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Promising techniques have recently been developed for creating nulls in the transmit sidelobes of a radar by using the signal from a nearby auxiliary antenna. In operational settings, the performance of these nulling techniques will be sensitive to electromagnetic scattering from objects in the vicinity of the antennas. This paper presents a theoretical analysis of the impact of environmental and...
Coherent Change Detection (CCD) is the title given to a process used to detect differences between pairs of Synthetic Aperture Radar (SAR) images. In this process, the estimated coherence between a pair of complex SAR images is calculated and used to infer the presence or absence of any changes. Typically, if the estimated coherence is high there is no change whereas low estimated coherence provides...
The spatial autocorrelation of an electric field associated with an electromagnetic wave packet is modified by propagation through the ionosphere. An analytic formula for the autocorrelation is derived based on a linear plasma density profile for the ionosphere and a power-law turbulence spectrum for ionospheric irregularities. This work provides guidance for interpreting the results of radio experiments...
Through-wall radar imaging using ultrawideband signals is of interest for mapping interior room layouts of buildings, for detection of targets concealed within buildings and for determining in-wall structure. In this paper, we present some experimental results that demonstrate the benefits of a multi-look fusion approach for both interior room mapping and concealed target detection. In particular,...
Space-Time Adaptive Processing (STAP) based on matched filter processing in the presence of additive clutter (modeled as colored noise) requires knowledge of the clutter covariance matrix. In practice, this is estimated via the sample covariance matrix using samples from the neighboring range bins around the reference bin. By applying compressive sensing, the number of training samples needed to estimate...
In this paper we introduce a novel non-parametric depth-based method for the target detection problem in noisy environments under nominal signal-to-noise ratios. Specifically, a distributed sensor network comprised of multiple transceivers is considered. Each sensor is able to transmit and receive a single tone; which is passed to a super sensor where the data is formed into a multistatic response...
Conventional Synthetic Aperture Radar (SAR) Coherent Change Detection (CCD) has been found to be of great utility in detecting changes that occur on the ground. The CCD procedure involves performing repeat pass radar collections to form a coherence product, where ground disturbances can induce detectable incoherence. However there is usually a difference in the radar collection geometry which can...
Employing signals of opportunity for synthetic aperture radar (SAR) imaging is the subject of recent research. This paper presents concepts on the collection and processing of WiMAX OFDM waveforms to produce SAR ground images. A radar collection model is presented followed by the signal processing approach based on previously derived OFDM phase history models. Two multi-symbol match filter designs...
We apply a molecule dictionary approach to synthetic aperture radar canonical feature extraction. These canonical features capture physically-relevant scattering geometry as a function of shape type, frequency, aspect, and polarization. The extraction problem is a nonlinear nonconvex optimization that includes model order selection, feature classification, and parameter estimation. Previous work used...
This paper reports on a technique based on the Singularity Expansion Method (SEM) to completely characterize antennas. This technique provides a full model of the Antenna Transfer Function (ATF) in the frequency domain or the Antenna Impulse Response (AIR) in the time domain based on a set of few parameters. However, some limitations are noted in the physical interpretation of these results. Performance...
This paper studies the passive radar imaging system for moving target based on digital video broadcasting (DVB) satellites. Firstly, the 3-dimensional (3-D) imaging model consisting of multiple DVB satellites and multiple receivers is established. After designing the “receiving stop-go” scheme, we derive the echo in a product-form of the wavenumber domain sampling and the velocity mismatch phase....
This paper addresses the problem of the estimation of the rotation motion of a target interested by roll, pitch and yaw. In a previous work it was proved that the exploitation of ISAR data acquired by multiple sensors located with angular separations among them lying on the same plane greatly improves the accuracy of the estimation of the rotation motion component normal to the sensors baseline with...
The radar signatures of automotive targets were measured from 22 to 29 GHz and 76 to 81 GHz inside an anechoic chamber using a vector network analyzer. Radar cross section maps of a sedan, truck, van, pedestrian, motorcycle, and bicycle as a function of effective radar sensor bandwidth, center frequency, and polarization are presented.
In this paper, we present a novel method for imaging of moving targets using bi-static synthetic aperture radar configurations. We present a forward model that maps the two-dimensional reflectivity and velocity of targets to the measured scattered field data. We then introduce a filtered-back-projection type method to reconstruct the reflectivity and use Renyi entropy to determine the two-dimensional...
Waveform design and waveform scheduling are addressed in the context of space time adaptive processing (STAP) for radar. An air-borne radar with an array of sensors is assumed, which interrogates ground based targets. The designed waveform is assumed to be transmitted over one coherent processing interval (CPI). The waveform design and waveform scheduling problems are formulated with a cost function...
In this paper, aiming to solve the problems of vegetation component is overestimated and is not sensitive to directional scattering features with traditional polarimetric SAR decomposition, a new decomposition method using a polarimetric interferometric similarity parameter (PISP) which is calculated from PolInSAR datasets to the scattering decomposition is proposed. The PISP of Building is high,...
The quality of Interferometric phase significantly affects the result of phase unwrapping and even the entire interferometric SAR application. Since traditional space borne interferometric products always contain much noise due to the influence of geometric decorrelation and temporal decorrelation phenomenon, it is necessary to remove the noise from the real interferometric phase. Because of the feature...
Due to limitations in the bandwidth resources, sharing the spectrum across several modalities has become increasingly important. In this paper, we will consider OFDM spectral sharing between radar and wireless communication systems. We will define and compute the importance of each sub-carrier to both the modalities by considering the radar detection performance and channel capacity. We will design...
This paper first describes the impact of wind turbines on air traffic control (ATC) radar based on theoretical modeling and simulation. Real data are collected from operational ATC radar sites surrounded by major wind farms and analyzed to demonstrate features of wind turbine signals. A series of systematic mitigation methods are proposed and implemented for the existing ATC radar to improve the aircraft...
One of the distinguishing feature of a wideband radar is its fine range resolution. Accordingly moving targets observed by such system are prone to migrate during the coherent processing interval. This range walk offers additional information about the target velocity that can be used to alleviate velocity ambiguity. In a former work, we presented a Bayesian algorithm giving a non-ambiguous and sparse...
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