Fault location in optical communication systems
First Claim
1. An optical transmission system including a data transmitter arranged to transmit a downstream scrambled data sequence, a data receiver, an optical fibre path for carrying transmitted optical signals therebetween, wherein said system incorporates means for retrieving from the transmission path signals including a reflection of the transmitted data sequence from a fault, and signal processing means for correlating said reflection of the transmitted data sequence with a time delayed copy of that data sequence so as to determine from the duration of said time delay a location in the optical fibre path of the fault from which the data sequence has been reflected, whereby the transmitted data sequence provides a test signal for fault detection while the transmission system is in service.
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Accused Products
Abstract
An optical transmission system comprises a transmitter and a receiver linked by an optical path having amplifier stations and incorporating a reflectometer for determining the location of an optical fault in the path. Transmitted signals are tapped from the path at an amplifier station and are processed by a correlation technique to detect the relative timing of reflections from a fault and thereby to determine the location of that fault.
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Citations
20 Claims
- 1. An optical transmission system including a data transmitter arranged to transmit a downstream scrambled data sequence, a data receiver, an optical fibre path for carrying transmitted optical signals therebetween, wherein said system incorporates means for retrieving from the transmission path signals including a reflection of the transmitted data sequence from a fault, and signal processing means for correlating said reflection of the transmitted data sequence with a time delayed copy of that data sequence so as to determine from the duration of said time delay a location in the optical fibre path of the fault from which the data sequence has been reflected, whereby the transmitted data sequence provides a test signal for fault detection while the transmission system is in service.
- 11. A method of determining the location of a fault generating an optical reflection in an optical transmission system including a data transmitter arranged to transmit a downstream scrambled data sequence, a data receiver, an optical fibre path for carrying transmitted optical signals therebetween, the method comprising retrieving from the transmission path signals including a reflection of the transmitted data sequence from the fault, and correlating said reflection of the transmitted data sequence with a time delayed copy of that data sequence so as to determine from the duration of said time delay a location in the optical fibre path of the fault from which the data sequence has been reflected, whereby the transmitted data sequence provides a test signal for fault detection while the transmission system is in service.
- 15. Apparatus for determining the location of a fault generating an optical reflection in an optical transmission system including a data transmitter arranged to transmit a downstream scrambled data sequence, a data receiver, an optical fibre path for carrying transmitted optical signals therebetween, the apparatus comprising means for retrieving from the transmission path signals including a reflection of the transmitted data sequence from a fault, and signal processing means for correlating said reflection of the transmitted data sequence with a time delayed copy of that data sequence so as to determine from the duration of said time delay a location in the optical fibre path of the fault from which the data sequence has been reflected, whereby the transmitted data sequence provides a test signal for fault detection while the transmission system is in service.
Specification