Metrotech Corporation

Stevan Polak

Thorkell Gudmundsson

James Long

Johan Överby

Jim Waite

Chunning Zhang

Russell N Bigelow

Joseph Shtargot

Gopalakrishnan R Parakulam

Niklas Lindstrom

In accordance with some embodiments, an antenna is presented. In some embodiments, an antenna includes a plurality of coil arrays arranged along a core; and a switch coupled to each of the plurality of coil arrays, the switch connecting the plurality of coil arrays in one of a plurality of configurations in response to one or more sensitivity control signal.

Antenna for underground line location

A detection apparatus with a self-test is presented. A detection apparatus such as a cable locator has an array of sensors in the form of ferrite antennas to detect an electromagnetic field produced by an object such as a buried cable. The signals are amplified, digitized and fed to a processing unit that outputs a detection signal to a display to indicate the detection of a cable. A programmable signal generator outputs a self-test signal via a voltage-current converter that is used to check the balance between the sensors. The self-test signal is directly coupled into each of the sensors through a wired connection and the processing unit uses the self-test signal to accurately determine the magnitude and phase balance of the sensors. The magnitude and phase data may be used to calibrate the instrument, apply data corrections or flag errors.

Systems and methods for object detection

Locator self-test

A line locator system that includes a metal detector is disclosed. In accordance with some embodiments of the invention, the line locator system includes a digital signal processor in a housing; a line locator portion mounted in the housing and coupled to the digital signal processor; and an active metal detector mounted in the housing and coupled to the digital signal processor.

Line locator with a metal detector

A new approach for locating an underground line described herein remains accurate in the face of bleedover by including both amplitude and phase from at least two magnetic field strength sensors in the measurement set. A numerical optimization step is introduced to deduce the positions and currents of each of several cables, of which one is the targeted cable and the others are termed bleedover cables. Furthermore, some embodiments of the method accounts for practical problems that exist in the field that relate to reliable estimation of cable positions, like the phase transfer function between transmitter and receiver, the estimation of confidence bounds for each estimate, and the rejection of false positive locates due to the presence of noise and interference.

Precise location of buried metallic pipes and cables in the presence of signal distortion

A transmitter for a line locator system that controls the electrical current, voltage or power applied to the target line is disclosed. Control of the electrical output of the transmitter can be achieved passively or by means of a feedback control system. A transmitter connected directly to a line can include an operator control and monitoring of current being supplied to a line to be located. Some transmitters include a current regulating circuit that controls current supplied to a line. In some transmitters, feedback controllers and feedback loops are used to regulate output current, voltage or power. Some control loops are based on monitoring currents in circuits; some control loops monitor power output from an inductive mode transmitter antenna. An inductively coupled transmitter with power output control is also disclosed.

Controlled power source for underground line location

A line locator having the capability of determining the horizontal position with respect to a line is described. The line locator includes a left sensor and a right sensor of any orientation. The left sensor and the right sensor are coupled to a convolution amplifier that amplifies the sum of the output signals from the left sensor and the right sensor. The detection circuitry includes automatic gain control amplification where the automatic gain control signal is obtained digitally from a digital controller. In addition, the detection circuitry includes phase detection circuitry where the phase reference signal is obtained from an external transmitter that is coupled to the line. In addition, the AGC signal and the phase reference signal may both be obtained by processing output signals from magnetic field detectors in the line locator.

Line locator with accurate horizontal displacement detection

An automatic gain control (AGC) system for use in line locators that detect concealed conductors is presented. The AGC system includes determining an AGC signal from a reference sensor and processing signals from one or more observed sensors utilizing the AGC signal. The reference sensor is located farther from the concealed conductor than the observed sensors. The AGC system can be implemented in analog form or can include a digital AGC determination in a microprocessor.

Growing community of inventors

Santa Clara, CA, United States of America

Stevan Polak