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Research on the Key Technology for Aperture Synthesis Microwave Radiometric Imaging System

Author: ChenKe
Tutor: ZhuYaoTing；GuoWei
School: Huazhong University of Science and Technology
Course: Communication and Information System
Keywords: Synthetic Aperture Radiometer Microwave radiation imaging Error model Error correction Image inversion algorithm Regularization Image evaluation Image signal - to - noise ratio
CLC: TP391.41
Type: PhD thesis
Year: 2010
Downloads: 166
Quote: 1
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Abstract

As a new interferometric array microwave radiation imaging system, Synthetic Aperture Radiometer the sparse aperture antenna array synthesis of a large physical observations caliber, reducing the size and weight of the antenna, and can be realized without scanning the entire field of view instantaneous imaging, to better meet the needs of practical applications, has a strong application prospects. However, the stronger restrictions on the ability to bring more. To achieve good imaging performance, synthetic aperture microwave radiometer in practical work need to address the following three key issues: (1) a variety of hardware non-ideal factors system error introduced how to correct? (2) how to solve synthetic aperture brightness temperature image reconstruction high-performance inversion numerical algorithm? (3) how the quantitative assessment of image retrieval algorithm performance and even system overall imaging performance? the three problems layer Progressive: synthetic aperture microwave radiation imaging system ultimate goal is to get a high quality bright temperature image, the judgment of the imaging performance of the system as a whole, need to rely on quantitative assessment of the brightness temperature image quality; from the measurement of the brightness temperature of the high-quality image data reconstruction, we need to achieve high-performance image inversion value algorithm; high-performance anti-algorithm requires accurate data, which must be to gain insight into the characteristics of the system error, system error correction as a precondition. In this paper, three key issues in the Synthetic Aperture Microwave Emission Imaging System solutions and critical theory to conduct research, the main contents are as follows: Firstly, the visibility function as an object, according to the nature of the role of systematic errors in the visibility function, will be divided into system additive error, regardless of the orientation multiplicative error and orientation of the multiplicative error into three categories, the first two proposed correction method using an external reference scenarios and external single secondary source system as a whole, and verified by experiment. The most important feature of this error analysis and correction ideas from the system as a whole, to simplify the overall correction of systematic errors without increasing the hardware complexity. Orientation multiplicative error cause the image reconstruction of synthetic aperture radiation imaging system in mathematics is a sick inverse problem, to get the solution need two elements: (1) the right image inversion numerical algorithm; (2) to obtain the system response matrix G. Radiometer under low SNR, the most common generalized solution will be serious noise pollution thus departing from the true value of solving the problem. To solve this problem, mathematical proposed use of the regularization parameter to find a balance between the true value and noise regularization solving ideas. In this paper, the mathematical model based on the synthetic aperture image reconstruction problem, regularization method used in the mathematical in synthetic aperture brightness temperature image reconstruction problem solving, the regularization image inversion numerical algorithm, and then use an external point source measure the actual system response matrix G, and finally a combination of both, successfully applied to synthetic aperture brightness temperature image reconstruction, the inversion of the brightness temperature of the high-quality image. The sensitivity is the traditional measure of the main indicators of the microwave radiometer measurement accuracy, but is not suitable to evaluate the image quality of the single-frame brightness temperature. This paper presents the image signal-to-noise ratio as the image evaluation indicators set in reference to a uniform background there is a single target scene, the image signal intensity is defined as the target and background brightness temperature, the image noise intensity is defined as the fluctuations of the homogeneous background, background space standard deviation. The image signal-to-noise ratio defined characterization of the spatial statistical properties of the single-frame brightness temperature image, and thus better able to achieve a quantitative assessment of the single frame image. The image signal-to-noise ratio is successfully applied to the synthetic aperture assessment of the test image, the performance of several inversion algorithm were compared, and, in turn, used a posteriori regularization parameter determination, promote regular inversion numerical algorithm research. Synthetic aperture microwave radiation imaging system and its key theoretical and technical more comprehensive description of its three key issues put forward their own solution, and all the theories and solutions are given the results of experimental verification, This is also one of the characteristics of this article. This paper aims to bridge the gap between theory and practical applications of synthetic aperture microwave radiation imaging system, to promote the technology widely used in various fields.

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