ELEE Doctor of Philosophy Dissertation Defense by Savas Erdim - ECE
Topic: Mitigating Interferer Motion with Universal Adaptive Beamformers
Zoom Conference Link: https://umassd.zoom.us/j/99344583625
Meeting ID: 993 4458 3625
Passcode: 979444
Abstract:
Fast-moving, close-range interferers with high bearing rates transits through resolution cells rapidly, challenging the minimum variance distortionless response (MVDR) beamformer’s ability to accurately place notches in the interferers' actual direction. This results in the MVDR notch slightly lagging behind the interferer's actual location, reducing the beamformer's ability to suppress the moving interferers. Many existing methods address this challenge by employing fixed, wide notches in the interferer direction. This conservative approach ensures interferer suppression but causes inefficient degrees of freedom (DoFs) use and significantly reduces white noise gain (WNG).
This dissertation introduces two hybrid beamformers, hybrid double zero beamformer (HDZ) and hybrid MVDR beamformer (HMVDR), designed to address the suppression of moving interferers while providing a high WNG. The proposed hybrid beamformers suppress the moving interferers by creating implicitly wide notches in the beampattern. These notches result from the convolution of smaller adaptive and fixed weight vectors, which, in the spatial domain, corresponds to factoring the beampattern into adaptive and fixed components. The HDZ and HMVDR beamformers differ in their approach to defining the adaptive component. The HDZ beamformer generates second-order notches by convolving the adaptive weights with themselves, while the HMVDR beamformer employs a first-order notch for the adaptive component. The factored beampattern enables the hybrid beamformers a flexible allocation of DoFs between the adaptive and fixed components. However, the primary challenge for hybrid beamformers lies in optimizing the allocation of DoFs for the adaptive component, particularly in dynamic environments with an unknown and time-varying number of interferers. To address this challenge, we introduce a universal hybrid beamformer that blends different factorizations to dynamically allocate DoFs between the adaptive and fixed components. Simulations and microphone array experiments confirm that the universal hybrid beamformer achieves better array output power and white noise gain than competing beamformers.
Advisor: Dr. John R. Buck, Chancellor Professor, Dept. of Electrical & Computer Engineering, UMass Dartmouth
Committee Members:
Dr. David A. Brown, Professor, Dept. of Electrical & Computer Engineering, UMass Dartmouth
Dr. Paul J. Gendron, Associate Professor, Dept. of Electrical & Computer Engineering, UMass Dartmouth
Dr. Kay Gemba, Naval Postgraduate School
NOTE: All ECE Graduate Students are ENCOURAGED to attend. All interested parties are invited to attend. Open to the public.
*For further information, please contact Dr. John R. Buck at 508.999.9237 or via email at jbuck@umassd.edu
Lester W. Cory Conference Room, Science & Engineering Building (SENG), Room 213A / Zoom Link: https://umassd.zoom.us/j/99344583625 Meeting ID: 993 4458 3625 Passcode: 979444
: 285 Old Westport Road, North Dartmouth, MA - Science & Engineering Building (SENG)
John R Buck
9237
jbuck@umassd.edu
https://umassd.zoom.us/j/99344583625