PhD Dissertation Defense
Science / Technology - Lecture/Discussion - WPI Only
Thursday, February 13, 2014
10:00 AM-12:00 PM
Enhanced Acquisition Techniques for GPS L1C Receivers
By PhD Candidate:
ECE Department, WPI
Professor William Michalson, ECE Department, WPI
Professor Alexander Wyglinski, ECE Department, WPI
Professor Peter Swaszek, ECE Department, University of Rhode Island
A new, open-access Global Positioning System (GPS) signal, known as L1C, is the most recent of several modernized Global Positioning System (GPS) signals. The first launch of a GPS satellite with this signal is expected to occur within a few years. One of the interesting features of modern Global Navigation Satellite System (GNSS) signals, including GPS L1C, is the presence of data and pilot components. The pilot component is a carrier with a deterministic overlay code but no data symbols; whereas, the data component carries the navigation data symbols used in the receiver processing. A unique aspect of GPS L1C is the asymmetrical power split between the two components, 75% of the power is used for the pilot and the remaining power, or 25%, for the data. In addition, the pilot and the data components are transmitted in phase with orthogonal spreading codes.
Unassisted acquisition of GNSS spread spectrum signals requires a two-dimensional search for the spreading code delay and Doppler frequency. For modern two-component GNSS signals, conventional GNSS acquisition schemes may be used on either component, correlating the received signal with either the pilot or the data spreading code. One obvious disadvantage of this approach is the wasting of power; hence, new techniques for combining, or joint acquisition of the pilot and the data components, have been proposed.
In this dissertation, acquisition of GPS L1C is analyzed and receiver techniques are proposed for improving acquisition sensitivity. Optimal detectors for GPS L1C acquisition in additive white Gaussian noise are derived, based on various scenarios for a GPS receiver. Monte Carlo simulations are used to determine the performance of these optimal detectors, based on detection and false alarm probabilities. After investigating the optimal detectors for GPS L1C acquisition, various sub-optimal detectors that are more efficient to implement are proposed, thoroughly investigated, and compared. Finally, schemes for joint acquisition of L1C and the legacy GPS C/A code signal are proposed and analyzed.
Suggested Audiences: College
Last Modified: January 31, 2014 at 2:56 PM