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Topic: Inverse Synthetic aperture radar

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	Radar - Printer-friendly - MSN Encarta
		Synthetic aperture radar and phased-array radar have special ways of positioning and pointing the antennas that improve resolution and accuracy.
		Simple pulse radar requires precise timing circuits in the duplexer to prevent the transmitter from transmitting while the receiver is acquiring a signal from the antenna, and to keep the receiver from trying to read a signal from the antenna while the transmitter is operating.
		Continuous wave radar systems are excellent at measuring the speed and direction of an object, but they are not as accurate as pulse radar at measuring an object’s position.
	encarta.msn.com /text_761569568___47/Radar.html (771 words)

	Inverse Synthetic Aperture Imaging Radar
		ISAR images are produced by rotating the target and processing the resultant doppler histories of the scattering centers.3 If the target rotates in azimuth at a constant rate through a small angle, scatters will be approaching or receding from the radar at a rate depending only on the cross range position.
		This occurs when the synthetic aperture to the target range is less than required by the 2D2/lambda limit where D id the required lateral extent of the target.
		A technique for transforming radar data acquired at a given location in space to another location in space (i.e., the form the near-field to the far-field) is to form a fully focused ISAR image of the target region and then use that image as a target model.
	www.nearfield.com /amta/amta85ds.htm (3740 words)

	RADAR and SAR Glossary (Site not responding. Last check: 2007-10-29)
		A mode of radar polarisation where the microwaves of the electric field are oriented in the horizontal plane for both signal transmission and reception by means of a radar antenna.
		A mode of radar polarisation where the microwaves of the electric field are oriented in the horizontal plane for signal transmission, and where the vertically polarised electric field of the backscattered energy is received by the radar antenna.
		In radar remote sensing the main function of the antenna is to concentrate a radiated microwave energy into a beam of required shape, referred to as the antenna pattern, to transmit it into the desired direction (look direction), and to receive the returned energy from surfaces or objects.
	envisat.esa.int /dataproducts/asar/CNTR5-2.htm (6587 words)

	Time-Frequency/Time-Scale Analysis for Radar Applications
		Radar transmits electromagnetic waves to a target which consists of a number of point scatterers and receives the scattered waves from the target.
		Traditionally, SAR refers to the situation where the radar is moving and the target is stationary; ISAR refers to the geometrical inverse in which the target is moving and the radar is stationary.
		For ISAR, the synthetic aperture is formed by coherently combining signals obtained from a single aperture as it observes a rotating target.
	airborne.nrl.navy.mil /~vchen/tftsa.html (1663 words)

	NRL - Polar Reformatting for ISAR Imaging
		Inverse synthetic aperture radar (ISAR) is a radar imaging technique that uses target motion to achieve the Doppler discrimination that is needed to form a 2-D image.
		The difference between tomographic reconstruction using radar signals and traditional tomographic reconstruction is that the radar's signal is modulated by the carrier frequency of the radar.
		As a result, the Fourier transform of the radar's pulse produces a line segment in 3-D Fourier space that is offset from the origin by the carrier frequency at an angle determined by the angle of the radar line of sight.
	www.nrl.navy.mil /content.php?P=02REVIEW124 (445 words)

	Synthetic Aperture Radar - Best of Radio and Optical Sensing
		The Canada Centre for Remote Sensing (CCRS) is working to develop operational applications for Synthetic Aperture Radar (SAR), such as crop monitoring (top left), species differentiation for forestry (top right), ice and navigation mapping (bottom left) and prospective areas for mining operations (bottom right).
		Just as an optical microscopist has difficulty resolving an object that is smaller than the wavelength of illuminating light, radar is inhibited by the size of the emitting antenna.
		Inverse SAR is a completely new field where an antenna passively listens for reflected radiometric energy.
	www.spie.org /web/oer/march/mar99/cover.html (1551 words)

	Arlen D. Schmidt's Oral Defense Announcement (Site not responding. Last check: 2007-10-29)
		Inverse Synthetic Aperture Radar (ISAR) is a technique for forming high-resolution images by utilizing the information inherent in the differential target Doppler that results from rotation of an object (the target) relative to the radar.
		In the past, satellite-imaging radar has primarily used microwave frequencies in order to provide high resolution with a relatively small synthetic aperture.
		In this work, the defocusing effect of the ionosphere is fully mitigated by using the radar data in conjunction with image focus quality metrics to estimate the Total Electron Content (TEC) and to then remove the ionospheric dispersion from the radar data.
	nova.stanford.edu /starlab_web_20030912/orals/98.11.11_ArlenSchmidt.html (358 words)

	International Ice Patrol (Site not responding. Last check: 2007-10-29)
		Radar shadows (an area of no radar return on the far range side of the target) indicate that a target is relatively tall and therefore more likely to be an iceberg.
		The high antenna-scan rate, the radar pulse frequency and duration, and sophisticated data processing permit reduction in sea clutter and an amplification of small target return.
		Imaging mode: The ISAR is a synthetic aperture radar mode that takes advantage of target motion relative to the antenna.
	www.uscg.mil /lantarea/iip/FAQ/ReconnOp_10.shtml (1859 words)

	DSTO > Publications > ISARLAB - Inverse Synthetic Aperture Radar Simulation and Processing Tool
		Inverse Synthetic Aperture Radar (ISAR) imaging is a relatively mature technique for generating 2-dimensional high resolution maps or images of target scattering.
		This leads to the challenge of training radar operators to understand the images acquired by the radar and subsequently, to be able to interpret them sufficiently to perform the classification task.
		This will be the first radar in the Australian Defence Force (ADF) inventory to incorporate a high resolution imaging capability, which means that training of radar operators in the effective use of this new technology is a significant issue.
	www.dsto.defence.gov.au /publications/2138 (751 words)

	Radar Glossary
		Inverse SAR (ISAR) is a variation on the SAR theme that uses the motion of the target relative to the radar to the same effect.
		Pulse-compression radars make use of specific signal processing techniques to provide most of the advantages of extremely narrow pulses widths whilst remaining within the peak power limitations of the transmitter.
		(RHI) is a radar display that represents the height of the target on the vertical axis, and uses the horizontal axis of the RHI to represent the target range.
	www.argospress.com /Resources/radar (1368 words)

	Selected Publications
		A simplified version is "Microlocal structure of high range-resolution inverse synthetic-aperture radar data", M. Cheney and B. Borden, in Wave Propagation, Scattering and Emission in Complex Media, ed.
		"Synthetic Aperture Inversion for Arbitrary Flight Paths and Non-Flat Topography", C.J. Nolan and M. Cheney, IEEE Trans.
		"Synthetic Aperture Inversion for Non-Flat Topography", C.J. Nolan and M. Cheney, Proceedings, 4th European Conference on Synthetic Aperture Radar (EUSAR2002), 4-6 June 2002, Cologne, Germany, VDE Verlag GMBH, Berlin, 2002.
	www.rpi.edu /~cheney/downloads.html (674 words)

	[No title] (Site not responding. Last check: 2007-10-29)
		ISAR images may be obtained by coherently processing the received target echoes of wide bandwidth transmitted pulses.
		This technique is typically applied to a stationary monostatic radar configuration observing a moving target, and relies on the target's rotation to form the synthetic aperture.
		ISAR imaging techniques have been extensively employed over the last few years in improving target classification algorithms, specifically those attempting to identify ship, airborne, and orbiting targets.
	peipa.essex.ac.uk /conf/Information/inversesar-5-05-call.html (249 words)

	Radars (RAD1) (Site not responding. Last check: 2007-10-29)
		The inverse synthetic aperture radar (ISAR) technique provides images of a satellite orbiting at a distance above 500 miles with a resolution above one meter.
		A radar sends a pulse of radio waves along a very narrow beam and measures the time lapse between the emission and the reception of the echo reflected by a target.
		The screen of a classical radar displays the intensity of the echo as a function of the distance for several orientations of the antenna (which generally scans along the horizon).
	www.onera.fr /cahierdelabo/english/rad1.htm (155 words)

	Inverse Synthetic Aperture Radar (Site not responding. Last check: 2007-10-29)
		Inverse Synthetic Aperture Radar (ISAR) is a well-establish technique to identify the reflectivity centers of the target with high spatial resolution.
		Fine two-dimensional reflectivity map of the target is generated by using large bandwidth transmitted signal, to have high range resolution, and by coherently processing the echoes received from different aspect angles of the target, to achieve fine cross-range resolution.
		Berizzi, G.Corsini, E. Dalle Mese, "An application of the Wigner-Ville distribution for the initialisation of ISAR image autofocusing techniques", in Proceedings of the Quartozième Colloque sur le Traitement du Signal et des Images, Juan Les Pins (France), 16 September 1993, Vol.2, pp.
	www.ing.unipi.it /~d7952/GRUPPO/ISAR.html (469 words)

	NRL Radar Division -- Inverse Synthetic ISAR (ISAR) Imaging (Site not responding. Last check: 2007-10-29)
		The ISAR Section of the Radar Analysis Branch works on developing advanced algorithms and processing systems for the radar imaging technique known as Inverse Synthetic Aperture Radar (ISAR) which is related to the better known SAR technique.
		The ISAR image is a two dimensional representation of the target, with the resolution in the horizontal dimension determined by the short pulse characteristic of the radar and the vertical dimension by the Doppler of the radar returns.
		The received radar pulse is a projection of all scatterers perpendicular to the line-of-sight of the radar and the Fourier transform of the pulse represents a line segment in 3-D Fourier space, which sweeps out a data surface as the aspect of the target changes (see below).
	radar-www.nrl.navy.mil /Areas/ISAR (505 words)

	Ultrawideband Random Noise ISAR (Site not responding. Last check: 2007-10-29)
		ISAR turntable experiments are being conducted at the Environmental Remote Sensing Laboratory of the University of Nebraska-Lincoln.
		Targets are places on the turntable, rotated at a known rate, and data are collected at a fixed range for a full 360 degree rotation.
		The radar operates in the 1-2 GHz frequency range.
	doppler.unl.edu /~dbell/isar.htm (267 words)

	CJSEW Research (Site not responding. Last check: 2007-10-29)
		The purpose of this research is to develop, implement, and test superresolution algorithms for synthetic aperture radar (SAR) and inverse synthetic aperture radar (ISAR).
		In normal radar cross-range resolution is proportional to real antenna beam width and range to the spot to be mapped.
		The factors which ultimately limit the cross-range resolution are such as frequency and phase stability of the radar equipment, errors caused by propagation of electromagnetic waves through the atmosphere, quadratic and higher order errors caused by motion, and the limited accuracy of motion compensation.
	www.nps.navy.mil /cjsew/projects/ewresrhc.html (338 words)

	Fundamentals of Radar Systems (Site not responding. Last check: 2007-10-29)
		This is a five-day teaching course which aims to cover the fundamental principles of radar systems (particularly coherent radar) in enough detail to show the significance and interrelation of system parameters throughout the radar, and provide a base from which more advanced design work can be undertaken.
		Synthetic & Inverse synthetic aperture radar (SAR & ISAR)
		The course is intended for engineers involved in the design, specification or operation of radar systems, and should broaden their knowledge beyond their primary design expertise.
	www.cee.hw.ac.uk /short-courses/courses/radar.html (279 words)

	Time-Frequency Transforms for Radar Imaging and Signal Analysis (Site not responding. Last check: 2007-10-29)
		It teaches you more efficient ways to extract dispersive scattering features; detect and extract weak signals in noise; form clear radar images; estimate parameters and perform motion compensation; detect and track moving targets in the synthetic aperture radar; and analyze vibration and rotation induced micro-Doppler.
		Moreover, the authors discuss future trends in time-frequency to analyze micro-Doppler, and provide you with a newly developed time-frequency approach to radar signal and image processing to help you solve problems associated with conventional approaches.
		Synthetic Aperture Radar Imaging of Moving Target – Radar Signatures of Moving Targets.
	www.scitechpub.com /Chen_Time_Freq.htm (375 words)

	Four Practical Applications of Joint Time-Frequency Analysis - Tutorial - Development Library - National Instruments
		Inverse synthetic aperture radar (ISAR) is an imaging radar that uses the target’s pitch, roll and yaw motions to generate an image in the range-Doppler plane.
		Note, that the only difference between the new and traditional ISAR systems is that the Doppler frequencies in the proposed ISAR are computed by the joint time-frequency transform rather than by DFT.
		While the DFT-based ISAR image is blurred due to the fast rotation of the aircraft, a clear aircraft image is observed from the JTFT-based ISAR.
	zone.ni.com /devzone/conceptd.nsf/webmain/BD7D314EE0E3B87086256866005A7D66?opendocument (3088 words)

	Radar - MSN Encarta
		Great books about your topic, Radar, selected by Encarta editors
		Introduction; How Radar Works; Types of Radar; Radar Applications; History
		Should students shun their favorite schools to save money?
	encarta.msn.com /encyclopedia_761569568_4/Radar.html (680 words)

	NRL Press Release
		Among the many new radar technology developments accomplished by NRL's Radar Division under Dr. Skolnik's supervision was the first successful development of HF over-the-horizon radar for the U.S. Navy and Air Force; new concepts for shipboard air-surveillance radar including the ECCM-capable radar called "Senrad;" the introduction of the AN/SPS-49 air-surveillance radar into the fleet;
		Skolnik is known to the world-wide radar community as the author of the highly popular text Introduction to Radar Systems and as editor of the Radar Handbook.
		In addition to radar, he was involved in these organizations with ballistic missile defense, electronic warfare, proximity fuzes, and phased array radar including self-focusing array antennas.
	www.nrl.navy.mil /pao/pressRelease.php?Y=2000&R=18-00r (310 words)

	CASR DND 101 [Synthetic Aperture Radar - Page 2] (Site not responding. Last check: 2007-10-29)
		For military use, radar is too heavy, too power-hungry, and just too useful to restrict to a single application.
		The answer was an inverse synthetic aperture radar which used the Doppler shift of moving vessels to create images instead of trying to filter out these distortions.
		A planar array allows the radar beam to be shaped and steered (at least in part) electronically with ease which, in turn, simplifies changing modes.
	www.sfu.ca /casr/101-cp140sar2.htm (397 words)

	Air and Spaceborne Radar Systems: An Introduction (Site not responding. Last check: 2007-10-29)
		The book examines radar's role within the system when carrying out is assigned missions, showing the possibilities of radar as well as its limitations.
		The authors review the current state of the main types of airborne and spaceborne radar systems, designed for specific missions as well as for the global environment of their host aircraft or satellites.
		Air and Spaceborne Radar Systems is a practical tool on radar systems that will be of major help to technicians, student engineers and engineers working in industry and in radar research and development.
	www.chipsbooks.com /airspace.htm (281 words)

	CASR DND 101 [Synthetic Aperture Radar - Page 1] (Site not responding. Last check: 2007-10-29)
		Radar imaging comes down to resolution and here radar runs into a physical limitation.
		Resolution is dictated by the width of the radiating beam – the narrower the beam, the finer the resolution.
		Producing a high-resolution radar image requires an antenna of gargantuan proportions – or so it seemed before the dawn of the current computer age.
	www.sfu.ca /casr/101-cp140sar1.htm (304 words)

	Radar Sensor Technology II (Site not responding. Last check: 2007-10-29)
		Radar research and development investments are increasingly being directed into dual-use and purely commercial application areas, in addition to traditional defense oriented programs.
		Of particular interest is the leveraging of military radar applications into civil/commercial applications.
		Another is to provide a forum for both researchers and system designers to provide visibility to the marketplace for their developments, experimental, and theoretical results that might be of broad interest to the general application developers.
	www.spie.org /web/meetings/calls/or97/or21.html (132 words)

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