US 7,023,942 B1 · Method and apparatus for digital data synchronization

Abstract

Synchronization and desynchronization of a data signal transported in a synchronous frame across a synchronous communications network, such as SONET/SDH, reduces waiting-time jitter. A timing estimate (F) indicative of a relationship between a data rate (f1) of the data signal and a reference frequency (f2) of the synchronous communications network is calculated and communicated through the synchronous communications network, for example in the Synchronous Payload Envelope of a SONET frame. The data signal is recovered using a desynchronizer Phase-Locked Loop steered by the timing estimate (F). The timing estimate (F) can be any one or more of: a ratio between the data rate (f1) and the reference frequency (f2); a difference between the data rate (f1) and the reference frequency (f2); and a phase difference between a recovered data clock signal associated with the data rate (f1) and a reference clock signal associated with the reference frequency (f2).

Claims27

Dependent claims

A method of synchronizing a data signal for transport across a synchronous communications network, the method comprising steps of:

calculating a timing estimate (F) indicative of a relationship between a data rate (f1) of the data signal and a reference frequency (f2) of the synchronous communications network;
mapping data of the data signal to a synchronous signal of the synchronous communications network in accordance with the reference frequency (f2), while inserting stuff bits into the synchronous signal in accordance with the timing estimate (F);
and
communicating the timing estimate (F) through the synchronous network.

1 more element

A method of desynchronizing a data signal transported across a synchronous communications network, the method comprising steps of:

receiving a synchronous payload envelope (SPE) of the synchronous communications network, the SPE containing data of the data signal and a timing estimate (F) indicative of a relationship between a data rate (f1) of the data signal and a reference frequency (f2) of the synchronous communications network;
and
demapping the data of the data signal from the SPE in accordance with the reference frequency (f2);
while extracting stuff bits from the synchronous signal in accordance with the timing estimate (F).

1 more element

A desynchronizer for desynchronizing a data signal transported across a synchronous communications network within a synchronous payload envelope (SPE) of the synchronous communications network, the SPE containing data of the data signal and a timing estimate (F) indicative of a relationship between a data rate (f1) of the data signal and a reference frequency (f2) of the synchronous communications network, the desynchronizer comprising:

a pointer processor for demapping the data of the data signal from the SPE in accordance with the reference frequency (f2);
while extracting stuff bits from the synchronous signal in accordance with the timing estimate (F).

Dependencies are inferred from the claim text.

Method and apparatus for digital data synchronization

Life of this patent

Method and apparatus for digital data synchronization

Life of this patent

Abstract

Claims27