摘要
有源定标器可以在不改变设备体积的情况下，通过调节内部放大器增益来获得较大的雷达截面积，但有源定标器定标精度受信杂比以及不同极化通道间信号干扰的影响，传统的解决方法给定标场选择和定标设备研制带来困难。为此，本文进行了编码定标技术的研究。
本文首先介绍了SAR定标基本原理，包括辐射定标基本概念，有源定标器原理和系统组成，分析了背景杂波对辐射定标测量精度的影响。在此基础上提出了编码定标技术，给出了信号处理流程，从编码方法和解码方法两方面研究了编码定标技术。在对编码方法的研究中，提出了码字选择原则，分析了所选码字特性，分析了编码性能和对背景杂波的抑制效果；在对解码方法的研究中，结合传统SAR信号处理提出了同步提取方法，分析了各种误差源对同步提取准确性的影响。在单通道SAR编码定标技术的基础上，提出了极化有源定标器编码技术，提出了码字选择原则，分析了所选码的特性，推导了编码定标技术对极化通道间信号干扰抑制的机理。
为了验证编码定标技术的可行性，本文进行了计算机仿真实验。实验结果表明，编码定标技术可以大大抑制背景杂波和通道间信号干扰，在相同信杂比以及相同极化隔离度情况下，采用本文提出的编码定标技术均可获得比传统有源定标更高的定标精度，大大降低定标场选择和定标器制造难度。
The active radar calibrator can achieve high RCS by adjusting the gain of inner amplifier, while the size of the equipment remains the same. However, the precession of calibration is affected by the signals of background. And on the polarimetric situation, the precession is also affected by the signals of other polarimetric channels. The classical solution causes difficulties in selection of calibration filed and implementation of calibrator. To solve this problem, this paper prescribes the encoding technique used for active radar calibrator.
First of all, some basic principles, such as the basic theory of radiometric calibration method for SAR and the concepts of active radar calibrator and the affection caused by the signals Of background. Based on these principles, the encoding technique used for calibration of single channel SAR is derived, and the signal procession is given. Then the study goes on in tow aspects: the encoding method and the decoding method. The study on the encoding method includes the principle of code selection, the characters of selected code, and the restraint to the signals of background. The study on the decoding method includes the synchronizing technique, the error analysis. The encoding technique used for polarimetric SAR calibration is derived. The new principle of code selection, the analysis of performance of selected code and the theory of restraining interference of signals from other channels is given.
The simulation is carried out to test the feasibility of the prescribed technique. The result shows that the prescribed technique can effectively restrain the influence of the background clutter and signals from other channels. A higher precision of radiometric calibration compared to the classic method can be achieved under the same condition, which means the selection of calibration filed and implementation of calibrator becomes much easier.
引文
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