Seektech, Inc.

Seescan, Inc.

Stephen M Bench

Mark S Olsson

Ray Merewether

Ryan B Levin

David A Cox

Jan Soukup

Michael E Turgeon

Mark Frederick Fleming

Lisa E Latimer

Edward N Denaci

Michael J Martin

Jeffrey A Prsha

Roger B Shaffer

Tran Nguyen

Jeffrey A Praha

A Quadrature Amplitude Modulation (QAM) method and apparatus including a QAM transmit modulator with at least one unbalanced mixer, which creates an asymmetric two-dimensional (2-D) QAM symbol constellation. The asymmetrical symbol constellation provides baseband symbol clock signal leakage sufficient to facilitate quick and simple baseband symbol clock recovery and signal channel compensation at the QAM receiver without significantly degrading the system bit-error rate (BER). While slightly degrading static BER, overall system performance is improved when considering baseband symbol clock recovery and received signal compensation for an imperfect signal channel. This allows QAM to be deployed in systems where QAM is otherwise prohibitively expensive and improves overall system performance for any existing QAM system application without additional bandwidth, cost or complexity.

Method and apparatus for high-speed data transfer employing self-synchronizing quadrature amplitude modulation

A pre-amplifier circuit for connection to an antenna of a human-portable locator includes a differential amplifier/mixer pair and means for allowing a common-mode 'phantom' signal to modulate a transfer function of the differential amplifier/mixer pair. The common-mode phantom signal modulates the transfer function of the differential pre-amplifier 'onboard' the antenna without the usual requirement for onboard power supply and signal oscillator. This technique uses the same electronic components to provide both pre-amplification and mixing functions, thereby improving circuit performance-to-cost ratio, reducing mixer power consumption, situating the necessary signal oscillator remotely from the mixer, and greatly improving the available system bandwidth by limiting spectral transmission demands to the mixed signal bandwidth alone.

Pre-amplifier and mixer circuitry for a locator antenna

A high-Q human-portable, battery-powered self-correcting tunable resonator in a transmitter apparatus for inducing alternating currents of high quality in buried conductors to facilitate their location is disclosed. The transmitter apparatus may employ an FET-driven capacitive tuning circuit and a coil design that achieves high precision, high-quality transmission signals, and which may be equipped with a high-voltage booster for facilitating fault-localization applications.

Spring clips for use with locating transmitters

An antenna useful in an antenna array of a man-portable buried utility locator includes a flexible bobbin made of copper foil. The bobbin has a plurality of axially spaced grooves and an axially extending gap formed therein. A layer of insulation surrounds an outer surface of the bobbin. A conductive wire is disposed in the grooves and wound around the bobbin over the layer of insulation to form a plurality of axially spaced sub-coils. A layer of copper-foil tape having an insulating backing is wound about the conductive wire and has a second gap aligned with the gap in the bobbin. A layer of a low dielectric material is wound about the copper-foil tape. The antenna provides more antenna wire surface for an equivalent coil cross-sectional area, compared to prior art antennas, thus yielding greater sensitivity. The construction of the antenna provides a series of Faraday-shielded sub-coils, which yield a greater useful antenna bandwidth by moving the inherent resonance of each coil to a higher frequency. The construction of the antenna also reduces inherent winding capacitance and provides a self-shielding effect that further improves sensitivity.

Locator antenna with conductive bobbin

Various pipe inspection systems include a camera head operatively connected to the distal end of a push-cable. Images may be automatically captured at predetermined distances of travel, or may be automatically captured based on the output signals from the auto-focus, auto-exposure and/or auto-white balance engines indicating, for example, that the camera motion within the pipe is substantially zero. Images may be captured in an automatic mode at predetermined intervals as the camera head travels within the pipe or in an override mode initiated by operator command. The system may include a data transmission circuit that transmits data between a plurality of nodes at a frequency that does not substantially interfere with a normal base band video transmission frequency.

Pipe inspection system with selective image capture

A high-Q human-portable, battery-powered self-correcting tunable resonator in a transmitter apparatus for inducing alternating currents of high quality in buried conductors to facilitate their location. The transmitter apparatus employs an FET-driven capacitive tuning circuit and a coil design that achieves high precision, high-quality transmission signals, and which is equipped with a high-voltage booster for facilitating fault-localization applications.

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Carlsbad, CA, United States of America

Stephen M Bench