Abstract: Systems and methods for estimating attitude and heading are provided. The systems and methods utilize carrier phase single difference (CSD) measurements or carrier phase double difference (CDD) measurements and a validation test for CSD or CDD measurement residuals. The systems and methods include applying a wrapping function with limit of ±half of the GNSS carrier signal wavelength to CSD or CDD measurement residuals to generate refined CSD or CDD measurement residuals and validating the refined CSD or CDD measurement residuals variance to determine valid CSD or CDD measurements. By using the validated CSD and CDD measurements, the systems and methods enable low grade hybrid inertial navigation systems to estimate attitude and heading with integrity and without a magnetometer or the need for integer ambiguity resolution even during the static or steady phases of flight/operation.

Abstract: Methods and systems to process and assure integrity of radar measurements, detect the effects of GNSS jamming and/or spoofing events, identify GNSS measurements affected by the GNSS jamming and/or spoofing events, and assure the integrity of the GNSS measurements unaffected by jamming and/or spoofing events in a vehicle navigation system are disclosed. The methods are implemented to integrate inertial measurements, GNSS measurements, and radar measurements for the vehicle, and apply solution separation techniques to all of the measurements. The solution separation techniques use a main filter for hybridization of the inertial measurements, the GNSS measurements, and the radar measurements, with additional sub-solution filters and sub-sub-solution filters that use combinations of these measurements. This provides common processing of the GNSS and radar sensors in a single hybridization and solution separation framework.

Abstract: Systems and methods are described that illustrate how to determine whether an image includes a travel way, and if so how to determine an angle between a longitudinal axis of a vehicle and a longitudinal axis of a travel way line, and a shortest distance between a reference point on a vehicle and a longitudinal axis of the travel way line.

Abstract: Methods and systems to process and assure integrity of DME and/or VOR measurements, detect the effects of GNSS jamming and/or spoofing events, identify GNSS measurements affected by the GNSS jamming and/or spoofing events, and assure the integrity of the GNSS measurements unaffected by jamming and/or spoofing events in a vehicle navigation system are disclosed. The methods are implemented to integrate inertial measurements, GNSS measurements, and DME/VOR measurements for the vehicle, and apply solution separation techniques to all of the measurements. The solution separation techniques use a main filter for hybridization of the inertial measurements, the GNSS measurements, and the DME/VOR measurements, with additional sub-solution filters and sub-sub-solution filters that use combinations of these measurements. This provides common processing of the GNSS and DME/VOR sensors in a single hybridization and solution separation framework.

Abstract: A system to provide navigation solutions for vehicle landing guidance comprises onboard aiding sensors, an IMU, a radar altimeter, a map database, and a navigation system including a navigation filter that outputs estimated kinematic state statistics for the vehicle. An onboard processor inputs horizontal and vertical position statistics from the navigation filter into the map database, and computes an estimated ground/object height, ground/object velocity, ground/object acceleration, and error statistics thereof, based on terrain and object map data.

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 a single-difference based pre-filter of measurements for use in solution separation framework are provided. In certain embodiments, a navigation system includes at least one receiver configured to receive a plurality of signals transmitted from a plurality of transmitters. The navigation system further includes a processing unit operatively coupled to the navigation system, the processor configured to identify a plurality of measurements associated with the plurality of transmitters. Additionally, executable instructions cause the processing unit to calculate an auxiliary navigation solution based on a calculated single difference between the plurality of measurements; calculate one or more single difference residuals for the auxiliary navigation solution; perform statistical tests on the one or more single difference residuals; and to identify a set of measurements in the plurality of measurements for use in a solution separation method based on the statistical tests.

Abstract: A system to provide navigation solutions for vehicle landing guidance comprises onboard aiding sensors, an IMU, a radar altimeter, a map database, and a navigation system including a navigation filter that outputs estimated kinematic state statistics for the vehicle. An onboard processor inputs horizontal and vertical position statistics from the navigation filter into the map database, and computes an estimated ground/object height, ground/object velocity, ground/object acceleration, and error statistics thereof, based on terrain and object map data.

Abstract: Systems and methods for calculating single delta range differences using synthetic clock steering are provided. In certain embodiments, a system includes a first GNSS receiver that provides first delta range measurements and first measurement times associated with a plurality of GNSS satellites. The system further includes a second GNSS receiver that provides second delta range measurements and second measurement times associated with the plurality of GNSS satellites. Additionally, the system includes a processing unit that executes instructions that cause the processing unit to synchronize the second delta range measurements with the first delta range measurements to create synchronized delta range measurements. The executable instructions also cause the processing unit to calculate a single difference of the first delta range measurements and the synchronized delta range measurements for at least one satellite in the plurality of GNSS satellites.

Abstract: Systems and methods for implementing single differences within a solution separation framework are provided. In certain embodiments, a method includes processing pseudorange measurements to determine a full navigation solution by applying a single difference between the pseudorange measurements. The method additionally includes performing innovation sequence monitoring. Also, the method includes processing a subset of the pseudorange measurements to determine a set of navigation sub-solutions by applying a single difference between the pseudorange measurements, wherein a result of the innovation sequence monitoring is applied to the set of navigation sub-solutions; and providing faults detection and computing protection levels of quantities of navigation information based on a full navigation solution estimate, navigation sub-solution estimates, dependence among the full navigation solution and the set of navigation sub-solutions, and probabilities of missed detection and false alert.

Abstract: A method to assure integrity of integrated certified and non-certified sensors or systems comprises calculating a certified main solution filter within a first software thread in a certified partition; calculating certified sub-solution filters, and sub-sub-solution filters within the first software thread; calculating a non-certified main solution filter within a second software thread in a non-certified partition; if applicable, reusing the certified main solution filter as a non-certified sub-solution filter, and reusing the certified sub-solution filters, as non-certified sub-sub-solution filters; calculating non-certified sub-solution filters, and sub-sub-solution filters, within the second software thread; based on the certified filters, determining protection limits of the certified partition, and/or providing execution of fault detection and exclusion; based on the non-certified filters, determining protection limits of the non-certified partition, and/or providing execution of fault detection and exc

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 estimating attitude and heading are provided. The systems and methods utilize carrier phase single difference (CSD) measurements or carrier phase double difference (CDD) measurements and a validation test for CSD or CDD measurement residuals. The systems and methods include applying a wrapping function with limit of ±half of the GNSS carrier signal wavelength to CSD or CDD measurement residuals to generate refined CSD or CDD measurement residuals and validating the refined CSD or CDD measurement residuals variance to determine valid CSD or CDD measurements. By using the validated CSD and CDD measurements, the systems and methods enable low grade hybrid inertial navigation systems to estimate attitude and heading with integrity and without a magnetometer or the need for integer ambiguity resolution even during the static or steady phases of flight/operation.

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: System and methods are described that illustrate how to more accurately determine at least one state variable of a vehicle using imaging of a travel way line. Imaging can be used to determine an angle between a longitudinal axis of the travel way line and a longitudinal axis of the vehicle, a shortest distance between the center axis and a reference point on or in the vehicle, and corresponding errors. The determined angle, the determined distance, and the corresponding errors can be used to more accurately determine the at least one state variable.

Abstract: Systems and methods are described that illustrate how to determine whether an image includes a travel way, and if so how to determine an angle between a longitudinal axis of a vehicle and a longitudinal axis of a travel way line, and a shortest distance between a reference point on a vehicle and a longitudinal axis of the travel way line.

Abstract: Systems and methods for calculating single delta range differences using synthetic clock steering are provided. In certain embodiments, a system includes a first GNSS receiver that provides first delta range measurements and first measurement times associated with a plurality of GNSS satellites. The system further includes a second GNSS receiver that provides second delta range measurements and second measurement times associated with the plurality of GNSS satellites. Additionally, the system includes a processing unit that executes instructions that cause the processing unit to synchronize the second delta range measurements with the first delta range measurements to create synchronized delta range measurements. The executable instructions also cause the processing unit to calculate a single difference of the first delta range measurements and the synchronized delta range measurements for at least one satellite in the plurality of GNSS satellites.

Abstract: Systems and methods for implementing single differences within a solution separation framework are provided. In certain embodiments, a method includes processing pseudorange measurements to determine a full navigation solution by applying a single difference between the pseudorange measurements. The method additionally includes performing innovation sequence monitoring. Also, the method includes processing a subset of the pseudorange measurements to determine a set of navigation sub-solutions by applying a single difference between the pseudorange measurements, wherein a result of the innovation sequence monitoring is applied to the set of navigation sub-solutions; and providing faults detection and computing protection levels of quantities of navigation information based on a full navigation solution estimate, navigation sub-solution estimates, dependence among the full navigation solution and the set of navigation sub-solutions, and probabilities of missed detection and false alert.

Abstract: Systems and methods for a single-difference based pre-filter of measurements for use in solution separation framework are provided. In certain embodiments, a navigation system includes at least one receiver configured to receive a plurality of signals transmitted from a plurality of transmitters. The navigation system further includes a processing unit operatively coupled to the navigation system, the processor configured to identify a plurality of measurements associated with the plurality of transmitters. Additionally, executable instructions cause the processing unit to calculate an auxiliary navigation solution based on a calculated single difference between the plurality of measurements; calculate one or more single difference residuals for the auxiliary navigation solution; perform statistical tests on the one or more single difference residuals; and to identify a set of measurements in the plurality of measurements for use in a solution separation method based on the statistical tests.

Abstract: A method for computing and applying alternative uncertainty limits is provided. The method includes generating a main solution from a plurality of received measurement signals. A solution separation is applied using a filter bank to generate sub-solutions from the received plurality of measurement signals. Each sub-solution uses all of the measurement signals from the plurality of measurement signals except one measurement signal to generate the associated sub-solution. Each sub-solution excludes a different measurement signal. One sub-solution is selected as fault free. A difference between the main solution and the selected sub-solution is determined. The determined difference is added to a rare normal protection limit to create a solution with improved integrity bounding. The solution with improved integrity bounding is then implemented.