Temporally adjusted complex ambiguity function mapping algorithm for geolocating radio frequency signals
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Authors
Moss, Andrew
Subjects
RF Signals
Geolocation
CAF
CAFMAP
SIGINT
Geolocation
CAF
CAFMAP
SIGINT
Advisors
Loomis, Herchel H.
Kragh, Frank
Date of Issue
2014-12
Date
Dec-14
Publisher
Monterey, California: Naval Postgraduate School
Language
Abstract
The Complex Ambiguity Function (CAF) allows simultaneous estimates of the Time Difference of Arrival (TDOA) and Frequency Difference of Arrival (FDOA) for two received signals. The Complex Ambiguity Function Geo-Mapping (CAFMAP) algorithm then directly maps the CAF to geographic coordinates to provide a direct estimation of the emitter’s position. The CAFMAP can only use short-duration CAFs, however, because the collector motion changes the system geometry over time. In an attempt to mitigate this shortfall and improve geolocation accuracy, the CAFMAP takes multiple CAF snapshots and sums the amplitudes of each. Unfortunately, this method does not provide the expected accuracy improvement, and a new method is sought. This thesis reformulates the equations used in computing the CAF, in order to account for the collector’s motion, and uses the results to derive a new CAFMAP algorithm. This new algorithm is implemented in MATLAB, and its results and characteristics analyzed. The conclusions are as follows: the new algorithm functions as intended, removes the accuracy limitations of the original method, and merits further investigation. Immediate future work should focus on ways to reduce its computation time and modifying the algorithm to account for 3-Dimensional reality, non-linear motion of collectors, and motion of the emitter.
Type
Thesis
Description
Series/Report No
Department
Electrical Engineering
Organization
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.