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Methods and apparatus for retiming and realigning SONET signals

A technique for retiming, signaling, used in telecommunications

Inactive Publication Date: 2009-02-04
TRANSWITCH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Known methods of calculating pointer leak rates often suffer from problems in the amount of code required to calculate the leak rate

Method used

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  • Methods and apparatus for retiming and realigning SONET signals
  • Methods and apparatus for retiming and realigning SONET signals
  • Methods and apparatus for retiming and realigning SONET signals

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Embodiment Construction

[0022] Turning now to FIG. 1 , a device 10 according to the present invention includes three FIFOs, preferably implemented in dual port RAM 12 , a write address generator 14 , a read address generator 16 , and a FIFO depth measurement circuit 18 . The RAM 12 has a data input WD (write data), a data output RD (read data), an address input WA (write address), an address output RA (read address), and a write enable input WE. Write address generator 14 receives input from a write demultiplexer (not shown) involving data for the three SPEs, SPE1, SPE2 and SPE3 and provides outputs to the WA and WE inputs of RAM 12. The read address generator receives input from a multiplexer (not shown) related to the read of data from SPE1, SPE2 and SPE3 and provides an output to the RA input of RAM 12.

[0023]The FIFO depth measurement circuit 18 includes a First_Byte detector 20 , a synchronizer 22 , three FIFO depth counters 24 and three FIFO depth latches 26 . First_Byte detector 20 receives...

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Abstract

Methods for retiming and realigning SONET signals include demultiplexing the STS-1 signal from the STS-3 signal, buffering each of the three signals in a FIFO (12), and determining the depth of the FIFO over time ( 24) and determining the pointer leak rate (28) based in part on the FIFO depth and based on the rate of received pointer motion. For a 28-byte deep FIFO, if the FIFO depth is 12-16 bytes (12), no pointer leaks are performed. If the depth is 0-4 bytes (12), a direct positive leak is performed. If the depth is 24-28 bytes (12), a direct negative leak is performed. If the depth is 5-11 bytes (12), then the calculated positive leakage is performed. If the depth is 17-23 bytes (12), then the calculated negative leakage is performed. The calculated leak rate is based on the net number of pointer movements (sum of positive and negative movement amplitudes) received every 32 seconds (256,000 frames) (20).

Description

[0001] This application is related to commonly owned US Patent No. 5,331,641, which is hereby incorporated by reference in its entirety. technical field [0002] The present invention relates to telecommunications. More particularly, the present invention relates to methods and apparatus for computing pointer leak rates for use in retiming SONET signals. Background technique [0003] Since the early 1960s, three different digital multiplexing and signaling systems have been researched in the world. These systems were developed in Europe, Japan and North America. Fortunately, these systems are all based on the same Pulse Code Modulation (PCM), which has a signaling rate of 8,000 samples per second, resulting in a 125 microsecond sampling slot (1 second / 8,000 samples = .000125 ). Both the Japanese and North American multiplex systems are based on the DS-1 rate of 1.544 Mbit / s ± 20 ppm, but the higher data rates in Japan do not correspond to the higher rates used in North Am...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04J3/06H04J3/07
CPCH04J3/0623H04J3/076
Inventor K·S·辛P·戈亚尔A·巴萨克V·库马D·C·乌普
Owner TRANSWITCH