scholarly journals Time-Varying SAR Interference Suppression Based on Delay-Doppler Iterative Decomposition Algorithm

2018 ◽  
Vol 10 (9) ◽  
pp. 1491 ◽  
Author(s):  
Jia Su ◽  
Haihong Tao ◽  
Mingliang Tao ◽  
Jian Xie ◽  
Yuexian Wang ◽  
...  
Keyword(s):  
Wigner Distribution ◽  
Interference Suppression ◽  
Synthesis Method ◽  
Ambiguity Function ◽  
Decomposition Algorithm ◽  
Eigenvalue Decomposition ◽  
Energy Concentration ◽  
Inverse Transformation ◽  
Complex Signals ◽  
Iterative Decomposition

Narrow-band interference (NBI) and Wide-band interference (WBI) are critical issues for synthetic aperture radar (SAR), which degrades the imaging quality severely. Since some complex signals can be modeled as linear frequency modulated (LFM) signals within a short time, LFM-WBI and NBI are mainly discussed in this paper. Due to its excellent energy concentration and useful properties (i.e., auto-terms pass through the origin of Delay-Doppler plane while cross-terms are away from it), a novel nonparametric interference suppression method using Delay-Doppler iterative decomposition algorithm is proposed. This algorithm consists of three stages. First, we present signal synthesis method (SSM) from ambiguity function (AF) and cross ambiguity function (CAF) based on the matrix rearrangement and eigenvalue decomposition. Compared with traditional SSM from Wigner distribution (WD), the proposed SSM can synthesize a signal faster and more accurately. Then, based on unique properties in Delay-Doppler domain, a mask algorithm is applied for interference identification and extraction using Radon and its inverse transformation. Finally, a signal iterative decomposition algorithm (IDA) is utilized to subtract the largest interference from the received signal one by one. After that, a well-focused SAR imagery is obtained by conventional imaging methods. The simulation and measured data results demonstrate that the proposed algorithm not only suppresses interference efficiently but also preserves the useful information as much as possible.

Optical Wigner distribution and ambiguity function for complex signals and images

1988 ◽  
Vol 67 (3) ◽  
pp. 177-179 ◽  
Author(s):  
Yao Li ◽  
George Eichmann ◽  
Michael Conner
Keyword(s):  
Wigner Distribution ◽  
Ambiguity Function ◽  
Complex Signals

scholarly journals МАТЕМАТИЧЕСКОЕ ОПИСАНИЕ ПРОЦЕДУР ПОСТРОЕНИЯ КОГЕРЕНТНЫХ ИЗОБРАЖЕНИЙ ПРИРОДНЫХ СРЕД В ЗОНЕ ФРАУНГОФЕРА МНОГОКАНАЛЬНЫМИ РАДИОТЕХНИЧЕСКИМИ СИСТЕМАМИ

2018 ◽  
pp. 92-97
Author(s):  
Валерий Константинович Волосюк ◽  
Семён Сергеевич Жила ◽  
Эдуард Алексеевич Цернэ ◽  
Александр Иванович Стороженко
Keyword(s):  
Electromagnetic Field ◽  
Fourier Transform ◽  
Spectral Component ◽  
Delta Function ◽  
Resonance Scattering ◽  
Ambiguity Function ◽  
Inverse Transformation ◽  
Basic Operation ◽  
Full Spectrum ◽  
Coherent Image

The structure of the electromagnetic field in the domain of its registration is considered in the case of the solution of problems of remote sensing of the underlying surfaces on the basis of the phenomenological approach. This approach is mainly based on the theory of ray optics and the Huygens-Fresnel principle. It allows to determine the radiated and scattered fields for complex types of surfaces. Analysis of the structure of the electromagnetic field shows that it can be regarded as a mathematical transformation over the true image of the surface. In this case, the basic procedures for the coherent imaging in the far-field Fraunhofer region by multichannel radio-engineering systems should be based on the inverse transformation. For incomplete restoration of the desired image, without the phase and attenuation due to propagation, the basic operation is the inverse Fourier transform on the angular coordinates. The quality of the imaging in the Fraunhofer zone is determined by the ambiguity function. In a simple case of a rectangular receiving domain, ambiguity function has the form of two sinc functions which width is proportional to wavelength, to height of sounding and the linear sizes of receiving domain. If the distance to each point of the surface is known, then it is possible to completely reconstruct the coherent image. In this case, it is necessary to apply sliding short-scale Fourier transform to the received electromagnetic field. Obtained results correspond to the classical theory of resonance scattering. While ambiguity function is constant in the infinite limits of integration for a specific fixed value of the direction, only one spectral component (spatial harmonic) can be extracted from the desired image.  it Is possible to allocate an ever wider range of spatial frequencies with the narrowing of the ambiguity function. In the limit, when the ambiguity function is a delta function, the full spectrum of frequencies of the desired image can be extracted, i.e. this function can be completely restored. If it is not possible to create a system with narrow ambiguity function then the higher-quality coherent image can be obtained by the same receiving domain by scanning or movement in space

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