Synchronization of asynchronous data signals
AssigneeNorthern Telecom Limited
InventorsJames A. McEachern, Wayne D. Grover
Life of this patent
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Abstract
In a synchronous network, asynchronous data signals are synchronized using positive/negative stuffing under the control of stuff request signals which are produced in dependence upon the phase difference between the asynchronous and synchronized data signals as compared to respective threshold values. The phase difference is, or the threshold values are, cyclically changed in a manner to produce additional stuffing, not necessitated by the asynchronous frequency difference, whereby the frequency of jitter, due to stuffing, in the synchronized data signal is increased. The increased frequency jitter is filtered out in an already-provided phase locked loop.
Claims48
A method of synchronizing an asynchronous signal to produce a synchronized signal by stuffing the asynchronous signal in dependence upon a stuff request signal produced from a comparison of phases of the asynchronous and synchronized signals, wherein the stuff request signal is produced with additional stuff requests thereby to change the frequency spectrum of jitter in the synchronized signal.
A method of synchronizing an asynchronous data signal to produce a synchronized data signal comprising the steps of:
- stuffing the asynchronous data signal in dependence upon a stuff request signal to produce the synchronized data signal;
- producing the stuff request signal in dependence upon the relative phases of the asynchronous and synchronized data signals;
- and
- modifying the production of the stuff request signal to include additional stuff requests therein, whereby the frequency of jitter, due to stuffing, in the synchronized data signal is increased.
A method of synchronizing an asynchronous data signal to produce a synchronized data signal comprising the steps of:
- stuffing the asynchronous data signal in dependence upon positive and negative stuff request signals to produce the synchronized data signal;
- producing the positive and negative stuff request signals in dependence upon the magnitude of a phase difference between the asynchronous and synchronized data signals in comparison to respective threshold values;
- and
- cyclically changing at least one of said phase difference and said threshold values thereby to produce additional stuff requests in the positive and negative stuff request signals, whereby the frequency of jitter, due to stuffing, in the synchronized data signal is increased.
Synchronizing apparatus comprising:
- means responsive to a stuff request signal for stuffing an asynchronous data signal to produce a synchronized data signal;
- means for producing the stuff request in a dependence upon the relative phases of the asynchronous and synchronized data signals;
- and
- modifying means for modifying the production of the stuff request signal to include additional stuff requests thereby to increase the frequency of jitter, due to stuffing, in the synchronized data signal.
Synchronizing apparatus comprising:
- means responsive to positive and negative stuff request signals for stuffing an asynchronous data signal to produce a synchronized data signal;
- means for producing the positive and negative stuff request signals in dependence upon the magnitude of a phase difference between the asynchronous and synchronized data signals in comparison to respective threshold values;
- and
- means for cyclically changing at least one of said phase difference and said threshold values thereby to produce additional stuff requests in the positive and negative stuff request signals, whereby the frequency of jitter, due to stuffing, in the synchronized data signal is increased.
A method of synchronizing an asynchronous data signal to produce a synchronized data signal, comprising the steps of:
- stuffing the asynchronous data signal in dependence upon a stuff request signal to produce the synchronized data signal;
- producing the stuff request signal in dependence upon the magnitude of a phase difference between the asynchronous and synchronized data signals in comparison to at least one threshold value;
- and
- modifying the production of the stuff request signal in dependence upon said comparison to increase the frequency of jitter, due to stuffing, in the synchronized data signal.
Synchronizing apparatus comprising:
- stuffing means responsive to a stuff request signal for stuffing an asynchronous data signal to produce a synchronized data signal;
- means for producing the stuff request signal in dependence upon the relative phases of the asynchronous and synchronized data signals in comparison to at least one threshold value;
- and
- means for varying the threshold value whereby the frequency of jitter, due to stuffing, in the synchronized data is increased.
Dependencies are inferred from the claim text.