短波抗干扰传输系统设计与实现

发布时间：2018-03-30 04:39

本文选题：短波通信　切入点：抗干扰波形　出处：《西安电子科技大学》2014年硕士论文

【摘要】：短波抗干扰数传指的是在很强的信号干扰,低信噪比下,在常规通信系统无法实现正常信息传输情况下,以极低的信息量传输来保证通信链路正常的一种数据通信方式。短波抗干扰数传能有效克服极低信噪比,较强的窄带干扰和较大的多径,在军事通信和民用领域中有重要意义。本文所讨论的题目是基于对第三代短波通信系统物理层的波形性能提升改造这个背景。在比较恶劣的通信环境下,尽可能实时准确地传输数据是人们对短波通信的需求。对短波抗干扰传输系统进行了研究,主要研究内容有以下几条:1、结合工程实践,本文中所设计的抗干扰数传采用直序扩频方式,期望实现信噪比-20dB,多径大于十几毫秒的恶劣条件下的低速率信息传输,以确保在以75~2400bps等常规数据传输技术失效的情况下,实现少量有效的正常通信。2、短波抗干扰数传中,信号捕获问题是数据接收过程中的关键技术问题,其抗干扰性能对整个系统性能有直接影响,在设计时必须充分考虑到极低信噪比下,短时突发信号的检测概率及虚警率对系统性能的影响。为此结合工程实际,提出了一种基于短PN分组的频域信号捕获算法,并详细的分析了该算法的性能。3、本文提出一种非线性多环路窄带干扰抑制算法,该算法为降低抑制干扰所引起的伪码信号失真,通过非线性判决反馈电路,判决反馈系统利用估算的伪码或扩频码CHIP序列来得出干扰信号的估算值,减少抑制噪声。然后将该估算值作为参照输入送入自适应滤波器。由于参照信号与原始信号的扩频码相关减小,此判决反馈能更好地抑制干扰且减少扩频信号的失真,有效提高了抗干扰能力。4、在抗干扰波形的关键技术软件仿真完成后,设计出适用于以TMS320C5509为核心的抗干扰波形的短波数字处理平台,完成了硬件的上变频设计、下变频设计及自动增益设计等,然后给出具体软件实现的流程。并在信道模拟器上进行了指标测试,实测结果验证了该设计方法的可行性和有效性。
[Abstract]:Shortwave anti-jamming data transmission means that under the condition of strong signal interference and low signal-to-noise ratio (SNR), the normal information transmission can not be realized in the conventional communication system. A data communication mode with very low amount of information to ensure the normal communication link. Shortwave anti-jamming data transmission can effectively overcome extremely low signal-to-noise ratio (SNR), strong narrowband interference and large multipath. This paper is based on the background of improving the waveform performance of the physical layer of the third generation shortwave communication system. The transmission of data in real time and accurate is the demand of people for shortwave communication. In this paper, the research on shortwave anti-jamming transmission system is carried out. The main research contents are as follows: 1, combined with engineering practice, In this paper, the design of anti-jamming data transmission adopts direct sequence spread spectrum mode, in order to realize the low rate information transmission under the bad condition of signal-to-noise ratio (SNR) -20dB and multipath more than 10 milliseconds, so as to ensure the failure of conventional data transmission technology such as 75~2400bps. In short wave anti-jamming data transmission, signal acquisition is a key technical problem in the process of data receiving, and its anti-jamming performance has a direct impact on the performance of the whole system. The influence of detection probability and false alarm rate of short time burst signal on system performance must be fully taken into account in the design. A frequency domain signal acquisition algorithm based on short PN packet is proposed. The performance of the algorithm is analyzed in detail. A nonlinear multi-loop narrowband interference suppression algorithm is proposed in this paper. In order to reduce the pseudo code signal distortion caused by interference suppression, the nonlinear decision feedback circuit is used. The decision feedback system uses the estimated pseudo code or spread spectrum code CHIP sequence to obtain the estimated value of the interference signal. The estimation is then fed into the adaptive filter as a reference input. Since the correlation between the reference signal and the original signal is reduced, the decision feedback can better suppress the interference and reduce the distortion of the spread spectrum signal. After the simulation of the key technology and software of the anti-jamming waveform is completed, a short-wave digital processing platform suitable for anti-jamming waveform with TMS320C5509 as the core is designed, and the up-conversion design of the hardware is completed. The downconversion design and the automatic gain design are given, and the flow chart of the software implementation is given. The test results on the channel simulator show that the design method is feasible and effective.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN973

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