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Back to the ’90’s: A Fresh Look at Positive Time-Frequency Distributions

Jim Pitton


The 1990’s were a very dynamic period for time-frequency analysis. Following rapid progress in new time-frequency methods during the ’80’s, the ’90’s saw the introduction of a range of adaptive techniques. These methods include signal-adaptive time-frequency representations that provide improved signal analysis tools, and adaptive decompositions that give sparse representations of signals using over-complete dictionaries of basis functions. These methods have in common being solved by constrained optimization, a lesson of the ’80’s being that fixed analysis methods could not provide satisfactory representations of nonstationary signals. Of these methods, positive time-frequency distributions arguably provide the highest quality representation of the time-varying energy of a signal. This talk will review the development of positive TFDs, and present recent work that links TFDs to adaptive decomposition methods.


Dr. Pitton is a Principal Engineer at the Applied Physics Laboratory, University of Washington (APL-UW) and an affiliate assistant professor with the Department of Electrical Engineering. From 2007 until 2010, he was the Associate Director for Ocean and Undersea Science at the US Office of Naval Research Global (ONRG) in London, UK. Prior to joining ONRG, Dr. Pitton was the Head of the Environmental and Information Systems Department at APL-UW from 2002 until 2007. Dr. Pitton received his Ph.D. in Electrical Engineering from the University of Washington in Seattle in 1994, and his B.S.E. and M.S.E. in Electrical Engineering from the University of Michigan in Ann Arbor in 1985 and 1986, respectively. From 1986 to 1989, he was a Member of Technical Staff with the Signal Processing Division of The Analytic Sciences Corporation in Reston, VA, where he worked in communications systems analysis. Following completion of his Ph.D., he was with the Speech Research Dept. of AT&T Bell Laboratories in Murray Hill, NJ, where he worked on signal processing front ends for speech recognition systems, with a special focus on time-frequency representations. From 1996 through 1999, he was a Research Scientist with the Statistical Sciences Division of MathSoft in Seattle, WA. He was Registration Chair at IEEE ICASSP’98, the International Conference on Acoustics, Speech, and Signal Processing, in Seattle. His ongoing research interests include statistical signal processing (sonar, automatic classification, nonstationary signal processing, array processing), digital communications (blind demodulation, modulation classification), and auditory science and psychoacoustics.

Jim Pitton Headshot
Jim Pitton
Applied Physics Lab (University of Washington)
EEB 105
8 Mar 2011, 10:30am until 11:30am