Stevan Polak

US Patent:

6407550, Jun 18, 2002

Filed:

Aug 19, 1998

Appl. No.:

09/136767

Inventors:

Gopalakrishnan R. Parakulam - Sunnyvale CA
Stevan Polak - Aptos CA

Assignee:

Metrotech Corporation - Sunnyvale CA

International Classification:

G01V 310

US Classification:

324326

Abstract:

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.

US Patent:

7091872, Aug 15, 2006

Filed:

Jul 1, 2002

Appl. No.:

10/189286

Inventors:

Russell N. Bigelow - Half Moon Bay CA, US
Stevan Polak - Aptos CA, US
James Long - Sunnyvale CA, US
Joseph Shtargot - Foster City CA, US

Assignee:

Metrotech Corporation - Santa Clara CA

International Classification:

G08B 21/00

US Classification:

340664, 34031015, 340537, 340538, 34087039, 323208, 333124

Abstract:

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.

US Patent:

7356421, Apr 8, 2008

Filed:

Apr 6, 2005

Appl. No.:

11/100696

Inventors:

Thorkell Gudmundsson - San Jose CA, US
Jim Waite - Los Gatos CA, US
Johan Överby - Sunnyvale CA, US
Stevan Polak - Aptos CA, US
Niklas Lindstrom - Sunnyvale CA, US

Assignee:

Metrotech Corporation, Inc. - Santa Clara CA

International Classification:

G01V 3/15

US Classification:

702 38, 324 67, 32420711, 32420717, 32420722, 32420726, 324237, 324243, 324326, 324327, 324328, 324329

Abstract:

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.

US Patent:

61305391, Oct 10, 2000

Filed:

Aug 19, 1998

Appl. No.:

9/136793

Inventors:

Stevan Polak - Aptos CA

Assignee:

Metrotech Corporation - Sunnyvale CA

International Classification:

G01V 311

US Classification:

324326

Abstract:

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.

US Patent:

20180081020, Mar 22, 2018

Filed:

Nov 28, 2017

Appl. No.:

15/824944

Inventors:

- SANTA CLARA CA, US
Stevan POLAK - Santa Clara CA, US

International Classification:

G01R 35/00
G01R 29/08

Abstract:

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.

US Patent:

20160223701, Aug 4, 2016

Filed:

Jan 29, 2016

Appl. No.:

15/011205

Inventors:

- SANTA CLARA CA, US
Stevan POLAK - Los Gatos CA, US

International Classification:

G01V 3/10
H01Q 7/08

Abstract:

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.

US Patent:

20150234029, Aug 20, 2015

Filed:

Feb 18, 2015

Appl. No.:

14/625458

Inventors:

- Santa Clara CA, US
Stevan POLAK - Santa Clara CA, US

International Classification:

G01R 35/00

Abstract:

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.