|Organizer: IEEE Toronto, Electromagnetics and Radiation Joint Chapter|
|Title: A Pragmatic Approach to Adaptive Antennas and Space-Time Adaptive Processing (STAP)|
Tapan K. Sarkar
Department of Electrical Engineering and Computer Science
Syracuse University, Syracuse, New York
In the conventional adaptive beamforming methodology typically weights are connected to each one of the antenna element in the array and the processing information is generated over time, as the correlation matrix of the data needs to be formed. Some of the problems associated with this procedure is that because of the formation of the covariance matrix and evaluation of its inverse it is difficult to carry it out in real time and its inverse may be comput- tationally unstable if the signal to noise ratio is large. It is difficult to handle coherent multipaths in this methodology unless some additional processing is carried out. This talk will present a novel methodology utilizing the direct data domain approach based on the spatial samples for the efficient computation of the adaptive weights in a phased array system. In this approach, the adaptive analysis is done on a snapshot-by-snapshot basis and therefore nonstationary environments can be handeled quite easily including coherent multipath environment. This is in contrast to conventional adaptive techniques where processing is done by taking the time averages as opposed to spatial averages. This approach is unlike the conventional statistical based techniques by eliminating the requirement of an interference covariance matrix and represents a rethinking of the entire conventional approach to adaptive processing. This approach provides greater flexibility in solving a wider class of problems at the expense of a slightly reduced number of degrees of freedom. Also in most adaptive processing the assumption that the target signal is coming from an exactly known direction will probably never be met in any real array. Or the adaptive array may be surveyed into location with small errors and thus the angle to the transmitter from the broadside of the array will be in error. Other applications of adaptive arrays will also have at least small errors in the direction of arrival of the desired signal. This talk will present methodologies to treat this signal cancellation problem through the main beam constraints. Example will be presented to illustrate the applicability of this methodology to a wide class of problems. Finally, it will be shown as how to extend this methodology to two-dimension, namely space-time adaptive processing (STAP). Example will be presented to illustrate the detection of a saberliner tracked by an airborne forward looking radar in the presence of land, urban and sea-clutter.
TAPAN KUMAR SARKAR received the B. Tech. degree from the Indian Institute of Technology, Kharagpur, India, in 1969, the M.Sc.E. degree from the University of New Brunswick, Fredericton, Canada, in 1971, and the M.S. and Ph.D. degrees from Syracuse University; Syracuse, New York in 1975. From 1975 to 1976 he was with the TACO Division of the General Instruments Corporation. He was with the Rochester Institute of Technology, Rochester, NY, from 1976 to 1985. He was a Research Fellow at the Gordon McKay Laboratory, Harvard University, Cambridge, MA, from 1977 to 1978. He is now a Professor in the Department of Electrical and Computer Engineering, Syracuse University; Syracuse, NY. His current research interests deal with numerical solutions of operator equations arising in electromagnetics and signal processing with application to system design. He obtained one of the "best solution" awards in May 1977 at the Rome Air Development Center (RADC) Spectral Estimation Workshop. He has authored or coauthored more than 210 journal articles and numerous conference papers and has written chapters 28 books and ten books including the latest one "Iterative and Self Adaptive Finite-Elements in Electromagnetic Modeling" which was published in 1998 by Artech House. Dr. Sarkar is a registered professional engineer in the State of New York. He received the Best Paper Award of the IEEE Transactions on Electromagnetic Compatibility in 1979 and in the 1997 National Radar Conference. He received the College of Engineering Research Award in 1996 and the chancellor's citation for excellence in research in 1998 at Syracuse University. He was an Associate Editor for feature articles of the IEEE Antennas and Propagation Society Newsletter, and he was the Technical Program Chairman for the 1988 IEEE Antennas and Propagation Society International Symposium and URSI Radio Science Meeting. He is on the editorial board of Journal of Electromagnetic Waves and Applications. He has been appointed U.S. Research Council Representative to many URSI General Assemblies. He was the Chairman of the Intercommission Working Group of International URSI on Time Domain Metrology (1990-1996). Dr. Sarkar is a member of Sigma Xi and International Union of Radio Science Commissions A and B. He received the title Docteur Honoris Causa from Universite Blaise Pascal, Clermont Ferrand, France in 1998.
|Time and Location: |
Monday, March 27th 2000,at 4:30 pm
Rosebrugh Building. Room RS208
University of Toronto, 4 Taddle Creek Rd.
The Institute of Electrical and Electronics Engineers,
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