October 2008
ECE Graduate Seminar Lecture (WPI Only)
Wednesday, 10/15/2008 2:00 PM-3:00 PM
Atwater Kent Laboratories, AK 108
Title:
An Introduction to Phased Arrays:
The Diffraction Limit
Speaker:
Tom Sikina
Raytheon Integrated Defense Systems (IDS)
Abstract:
Sensors are expanding into many fields today: medicine, communications, radar, remote sensing, satellites, and others. Engineers are learning about the benefits found in expanding the degrees of freedom to include the spatial domain. There they discover some of the marvels and capabilities found in phased array apertures and antennas, sometimes considered an area of magic, in engineering circles. Some of these powerful and insightful subjects include:
1) The diffraction limit: near and far field regions
2) Mutual coupling and the aperture reactive field
3) Imaginary space: part of a phased array engineers
toolbox
4) Polarization diversity and how it is used in systems
5) The array lattice and its design
6) Aperture impedance matching, narrowband and broadband
systems
7) Digital and analogue modeforming techniques
We choose the diffraction limit (1) topic, exploring it from a top-level theoretical viewpoint and in terms of its practical usefulness. The theoretical treatment is brief and focuses on the physical fundamentals. The practical applications are based on straightforward examples that show the effect of the diffraction limit and its practical use in communications and sensor systems. The discussion includes, the diffraction limit, and its effect on the use of the electromagnetic spectrum Antenna near (Fresnel) and far (Fronhoffer) regions in elementary terms Huygens theory: the origin of antenna sidelobes and spherical wave expansion. The basis for the Friis equation, its simplicity. A practical example.
______________
Bio:
Tom Sikina has a 30 year background in antenna design and development, with numerous publications (restricted distribution) and patents. He currently serves on the Raytheon IDS Electronic Design Directorate staff.
_____________
Host: Prof. Ted Clancy
For more information, e-mail ecesec@ece.wpi.edu.
ECE Graduate Seminar Lecture (WPI Only)
Wednesday, 10/22/2008 2:00 PM-3:00 PM
Atwater Kent Laboratories, AK 108
The CRLB in the Presence of False Measurements with Application to Track Detection and Estimation for Low Observable Targets
Speaker:
Yaakov Bar-Shalom
Professor, ECE Department
University of Connecticut
Abstract:
The CRLB is known to to provide the minimum achievable mean-square estimation error. An implicit assumption in it is that there is no "origin uncertainty" in the measurements. The work presented here solves the problem of deriving the CRLB in the presence of false measurements, an unavoidable situation when one deals with "low observable" (LO) targets. This result is illustrated for a passive sonar problem. Another novel aspect of this work is the quantitative utilization of a target feature, namely, the amplitude information (AI). In conventional tracking systems, target amplitude information at the output of the signal processor is used only to declare detections and provide measurements. We show that the AI can be used in the estimation process itself to enhance the performance in the presence of clutter where the target-originated measurements cannot be identied with certainty, i.e., for LO (low SNR) targets. A probabilistic data association based maximum likelihood (ML-PDA) estimator for target motion analysis that uses amplitude information is derived. It is shown that the Fisher Information matrix (FIM) in the case of measurement origin uncertainty is given by the FIM from the perfect-certainty measurement-origin case multiplied by a less-than-unity scalar information reduction factor. The ML-PDA estimation technique has been shown to be ecient (it meets the CRLB) in a passive sonar problem with 6dB SNR in a resolution cell [1,2]. The same methodology can be used for radar acquisition of LO targets, where it is ecient down to 4dB SNR in a cell [3]. REFERENCES [1] Y. Bar-Shalom and X. R. Li, Multitarget-Multisensor Tracking: Principles and Techniques, YBS Publishing, 1995. [2] T. Kirubara jan and Y. Bar-Shalom, "Low Observable Target Motion Analysis Using Amplitude Information", IEEE Trans. Aerosp. Electronic Systems, AES-32(4):1367 1384, Oct. 1996. [3] S. Sivananthan, T. Kirubara jan and Y. Bar-Shalom, "A Radar Power Multiplier Algorithm for Acquisition of LO Ballistic Missiles Using an ESA Radar", IEEE Trans. Aerosp. Electronic Systems, AES-37(2):401418, April 2001.
Bio:
Yaakov Bar-Shalom received his B.S. and M.S. degrees from the Technion, Israel Institute of Technology, in 1963 and 1967 and his Ph.D. degree from Princeton University in 1970, all in electrical engineering. From 1970 to 1976 he was with Systems Control, Inc., Palo Alto, California. Currently he is Board of Trustees Distinguished Professor in the Dept. of Electrical and Computer Engineering and Marianne E. Klewin Professor in Engineering at the University of Connecticut. He is also Director of the ESP (Estimation and Signal Processing) Lab. His current research interests are in estimation theory and target tracking. While he started his career in stochastic control, currently he is out of control, except for the (suboptimal) multivariable (12) control of his sloop "Syrah" (see the cap in picture) when racing her. He has published over 350 papers and book chapters in these areas and in stochastic adaptive control.
He has been elected Fellow of IEEE for "contributions to the theory of stochastic systems and of multi target tracking". He has been consulting to numerous companies and government agencies, and originated the series of Multitarget-Multisensor Tracking short courses offered via UCLA Extension, at Government Laboratories, private companies and overseas.
For more information, e-mail ecesec@ece.wpi.edu.
Powered by the Social Web - Bringing people together through Events, Places, & Common Interests
October 2008
ECE Graduate Seminar Lecture (WPI Only)
Wednesday, 10/15/2008 2:00 PM-3:00 PM
Atwater Kent Laboratories, AK 108
Title:
An Introduction to Phased Arrays:
The Diffraction Limit
Speaker:
Tom Sikina
Raytheon Integrated Defense Systems (IDS)
Abstract:
Sensors are expanding into many fields today: medicine, communications, radar, remote sensing, satellites, and others. Engineers are learning about the benefits found in expanding the degrees of freedom to include the spatial domain. There they discover some of the marvels and capabilities found in phased array apertures and antennas, sometimes considered an area of magic, in engineering circles. Some of these powerful and insightful subjects include:
1) The diffraction limit: near and far field regions
2) Mutual coupling and the aperture reactive field
3) Imaginary space: part of a phased array engineers
toolbox
4) Polarization diversity and how it is used in systems
5) The array lattice and its design
6) Aperture impedance matching, narrowband and broadband
systems
7) Digital and analogue modeforming techniques
We choose the diffraction limit (1) topic, exploring it from a top-level theoretical viewpoint and in terms of its practical usefulness. The theoretical treatment is brief and focuses on the physical fundamentals. The practical applications are based on straightforward examples that show the effect of the diffraction limit and its practical use in communications and sensor systems. The discussion includes, the diffraction limit, and its effect on the use of the electromagnetic spectrum Antenna near (Fresnel) and far (Fronhoffer) regions in elementary terms Huygens theory: the origin of antenna sidelobes and spherical wave expansion. The basis for the Friis equation, its simplicity. A practical example.
______________
Bio:
Tom Sikina has a 30 year background in antenna design and development, with numerous publications (restricted distribution) and patents. He currently serves on the Raytheon IDS Electronic Design Directorate staff.
_____________
Host: Prof. Ted Clancy
For more information, e-mail ecesec@ece.wpi.edu.
ECE Graduate Seminar Lecture (WPI Only)
Wednesday, 10/22/2008 2:00 PM-3:00 PM
Atwater Kent Laboratories, AK 108
The CRLB in the Presence of False Measurements with Application to Track Detection and Estimation for Low Observable Targets
Speaker:
Yaakov Bar-Shalom
Professor, ECE Department
University of Connecticut
Abstract:
The CRLB is known to to provide the minimum achievable mean-square estimation error. An implicit assumption in it is that there is no "origin uncertainty" in the measurements. The work presented here solves the problem of deriving the CRLB in the presence of false measurements, an unavoidable situation when one deals with "low observable" (LO) targets. This result is illustrated for a passive sonar problem. Another novel aspect of this work is the quantitative utilization of a target feature, namely, the amplitude information (AI). In conventional tracking systems, target amplitude information at the output of the signal processor is used only to declare detections and provide measurements. We show that the AI can be used in the estimation process itself to enhance the performance in the presence of clutter where the target-originated measurements cannot be identied with certainty, i.e., for LO (low SNR) targets. A probabilistic data association based maximum likelihood (ML-PDA) estimator for target motion analysis that uses amplitude information is derived. It is shown that the Fisher Information matrix (FIM) in the case of measurement origin uncertainty is given by the FIM from the perfect-certainty measurement-origin case multiplied by a less-than-unity scalar information reduction factor. The ML-PDA estimation technique has been shown to be ecient (it meets the CRLB) in a passive sonar problem with 6dB SNR in a resolution cell [1,2]. The same methodology can be used for radar acquisition of LO targets, where it is ecient down to 4dB SNR in a cell [3]. REFERENCES [1] Y. Bar-Shalom and X. R. Li, Multitarget-Multisensor Tracking: Principles and Techniques, YBS Publishing, 1995. [2] T. Kirubara jan and Y. Bar-Shalom, "Low Observable Target Motion Analysis Using Amplitude Information", IEEE Trans. Aerosp. Electronic Systems, AES-32(4):1367 1384, Oct. 1996. [3] S. Sivananthan, T. Kirubara jan and Y. Bar-Shalom, "A Radar Power Multiplier Algorithm for Acquisition of LO Ballistic Missiles Using an ESA Radar", IEEE Trans. Aerosp. Electronic Systems, AES-37(2):401418, April 2001.
Bio:
Yaakov Bar-Shalom received his B.S. and M.S. degrees from the Technion, Israel Institute of Technology, in 1963 and 1967 and his Ph.D. degree from Princeton University in 1970, all in electrical engineering. From 1970 to 1976 he was with Systems Control, Inc., Palo Alto, California. Currently he is Board of Trustees Distinguished Professor in the Dept. of Electrical and Computer Engineering and Marianne E. Klewin Professor in Engineering at the University of Connecticut. He is also Director of the ESP (Estimation and Signal Processing) Lab. His current research interests are in estimation theory and target tracking. While he started his career in stochastic control, currently he is out of control, except for the (suboptimal) multivariable (12) control of his sloop "Syrah" (see the cap in picture) when racing her. He has published over 350 papers and book chapters in these areas and in stochastic adaptive control.
He has been elected Fellow of IEEE for "contributions to the theory of stochastic systems and of multi target tracking". He has been consulting to numerous companies and government agencies, and originated the series of Multitarget-Multisensor Tracking short courses offered via UCLA Extension, at Government Laboratories, private companies and overseas.
For more information, e-mail ecesec@ece.wpi.edu.
Powered by the Social Web - Bringing people together through Events, Places, & Common Interests