterion. The clock is then employed for generating the digital data stream output. The output is preferably employed by a digital regenerator circuit which employs the same clock as used in the data clock recovery circuit. The apparatus can change the clock generator output phase, keeping the frequency fixed, or can insert a delay, of variable discrete increments, in the input data path. |
