Clock recovery arrangement
AssigneeGeneral Electric Company
InventorMichael W. Evans
Life of this patent
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Abstract
A clock recovery arrangement particularly suitable for recovering a clock signal from Manchester-encoded data. The system includes a locally generated clock at twice the data rate. This locally generated clock is phase locked to the incoming data transitions. Then, the locked locally generated clock is divided by two to produce a clock signal corresponding to the data rate. A clock flipper circuit operating according to a predetermined algorithm determines whether to change the polarity of the clock signal to provide a correct polarity recovered clock.
Claims21
A clock recovery arrangement for recovering a clock signal at a first frequency, which clock signal is synchronized to a received data stream having a characteristic data bit frequency equal to said first frequency, comprising:
- means for detecting edge transitions of said data stream and producing an edge signal indicative thereof;
- means for generating a local second frequency clock signal, said second frequency being twice that of said first frequency, said second frequency clock signal not being phase synchronized with said received data stream;
- means for phase locking said second frequency clock signal to said edge transitions to produce a phase locked second frequency clock;
- means for dividing said phase locked second frequency clock by two to produce a clock signal at said first frequency that is phase locked to said edge signal and therefore phase locked to said received data stream;
- and
- means for changing the polarity of said phase locked first frequency clock according to a predetermined function of said edge signals, thereby producing a received clock synchronized to said received data stream.
A data and clock recovery system comprising:
- means for receiving a data stream having a first characteristic data bit frequency;
- means for detecting edge transitions of said data stream and producing an edge signal indicative thereof;
- means for generating a local second frequency clock signal, said second frequency being twice that of said first frequency, said second frequency clock signal not being phase synchronized with said received data stream;
- means for phase locking said second frequency clock signal to said edge transitions to produce a phase locked second frequency clock;
- means for dividing said phase locked second frequency clock by two to produce a clock signal at said first frequency that is phase locked to said edge signal and therefore phase locked to said received data stream;
- and
- means for changing the polarity of said phase locked first frequency clock according to a predetermined function of said edge signals, thereby producing a received clock synchronized to said received data stream.
An arrangement for recovering a clock from Manchester coded data having a first characteristic frequency, comprising:
- means for detecting edge transitions of said data stream and producing an edge signal indicative thereof;
- means for generating a local second frequency clock signal, said second frequency being twice that of said first frequency, said second frequency clock signal not being phase synchronized with said recovered data stream;
- means for phase locking said second frequency clock signal to said edge transitions to produce a phase locked second frequency clock;
- means for dividing said phase locked second frequency clock by two to produce a clock signal at said first frequency that is phase locked to said edge signal and therefore phase locked to said received data stream;
- and
- means for changing the polarity of said phase locked first frequency clock according to a predetermined function of said edge signals, thereby producing a recovered clock synchronized to said received data stream.
Dependencies are inferred from the claim text.