GPS-based precision approach and landing navigation: Emphasis on inertial and pseudolite augmentation and differential ionosphere effect.

摘要

The Differential Global Positioning System-based precision approach and landing architectures proposed by the Federal Aviation Administration (FAA) include the Wide Area Augmentation System (WAAS) and the Local Area Augmentation System (LAAS) for performing landings in Category (CAT) I and CAT III minimums, respectively. The Required Navigation Performance (RNP) for GPS-based satellite navigation systems includes accuracy, continuity, integrity and availability. Previous studies have demonstrated that both the WAAS and the LAAS provide the required accuracy and are susceptible to possible interference and jamming that could damage their continuity and availability. Additionally, the influence of the carrier smoothed code, the official LAAS algorithm, on the error due to the differential ionosphere remains unexamined. Therefore, this thesis discusses the following topics: (1) Inertial backup of GPS-Based precision approach and landing systems. This topic includes (a) Accuracy and continuity evaluation of an integrated WAAS/INS system. (b) Accuracy comparison among various LAAS algorithms and the integrated LAAS/INS system. (c) A backup system based on the integration of three pseudolites (PLs) with INS. (2) The impact of the differential ionosphere error on the LAAS. This topic includes (a) Evaluation of the threat. (b) Seeking solutions and evaluating their costs and benefits.; Experimental data are used to develop the error models for both the WAAS and LAAS and the linear covariance analysis technique is used for the performance analysis. Analysis results indicate the following: (1) WAAS/INS provides a temporary backup for GPS outages to satisfy the CAT I requirement. However, the possibility of extending the WAAS/INS performance to satisfy the CAT II requirement is limited. (2) LAAS/INS provides comparable accuracy to LAAS using a carrier phase algorithm. (3) The 3-PLs/INS system provides touch down performance in the absence of the data link, pseudolite synchronization and GPS signals. (4) The differential carrier smoothed ionosphere delay (DCSID), identified as a threat to LAAS availability in this research, ensures that the ionosphere spatial decorrelation error is not negligible. (5) The ionosphere monitoring and calibration algorithm developed herein can control the DCSID effect at a cost of increasing the bandwidth of the data link to transmit the ground monitored ionosphere gradients.