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Biological SciencesBiochemistry

Navigation Using Orthogonal Frequency Division Multiplexed Signals of Opportunity

Authors: Jamie S. Velotta; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
Abstract:
The global positioning system (GPS) provides high-accuracy position measurements anywhere in the world. However, a limitation of this system is that a line of sight to multiple satellites is required; therefore, it is unsuitable to use indoors or in urban canyons. Also, in the presence of radio-frequency interference or jamming, GPS may be unavailable. Alternative methods of navigation and positioning are need to either compliment GPS as a backup or for use in areas unreachable by satellites. This research analyzes a feature-based correlation approach for determining reception differences between two Orthogonal Frequency Division receivers for the purpose of TDOA calculations. Multicarrier signals have a very defined signal structure which allows for non-cooperative symbol detection techniques. Simulations are conducted with different correlation windows sizes, SNR values, and eight different statistical features. Out of the eight features tested the symbol mean and average symbol phase proved to be the most promising because they are able to achieve accurate symbol difference estimations at SNR values below 0 dB.

Limitations: APPROVED FOR PUBLIC RELEASE
Description: Master thesis
Pages: 87
Report Date: SEP 2007
Report Number: A267674
Keywords relating to this report:
*CODING
*FREQUENCY DIVISION MULTIPLEXING
*GLOBAL POSITIONING SYSTEM
*INERTIAL NAVIGATION
*JAMMING
*RADIOFREQUENCY INTERFERENCE
ARTIFICIAL SATELLITES
CORRELATION
DETECTION
DIGITAL COMMUNICATIONS
LINE OF SIGHT
MEAN
MEASUREMENT
SIGNAL PROCESSING
SIMULATION
SYMBOLS
THESES
TRANSMITTERS
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