Electronic marker locator systems and methods

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.

Description

FIELD OF THE INVENTION[0001]Embodiments of the present invention relate to systems and methods for locating electronic markers. In particular, embodiments of the present invention relate to the estimation of the depth of buried electronic markers.BACKGROUND[0002]Buried electronic markers are used to indicate the location of a buried structure or utility. A buried marker is made from a circular coil that is arranged in a resonant circuit and designed to resonate at a specific frequency. An oscillatory electric current may be induced in this circuit by an externally applied pulse or pulses of magnetic flux linking the coil. The oscillatory current in the coil gives rise to an oscillatory magnetic field around the coil. The presence of this oscillatory magnetic field may be detected, allowing the position of the marker to be determined. The axis of the coil in the buried electronic marker is arranged to be oriented vertically so that the location of the buried marker may be found direc...

AI Technical Summary

Benefits of technology

[0021]Because the first and second reception antennas are displaced from one another along the major axis, the magnitude of the magnetic field at two locations can be obtained without the need for the position of the locator to be changed. This provides an increased accuracy of depth calculation since the separation of the antennas is fixed and the user is not required to estimate the distance between positions for two readings.

[0027]In an embodiment the controller is configured cause the transmission antenna to generate the oscillatory magnetic field having the target frequency for a first time interval and to prevent the first reception antenna from generating the first detected signal and the second reception antenna from generating the second detected signal for at least the first time interval.

[0028]As described above, the reception channels may be blanked when the transmission antenna is transmitting to the electromagnetic marker. This prevents the excitation signal transmitted from the transmission antenna from interfering with the signals from the electromagnetic marker detected by the reception antennas.

Problems solved by technology

As the depth equation contains an inverse sixth power, this system is highly sensitive to errors in determining R and suffers the disadvantage of requiring the user to lift the apparatus through a predefined distance s, introducing a further source of error.