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ECE Colloquium Series – Professor John Buck
November 16, 2017 @ 4:00 pm - 5:30 pm
As part of the *Eleanore Hale Wilson Lecture Series, ECE is proud to present:
Estimating the Spatial Spectra of Gaussian Processes with Co-Prime Sensor Arrays
Professor John Buck
University of Massachusetts, Dartmouth
Host: Professor Jarvis Haupt
A co-prime sensor array (CSA) is a nonuniform line array formed by interleaving two undersampled uniform line arrays (ULAs). The CSA requires fewer sensors to span the same aperture as a densely sampled ULA. Consequently, the CSA matches the resolution of the ULA for direction of arrival estimation for narrowband plane waves. However, each CSA subarray array suffers from aliasing, or grating lobes, due to the spatial undersampling. Vaidyanathan and Pal (2011) proved that if the undersampling factors for the uniform subarrays are co-prime, sharing no common factors greater than one, the aliasing can be resolved by multiplying the spatial spectra of the subarrays. This product spatial spectra is the spatial cross-spectral density between the arrays, and is an estimate of the spatial power spectral density (PSD). In this talk, we extend the classic results of Jenkins and Watts (1968) on the periodogram PSD estimator for Gaussian processes to obtain results for the bias, variance and covariance for the CSA product spectra. Additionally, we demonstrate that the CSA’s product PSD estimate is not necessarily positive definite (Adhikari & Buck, 2017). Consequently, the CSA product spectrum may fail to detect weak signals in the presence of strong interferers. We propose an alternative approach for resolving the aliasing ambiguity: choosing the minimum of the two subarray periodograms at each bearing. The resulting nonlinear spectral estimator performs better than the product estimator at detecting weak signals in the presence of loud interferers, and guarantees a positive definite power spectrum (Liu & Buck, Asilomar, 2015). The results in this talk are the fruit of collaborations with Dr. Kaushallya Adhikari and Mr. Yang Liu. [Work supported by the ONR Basic Research Challenge Program]
John R. Buck received his Ph.D. from the MIT/WHOI Joint Program in Oceanographic and Electrical Engineering in 1996. He joined the faculty of UMass Dartmouth later that year, and is presently a Professor in the ECE Dept. He is a past recipient of the UMass Manning Prize for Excellence in Teaching (2016), the IEEE Education Society’s Mac Van Valkenburg Early Career Teaching Award (2005), the UMass Dartmouth Faculty Federation Leo M. Sullivan Teacher of the Year Award (2008), the ONR Young Investigator Award (2000) and the NSF CAREER award (1998). He is a Fellow of the Acoustical Society of America, three time chair of the IEEE Underwater Acoustic Signal Processing Workshop, and a former Associate Editor for the IEEE Journal of Oceanic Engineering. He spent 2003-2004 as a Fulbright Senior Scholar at the Australian Defense Science and Technology Organisation and Sydney University, and has also held visiting appointments at the University of Illinois at Urbana-Champaign, the University of New South Wales, George Mason University, Brown University and the Woods Hole Oceanographic Institution. His research interests include array processing, underwater acoustics, animal bioacoustics and engineering pedagogy.
*Established in 2009, the Eleanore Hale Wilson Fund supports engineering field leaders for travel to Minnesota to share their expertise and discoveries with University of Minnesota graduate students, faculty, and alumni. The fund also supports the receptions held in honor of each speaker.