Abstract: An arrangement for monitoring a submarine reservoir includes a number of sensor units located in an array on the seabed, and an interrogator unit for obtaining data on the reservoir from the sensor units. The interrogator unit includes a transmitter unit for sending optical signals to the sensor array and a receiver unit for receiving modulated optical signals from the array. Optical radiation from an optical source is transmitted along an uplink optical fiber which is split in a number of positions to form the array. The receiver unit includes optical-to-electrical converters for converting the optical signals to electrical signals, a phase demodulator, a multiplexer, a signal processor, and recording unit. The interrogator unit is divided into a concentrator and an interrogator hub, where signals are transmitted between the interrogator hub and concentrator along a riser cable. This enables the interrogator to be moved between a platform and the seabed.

Abstract: An arrangement for monitoring a submarine reservoir comprises a number of sensor units located in an array (1) on the seabed, and an interrogator unit for obtaining data on the reservoir from the sensor units. The interrogator unit comprises a transmitter unit (20) for sending optical signals to the sensor array and a receiver unit for receiving modulated optical signals from the array. Optical radiation from an optical source (22) is transmitted along an uplink optical fibre which is split in a number of positions 36, 38 to form the array. The receiver unit comprises optical-to-electrical converters (54) for converting the optical signals to electrical signals, a phase demodulator (58), a multiplexer (60) for multiplexing signals from the phase demodulator, a signal processor (68) and recording unit (70).

Abstract: A fiber-optic surveillance system (10) includes a fiber-optic sensor (15) comprising a serial array (15) of fiber-optic point-sensors (16), successive point-sensors being linked by a distributed fiber-optic sensor (18). The system allows the location of intruder events along the sensor to be determined, and provides a reduction in the incidence of false-alarms compared to prior art systems.

Abstract: A traffic monitoring system comprises at least one sensor station (2) and an interferometric interrogation system (9); wherein the at least one sensor station (2) comprises at least one optical fiber sensor (5) deployed in a highway (1); and wherein the interferometric interrogation system (9) is adapted to respond to an optical phase shift produced in the at least one optical fiber sensor (5) due to a force applied by a vehicle passing the at least one sensor station (2).

Abstract: A traffic monitoring system comprises at least one sensor station (2) and an interferometric interrogation system (9); wherein the at least one sensor station (2) comprises at least one optical fibre sensor (5) deployed in a highway (1); wherein the at least one optical fibre sensor (5) comprises a former (14), an optical fibre (13) wound on the former, a casing (15) and compliant material (16) provided between the casing and the former; such that the compliant material reduces the sensitivity of the sensor (5); and wherein the interferometric interrogation system (9) is adapted to respond to an optical phase shift produced in the at least one optical fibre sensor due to a force applied by a vehicle passing the at least one sensor station (2).

Abstract: A traffic monitoring system comprises at least one sensor station (2) and an interferometric interrogation system (9); wherein the at least one sensor station (2) comprises at least one optical fibre sensor (5) deployed in a highway (1); and wherein the interferometric interrogation system (9) is adapted to respond to optical phase shift produced in the respond to an optical phase shift produced in the at least one optical fibre sensor.

Abstract: A traffic monitoring system comprises at least one sensor station (2) and an interferometric interrogation system (9); wherein the at least one sensor station (2) comprises at least one optical fibre sensor (5) deployed in a highway (1); wherein the at least one optical fibre sensor (5) comprises a former (14), an optical fibre (13) wound on the former, a casing (15) and a compliant material (16) provided between the casing and the former; such that the compliant material reduces the sensitivity of the sensor (5); and wherein the interferometric interrogation system (9) is adapted to respond to an optical phase shift produced in the at least one optical fibre sensor due to a force applied by a vehicle passing the at least one sensor station (2).

Abstract: An optical sensing system (e.g. hydrophone) includes a plurality of laser light sources for producing light signals of different frequencies which are combined by a Bragg cell and launched into a single optical fibre leading to an optical sensor array arrangement. This sensor array arrangement includes a plurality of optical sensors separated by redirecting means for redirecting light signals along an optical fibre in time displaced relationship to an optical detector.

Abstract: Many optical sensing systems include an interferometer comprising a plurality of contiguous optical fibre sensor lengths with partially reflecting discontinuities therebetween. An inherent problem with these systems is however that the number of sensors that can be configured is limited by the pulse repetition or sensor interrogation rate. In the present system the pulse repetition rate is effectively increased without having to reduce optical fibre sensor lengths or numbers by interleaving several interrogating signals.