Metrotech Corporation

Radiodetection Limited

Stephen John Petherick

John Mark Royle

David William Flatt

George Mainescu

Razvan Gabriel Stefanoiu

Ion Dracea

Robert Ashworth Worsely

William Moore

Andrzej Zbigniew Regini

A precise line locator is presented that provides precise line location. The locator includes a housing; a wand attached to the housing, the wand including an array of low frequency antennas arranged along the wand, the array of low frequency antennas defining an electromagnetic locate axis of the line locator system; a real-time kinematic (RTK) Global Navigation Satellite (GNSS) antenna attached to the housing; a user interface positioned in the housing; and a processing circuit coupled to the array of low frequency antennas, the RTK GNSS antenna, and the user interface, wherein the underground line locator determines locate data of the underground line based on signals from the array of low frequency antennas and determines a precise position of the underground line locator from the RTK GNSS antenna.

Underground line locator system with real time kinematic and global satellite positioning

A transmitter and receiver for performing a signal select algorithm are provided. A transmitter for providing a signal on a line to be located includes at least one direct digital synthesizer, the direct digital synthesizer producing two component frequencies in response to an input square wave signal; and a feedback loop providing the input square wave.

Signal select in underground line location

A system and method of for estimating the depth of a marker may include a marker locator. The marker locator may include a first transmitter that generates a first activation signal, second transmitter that generates a second activation signal, a receiver that detects first and second response signals, and a processor that determines a depth of a marker based on the first and second response signals. The first transmitter is located at a first position, and the second transmitter is located at a second position apart from the first position. The first and second response signals respectively correspond to the first and second activation signals. The processor is coupled to the receiver. According to some embodiments, the first and second activation signals and the first and second response signals may be separated by time division multiplexing.

System and method for locating a marker using a locator with multiple transmitters

In accordance with some embodiments, a method and apparatus for providing both a low-pass filter value and a high-pass filter value is presented. The combined filter receives an input value into a half-band finite impulse response (FIR) filter with an odd number of taps labeled 0 through N with corresponding filter coefficients labeled 0 through N where odd numbered filter coefficients are zero, the FIR filter providing a filter value. The median value from the FIR filter is digitally shifted to provide a half median value. The half median value is added to the filter value to provide the low-pass filter value and is subtracted from the filter value to provide the high-pass filter value.

Signal processing for a cable locating instrument

Cathodic protection voltages are used to resist the damage to pipes or cables from electrolytic effects. However, localized fields can lead to stray currents and may result in corrosion and it is therefore desirable to detect and analyse those stray currents. Frequently there are several pipes in the area of interest and so it is necessary to distinguish between those pipes. Therefore the cathodic voltage on the pipes is modulated, with different pipes having different modulations. This modulation may be applied using an interrupter. Orthogonal modulations with non-unitary aspect ratios improve the discrimination between the pipes while maximizing the energy content of the modulation pattern. The analysis is improved when the interrupters are synchronized with each other and so repeating on the same time-base. This synchronization may be achieved using an external time signal such as GPS. An interrupter which can be used in this regard is also proposed, and may be powered from the cathodic voltage itself.

Pipeline mapping and interrupter therefor

Cathodic protection voltages are used to resist the damage to pipes or cables from electrolytic effects. However, localised fields can lead to stray currents and may result in corrosion and it is therefore desirable to detect and analyse those stray currents. Frequently there are several pipes in the area of interest and so it is necessary to distinguish between those pipes. Therefore the cathodic voltage on the pipes is modulated, with different pipes having different modulations. This modulation may be applied using an interrupter. Orthogonal modulations with non-unitary aspect ratios improve the discrimination between the pipes whilst maximising the energy content of the modulation pattern. The analysis is improved when the interrupters are synchronised with each other and so repeating on the same time-base. This synchronisation may be achieved using an external time signal such as GPS. An interrupter which can be used in this regard is also proposed, and may be powered from the cathodic voltage itself.

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Exeter, United Kingdom

Stephen John Petherick