Gas Research Institute

Mark Sweeny

William L Goodman

A method for demodulation of a phase shift keyed signal in which the phase shift keyed signal is converted into a plurality of successive outputs, each of which is representative of a phase and amplitude of the phase shift keyed signal over additional sets of windows and carrier phases. Each said additional set has a different offset in time and carrier phase from the other additional sets of windows and carrier phases. The carrier phase and window offsets of the phase shift keyed signal are estimated using the plurality of successive outputs. The phase shift keyed signal is then decoded back into digital data using the estimates.

Method and apparatus for demodulation of phase shift keyed signals

A method for reducing noise in borehole electromagnetic telemetry systems in which a signal receiver is positioned at a distance from a drill site borehole at which the signal receiver couples strongly to a signal from a signal transmitter disposed in the borehole and weakly to drill site noise emanating from the drill borehole, a noise receiver is positioned at a distance from the drill site borehole at which the noise receiver couples substantially only to magnetotelluric and/or drill site noise, the contributions of the magnetotelluric noise and drill site noise are determined, and subtracted from the signal received by the signal receiver, resulting in a reduced noise signal.

Method of reducing noise in a borehole electromagnetic telemetry system

A circuit for driving a current into an inductor, which circuit includes at least one main capacitor, a power supply operably connected to the main capacitor, the inductor, and at least two pairs of switches connecting the main capacitor to the inductor, whereby the connection of the main capacitor to the inductor is made in either polarity. Current is driven into the inductor by applying a current to the main capacitor, applying a voltage to the inductor from the main capacitor resulting in generation of inductive energy, and recapturing the inductive energy with the main capacitor at the end of a cycle.

Efficient transmitters for phase modulated signals

A downhole magnetic hollow core dipole antenna has a high permeability material magnetic core composed of laminated sections placed around a section of drill pipe and running substantially along the length of the pipe. The magnetic core is then surrounded by electrically conductive windings, which in turn are surrounded by a protective sleeve which, if conductive, is split to prevent power-robbing eddy current generation.

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Belmont, CA, United States of America

Mark Sweeny