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The principle and performance of Synthetic Impulse and Antenna Radar(SIAR) are analyzed with the concept of 3D matched filtering. The discussion here is concentrated on the characteristics of SIAR in the case of three dimensions....
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The principle and performance of Synthetic Impulse and Antenna Radar(SIAR) are analyzed with the concept of 3D matched filtering. The discussion here is concentrated on the characteristics of SIAR in the case of three dimensions. The results obtained are helpful for designing this new style radar.
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Timed arrays are the time-domain counterpart of phased arrays, where each array element is excited by wideband instead of narrowband signals. By referring to idealized, but meaningful canonical configurations, the array parameters...
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Timed arrays are the time-domain counterpart of phased arrays, where each array element is excited by wideband instead of narrowband signals. By referring to idealized, but meaningful canonical configurations, the array parameters in the transmit and receive mode are defined in a simple way, by following a purely time-domain intuitive analysis. Obtained results extend steady-state concepts of beamwidth, directivity, gain, effective receiving area, Fresnel and Fraunhofer regions to the case of transient excitation. Application is made to both real and synthetic arrays. The final main conclusion is that the role of the carrier wavelength associated with narrowband excitation is taken by the spatial width of the (carrierless) pulse. This result appears to be rather robust, because it turns out to be independent from the different norms used in the definition of the antenna parameters: it sheds light on the physics of the transient radiation and may be very useful for initiating a more technical analysis of the array performance.
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As research conducted by US State Department, Landmines maim or kill an estimated five hundred people per week worldwide. Direct casualties are not the only problem. The areas of arable land cannot be farmed due to the threat of l...
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As research conducted by US State Department, Landmines maim or kill an estimated five hundred people per week worldwide. Direct casualties are not the only problem. The areas of arable land cannot be farmed due to the threat of landmines. According to the United Nations, in 64 countries around the world, there are an estimated 110 million land mines still actively lodged in the ground. Landmines can be metallic or non-metallic types. The metal detectors can easily detect metallic types, which are buried close to the ground surface, however the ones, which are buried deep in the soil, cannot be detected by the metal detectors. The landmines which are non- metallic types (Plastics, Low metal containing landmines) also has a high probability that metal detector could not discriminate. For metallic types and non- metallic types, the probability of false alarm is very high. In this paper, we propose High Resolution Signal Processing Method using SAR algorithm which is based on migration techniques for the detection and discrimination of antipersonnel landmines using Impulse GPR. The Signal Processing Algorithm makes use of the High resolution GPR data from Landmine Detecting Array Radar (LAMDAR-III) to give the better imaging of the buried object.
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Synthetic impulse and aperture radar (SIAR) is an orthogonal multiple input multiple output radar. It has several advantages, including the ability to detect multiple targets, Antiradiated Missiles (ARM), and stealth targets. Desp...
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Synthetic impulse and aperture radar (SIAR) is an orthogonal multiple input multiple output radar. It has several advantages, including the ability to detect multiple targets, Antiradiated Missiles (ARM), and stealth targets. Despite its four-dimensional (4-D) nature, it exhibits a strong coupling between range and angle, which dictates how well SIAR performs in the range-angle domain. Not only does the SIAR use frequency codes to separate the antennas, but also to ensure orthogonality. They can, however, mitigate the strong coupling between range and angle. Pulse-to-pulse frequency code agility is a technique for suppressing the SIAR radar's sidelobes. In this letter, we propose a method for reducing the coupling between range and angle by combining sequential positive, negative and random code with the dot product. The idea of coupling reduction presented in this letter is based on the ratio of each antenna position and frequency codes, which is referred to $\alpha $k, and multiple $\alpha $k in an array provides new advantages for target detection. This technique has the potential to significantly reduce the sidelobe levels.
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This paper introduces three methodologies to improve synthetic aperture radar (SAR)-based techniques used in ground-penetrating radar (GPR) systems. They consist of: 1) equalization of the frequency response of the transmitting (T...
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This paper introduces three methodologies to improve synthetic aperture radar (SAR)-based techniques used in ground-penetrating radar (GPR) systems. They consist of: 1) equalization of the frequency response of the transmitting (Tx) and receiving (Rx) antennas; 2) processing of SAR images using partially overlapped frequency subbands; and 3) imaging domain clustering. The goal is to combine ground penetration capabilities of lower frequency bands with the resolution achieved when increasing the overall frequency band, resulting in enhanced detection and imaging capabilities. Validation of these techniques has been done at three levels: first using simulations, next by means of measurements in a controlled scenario, and, finally, using a portable setup deployed in a realistic scenario.
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This article proposes a novel synthetic aperture radar visual-inertial odometry (SAR-VIO) consisting of an SAR and an inertial measurement unit (IMU), which aims to enable the observation platform to complete successfully a contin...
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This article proposes a novel synthetic aperture radar visual-inertial odometry (SAR-VIO) consisting of an SAR and an inertial measurement unit (IMU), which aims to enable the observation platform to complete successfully a continuous observation mission in the context of low-cost demand and lack of enough navigation information. First, we establish the observation models of the SAR in a continuous observation process based on the SAR frequency-domain imaging algorithm and the SAR time-domain imaging algorithm, respectively. With the preintegrated IMU data, we then propose a method for estimating the geographic locations of the matched targets in the SAR images and verify the condition and correctness of the method. The optimization of the track and the locations of the targets is achieved by bundle adjustment according to the minimum reprojection error criterion, and a sparse point-cloud map can be obtained. Finally, these methods and models are organized into a complete SAR-VIO framework, and the feasibility of the framework is verified through experiments.
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Imaging a fast maneuvering target has been an active research area in past decades. Usually, an array antenna with multiple elements is implemented to avoid the motion compensations involved in the inverse synthetic aperture radar...
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Imaging a fast maneuvering target has been an active research area in past decades. Usually, an array antenna with multiple elements is implemented to avoid the motion compensations involved in the inverse synthetic aperture radar (ISAR) imaging. Nevertheless, there is a price dilemma due to the high level of hardware complexity compared to complex algorithm implemented in the ISAR imaging system with only one antenna. In this paper, a wideband multiple-input multiple-output (MIMO) radar system with two distributed arrays is proposed to reduce the hardware complexity of the system. Furthermore, the system model, the equivalent array production method and the imaging procedure are presented. As compared with the classical real aperture radar (RAR) imaging system, there is a very important contribution in our method that the lower hardware complexity can be involved in the imaging system since many additive virtual array elements can be obtained. Numerical simulations are provided for testing our system and imaging method.
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In this letter, we propose graph signal processing-based imaging for synthetic aperture radar (SAR). Our method provides improved denoising and resolution enhancing capabilities, along with a reduction in computational complexity,...
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In this letter, we propose graph signal processing-based imaging for synthetic aperture radar (SAR). Our method provides improved denoising and resolution enhancing capabilities, along with a reduction in computational complexity, by exploiting the concept of extended neighborhood in SAR images. We present a modified version of a fused least absolute shrinkage and selection operator (LASSO) to cater for graph structure of the SAR image. It can also accommodate the compressed sensing framework. We solve the optimization problem via the alternating direction method of multipliers. Experimental results on a backhoe target corroborate the validity of our proposed method.
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Jamming of synthetic aperture radar (SAR) is more difficult than the conventional radars because of its high processing gain. The defocusing of fake or virtual scatterers is the main problem that any jamming technique needs to tac...
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Jamming of synthetic aperture radar (SAR) is more difficult than the conventional radars because of its high processing gain. The defocusing of fake or virtual scatterers is the main problem that any jamming technique needs to tackle. An algorithm based on fractional Fourier transform is proposed for the efficient jamming of SAR. The results show that the performance o proposed algorithm is better than conventional Range Doppler Algorithm.
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Monitoring ground deformations arising from groundwater dynamics in dense urban coastal terrains is crucial for the sustainable development of infrastructures in these highly populated areas. The city of Montreal, which is located...
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Monitoring ground deformations arising from groundwater dynamics in dense urban coastal terrains is crucial for the sustainable development of infrastructures in these highly populated areas. The city of Montreal, which is located in the Saint-Laurent plain in eastern Canada, with its fast-growing populations, is a unique case study for other similar cities in coastal terrains. The city undergoes high-level house foundation damages with densities reaching up to 89 repairs/km resulting from time-dependent ground deformations that are correlated to groundwater dynamics and evapotranspiration. Using Radarsat-2 C-Band synthetic aperture radar interferometry, we observe 3- to 5-mm ground line-of-sight displacement variations temporally outphased by few months relative to the 2-m subartesian aquifer hydraulic head variations. The deformations are observed over a 60-km area located in the central part of the Montreal Island in Canada, from 2008 to 2010. We observe displacements of ∼1 mm/year uplift in the areas covered by 15-m-thick clay layer. These displacements are well correlated to the number of house repairs. We also observe ∼2 mm/year subsidence on elevated terrains, associated with evapotranspiration. The amplitudes of the displacements observed during this two-year study are significant when integrated over the average lifetime of urban structures. We conclude that the observed ground deformations are related to the seasonal variation of hydraulic head in most of the areas of Montreal. Moreover, wetter climate forecasts over upcoming decades for this area, will accentuate groundwater level fluctuations; thus, more ground deformations are foreseen, and have to be considered in future infrastructure design standards.
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