Impact of nominal signal deformations on satellite navigation systems
- Global Navigation Satellite Systems (GNSS), of which GPS is the standard-bearer, are ubiquitous and widely used in various applications including aviation, agriculture, automobile navigation, search and rescue, and recreation. GNSS are steadily being improved with the addition of new constellations, new frequencies, and new signals. Future multi-frequency GNSS will eliminate one of the largest error sources (ionosphere) and promises even better performance: improving accuracy from approximately 5 meters to 1 meter. Unfortunately, the new frequencies and signals will have small but unavoidable biases relative to one another. The impact of these biases increases as other error sources are eliminated. Nominal satellite signal deformations -- deviations of broadcast GPS satellite signals from ideal -- result in tracking errors, range biases, and position errors in GPS receivers. It is thus imperative that these errors are quantified, to enable the design of appropriate error budgets and mitigation strategies for various application fields. Traditional measurement methods for these signal deformations can be broadly classified into two categories. The first category uses large antenna dishes paired with high-resolution, high-bandwidth measurements and is limited to short time intervals (seconds) due to data storage constraints. However, these measurements could be subject to time-varying effects that are unobservable between data sets. The second category uses lower-resolution, lower bandwidth measurements over long continuous time periods, but less effectively attenuates error sources such as multipath that obscure the signal deformations of interest. The major contribution in this dissertation is the development of an innovative measurement method that combines the merits of both past approaches while mitigating the disadvantages, rendering nominal signal deformations measurable. Furthermore, these measurements were repeatable over long time periods of hours, days, and months. A good estimate of the position error impact on user receivers could be obtained using these highly consistent measurements. A mitigation strategy was developed in response and verified using this measurement method. The results show that the position error impact could be substantial, but could also be effectively mitigated with the use of an appropriate mitigation strategy. This work is a critical component toward the successful implementation of future dual-frequency GNSS-based landing systems for aviation.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Wong, Gabriel Hoong Wen
|Stanford University, Department of Electrical Engineering.
|Statement of responsibility
|Gabriel Hoong Wen Wong.
|Submitted to the Department of Electrical Engineering.
|Thesis (Ph.D.)--Stanford University, 2014.
- © 2014 by Hoong Wen Gabriel Wong
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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