Abstract: Methods, systems and locators for detecting faults in an insulation layer of an insulated conductor buried beneath a ground surface are described. The locator comprises a magnetometer arranged to detect a magnetic field generated by the alternating current and to generate a current signal on the basis of the detected magnetic field, and an Alternating Voltage Gradient receiver comprising a pair of probes arranged to make electrical contact with the ground surface, which is arranged to generate a voltage signal indicative of a voltage between the pair of probes. A processor is configured to substantially synchronously sample the current signal and the voltage signal. This enables improved detection of faults in the insulation layer of the insulated conductor.

Abstract: A locator for determining the depth of a buried electromagnetic marker includes a transmission antenna and two reception antennas. The locator has a major axis and is configured. The transmission antenna is configured to generate an oscillatory magnetic field parallel to the major axis. The first reception antenna of the two reception antennas is configured to couple with an oscillatory magnetic field parallel to the major axis emitted by the electromagnetic marker and to generate a first detected signal. The second reception antenna is displaced along the major axis from the first antenna and configured to couple with an oscillatory magnetic field parallel to the major axis emitted by the electromagnetic marker and to generate a second detected signal. The locator includes analogue to digital converters and a processor which is configured to calculate the depth of the electromagnetic marker.

Abstract: A locator for determining the depth of a buried electromagnetic marker includes a transmission antenna and two reception antennas. The locator has a major axis and is configured. The transmission antenna is configured to generate an oscillatory magnetic field parallel to the major axis. The first reception antenna of the two reception antennas is configured to couple with an oscillatory magnetic field parallel to the major axis emitted by the electromagnetic marker and to generate a first detected signal. The second reception antenna is displaced along the major axis from the first antenna and configured to couple with an oscillatory magnetic field parallel to the major axis emitted by the electromagnetic marker and to generate a second detected signal. The locator includes analogue to digital converters and a processor which is configured to calculate the depth of the electromagnetic marker.

Abstract: A locator for locating a concealed conductor carrying an alternating current having at least first and second frequencies, the alternating current produced by at least one dedicated signal generator. The locator includes at least one magnetic field sensor operable to convert electromagnetic radiation from the conductor into a field strength signal; a digital analog converter configured to generate a digitized signal dependent upon the field strength signals from the magnetic field sensor; a digital signal processor configured to isolate components of the digitized signal resulting from the first frequency and the second frequency; and process the isolated components to generate one or more signals indicative of the proximity of the conductor to the detector; and an output configured to generate an audio and/or visual indication of the proximity of the conductor, wherein the isolated signal components resulting from the first frequency signal and the second frequency signal are contemporaneously processed.

Abstract: A system for detecting a plurality buried conductors includes a transmitter configured to generate an alternating test signal for a plurality of buried conductors. The system further includes a receiver configured to detect an electromagnetic field produced by the alternating test signal in the plurality buried conductors and a remote control configured to control the transmitter to generate the alternating test signal in one of the plurality of buried conductors.

Abstract: A locator for determining the location and/or orientation of a concealed conductor, comprising a reference field detector operable to detect an alternating magnetic field along a reference axis; a first field detector operable to detect an alternating magnetic field along a first axis; and a processor operable to calculate an in-phase component of a signal detected by the first field detector, the in-phase component being in phase with a signal detected at the reference field detector and to calculate a signal indicative of a position of the concealed conductor relative to the locator using at least the in-phase component.

Abstract: A locator for locating a concealed conductor comprises a first field detector operable to detect an alternating magnetic field along a first axis parallel to a primary axis of the locator; a second field detector, displaced from the first field detector and operable to detect an alternating magnetic field along a second axis parallel to the primary axis of the locator; and a processor operable to calculate a difference between a field detected by the first detector and a field detected by the second detector, and to calculate an indication of the lateral displacement of the concealed conductor from the primary axis of the locator using the difference.

Abstract: A detector for calculating the distortion of an electromagnetic field produced by a buried current carrying conductor comprises three antennas B, M, T. Outputs of two pairs of antennas are compared and the depth of the buried conductor is calculated using two different methods. If there is a significant difference in the two calculated depths then it is deemed that the electromagnetic field produced by the buried current carrying conductor is significantly distorted by the material in which the conductor is buried.

Abstract: A locator for locating a concealed conductor carrying an alternating current having at least first and second frequencies, the alternating current produced by at least one dedicated signal generator. The locator includes at least one magnetic field sensor operable to convert electromagnetic radiation from the conductor into a field strength signal; a digital analogue converter configured to generate a digitized signal dependent upon the field strength signals from the magnetic field sensor; a digital signal processor configured to isolate components of the digitized signal resulting from the first frequency and the second frequency; and process the isolated components to generate one or more signals indicative of the proximity of the conductor to the detector; and an output configured to generate an audio and/or visual indication of the proximity of the conductor, wherein the isolated signal components resulting from the first frequency signal and the second frequency signal are contemporaneously processed.

Abstract: A signal generator for coupling to a concealed conductor including a first oscillator configured to generate a first waveform having a first frequency, a first terminal coupled to the first oscillator through a first band pass filter configured to pass signals of the first frequency, a second oscillator configured to generate a second waveform having a second frequency, and a second terminal coupled to the second oscillator through a second band pass filter configured to pass signals of the second frequency.

Abstract: A locator for locating a concealed conductor comprises a first field detector operable to detect an alternating magnetic field along a first axis parallel to a primary axis of the locator; a second field detector, displaced from the first field detector and operable to detect an alternating magnetic field along a second axis parallel to the primary axis of the locator; and a processor operable to calculate a difference between a field detected by the first detector and a field detected by the second detector, and to calculate an indication of the lateral displacement of the concealed conductor from the primary axis of the locator using the difference.

Abstract: A locator for determining the location and/or orientation of a concealed conductor, comprising a reference field detector operable to detect an alternating magnetic field along a reference axis; a first field detector operable to detect an alternating magnetic field along a first axis; and a processor operable to calculate an in-phase component of a signal detected by the first field detector, the in-phase component being in phase with a signal detected at the reference field detector and to calculate a signal indicative of a position of the concealed conductor relative to the locator using at least the in-phase component.

Abstract: A detector for calculating a depth of a buried conductor is provided. The detector includes first, second and third antennas and a microprocessor. The second antenna has an axis parallel to an axis of the first antenna and is spaced a distance s from the first antenna. The third antenna has an axis parallel to the axes of the first and second antennas and is spaced a distance 2s from the first antenna and a distance s from the second antenna. The microprocessor is configured to compare magnetic fields at the first and second antennas to produce a first compared value, compare magnetic fields at the first and third antennas to produce a second compared value, and calculate the depth of said buried conductor based on the first and second compared values.

Abstract: A detector for calculating a depth of a buried conductor is provided. The detector includes a plurality of antennas for detecting an electromagnetic field radiated by the conductor and one or more signal processors for calculating the depth of the conductor based on the field detected by the antennas. The calculated depth of the conductor is displayed when one or more predetermined criteria are satisfied.

Abstract: A detector for detecting a buried conductor comprises a plurality of antennas B, T. Each antenna B, T has a winding wound around the antenna, the winding being connected to a current source for providing a predefined current in the winding. When the predefined current is applied to the winding an electromagnetic field is generated at the antenna which induces a test current in the antenna. The test current is compared to calibration data stored in the detector to validate the correct operation of the detector.

Abstract: A system for detecting a buried conductor comprises a transmitter for producing an alternating test current in the buried conductor and a receiver for detecting an electromagnetic field produced by the test current in the buried conductor. A communication link is provided between the receiver and the transmitter. The receiver measures the signal to noise ratio, SNR, of the electromagnetic field produced by the test current and if the SNR is below a threshold then the receiver controls the transmitter to set frequency and/or power characteristics of the test current.

Abstract: A system for detecting a buried conductor comprises a transmitter for generating a test signal in the buried conductor and a detector for detecting an electromagnetic signal resulting from the test signal flowing in the buried conductor. The transmitter comprises a waveform generator for generating a drive waveform signal, a power supply, an amplifier, connected to the power supply and the waveform generator for producing an output drive signal based on the drive waveform signal and an output circuit for acting on the output drive signal to generate an output signal having a current and a voltage. In-phase and quadrature components of the current and voltage of the output signal are fed back for controlling the amplifier.

Abstract: The present invention provides a time domain reflectometer for testing an electrical cable. The time domain reflectometer includes a test signal generator, at least one line feed resistor, connected between the test signal generator and a pair of terminals, for connection to the ends of the electrical cable under test, and a signal processor, connected to the terminals, to receive a line signal including a reflection of a test signal transmitted into the cable under test. The signal processor is programmed to filter the line signal to enhance a portion of the signal indicative of any fault on the cable by balancing the signal according to the electrical characteristics of a normal cable of the same type as the cable under test by applying a filter function, and acquiring at least one estimate of the input admittance of the transmission line from known or estimated electrical characteristics of the cable under test.

Abstract: A system for detecting a buried conductor comprises a transmitter for producing an alternating test current in the buried conductor and a receiver for detecting an electromagnetic field produced by the test current in the buried conductor. A communication link is provided between the receiver and the transmitter. The test current comprises first and second components of different frequency. The receiver monitors the phase creepage of the first and second components and controls the transmitter to reset the phase difference between the first and second components as phase creepage increases.