Hewlett-packard Company

Allan Space-time Solutions, LLC

John A Kusters

Michael C Fischer

Jerry G Leach

Gus Ryan German

David W Allan

A sensor array made up of 2n piezoelectric oscillators (preferably paired quartz oscillators) is provided in which n equals the number of axes of interest and each one of the pairs of oscillators has a principle axis directed oppositely from the other of its pair. A controller which preferably includes a microprocessor, makes use of the dynamic relationships of the sensors in the array to adaptively assess the magnitude of weighting factors needed to correct the output signal from each oscillator for environmental and systematic effects to provide optimum frequency and phase output for computing position, velocity, and acceleration. Preferably, a seventh reference oscillator is provided in the center of the array which is canted relative to each of the three orthogonal axes by 45&#xb0;. This adaptive sensor array is capable of determining position within one meter along any of the x, y, and z axes without the need for any external (e.g., GPS) signal. In addition, unlike other sensor systems, it is capable of providing local vertical on a continuous basis. The array can also determine if an object is moving in any translational or rotational direction, within the measurement capabilities of the system.

Adaptive multi-axis sensor array

A method and apparatus for obtaining an accurate measure of the frequency of an applied signal by generating a pair of independent frequency signals wherein one of the independent frequency signals has a frequency value which is indicative of the operating temperature of the counter. The counter has two modes of operation: a calibration mode and a measurement mode. In the calibration mode, an accurate signal having a preselected frequency value is applied to the counter. The frequency of this signal is measured with reference to the other of the pair of independent frequency signals and this measured value is then algebraically combined with a prestored value that is equivalent to the preselected frequency of the applied signals. The combined value represents the necessary normalized correction factor for any measured frequency when the counter is at the corresponding temperature. The value of the one of the independent frequency signals in this mode serves as a pointer to the memory location where this correction factor is to be stored. This procedure is then repeated several times as the temperature environment of the counter varies. In the measurement mode an unknown signal is applied to the counter, its frequency value is measured against the other of the independent frequency signals, the value of the one of the independent frequency signals is utilized as a pointer to the necessary correction factor at the then operating temperature of the counter, the measured frequency value is corrected algebraically with this correction factor, and the final result outputted for further use by the user.

Self calibrating crystal controlled frequency counter method and

A method and apparatus utilizing a quartz crystal resonator with an orientation substantially equal to (yxwl) 21.93.degree./33.93.degree. vibrating simultaneously in two thickness modes to provide a stable frequency signal source. By combining a quartz crystal resonator of the above type with either digital or analog compensation, the frequency-temperature deviation of one of the crystal mode frequencies is used as an internal thermometer and the second crystal mode frequency as a reference frequency signal. The frequency signal for the thermometer function is utilized by the compensation network to stabilize the frequency of the reference signal. Additionally, the analog or digital compensation is accomplished by means of either a curve-fitting routine or an interpolation look-up table routine.

Oscillator having a quartz resonator cut to compensate for static and

A method and apparatus utilizing a quartz crystal resonator with an orientation substantially equal to (yxwl) 21.93.degree./33.93.degree. vibrating simultaneously in two thickness modes to accurately measure temperature and unknown frequencies or to provide a stable frequency signal source. By combining a quartz crystal resonator of the above type with either digital or analog compensation, the frequency-temperature deviation of one of the crystal mode frequencies is used as an internal thermometer and the second crystal mode frequency as a reference frequency signal. The frequency signal for the thermometer function is utilized by the compensation network to correct the measurements made with, or to stabilize, the frequency of the reference frequency signal. Additionally, the analog or digital compensation is accomplished by means of either a curve-fitting routine or an interpolation look-up table routine.

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Cupertino, CA, United States of America

John A Kusters