AMBIGUITY RESOLUTION ALGORITHMS FOR DIRECTION OF ARRIVAL ESTIMATION

Date

2024-11-29

Author

Erol, İlker

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In direction finding, it is well known that angular accuracy increases as the array aperture increases. However, array aperture cannot be made larger than the theoretical limit which indicates that inter-element spacing should be less than half the wavelength. In the literature, there are methods which overcome this limit with a trade off on the array robustness for different distortions. In this thesis, ambiguity resolution techniques are investigated and a new array structure together with an ambiguity resolution method is proposed. More specifically, it is proposed to use SODA geometry in four elements planar structure and rotate the array to cover 360 degrees with high accuracy and isometric response. In this context, different methods of ambiguity resolution such as amplitude and phase comparison methods, Hybrid Amplitude/Phase, Hybrid Amplitude/MUSIC (MUltiple SIgnal Classification), rotating interferometer, and SODA (Second Order Difference Array) interferometer methods are considered and their performances are compared. Considering the potential of the SODA array structure, SODA structure has been modified to have four elements planar form. While this structure has no ambiguity, it is almost close to a linear array and hence its performance is handicapped in certain directions. In order to remove this deficiency and have an isometric angular response, it is proposed to rotate the array to have 360 degrees of coverage. The Doppler effect due to rotation is accounted for and the performance of a variety of SODA structures are investigated by using both Cramér-Rao Bound (CRB) and simulations. It is shown that the proposed SODA structure is very effective and the array accuracy is significantly high without imposing ambiguity.

Subject Keywords

Direction Finding, Ambiguity Resolution, Soda Array, Interferometer, Rotating Arrays

URI

https://hdl.handle.net/11511/112712

Collections

Graduate School of Natural and Applied Sciences, Thesis