Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method for navigating an autonomous vehicle along a desired path is described. The method includes manually navigating the vehicle along the desired path, measuring an environment in the vicinity of the desired path, during the manual navigation, using at least one sensor affixed to the vehicle, storing the environmental measurements as a programmed path within the vehicle, and subsequently utilizing an algorithm, the stored environmental measurements, and additional environmental measurements, to navigate the vehicle along the programmed path.

Abstract: A plan position indicator display is converted to a correctly scaled perspective display based on aircraft altitude and display parameters. Two cartesian based display memories are involved. One memory stores the plan position indicator image to be converted and the other memory stores the converted image ready for direct display on a bit-mapped display device. The arrangement is such that a plan position indicator display pixel address is provided for each pixel in the memory which stores the converted image for permitting said latter memory to be completely filled with the most appropriate pixel values at the frame rate without the need for further pixel filling or erasing.