Synchronization of asynchronous data signals
First Claim
1. 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 with a threshold level of a phase difference between read and write phases with which the synchronized and asynchronous signals are respectively read from and written into a store, wherein a read address for the store is determined in synchronism with a time division multiplex frame of the synchronized signal, and the phase difference is determined at a time synchronized to a write clock for the store.
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Abstract
A method of and apparatus for synchronizing an asynchronous DS1 signal to produce a synchronized signal in the SONET format is described. The asynchronous signal is stuffed in dependence upon a stuff request signal which is produced from a comparison with a threshold level of a phase difference between read and write phases with which the synchronized and asynchronous signals are respectively read from and written into an elastic store. The phase detection and threshold comparison are effected synchronously with the respective signals. To this end, the read address for the store is latched in synchronism with the synchronized frames, and its difference from the write address and the resulting threshold level comparison is effected in synchronism with the write clock for the store and hence with the asynchronous signal. The synchronizer provides a reduced waiting time jitter in the synchronized signal.
81 Citations
8 Claims
- 1. 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 with a threshold level of a phase difference between read and write phases with which the synchronized and asynchronous signals are respectively read from and written into a store, wherein a read address for the store is determined in synchronism with a time division multiplex frame of the synchronized signal, and the phase difference is determined at a time synchronized to a write clock for the store.
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6. Synchronizing apparatus comprising:
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a store; means for writing data of an asynchronous signal into the store at a write address and means for reading data from the store at a read address to produce a synchronized data signal; means for latching the read address in synchronism with a time division multiplex frame of the synchronized signal; means responsive to a difference between the write address and the latched read address for producing a stuff request signal; and means responsive to the stuff request signal for providing stuffed information in the synchronized signal. - View Dependent Claims (7, 8)
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Specification
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- Resources
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Current AssigneeNortel Networks Limited (Nortel Networks Corporation)
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Original AssigneeNorthern Telecom Limited (Nortel Networks Corporation)
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InventorsMoore, Thomas E., Wight, Mark S., McEachern, James A.
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Primary Examiner(s)Olms, Douglas W.
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Assistant Examiner(s)HSU, ALPUS
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Application NumberUS07/357,244Time in Patent Office361 DaysField of Search370/102, 370/100, 370/105, 325/118, 325/111, 325/112US Class Current370/506CPC Class CodesH04J 3/076 Bit and byte stuffing, e.g....
