Honeywell International Inc.

Reed R May

Kenneth Steven Morgan

Ruth Dagmar Kreichauf

Michael O Vaujin

Charles P Eckert

Delroy J Sowada

Maurice A Shrader-Frechette

Jeff S Willis

Michael G Symonds

A system comprises a GNSS receiver that receives a GNSS signal and produces GNSS measurements; a plurality of inertial sensors that produce inertial data; and a navigation system comprising a Kalman filter and an inertial navigation unit. The Kalman filter receives the GNSS measurements and calculates pseudo-range residuals, delta-range residuals, pseudo-range chi square values, delta-range chi square values, accelerometer bias estimates, and gyroscope bias estimates. A spoof detection system communicates with the Kalman filter and comprises a set of detection monitors that determine an integrity of the GNSS measurements. The detection monitors detect if the pseudo-range residuals, the delta-range residuals, the pseudo-range chi-square values, the delta-range chi-square values, the accelerometer bias estimates, or the gyroscope bias estimates, go beyond a fail threshold indicating that the GNSS signal is abnormal. When one or more of the detection monitors indicates that the GNSS signal is abnormal, a spoof event alert is outputted.

Systems and methods using kalman filter monitors to detect spoofed GNSS signals

A method and system for navigation quality estimation is provided. The method comprises obtaining an alignment observation, comparing the alignment observation to a current heading estimate, and updating the current heading estimate based on the comparison. A heading error estimate is updated based on the updated current heading estimate, and an estimated drift rate is determined based on the heading error estimate and an operational latitude. A determination is then made whether a drift rate requirement is met by the estimated drift rate. If the drift rate requirement is not met, the method is repeated until the drift rate requirement is met.

Method and system for latitude adaptive navigation quality estimation

An improved system and method is disclosed for dynamically estimating the output variances of carrier-smoothing filters used, for example, in GPS receivers. By accurately estimating the output variances of the carrier-smoothing filters as they transition from initialization to steady-state operation, it is possible to calculate any required protection levels without having to wait for the filters to fully stabilize. As one example, a system for estimating output variances of a carrier-smoothing filter for use in a satellite navigation system receiver is disclosed, which includes a plurality of smoothing filters associated with a navigation processing unit in a satellite navigation receiver. One or more processors associated with the navigation processing unit executes an algorithm for each smoothing filter, which provides a method for dynamically calculating an output variance for a respective smoothing filter as it transitions in response to new input variance values. The method also predicts the settling point of the output variance for that smoothing filter given a set of pseudorange and carrier-phase values to be applied. Therefore, using this novel output variance prediction method, precision navigation applications such as, for example, airborne GPS-based precision landing system applications can begin operations with suitable calculated protection level values without having to wait for the smoothing filters to stabilize. Thus, such precision landing systems are available for use as soon as the required protection level values are reached.

System and method for dynamically estimating output variances for carrier-smoothing filters

A method and system for degimbalization of sensor outputs is provided. Data output from an embedded GPS inertial navigation system (EGI), which is mounted within a gimbaled system on a vehicle, is processed to provide degimballed navigation data. Generally, motion of the EGI is due to the vehicle motion and the gimbal motion. To provide navigation information relating solely to the vehicle, effects of the gimbal motion within the EGI outputs can be removed.

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Seminole, FL, United States of America

Reed R May