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GPS RECEIVER IMPROVEMENTS
FOR
LOW SIGNAL-TO-NOISE RATIO APPLICATIONS.
by
Manorama Gollakota
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(ELECTRICAL ENGINEERING- SYSTEMS)
August 2007
Copyright 2007 Manorama Gollakota
Object Description
| Title | GPS receiver improvements in low signal-to-noise ratio applications |
| Author | Gollakota, Manorama |
| Author email | rama.gollakota@aero.org |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Electrical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2006-12-22 |
| Date submitted | 2007 |
| Restricted until | Unrestricted |
| Date published | 2007-06-05 |
| Advisor (committee chair) | Ioannou, Petros A. |
| Advisor (committee member) |
Weber, Chuck Safonov, Michael G. Vorel, Zdonek |
| Abstract | The value of GPS for position determination, and the need for its availability in challenging signal-to-noise (SNR) environments cannot be overstated. GPS is being used not only for military applications but also for civil aviation, mining, surveying, and search and rescue missions. In this work, we focus on Inertial Navigation System (INS) -aided GPS, and The Aerospace Corporation's (Aerospace)- patented approach for GPS-INS coupling mechanization referred to in this report as Ultra Tight Processing (UTP). There has been a proliferation of GPS-INS mechanizations in the industry based on Aerospace's UTP approach.; In this work, we use lessons from Classical GPS-processing that use tracking loops from communications systems, and apply those to the UTP approach. In particular, the concept of lock detectors used in classical GPS receivers is applied to UTP. This method is called "Observation Lock Detectors" (OLD).; A MATLAB model of UTP has been developed including models of OLD. MATLAB simulations of OLD using Carrier and Code lock detectors have demonstrated that Code and Carrier OLD work. In the simulations, we track true carrier phase information and the predicted carrier phase error in challenging SNR situations. The carrier OLD indicate when RF interference makes carrier phase error unacceptable. The simulation results are compared to the truth that in practice a receiver would not know. The work attempts to answer such questions as what is the benefit from using both code and carrier information? At what point do we turn off carrier information? Observation Lock Detectors provide answers to such questions. It appears that one can continue to use carrier information even after the onset of interference for some time before discarding it.; Since observation lock extends traditional lock detection concept to UTP, it can be used for comparing UTP-based receiver performance to the performance of traditional GPS receiver systems. As such it serves as a useful performance metric for UTP systems. -- The report ends with a discussion of other challenging problems to be solved in this area. Several topics for continuing research in this area are suggested. |
| Keyword | GPS; INS; ultra-tight processing; observation lock detectors; receiver improvement |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Type | texts |
| Legacy record ID | usctheses-m511 |
| Contributing entity | University of Southern California |
| Rights | Gollakota, Manorama |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Gollakota-20070605 |
| Archival file | uscthesesreloadpub_Volume62/etd-Gollakota-20070605.pdf |
Description
| Title | Page 1 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | GPS RECEIVER IMPROVEMENTS FOR LOW SIGNAL-TO-NOISE RATIO APPLICATIONS. by Manorama Gollakota A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (ELECTRICAL ENGINEERING- SYSTEMS) August 2007 Copyright 2007 Manorama Gollakota |
