Binaura Corporation

Precision Navigation, Inc.

Other

Magknowledge Inc.

Timothy J Hawks

Nam H Kim

A method and apparatus is disclosed which spatially enhances stereo signals without sacrificing compatibility with monophonic receivers. In accordance with one embodiment of the present invention, a stereo enhancement system is implemented using only two op-amps and two capacitors and may be switched between a spacial enhancement mode and a bypass mode. In other embodiments, simplified stereo enhancement systems are realized by constructing one of the output channels as the sum of the other output channel and the input channels. In other embodiments, a pseudo-stereo signal is synthesized and spatially enhanced according to stereo speaker crosstalk cancellation principles. In yet other embodiments, the respective spacial enhancements of monophonic signals and stereo signals are integrally combined into a single system capable of blending, in a continuous manner, the enhancement effects of both.

Method and apparatus for spatially enhancing stereo and monophonic

Magnetometer circuits are disclosed in which a solenoidal sensor coil including a saturable core is provided a source potential to bring the coil towards saturation, followed by deactivation of the potential to the coil. The current through the coil is sensed and the magnetic field effecting the coil may be determined based on the amount of time which is required for the current in the coil to decline from a first level to a second level. A current sensor connected to the sensor coil provides a first output signal in response to the current through the coil increasing to a first value in a first portion of an operational cycle, and provides a second output signal in response to the current through the coil decreasing to a second value. The time period between the first and second output signals from the current sensor is indicative of the magnitude of the field affecting the coil.

Low power magnetometer circuits having zero offset compensation

Low power magnetometer circuits requiring a single switching cycle

A magnetometer technology is provided based on a simple axial sensor which operates using the non-linear nature of saturating magnetic core material. The sensor appears electrically as an inductor with a non-linear inductance that varies both with magnetic field applied externally and the field created by the coil current. By using this sensor as the inductor of an LR relaxation oscillator, a change in applied magnetic field will cause a change in inductance, which will in turn cause a change in the oscillator period. The period of the oscillator can be converted to a digital form by using simple counting techniques. By introducing an enhancement of this scheme whereby two different periods are measured with different oscillator characteristics, the magnetometer will have no output drift when no field is applied.

Zero-offset magnetometer having coil and core sensor controlling period

A digital compass (20) has a sensing coil (60) wound on an elongated strip of high direct current permeability magnetic material. The sensing coil (60) is connected to a sensing circuit (56). The sensing coil and sensing circuit are responsive to the Earth's magnetic field to provide an oscillating signal at an output (28) of the sensing circuit (56) which varies in frequency with orientation of the at least one sensing coil (60) with respect to the Earth's magnetic field. A microprocessor (36) is connected to receive information inputs from the oscillating signal. The microprocessor converts the information inputs to an indication of orientation of the sensing coil with respect to the Earth's magnetic field based on the frequency of the oscillating signal. A display (52) receives the orientation indication from the microprocessor.

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Palo Alto, CA, United States of America

Timothy J Hawks