The Johns Hopkins University

Lloyd A Linstrom

Dennis J Duven

Mark S Asher

William S Devereux

Thomas L Kusterer

Kim Strohbehn

Robert C Moore

Robert L Henderson

Thomas R McKnight, Jr

Albert A Chacos

Richard C Morgan

Michael H Boehme

Stephen J Stafford

John R Meyer

Martin G Sommerville

Robert J Heins

Don M Gruenbacher

Paul D Grimm

Paul R Snow

Methods and systems to detect navigation signals, including to identify up to multiple range-Doppler hypotheses from each of j range-Doppler correlation grids based on a relatively low first threshold, generate navigation solutions from combinatorial sets of k of the identified hypotheses, evaluate the navigation solutions to identify plausible solutions, iteratively and combinatorially augment the plausible solutions with additional hypotheses from grids that are not represented in the corresponding k-hypotheses based navigation solutions, replace plausible solutions with corresponding augmented plausible solutions when appropriate, and select one of a plurality of plausible solutions as a best plausible solution, j and k being positive integers. Where a grid energy peak exceeds a second threshold, a corresponding hypothesis may be identified as a sole hypothesis for the corresponding navigation signal. The relatively low first threshold permits detection of weaker signals. Subsequent evaluations effectively transform a per-navigation-signal false alarm rate to per-navigation-solution false alarm rate.

Methods and systems to diminish false-alarm rates in multi-hypothesis signal detection through combinatoric navigation

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

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.

Autonomous satellite navigation system

A small, multi-function device called the GPS/Telemetry Transmitter (GTT) that can recover telemetry (TM) data from missiles, spacecraft, balloons, or any moving platform or vehicle, and generate high accuracy trajectory estimates using GPS data is disclosed. Additionally, the concept underlying the GTT of transmitting high-data-rate telemetry and instrument data concurrently with transdigitized GPS data is incorporated in a GPS-Linked Transponder (GLT) resulting in a simpler and cheaper satellite positioning system.

Global positioning system (GPS) linked satellite and missile

Growing community of inventors

Columbia, MD, United States of America

Lloyd A Linstrom