Abstract: An electronic circuit for detecting a change in a property of interest, the circuit comprising a voltage detector having an input and a device for providing a bias current to the input of the voltage detector, wherein the circuit is arranged such that a change in the property of interest modifies the current received at the input of the voltage detector. A change in the property of interest may modify the current by adding or subtracting a current to the bias current. The property of interest may be a signal which is combined with the bias current thereby to alter the current at the input of the voltage detector. The signal may be capacitively coupled into the bias current. The signal may be provided by a sensor, which may be a voltage generating sensor and could be an antenna, rectenna, microphone or any other suitable sensor.

Abstract: An electronic circuit for detecting a change in a property of interest, the circuit comprising a voltage detector having an input and a device for providing a bias current to the input of the voltage detector, wherein the circuit is arranged such that a change in the property of interest modifies the current received at the input of the voltage detector. A change in the property of interest may modify the current by adding or subtracting a current to the bias current. The property of interest may be a signal which is combined with the bias current thereby to alter the current at the input of the voltage detector. The signal may be capacitively coupled into the bias current. The signal may be provided by a sensor, which may be a voltage generating sensor and could be an antenna, rectenna, microphone or any other suitable sensor.

Abstract: An offshore reservoir monitoring system (100) comprises a vertical array (110) with multiple seismic receivers (120) less than 10 m apart. During operation, the vertical array is deployed in a shallow borehole (111) in a seabed (10) away from noise at a seafloor (11). The dense spacing of receivers (120) ensures an adequate number of sensors (120) in the shallow borehole (111) and a spatial sampling rate appropriate for suppressing coherent noise in the shallow layers under the seafloor (11). Vertical arrays (110) can be added to the system (100) at any time.

Abstract: A method of operating a spectrometer to determine the wavelength of an optical signal, in particular for determining the resonant wavelength of an optical fiber Bragg grating. The spectrometer comprises an array of photosensitive pixels each of which generates an output signal in response to the intensity of light incident on the pixel, and a refractive element arranged to direct light to a particular position in the array depending on the wavelength of the light. The method involves selecting a first group of pixels in the array by reference to an expected wavelength distribution of the optical signal and monitoring the output signals from the first group of pixels. On the basis of the output signals from the first group of pixels a second group of pixels is selected and the wavelength of the optical signal is determined from the output signals of the second group of pixels.

Abstract: The present invention discloses a wireless data command, control and instrumentation system for deployment within a subsurface hydrocarbon production system. Low frequency magnetic signalling is used to communicate from a first transceiver deployed inside a riser pipe to a second transceiver positioned outside the riser pipe. In some embodiments data is related to a control centre. Through pipe communications may be bi-directional.

Abstract: A curvature sensing device 10 comprising, a first fiber Bragg grating (FBG) strain sensor 12, a second FBG strain sensor 14, a flexible piece comprising two end pieces 16, 18 joined by a tubular mid-section 20. The device 10 further comprises 16 contact rollers 22 provided on the internal surfaces of the end pieces 16, 18, which maintain the end pieces 16, 18 tangential to a pipe around which the device 10 is located. The FBG strain sensors 12, 14 are embedded within the mid-section 20 and are arranged in two generally orthogonal planes, so that the curvature is measured in two dimensions. This enables the device 10 to detect both the magnitude and direction of bending/curvature within a pipe. Bending in a pipe is transferred through the end pieces 16, 18 to the mid-section 20. The FBG sensors 12, 14 measure bending of the mid-section 20 from which bending of the pipe can be inferred.

Abstract: A vibration detector (1) comprising at least one fiber optic sensor (2) mechanically coupled to a flexible support member (3). The vibration detector (1) is mounted on the outside of the pipeline and a signal from the fiber optic sensor is measured. This signal is indicative of whether the vibration detector is experiencing vibrations due to collisions of contaminant particles with each other and/or with the walls of the pipeline. A method for detecting particulate contaminants in a fluid flowing in a pipeline is also provided.

Abstract: A system for the structural monitoring of blades 1 on a wind turbine. Each blade 1 has respective optical fiber bragg grating sensors 5. The system has a number of input connectors, which connect to the strain sensors 5 of respective blades 1. A single output connector connects to a data processing device 3 which processes signals from the strain sensors 5. The input connectors each have a signal path to the output connector that is different in length to the signal path from the other input connectors, such that signals from a given blade 1 can be identified at the data processing device 3 by the time of arrival of the signals. The system has the advantage that the each of the blades 1, including the sensors attached to it or embedded within it can be identical and therefore interchangeable.

Abstract: An optical fiber strain sensor array comprises several sensor support panels spaced in its longitudinal direction and at least one connecting member extending in the longitudinal direction, which mechanically interconnects the sensor support panels. An optical fiber is supported by the sensor support panels and the connecting member. The optical fiber extends with the connecting member between the sensor support panels and forms a curve on the sensor support panel, the curve including at least one portion of the optical fiber that extends in the transverse direction. The width of the connecting member is substantially less than the width of the sensor support panels, such that the connecting member is capable of flexure in the transverse direction. This has the advantage that the connecting member can be flexed to take up any slack during installation of the optical fiber strain sensor array in a wind turbine blade and can be fitted to the turbine blade even if the blade has a conical shape.

Abstract: Apparatus for interrogating an optical fiber comprising a plurality of fiber Bragg gratings each having a resonant wavelength in a different discrete wavelength band. The apparatus comprises a delay arrangement interposed in use in an optical path for light supplied to and/or reflected from the fiber Bragg gratings. The delay arrangement is configured to apply a different time delay to light in each of the discrete wavelength bands, whereby the light reflected from each of the fiber Bragg gratings is received at an interrogator port of the apparatus in a different discrete time interval.

Abstract: A system for underwater communications through a region between a transmit antenna and a receive antenna using electromagnetic signals. When the system is in an inactive mode, the region is occupied by water. When the system is in an active mode, fluid having a reduced conductivity is introduced into the region to provide transmission of electromagnetic signals with a lower attenuation and thereby facilitate a higher data transfer rate for a given range of communication between the transmit antenna and the receive antenna.

Abstract: A method of monitoring strain on a wind turbine blade that has several structural components comprises locating at least three strain sensors (2a, 2b, 2c) on one of the structural components of the turbine blade, the positions of the strain sensors defining a plane transverse to the longitudinal direction of the turbine blade and resolving strain signals from the three strain sensors into strain measurements in two orthogonal directions.

Abstract: The present invention discloses a system that implements data communications through a barrier composed of composite, layered materials. A low frequency electromagnetic signal is used to achieve acceptable channel losses as the signal passes through a composite barrier which may comprise materials with variable conductivity and/or permeability.

Abstract: A signal coupling system for data and/or power signalling in tubing within a hydrocarbon extraction well. First and second transceivers are arranged with primary and secondary loops lying orthogonal to the ends of the transceivers. The transceivers can be narrower for access downhole. Each loop is housed in a semi-cylindrical housing with a planar face, so providing a cylindrical body when oppositely arranged for the transfer of electromagnetic radiation therebetween. Guiding surfaces are also provided on the housing to assist in bring the coupling system together downhole. The present invention provides reliable real-time data from any location within the wellbore and improves reservoir management, well planning and resource exploitation.

Abstract: A pipeline instrumentation and control system comprising a first electrically insulated radiating cable for controlled radiation and reception of electromagnetic signaling carried to a second electrically insulated radiating cable wherein first and second electrically insulated radiating cables are axially disposed along a production well pipe and wherein first axially radiating cable comprises a section configured to substantially overlap second radiating cable section and further wherein electrical signals present in first radiating cable section is configured to induce a corresponding signal in said second radiating cable section to facilitate the transfer of electromagnetic radiation therebetween. The present invention provides reliable data communication from any location within the production system and improves reservoir management, well planning and resource exploitation.

Abstract: A signal coupling system for data and/or power signalling in a confined space such as in tubing within a hydrocarbon extraction well. First and second transceivers are arranged with primary and secondary loops lying orthogonal to the ends of the transceivers. The transceivers can be narrower for access to confined spaces. Each loop is housed in a semi-cylindrical housing with a planar face, so providing a cylindrical body when oppositely arranged for the transfer of electromagnetic radiation therebetween. Guiding surfaces are also provided on the housing to assist in bring the coupling system together in the confined space.

Abstract: A method of operating a spectrometer to determine the wavelength of an optical signal, in particular for determining the resonant wavelength of an optical fibre Bragg grating. The spectrometer comprises an array of photosensitive pixels each of which generates an output signal in response to the intensity of light incident on the pixel, and a refractive element arranged to direct light to a particular position in the array depending on the wavelength of the light. The method involves selecting a first group of pixels in the array by reference to an expected wavelength distribution of the optical signal and monitoring the output signals from the first group of pixels. On the basis of the output signals from the first group of pixels a second group of pixels is selected and the wavelength of the optical signal is determined from the output signals of the second group of pixels.

Abstract: A method of monitoring the structural integrity of a wind turbine blade 1 is disclosed. The blade 1 has at least two shell portions 2a, 2b, forming the outer surface of the turbine blade 1. At least one web member 3a, 3b connects the shell portions 2a, 2b in a transverse direction. The method comprises measuring a bending moment on the turbine blade 1 in a plane containing the longitudinal and transverse directions, measuring the transverse strain on the web member 3a, 3b at least one location, and comparing the measured transverse strain to an expected value for the transverse strain at the measured bending moment to provide an indication of debonding between the web member 3a, 3b and at least one shell portion 2a, 2b.

Abstract: The present invention provides a system for underwater communications by electromagnetic signals capable of providing a higher data transfer rate for a given range of communications than current prior art systems for underwater communications by electromagnetic signals. The system has an active mode of operation and an inactive mode. In the inactive mode the transmit antenna and the receive antenna are arranged so that the region extending between them is occupied by water. During the active mode, a fluid modifying means provides a reduced conductivity fluid in the region between the transmit antenna and the receive antenna and electromagnetic signals are transmitted from the transmitter to the receiver via the reduced conductivity fluid thereby providing a higher data transfer rate for a given range of communications.

Abstract: A device for detecting lightning currents in a wind turbine comprises an inductive loop (1) for carrying a current representative of a lightning current and a sensitive element, such as a resistance or a piezoelectric element electrically connected to the inductive loop (1). The apparatus further comprises an optical fibre strain sensor mechanically connected to the sensitive element, such that, in use, a lightning current results in expansion of the sensitive element and the optical fibre strain sensor produces an optical signal indicative of the strain on the sensitive element due to the expansion. The device has the advantage that the optical signal from the optical fibre strain sensor can be processed by the same signal processing equipment that processes signals from other strain sensors provided on the wind turbine.