Optical network loss-of-signal detection
US6178025A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 3, 1997 |
| Grant date | Jan 23, 2001 |
| Priority date | — |
| Expiry date | Dec 3, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B2210/071
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Loss of optical signal is detected in a synchronous communications system by detecting features of a monitor signal occurring at a detection frequency corresponding to the frame rate. Since the frame rate is substantially less than the bit rate, monitoring and detection can be performed at a lower bandwidth than the bit rate. An auto-correlation circuit utilises delays which are an integral multiple of the frame rate and produces a detection value which is compared with a threshold value. Alternatively, detection may be based on a power measurement of a band pass filtered monitor signal by setting the lower bandwidth limit above zero frequency and normalizing the measurement of power relative to an average power measurement. A loss of signal may then be detected by a change in power measurement relative to a threshold and can be used for asynchronous systems as well as synchronous systems. Loss of signal detection may be utilised to control an optical switch to re-route optical signals and generate alarm signals. The use of such detection in all optical networks avoids the requirement for electronic processing at the bit rate as a means of detection of loss of signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.