A general synthetic aperture radar (SAR) signal model is derived based on the Maxwells equation, and three numerical simulations are analyzed and discussed. With this signal model, compressive sensing is applied to ge...
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ISBN:
(纸本)9780819495051
A general synthetic aperture radar (SAR) signal model is derived based on the Maxwells equation, and three numerical simulations are analyzed and discussed. With this signal model, compressive sensing is applied to get a better image.
Nonlinear radar exploits the electronic response from a target whose reflected frequencies are different from those transmitted. Reception of frequencies that are not part of the transmitted probe distinguishes the re...
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ISBN:
(纸本)9780819495051
Nonlinear radar exploits the electronic response from a target whose reflected frequencies are different from those transmitted. Reception of frequencies that are not part of the transmitted probe distinguishes the received signal from a linear return produced by clutter and indicates the presence of electronics. Presented in this paper is a type of nonlinear radar that transmits multiple frequencies and listens for a harmonic of these frequencies as well as other frequencies near that harmonic. A laboratory test-bed has been constructed to demonstrate the multitone radar concept. Measurements of nonlinear responses from RF devices probed by multiple tones are reported.
A hybrid-aperture radar system is being developed for passive, GNSS-based sensing and imaging missions. Different from previous work, the real aperture (RA) array has excellent cross-range resolution and electronic sc...
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ISBN:
(纸本)9780819495051
A hybrid-aperture radar system is being developed for passive, GNSS-based sensing and imaging missions. Different from previous work, the real aperture (RA) array has excellent cross-range resolution and electronic scanning capability, and synthetic aperture processing is applied for the dimension along the UAV/aircraft flight path. The hybrid aperture thus provides real-time, combined sensing capability and multiple functions. Multi-level signal synchronization and tracking is used to ensure the signal phase coherency and integrity. The advantages of covert radar sensing and reduced onboard computing complexity of this sensor are being demonstrated through experiments.
The electromagnetic scattering responses of nonlinearly loaded antenna structures excited by single-tone or multi-tone incident fields are considered in the frequency domain by employing a combination of the method-of...
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ISBN:
(纸本)9780819495051
The electromagnetic scattering responses of nonlinearly loaded antenna structures excited by single-tone or multi-tone incident fields are considered in the frequency domain by employing a combination of the method-of-moments and a harmonic balance technique. Subsequently, standoff detection and localization of the scatterers in the presence of a half space is demonstrated with a subspace imaging procedure by exploiting the harmonic scattering responses.
Regular micro and nano radars cannot provide reliable tracking of low altitude low profile aerial targets in urban and mountain areas because of reflection and re-reflections from buildings and terrain. They become vi...
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ISBN:
(纸本)9780819495051
Regular micro and nano radars cannot provide reliable tracking of low altitude low profile aerial targets in urban and mountain areas because of reflection and re-reflections from buildings and terrain. They become visible and vulnerable to guided missiles if positioned on a tower or blimp. Doppler radar cannot distinguish moving cars and small low altitude aerial targets in an urban area. A new concept of pocket size distributed radartechnology based on the application of UAV (Unmanned Air Vehicles), UGV (Unmanned Ground Vehicles) is proposed for tracking of low altitude low profile aerial targets at short and medium distances for protection of stadium, camp, military facility in urban or mountain areas.
An increasingly cluttered electromagnetic environment (EME) is a growing problem for radar systems. This problem is becoming critical as the available frequency spectrum shrinks due to growing wireless communication d...
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ISBN:
(纸本)9780819495051
An increasingly cluttered electromagnetic environment (EME) is a growing problem for radar systems. This problem is becoming critical as the available frequency spectrum shrinks due to growing wireless communication device usage and changing regulations. A possible solution to these problems is cognitive radar, where the cognitive radar learns from the environment and intelligently modifies the transmit waveform. In this paper, a cognitive nonlinear radar processing framework is introduced where the main components of this framework consist of spectrum sensing processing, target detection and classification, and decision making. The emphasis of this paper is to introduce a spectrum sensing processing technique that identifies a transmit-receive frequency pair for nonlinear radar. It will be shown that the proposed technique successfully identifies a transmit-receive frequency pair for nonlinear radar from data collected from the EME.
A unified digital pulse compression processor is introduced as a radar-application-specific-processor (RASP) architecture for the next generation of adaptive radar. Based on traditional pulse compression matched filte...
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ISBN:
(纸本)9780819495051
A unified digital pulse compression processor is introduced as a radar-application-specific-processor (RASP) architecture for the next generation of adaptive radar. Based on traditional pulse compression matched filter and correlation receiver, the processor integrates specific designs to handle waveform diversities, which includes random noise waveforms, as well as digital transceiver self-reconfiguration for adaptive radars. Initial prototype of this processor is implemented with the latest Xilinx FPGA device and tested with an RF spaceborne radar transceiver testbed. Initial validation results show the effectiveness of real-time processing and engineering concepts.
Large-scale, full-wave modeling of multistatic target imaging in a rough ground environment is described. The emulation methodology employs a parallelized three-dimensional "near-field" finite-difference tim...
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ISBN:
(纸本)9780819495051
Large-scale, full-wave modeling of multistatic target imaging in a rough ground environment is described. The emulation methodology employs a parallelized three-dimensional "near-field" finite-difference time-domain algorithm in characterizing the electromagnetic scattering from the ground surface and buried and on-surface targets in the form of landmines and unexploded ordnances;subsequent focusing of the scattered fields into an image is obtained with the time-reversal technique. The emphasis of this study is on investigating the detectability of discrete ground targets in the presence of distributed variable ground clutter as relevant to performance prediction for ultra-wideband forward-looking radar applications.
This paper describes the study of a through-the-wall radar system for three-dimensional (3-D) building imaging, based on computer simulations. Two possible configurations are considered, corresponding to an airborne s...
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ISBN:
(纸本)9780819495051
This paper describes the study of a through-the-wall radar system for three-dimensional (3-D) building imaging, based on computer simulations. Two possible configurations are considered, corresponding to an airborne spotlight and a ground-based strip-map geometry. The paper details all the steps involved in this analysis: creating the computational meshes, calculating the radar signals scattered by the target, forming the radar images, and processing the images for visualization and interpretation. Particular attention is given to the scattering phenomenology and its dependence on the system geometry. The images are created via the backprojection algorithm and further processed using a constant false-alarm rate (CFAR) detector. We discuss methods of 3-D image visualization and interpretation of the results.
This paper investigates the feasibility of using a noise waveform in an ultra-wideband (UWB) radar system for two-dimensional tomographic imaging of a stationary object with a multistatic tomographic geometry. Multipl...
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ISBN:
(纸本)9780819495051
This paper investigates the feasibility of using a noise waveform in an ultra-wideband (UWB) radar system for two-dimensional tomographic imaging of a stationary object with a multistatic tomographic geometry. Multiple UWB transmitters and receivers are positioned along each side of the imaging area. We perform several numerical simulations in time-domain, and the successful imaging of the target is achieved by visual inspection of the formed images.
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