Aircraft landing using a modernized global positioning system and the wide area augmentation system

This research investigates the performance of an airborne GPS receiver using differential corrections and associated error bounds from the WAAS when three civil GPS signals become available. There are three ways to take advantage of the multiple frequencies. First, one can measure ionospheric delay directly in the airplane. This would replace the grid of ionosphere delay corrections currently broadcast by the WAAS. This direct use of multiple frequencies would be more accurate, and offer higher availability. Second, one can use the additional GPS frequencies to mitigate unintentional radio frequency interference (RFI). Even if two frequencies are lost, the user could revert to the WAAS grid. Third, one can take advantage of stronger civil signal power of the modernized GPS to acquire a low elevation satellite before using it for the position solution. Earlier acquisition would allow for longer carrier-aided smoothing of multipath.; This research evaluates the performance of a multiple-frequency GPS landing system that depends on the number of available GPS frequencies and includes the following scenarios: Case 1. All three GPS frequencies are available, Case 2. Two of three GPS frequencies are available, Case 3. One of three GPS frequencies is available.; This research also presents a solution to sustain multiple frequency performance when an aircraft descends into an RFI field and loses all but one of the frequencies. There are three available techniques. First, one can use the code-carrier divergence to continue ionospheric delay estimation. Second, one can use the WAAS ionospheric threat model to bound the error. Third, one can use the maximum ionospheric delay gradient model to bound the ionospheric delay during the ionosphere storm period. These three techniques all provide the ability to continue operation for more than 10 minutes after the onset of RFI.; This research provides the first three-frequency GPS/WAAS LPV coverage predictions for CONUS. The current L1-only WAAS user has LPV precision approach services available 99.9% of the time over 97.46% of CONUS, although this may be reduced during ionosphere storms. After the GPS and WAAS modernizations, an L1-L2-L5 three-frequency user, an L1-L2 dual-frequency user, and an L1-L5 dual-frequency user all have LPV precision approach services available 99.9% of time over 100% of CONUS even during ionosphere storms.