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X波段雷达接收机关键组件的优化设计
【作者】 刘源；
【导师】 田忠；
【作者基本信息】 电子科技大学 ， 电路与系统， 2012， 硕士
【摘要】 随着国内造船工业的迅猛发展，必将给船舶类电子产品带来巨大市场，但是调查显示，民用船用雷达的关键技术主要掌握在在少数的外企手中，国产的导航雷达仍处于不利的竞争地位。这是因为民用的磁控管脉冲雷达存在接收前端易烧毁、发射频率不稳定、动态范围小、可靠性低等缺点，本文就是针对现在国内船用雷达存在这些问题，以接收机作为研究平台，展开一系列的研究和优化设计，在不增加成本的基础上，改善雷达整机性能，增强市场的竞争力。论文首先介绍了接收机优化设计的思路，从系统原理出发，选择了适用的接收机结构和工作频率。分析了接收机各项性能参数的意义，提出了优化设计后应该达到的指标。根据指标将接收机系统分为了射频前端、中频处理电路和微机控制三个部分来深入讨论和研究。1.接收前端：为了增强雷达的抗烧毁能力，对射频前端进行了改进，设计了收发开关加限幅器的保护方案；在混频器之前增加了低噪声放大器，可以控制系统的噪声和弥补信号变频产生的损耗；接着对设计好的前端进行了性能测试和功能验证。2.中频处理电路：传统的大动态范围设计采用STC、AGC等方法，但是会降低雷达的检测能力，这里选用对数接收机的形式，实现了更大的动态范围。3.微机控制：由于磁控管频率存在温度漂移，为了提高接收机的中频稳定度，设计了基于单片机的模数混合AFC模块，并测试证明它的调谐精度远大于一般的模拟AFC电路。接着为了整机系统的控制和连接，与信号后端制定了统一的通信协议并编程实现接收机的串口通信。此外，本文对接收机的测试平台做出了优化，用信号模拟器取代发射天线端产生雷达回波信号，降低了实验成本和场地开销，并使用该平台测试、评估了论文所设计的接收机的性能。最后，展开雷达整机系统的装船测试，分析了雷达的成像质量，证明本文工作对雷达性能有了一定的改善。
【Abstract】 With the fast development of ship industry, there must be a huge market for thenavigation electronic equipment on boat. According to a survey, Chinese marine radarcompany is still lacking of competitive power against the foreign company who ownsthe key of radar technology. Through the magnetron pulse radar has been widely used,it exposes some obvious weak points such as the frequency shifting, the receiverfront’s damage, the small dynamic range and the lower reliability. Focus on theseproblems, a line of research on radar receiver has been done in this paper, in order toimprove the system’s performance and make Chinese radar more competitive.Based on the principle of radar receiver, the method of optimizing and designingis introduced at first, and then the work frequency and super heterodyne structure areselected. After analyzing all of the action parameters, the goals of optimization havebeen determined. Further study continues while receiver being divided into three parts:RF front, IF signal processor and micro-control unit. To protect the front against thehigh transmit power, a TR switch and limiter hybrid circuit is designed. Meanwhile alow noise amplifier before mixer can help system control the noise and add the signalgain. Next there is a RF front performance test to indicate the function. Instead of sometraditional ways (AGC or STC) which can expand the dynamic range by cutting downthe detection ability, logarithm receiver is used here. Because of the magnetronfrequency shifting who affect the stability lot, an analog-digital AFC module controlledby a chip is also designed and its rest detuning is improved more from the commonAFC. Additionally, some codes for the serial port communication between receiver andDSP are completed to get the whole system connection possible.Besides, considering the experiment condition of high cost and large field, a radarback-wave generator has been made to replace the transmitter and antenna in receivertest. On the optimized test bench, the receiver designed in the dissertation is estimated.At last, all these work above are proved helpful to improve the performance of receiver,by analyzing the detection images of radar system which is fixed on the ship.