Abstract: A system detects slowly diverging navigational signals by updating the current location from purely internal navigational aids for a period of time. The updated location compared to a continuously corrected current location; if the comparison indicates a deviation outside an expected boundary threshold, the external source is excluded from further measurements. Multiple monitoring elements may be staggered such that one or more monitoring elements are always sequestered for future comparisons. The multiple monitoring elements may monitor different external sources with different weights to identify a specific faulty external source.

Abstract: Systems and methods for navigation of a vehicle use a processing system. The systems and methods can allow an aircraft to take-off in low visibility conditions. The processing system includes a cross tracker, an error processor and an error estimator. The cross tracker is configured to determine a cross track deviation using a hybrid positon and runway heading data. The error processor is configured to determine the hybrid positon from inertial reference system data and corrected error data, and the error estimator is configured to provide the corrected error data using estimates derived from delta range data from a global navigation satellite system receiver.

Abstract: Systems and related methods for simultaneous high precision synchronization and syntonization of multiple sensors or clocks utilize a precision estimator that receives clock signals and time mark signals from both sensors (a reference sensor and a clock to be measured against the reference sensor). A precision time and frequency estimator determines a time offset, frequency offset, and phase offset of the measured sensor relative to the reference sensor. Associated systems can additionally determine the propagation delay between two remote subsystems connected by a communications channel. The communications channel may be a bidirectional duplexed or multiplexed channel allowing for mutual exchange of timing information along a single non-dedicated cable between sensors. Sensors may be synchronized to within 10 ps of each other without the need for THz clocks or fiber-optic cabling.

Abstract: A geo-registration system with a camera receives an image of a scene, identifies features in the image, and computes vectors for each feature based on the known location and orientation of the camera. The system then compares the computed vectors to vectors associated with the same features identified in prior images. The geo-registration system then uses stochastic kriging techniques to create a geo-registration model based on the vectors.

Abstract: A system and method are disclosed for autonomous authentication of a received signal based on characteristics of the signal. The method receives, acquires and tracks a signal to first determine if a carrier clock phase variable associated with the signal meets a phase consistency threshold. If so, the signal is labeled authentic and configured for output to a positioning system. Second and optionally, the system may determine if a data set measurement associated with a unique satellite identification of the signal meets a data set threshold. If not, the signal is labeled as inconsistent and discarded. The system and method continuously monitors the signal for consistency as well as authenticity based on the data set threshold and the phase consistency threshold. Should any tracked signal fall below either threshold, the signal is discarded from the possible positioning solution.

Abstract: A method for providing collaborative PNT for a plurality of nodes in a distributed sensing system is disclosed. The method may include receiving carrier phase and pseudorange measurements from a first node and a second node of the plurality of nodes; providing a process model for each node, where the process model for each node is configured for modeling error characteristics associated with that node; determining an error covariance between the first node and the second node; and estimating a PNT solution for the first node and a PNT solution for the second node based on: the carrier phase and pseudorange measurements received from the first node, the carrier phase and pseudorange measurements received from the second node, the process model for the first node, the process model for the second node, and the error covariance between the first node and the second node.

Abstract: A navigation system/solution, suitable for use in a GPS-denied environment, may be implemented via a node, the node being mounted on-board a vehicle, such as a tactical aircraft. The system/solution allows for a single component of the node to obtain/determine a bearing measurement (via an orientation transfer scheme) and a range measurement (via a round trip timing scheme) based upon signals transmitted between the node and a second node, and further allows for the bearing and range measurements to be received and processed by a navigation processor of the node for determining a location of the node.

Abstract: The present invention is a geolocation system for providing coordinated sensing and precision geolocation of a target emitter. The system may include a Quint Networking Technology (QNT) subsystem which may be configured receiving, detecting and identifying a target emitter signal. The QNT subsystem may be further configured for extracting a carrier phase of the signal. The system may further include a Real Time Kinematic Global Positioning System (RTK GPS) subsystem for determining a position of the geolocation system relative to a position of a second geolocation system. Further, the system may be configured for communicating with the second geolocation system via a QNT communication data link for: determining a QNT time difference via signal carrier phase differencing for calculating a time difference between the geolocation systems and geolocating the target emitter based on both the relative position information of the geolocation systems and the calculated time difference between the geolocation systems.

Abstract: The present invention is a targeting system for tracking angle changes from a reference azimuth. The system includes a mount. The mount may be configured for supporting a sighting scope. The system further includes an angle encoder which is integrated within the mount and is configured for tracking angle changes from the reference azimuth. The system further includes an inertial sensor which is communicatively which is also integrated within the mount and is configured for tracking angle changes from the reference azimuth. The system may be configured for selectively relying on angle change tracking provided by either the angle encoder or the inertial sensor.

Abstract: A vertical integrity monitoring method and system are described. The vertical integrity monitoring method includes determining a noise sigma ratio parameter. The method also includes determining two vertical protection limit slopes and an associated covariance matrix. The method further includes determining a vertical integrity limit and set of weights based on the VPL slopes, covariance and the parameter; and applying the set of weights based on the parameter to calculate a vertical solution. An integrity monitoring system may have hardware and/or software embodying the one or more methods described.

Abstract: An integrity monitoring method for an aircraft is disclosed. The integrity monitoring method includes determining a set of non-uniform weights. The non-uniform weights are based on a least squares approximation of a linearized measurement equation. The integrity monitoring method also includes applying the non-uniform weights in a receiver autonomous integrity monitoring (RAIM) system. Further, the integrity monitoring method includes determining a reduced integrity limit based on the output of the RAIM system.

Abstract: A method and apparatus for improving differential navigation accuracy uses time transfer over a two-way communications link. The communications link transmits an overall time offset between a differential reference station and a remote user. A differential navigation position solution is modified at the remote user with the overall time offset to improve the differential navigation accuracy. A first time offset between a first communications device and a first navigation receiver at the remote user is determined. A second time offset between the first communications device at the remote user and a second communications device at the differential reference station is determined. A third time offset between the second communications device and a second navigation receiver at the differential reference station is determined. An overall time offset from the first time offset, the second time offset, and the third time offset is computed and used to improve the differential navigation accuracy.

Abstract: A method and apparatus for improving differential navigation accuracy uses time transfer over a two-way communications link. The communications link transmits an overall time offset between a differential reference station and a remote user. A differential navigation position solution is modified at the remote user with the overall time offset to improve the differential navigation accuracy. A first time offset between a first communications device and a first navigation receiver at the remote user is determined. A second time offset between the first communications device at the remote user and a second communications device at the differential reference station is determined. A third time offset between the second communications device and a second navigation receiver at the differential reference station is determined. An overall time offset from the first time offset, the second time offset, and the third time offset is computed and used to improve the differential navigation accuracy.

Abstract: A method of detecting GPS signal tampering uses two GPS receivers. A first receiver measures carrier phases of two or more satellite signals and of a tampered signal. A second receiver measures carrier phases of the two or more satellite signals and the tampered signal. A baseline vector between the receiver antennas is measured. Direction cosine vectors of the two or more satellite signals are computed and a dot product is computed from the baseline vector to translate measurements made at antennas of the GPS receivers to a virtual zero baseline condition. The carrier phase measurements are double differenced to obtain double difference residuals. A test statistic of the double difference residuals is computed and tested for phase coherency. An inconsistency in measured signals is flagged when there is an inconsistency in phase coherence indicating the tampered signal is present.

Abstract: A method of determining absolute positions of devices in a network. Relative distances between the devices are determined. For each of at least one of the devices, a range is calculated from a number of distant ranging sources that is less than an amount required to obtain a precise location of the device. The calculated ranges are combined with the determined relative distances to determine a unique absolute position of the devices in the network.

Abstract: A method of generating a synthetic pressure altitude is disclosed. The method includes providing a static air temperature to a data processing device. The method also includes receiving a geometric altitude from a geometric altitude sensing device and performing a numerical integration based on the static air temperature and the geometric altitude resulting in a synthetic pressure altitude. The method further includes receiving a pressure altitude from a pressure altitude sensing device, comparing the pressure altitude and the synthetic pressure altitude and generating an average of the pressure altitude and the synthetic pressure altitude. The method still further includes providing selectively, based on the comparing step, the average as output.

Abstract: A device for measuring a velocity and/or position of a body includes a magnetometer and a measurement unit. The magnetometer is configured to sense a magnetic flux to which the body is exposed. The measurement unit includes a sensor sensing one of an acceleration and a velocity of the body. The measurement unit also includes a processor coupled to the magnetometer and to the measurement unit and configured to determine one on a velocity value and a position value for the body based on the sensed magnetic flux and based or one of the sensed acceleration and the sensed velocity of the body.

Abstract: The present invention is a method of deriving a ground speed of an aircraft on a descent along a flight path. A vertical speed signal is produced as a function of an altitude signal and a vertical acceleration signal. The vertical speed signal is transformed to a nominal ground speed signal based upon a glide slope defined by a glide slope beam. A correction is produced based on a glide slope deviation rate representative of deviation of the aircraft from the glide slope. The nominal ground speed signal is corrected with the correction to produce a corrected ground speed signal. The corrected ground speed signal is filtered with a horizontal acceleration signal and a runway heading signal to produce a smoothed ground speed signal.

Abstract: A method and apparatus are provided for deriving a position solution in a global positioning system mobile station. The method includes the steps of forming a position solution by the mobile station during a first time period based upon a first set of signal measurements made by the mobile station of signals from a set of global positioning system satellites and a corresponding first set of satellite signal measurements made by a ground-based reference station at a known location remote from the mobile station and forming a second position solution by the mobile station during a second time period based upon a second set of satellite signal measurements made by the mobile station of the set of satellites during the second time period and the corresponding first set of measurements from the reference station.

Abstract: A sole means global navigation apparatus adapted for use on an aircraft includes a GPS receiver to provide GPS measurement data and an inertial sensor system adapted to provide inertial translational and rotational data which during time periods is independent of the GPS position data. A navigation system coupled to both of the GPS receiver(s) and the inertial sensor system determines a navigation solution as a function of both the condition of the GPS satellite data and the uncertainty in the Inertial data. An augmentation system coupled to the navigation solution determining system is used to increase the accuracy and/or integrity of the GPS/inertial sensor, thereby achieving style means navigation requirements.