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Full-Text Articles in Navigation, Guidance, Control and Dynamics
Aiding Gps With Additional Satellite Navigation Services, Yasin A. Mutlu
Aiding Gps With Additional Satellite Navigation Services, Yasin A. Mutlu
Theses and Dissertations
In modern warfare navigation services are very important. GPS is currently providing service for accurate navigation, except in some areas, especially urban areas, where GPS signals cannot always be tracked by users. In these cases some additional navigation support could be provided by other global navigation satellite systems. If GPS is combined with other navigation systems than the navigation gap will be minor. In this thesis, the effect of combining GPS with other satellite navigation systems, specifically GLONASS, Galileo and Compass, is evaluated in terms of availability and position dilution of precision (PDOP) values. First, satellite constellations are simulated in …
Failure Detection Of A Pseudolite-Based Reference System Using Residual Monitoring, Michael A. Ciampa
Failure Detection Of A Pseudolite-Based Reference System Using Residual Monitoring, Michael A. Ciampa
Theses and Dissertations
The 746th TS uses a flight reference system referred to as the Central Inertial and GPS Test Facility (CIGTF) Reference System (CRS). Currently the CRS is the modern standard flight reference system for navigation testing, but high accuracy is dependent on the availability of GPS. A pseudolite system is currently being developed to augment the CRS and supply the capability to maintain high accuracy navigation under normal and jamming conditions. Pseudolite measurements typically contain cycle slips and other errors (such as multipath, tropospheric error, measurement noise) that can affect reliability. Past work relied on the receiver-reported signal-to-noise (SNR) value to …
Fusion Of Imaging And Inertial Sensors For Navigation, Michael J. Veth
Fusion Of Imaging And Inertial Sensors For Navigation, Michael J. Veth
Theses and Dissertations
The motivation of this research is to address the limitations of satellite-based navigation by fusing imaging and inertial systems. The research begins by rigorously describing the imaging and navigation problem and developing practical models of the sensors, then presenting a transformation technique to detect features within an image. Given a set of features, a statistical feature projection technique is developed which utilizes inertial measurements to predict vectors in the feature space between images. This coupling of the imaging and inertial sensors at a deep level is then used to aid the statistical feature matching function. The feature matches and inertial …
The Use Of X-Ray Pulsars For Aiding Gps Satellite Orbit Determination, Dennis W. Woodfork Ii
The Use Of X-Ray Pulsars For Aiding Gps Satellite Orbit Determination, Dennis W. Woodfork Ii
Theses and Dissertations
This research proposes the use of an existing "signal of opportunity" - namely x-ray pulsars - to improve the accuracy and robustness of the GPS satellite and clock estimation algorithm. Improvement in satellite and clock accuracy results in a direct benefit to the user. A simulation has been developed to determine the effects of using x-ray pulsar measurements on the GPS Operational Control Segment. The epoch-specific position, velocity, and clock errors of all GPS satellites in the constellation were estimated using both pseudoranges and time-difference-of-arrival (TDOA) measurements from pulsars. The primary measure of accuracy is a constellation Signal-In-Space Range Error …
Development And Testing Of A Multiple Filter Approach For Precise Dgps Positioning And Carrier-Phase Ambiguity Resolution, Paul E. Henderson
Development And Testing Of A Multiple Filter Approach For Precise Dgps Positioning And Carrier-Phase Ambiguity Resolution, Paul E. Henderson
Theses and Dissertations
The most precise relative positioning obtained using differential GPS depends on accurately determining carrier-phase integer ambiguities. To achieve high precision, many current static and kinematic algorithms use a floating-point solution until enough information becomes available to fix the carrier-phase ambiguities accurately. A mew method is presented that uses a multiple model Kalman filter to resolve the carrier-phase integer ambiguities. This method starts with the floating-point results, yet smoothly and rapidly attains the precision of the correct fixed-integer solution, eliminating the need to decide when to switch from the floating to the fixed-integer solution. This method is based on a theoretically …
Optimization Of A Gps-Based Navigation Reference System, Jason B. Mckay
Optimization Of A Gps-Based Navigation Reference System, Jason B. Mckay
Theses and Dissertations
The development of increasingly accurate new aircraft navigation systems has caused the Air Force to develop a new Navigation Reference System to test them, called the Submeter Accuracy Reference System (SARS). The SARS is an inverted GPS system which consists of an array of GPS receivers on the ground and an airborne pseudolite mounted on the test aircraft. The SARS will provide a proof position estimate that is used to check the navigation system under test. Unfortunately, ground based inverted GPS systems tend to suffer from high geometric sensitivity to measurement errors. This research tackles the problem of optimizing the …