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This paper describes three different continuous wave (CW) radar waveforms which are applied in automotive radar sensors. The radar sensor should be able to detect all objects inside the observation area and to estimate range, radial velocity and azimuth angle simultaneously even in multi target situations. A classical Linear Frequency Modulation (LFM) waveform provides a very high range and velocity...
Helicopters are essential for any mission of humanitarian or assisting nature in disaster areas. Very often they have to cope with missing infrastructure and extreme environmental conditions. Besides darkness and adverse weather, dust and snow are two of the most dangerous conditions for helicopter landing. At the time being, helicopter pilots have no adequate sensors to get information on height...
A MIMO radar system with M transmitters and N receivers is used for target identification of unknown non-cooperative radar targets. The radar system is assumed wideband with sufficient bandwidth to obtain a target impulse response that shows significant scattering mechanisms and correlates well with the geometry of the target. Contributions in this paper are threefold: First, target identification...
Based on nonuniform L-shaped array, the paper presents a new time-space processing method for joint estimation of the frequency and 2D arrival angles of coherent signals over a wide frequency band, which is called wide-band time-space smoothing (WTSS) algorithm. The algorithm can precisely estimate 3D parameters of coherent signals with same digital frequency. Getting rid of the costly multidimensional...
Synthetic aperture radar (SAR) is active and coherent microwave high resolution imaging system, which has the capability to image in all weather and day-night conditions. SAR transmits chirp signals and the received echoes are sampled into In-phase (I) and Quadrature (Q) components, generally referred to as raw SAR data. Raw data compression is an essential future requirement for high resolution space...
Current weather radar surveillance networks are based upon conventional sensing paradigm of widely-separated, standalone sensing systems using long range radars that operate at wavelengths in 5-10 cm range. Such configuration has limited capability to observe close to the surface of the earth because of the earthpsilas curvature but also has poorer resolution at far ranges. The center for Collaborative...
In this paper, ground penetrating radar and tomography are combined to detect and identify hidden targets, such as underground facilities and hard and deeply buried targets. Past experience in below-ground imaging is described, current measurement results are presented, and future plans are discussed.
This paper presents a novel fusion technique for automatic target recognition from high range resolution radar profiles when observations from multiple viewpoints are available. The fusion technique entails only a straightforward modification of the transition probabilities of a single-viewpoint target model in which a Hidden Markov Model is used to represent the unknown target orientation. Evaluations...
Cross-correlation based image subtraction for detection of targets within an urban structure from synthetic aperture radar images is presented. In surveillance operations requiring re-imaging of the same scene, small displacements in array element locations may cause large phase and amplitude offsets. Subsequently, clutter will not cancel out, but will rather persist when subtracting two images, one...
For composite hypothesis testing, the generalized likelihood ratio test (GLRT) and the Bayesian approach are two widely used methods. This paper investigates the two methods for signal detection of a known waveform and unknown amplitude with distributed sensors. It is first proved that the performance of the GLRT can be poor. Secondly, a direct way of improving the GLRT is proposed. Thirdly, an approximate...
A stylized compressed sensing radar is proposed in which the time-frequency plane is discretized into an N by N grid. Assuming that the number of targets K is small (i.e. KLtN2), then we can transmit a sufficiently ldquoincoherentrdquo pulse and employ the techniques of compressed sensing to reconstruct the target scene. A theoretical upper bound on the sparsity K is presented. Numerical simulations...
The integration of current traffic monitoring operational systems in the field of maritime surveillance is widely acknowledged as a key requirement for borders control and illegal trafficking prevention. In this paper, an overview of the satellite-extended-vessel traffic service (SEV) system for in-situ and earth observation (EO) data association is presented. The description of the cognitive data...
In a world, where terrorism is threatening human life in particular that of those forces and civilian personnel who are involved in peace keeping and peace enforcing missions, the defence against snipers is a necessary safety demand. For this purpose sensor systems based upon various principles are in use and still under development. Among those acoustic and electro optical sensors are the most common...
The fractal geometry proved to be the most appropriate mathematical instrument in describing natural scenes, by means of few effective and reliable geophysical parameters. In this paper we describe a complete processing chain for the retrieving of SAR image fractal parameters and for change detection purposes. We present an overall framework employing fractal based models, algorithms and tools to...
In recent work we introduced the notion of diversity in distributed radar systems and we evaluated the diversity order of fully distributed networks. Our long-term goal is to analyze the trade-off between distributed detection and detection using co-located antennas. In this paper, we extend our earlier analysis and we evaluate the diversity of joint detection for symmetric noise-limited systems....
The SAR Polarimetry represents an active area of research in Radar Remote Sensing. This interest is clearly supported by the fact that nowadays there exists a non negligible quantity of launched Polarimetric SAR Spaceborne sensors. The aim of this communication is to present the current state of the art in SAR Polarimetry ranging from theory to applications, with special emphasis in the analysis of...
In this paper we describe a joint waveform design methodology for distributed imaging RADARs using the concepts of compressive sensing. Compressive sensing is an active area of research that offers the promise of good object reconstruction with a sparse measurement set. The measurement set of the scene is based on a set of dasiaprobes,psila the radar waveforms. The set of measurements must satisfy...
Antenna beam pointing accuracy and stability are key issues for obtaining reliable and high quality remote sensing data in space-borne SAR sensors. A wide set of causes, related to technological aspects and environmental conditions acting at both bus and payload level, contribute to misalign the actual antenna bore sight from the theoretical direction. Even very small error angles on the yaw, pitch...
When an unknown target emits a radio signal, its position can be localized by a network of sensors (or radar receivers) using the time difference of arrival (TDOA) information. In this paper, we consider the maximum likelihood formulation of this target localization problem and provide efficient convex relaxations for this nonconvex optimization problem. In addition, we propose a robust target localization...
Active phased array antennas in state of art radars, adopt many high power amplifiers. High power transmit-receive modules are assembled in dense electronic environments and they have to cope with severe environmental operative condition. Radar state of art systemic signal processing requires growing and enormous power calculation in order to obtain unprecedented hard real-time performances as well...
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