Abstract: Systems and methods for fault detection, exclusion, isolation, and re-configuration of navigation sensors using an abstraction layer are provided. In certain embodiments, a system includes a plurality of sensors that provide redundant sensor measurements, wherein redundancy of the redundant sensor measurements is achieved based on an independence between measurements from different physical sensor units in the plurality of sensors. The system additionally includes a fusion function configured to receive the redundant sensor measurements from each sensor in the plurality of sensors and calculate fused navigation parameters. Further, the system includes an abstraction layer that calculates an estimated state based on the fused navigation parameters, wherein the estimated state comprises safety assessment information for the fused navigation parameters and the fused navigation parameters.

Abstract: Systems and methods for integrity monitoring of primary and derived parameters are described herein. In certain embodiments, a method includes transforming an estimated error state covariance matrix of at least one primary integrity monitoring parameter of a navigation system onto an error state covariance matrix of one or more derived integrity monitoring parameters, wherein the one or more derived integrity monitoring parameters depends from the at least one primary integrity monitoring parameter. The method also includes transforming an integrity threshold of the at least one primary integrity monitoring parameter onto separation parameters of the one or more derived integrity monitoring parameters. The method further includes computing a protection limit for the one or more derived integrity monitoring parameters.

Abstract: Systems and methods for fault detection, exclusion, isolation, and re-configuration of navigation sensors using an abstraction layer are provided. In certain embodiments, a system includes a plurality of sensors that provide redundant sensor measurements, wherein redundancy of the redundant sensor measurements is achieved based on an independence between measurements from different physical sensor units in the plurality of sensors. The system additionally includes a fusion function configured to receive the redundant sensor measurements from each sensor in the plurality of sensors and calculate fused navigation parameters. Further, the system includes an abstraction layer that calculates an estimated state based on the fused navigation parameters, wherein the estimated state comprises safety assessment information for the fused navigation parameters and the fused navigation parameters.

Abstract: A method of supplementing a satellite based augmentation system approach during low visibility conditions is provided. The method includes acquiring satellite range measurements and additional measurements from at least one additional onboard independent sensor. Core sigma values are assigned for satellite range measurements and for each additional measurement from the at least one additional onboard independent sensor. A weighted position solution is determined using the acquired satellite range measurements, the acquired additional measurements and the assigned core sigma values. A discriminator is applied that utilizes vehicle positions derived from the acquired satellite range measurements and from the additional measurements to determine if a fault is present in the weighted position solution. An alert is generated if an output of the discriminator is outside a set tolerance value needed for low visibility operation.

Abstract: A Global Navigation Satellite System (GNSS) based navigation system with signal fault detection is provided. A least one controller is configured to; determine a true carrier phase measurement associated with each satellite signal received at each antenna of a plurality of spaced antennas; resolve integer ambiguities in true carrier phase measurement differences; and calculate at least one variable of a first navigation solution based on the obtained first set of resolved integer ambiguity measurements. The at least one controller is further configured to apply a solution separation process to repeatedly; calculate the at least one variable of a second navigation solution; determine a difference between the at least one variable of the second navigation solution and the first navigation solution; and detect a fault in satellite signals when the determined difference exceeds a defined threshold.

Abstract: A Global Navigation Satellite System (GNSS) based navigation system with signal fault detection is provided. A least one controller is configured to; determine a true carrier phase measurement associated with each satellite signal received at each antenna of a plurality of spaced antennas; resolve integer ambiguities in true carrier phase measurement differences; and calculate at least one variable of a first navigation solution based on the obtained first set of resolved integer ambiguity measurements. The at least one controller is further configured to apply a solution separation process to repeatedly; calculate the at least one variable of a second navigation solution; determine a difference between the at least one variable of the second navigation solution and the first navigation solution; and detect a fault in satellite signals when the determined difference exceeds a defined threshold.

Abstract: Systems and methods for integrity monitoring of primary and derived parameters are described herein. In certain embodiments, a method includes transforming an estimated error state covariance matrix of at least one primary integrity monitoring parameter of a navigation system onto an error state covariance matrix of one or more derived integrity monitoring parameters, wherein the one or more derived integrity monitoring parameters depends from the at least one primary integrity monitoring parameter. The method also includes transforming an integrity threshold of the at least one primary integrity monitoring parameter onto separation parameters of the one or more derived integrity monitoring parameters. The method further includes computing a protection limit for the one or more derived integrity monitoring parameters.

Abstract: A method of operating a global positioning receiver is provided. The method includes receiving a plurality of signals from a plurality of satellites. At least a measurement from and location of each satellite is determined based on the received plurality of signals. An approximate vehicle velocity vector is determined based on the received plurality of signals. A dot product between a line of sight between each satellite and a vehicle having the receiver and the determined vehicle velocity vector is determined. Each measurement associated with each determined dot product that is below a minimum dot product threshold is removed to obtain a resultant set of measurements. A position solution based on the resultant set of measurements is then determined.

Abstract: A method of supplementing a satellite based augmentation system approach during low visibility conditions is provided. The method includes acquiring satellite range measurements and additional measurements from at least one additional onboard independent sensor. Core sigma values are assigned for satellite range measurements and for each additional measurement from the at least one additional onboard independent sensor. A weighted position solution is determined using the acquired satellite range measurements, the acquired additional measurements and the assigned core sigma values. A discriminator is applied that utilizes vehicle positions derived from the acquired satellite range measurements and from the additional measurements to determine if a fault is present in the weighted position solution. An alert is generated if an output of the discriminator is outside a set tolerance value needed for low visibility operation.

Abstract: A Global Navigation Satellite System (GNSS) based navigation system with signal fault detection is provided. A least one controller is configured to; determine a true carrier phase measurement associated with each satellite signal received at each antenna of a plurality of spaced antennas; resolve integer ambiguities in true carrier phase measurement differences; and calculate at least one variable of a first navigation solution based on the obtained first set of resolved integer ambiguity measurements. The at least one controller is further configured to apply a solution separation process to repeatedly; calculate the at least one variable of a second navigation solution; determine a difference between the at least one variable of the second navigation solution and the first navigation solution; and detect a fault in satellite signals when the determined difference exceeds a defined threshold.

Abstract: A method of operating a global positioning receiver is provided. The method includes receiving a plurality of signals from a plurality of satellites. At least a measurement from and location of each satellite is determined based on the received plurality of signals. An approximate vehicle velocity vector is determined based on the received plurality of signals. A dot product between a line of sight between each satellite and a vehicle having the receiver and the determined vehicle velocity vector is determined. Each measurement associated with each determined dot product that is below a minimum dot product threshold is removed to obtain a resultant set of measurements. A position solution based on the resultant set of measurements is then determined.

Abstract: Systems and methods for a code carrier divergence (CCD) high-pass filter monitor are provided.

Abstract: A method of implementing a real-time screening process for phase scintillation is presented. The method includes detecting a phase scintillation event during a sample time period at a phase scintillation monitor; excluding associated satellite measurement data from further use based on the detection of the phase scintillation event at the phase scintillation monitor; detecting an end to the phase scintillation event at the phase scintillation monitor; and readmitting associated satellite measurement data collected after the end of the phase scintillation event as detected by the phase scintillation monitor.

Abstract: Systems and methods for averaging satellite sigmas and readmitting excluded satellite measurements into differential corrections and integrity monitors are provided. In one embodiment, a method comprises: calculating a first RFI based averaged sigma and a second RFI based averaged sigma, wherein the first RFI based averaged sigma includes a sigma for the excluded satellite measurement and wherein the second RFI based averaged sigma does not include the sigma for the excluded satellite measurement; and, readmitting the excluded satellite measurement into either a differential correction broadcast or a respective integrity monitor when the first RFI based averaged sigma is less than or equal to the second RFI based averaged sigma.

Abstract: Systems and methods for attitude fault detection in an inertial measurement unit (IMU) are disclosed. In one embodiment, an avionics system comprises: an IMU configured to produce a calculated pitch solution, a calculated roll solution, or both; a monitor coupled to the IMU and configured to produce an estimated pitch solution, an estimated roll solution, or both; a comparator, wherein the comparator determines the difference between the calculated pitch solution and the estimated pitch solution, the difference between the calculated roll solution and the estimated roll solution, or both; and a display device communicatively coupled to the comparator; wherein the display device receives a warning message from the comparator when the difference between the calculated pitch solution and the estimated pitch solution is greater than a pitch threshold, or when the difference between the calculated roll solution and the estimated roll solution is greater than a roll threshold, or both.

Abstract: A method of implementing a real-time screening process for amplitude scintillation is presented. The method includes detecting an amplitude scintillation event during a sample time period at an amplitude scintillation monitor; excluding associated satellite measurement data from further use based on the detection of the amplitude scintillation event at the amplitude scintillation monitor; detecting an end to the amplitude scintillation event at the amplitude scintillation monitor; and readmitting associated satellite measurement data collected after the end of the amplitude scintillation event as determined by the amplitude scintillation monitor.

Abstract: Systems and methods for attitude fault detection based on integrated GNSS/inertial hybrid filter residuals are provided. In one embodiment, a fault detection system for aircraft attitude measurement system comprises: a sensor monitor coupled to a first inertial measurement unit, the sensor monitor comprising: a navigation error model for the first inertial measurement unit, the model configured to model a plurality of error states including at least an attitude error state vector, an velocity error state vector, and a position error state vector determined from data generated by the first inertial measurement unit; and a propagator-estimator configured to propagate and update error states based on GNSS data; and a residual evaluator configured to input measurement error residual values generated by the propagator-estimator, wherein the residual evaluator outputs an alert signal when the measurement error residual values exceed a threshold.

Abstract: Systems and methods for attitude fault detection based on integrated GNSS/inertial hybrid filter residuals are provided. In one embodiment, a fault detection system for aircraft attitude measurement system comprises: a sensor monitor coupled to a first inertial measurement unit, the sensor monitor comprising: a navigation error model for the first inertial measurement unit, the model configured to model a plurality of error states including at least an attitude error state vector, an velocity error state vector, and a position error state vector determined from data generated by the first inertial measurement unit; and a propagator-estimator configured to propagate and update error states based on GNSS data; and a residual evaluator configured to input measurement error residual values generated by the propagator-estimator, wherein the residual evaluator outputs an alert signal when the measurement error residual values exceed a threshold.

Abstract: Systems and methods for attitude fault detection in an inertial measurement unit (IMU) are disclosed. In one embodiment, an avionics system comprises: an IMU configured to produce a calculated pitch solution, a calculated roll solution, or both; a monitor coupled to the IMU and configured to produce an estimated pitch solution, an estimated roll solution, or both; a comparator, wherein the comparator determines the difference between the calculated pitch solution and the estimated pitch solution, the difference between the calculated roll solution and the estimated roll solution, or both; and a display device communicatively coupled to the comparator; wherein the display device receives a warning message from the comparator when the difference between the calculated pitch solution and the estimated pitch solution is greater than a pitch threshold, or when the difference between the calculated roll solution and the estimated roll solution is greater than a roll threshold, or both.

Abstract: Systems and methods for attitude fault detection based on air data and aircraft control settings are provided. In one embodiment, a sensor monitor for an aircraft attitude measurement system comprises: an aircraft model configured to model a plurality of states, the plurality of states including at least an aircraft attitude state, an aircraft velocity state, a sink rate error state, and a wind velocity state; a propagator-estimator configured to utilize the plurality of states of the aircraft model to process air data measurements and attitude measurements from a first inertial measurement unit of the aircraft attitude measurement system; and a residual evaluator configured to input residual error values generated by the propagator-estimator, wherein the residual evaluator outputs an alert signal when the residual error values exceed a predetermined statistical threshold.