The Johns Hopkins University

Syntonics, LLC

Dennis J Duven

Mark S Asher

Lloyd A Linstrom

William S Devereux

Thomas L Kusterer

Albert A Chacos

Richard C Morgan

Joseph J Suter

Kim Strohbehn

Bruce G Montgomery

Robert L Henderson

Robert J Heins

Don M Gruenbacher

An ensemble clock comprises: an input for receiving a reference signal; multiple free-running oscillators each configured to generate a corresponding free-running frequency; an output oscillator configured to generate a controlled frequency having a frequency responsive to a control signal; a differencer unit configured to derive difference measurements indicative of time and frequency-based errors associated with each of (i) the controlled frequency, and (ii) the free-running frequency, relative to the reference signal; and a controller configured to generate the control signal responsive to the difference measurements.

Ensemble oscillator and related methods

In an ensemble oscillator system including multiple free-running oscillators, a voltage controlled oscillator having a frequency responsive to a control signal, and a differencer unit that measures time differences between the oscillators, an adaptive Kalman Filter Processor (AKFP) generates the control signal responsive to the time differences. The AKFP uses oscillator noise models to model noise/errors of the ensemble system oscillators, including random noise parameters, and adaptively estimates the errors and the random noise parameters to derive the control signal.

Adaptive Kalman Filter process for controlling an ensemble clock

A receiving station tracking system for receiving GPS data and tracking a mobile vehicle. The receiving station tracking system includes at least one processing stage receiving and processing at least a portion of the GPS data, and a control module receiving and filtering the processed GPS data and outputting at least one control signal in accordance with filtering results. The at least one control signal controls decreasing or increasing a quantity of processing stages of the at least one processing stage.

GPS receiver tracking system

An autonomous navigation system for an orbital platform incorporating a global positioning system based navigation device optimized for low-Earth orbit and medium-Earth orbit applications including a 12 channel, GPS tracking application-specific integrated circuit () operating in concert with a computer system () implementing an extended Kalman filter and orbit propagator which autonomously generates estimates of position, velocity and time to enable planning, prediction and execution of event-based commanding of mission operations.

Extended kalman filter for autonomous satellite navigation system

Disclosed is a system and method for increasing the weak signal recovery capability of a Global Positioning System (GPS) receiver correlating each of the plurality of digital signals by multiplying the I and Q phases by the carrier and code, adding a location offset, accumulating the results of the correlation, and latching the results until a predetermined time; coherent combining the accumulated results at the predetermined time; non-coherent combining the coherent combined results for a time period sufficient to raise a correlation peak to a predetermined point above a noise floor to produce a plurality of non-coherent bin observables; determining a maximum value of the plurality of bin observables and comparing the maximum value to predetermined threshold; determining grid locations of bin observables having maximum values greater than the predetermined threshold; determining a bi-quadratic surface using the grid locations; determining an argument maximum of the bi-quadratic surface; estimating epoch pseudorange and Doppler variables based on the argument maximum; estimating errors in at least one of position, velocity, orientation, user clock, frequency, and ionosphere states on the estimated epoch pseudorange and Doppler variables; and determining at least one of position, velocity and orientation by correcting for the estimated errors.

Weak signal and anti-jamming Global Positioning System receiver and method using full correlation grid

An autonomous navigation system for an orbital platform incorporating a global positioning system based navigation device optimized for low-Earth orbit and medium-Earth orbit applications including a 12-channel, GPS tracking application-specific integrated circuit operating in concert with a microprocessor implementing an extended Kalman filter and orbit propagator which autonomously generates estimates of position, velocity, and time to enable planing, prediction and execution of event-based commanding of mission operations.

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Silver Spring, MD, United States of America

Dennis J Duven