US4928275A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Synchronization of asynchronous data signals
Assignee: Nortel Networks Ltd
•
Filing: 1989-05-26
•
Granted: 1990-05-22
•
Expires: 2009-05-26
Abstract
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.
Inventors
- 👤 Thomas E. Moore
- 👤 James A. McEachern
- 👤 Mark S. Wight
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:33
CPC Classifications
H; H04; H04J; H04J3/00; H04J3/02; H04J3/06; H04J3/07; H04J3/076
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
95 words
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.
Claim 2
Independent Claim
95 words
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.
Claim 3
Dependent Claim
58 words
A method as claimed in claim 1 wherein the is latched read address for the store in synchronism with a read clock for the store at a predetermined time during the frame of the synchronized signal, and the phase difference is subsequently determined from a difference between a write address for the store and the latched read address.
Claim 4
Dependent Claim
23 words
A method as claimed in claim 1 wherein the stuff request signal is produced in synchronism with the frame of the synchronized signal.
Claim 5
Dependent Claim
23 words
A method as claimed in claim 2 wherein the stuff request signal is produced in synchronism with the frame of the synchronized signal.
Claim 6
Dependent Claim
15 words
A method as claimed in claim 4 wherein the asynchronous signal comprises a DS1 signal.
Claim 7
Dependent Claim
92 words
Synchronizing apparatus comprising: 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.
Claim 8
Dependent Claim
92 words
Synchronizing apparatus comprising: 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.
Claim 9
Dependent Claim
84 words
Apparatus as claimed in claim 6 wherein the means responsive to the difference between the write address and the latched read address comprises subtracting means for producing a binary signal dependent upon the difference between the write and read addresses relative to a threshold level, means for latching the binary signal in synchronism with the writing of data in the store, and means for latching the latched binary signal in synchronism with the frame of the synchronized signal to produce the stuff request signal.
Claim 10
Dependent Claim
18 words
Apparatus as claimed in claim 7 wherein each means for latching the binary signal comprises an edge-triggered flip-flop.
References Cited (Backward Citations)
US4397017A
Cited
US4674088A
Cited
US4757452A
Cited
US4764942A
Cited
US4667324A
Cited
US4811340A
Cited
US4847875A
Cited
US4791652A
Cited
US4823365A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-05-21 | 1993-11-20 | 1994-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-21 | 1997-11-20 | 1998-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-21 | 2001-11-20 | 2002-05-22 | $7700.00 | Window Closed / Lapsed |