Side-tone OTDR for in-service optical cable monitoring
US5926263A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 10, 1996 |
| Grant date | Jul 20, 1999 |
| Priority date | — |
| Expiry date | Oct 10, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B10/071
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An OTDR provides both in-service and out-of-service measurement information for an optical transmission system with multiple repeaters. The repeaters include an optical high-loss loop back (HLLB) path and an OTDR path. The OTDR is coupled to the input lines of the optical transmission system via an optical coupler so that both traffic signals and test signals from the OTDR can be transmitted simultaneously. When the OTDR is providing in-service measurement information, test signals in the form of side-tone pulses are transmitted on the transmission system. The wavelengths of the test signals are sufficiently offset from the wavelength of the traffic signal so there is minimal interference between them. The level of the test signals is low relative to the traffic signal to also minimize interference. The OTDR filters out the traffic signal from the returned signal. The HLLB path through the amplifier pairs of each repeater is distinguishable in the filtered returned signal. When the OTDR is providing out-of-service measurement information, the level of the side-tone pulses is increased because interference with traffic signal is no longer a concern. Both the HLLB path and the OTDR p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.