基于脉冲压缩的宽带数字接收机设计

Design of Wideband Digital Receiver Based on Pulse Compression

针对传统宽带数字接收机存在跨信道问题以及在低信噪比下检测能力差、对宽带同时到达信号处理能力差的缺点,提出一种基于脉冲压缩的新型宽带数字接收机结构进行雷达信号的截获及脉冲描述字参数的提取.将基于脉冲压缩的接收机结构从模拟域扩展到离散域,推导出信号经过数字压缩接收机后的数字离散形式.新型接收机结构采用线性调频信号与接收信号混频得到混频信号,将混频信号送入数字延迟模块进行卷积运算得到输出的脉冲尖峰.新型接收机结构本身不存在跨信道问题,并且可以有效地处理低信噪比环境下的信号及同时到达信号.通过推导给出输入信号频率与扫频信号带宽和数字延迟信号带宽的约束关系,并且进一步给出了雷达信号经过新型宽带数字接收机后的载频、带宽、脉宽、幅度等脉冲描述字信息的计算公式.仿真给出了新型宽带数字接收机在低信噪比下的信号检测能力、大带宽同时到达信号处理性能以及脉冲描述字提的取能力,并进一步分析了不同环境参数对脉冲描述字提取性能的影响.通过和传统信道化数字接收机信号检测和测频能力的对比,仿真结果证明了新型数字接收机结构在低信噪比下信号检测和参数提取的有效性.为数字压缩接收机的物理实现提供了理论基础,也提供了新的宽带数字接收机的设计理念.

The traditional wideband receivers have some shortcomings , such as the problem of cross-channel signal , poor ability of processing simultaneously arrived signals , and poor signal detection when receiving wideband radar signals under low signal-to-noise ratios ( SNRs ). To solve these problems , a wideband digital receiver structure based on pulse compression is proposed to intercept radar signals and extract the pulse descriptor word ( PDW ). The receiver structure , which is based on pulse compression , is extended from the analog domain to the digital domain. The discrete form of the signals through the compressive receiver is derived. In this novel structure , the received signals are mixed with the linear frequency modulation signal , and the convolution operation is performed in the digital delay module to obtain the pulse spike. The novel receiver can effectively process signals in low SNR conditions as well as process simultaneously arrived signals , and it does not generate the problem of cross-channel signal. Experimental results show the respective constraint relations between the frequency of input signals and the bandwidths of sweep and digital delay signals. Furthermore , the formula for measuring the PDW information , which includes frequency , bandwidth , pulse width , and amplitude after the radar signals pass through the new wideband digital receiver , is given. The simulation demonstrates the abilities of detecting signals in low SNR , processing simultaneously arrived wideband signals , and extracting PDW. The simulation also analyzes the influence of the PDW extraction ability under different conditions. The simulation results prove the effectiveness of signal detection under low SNR and parameter extraction using the novel digital receiver through comparison of the signal detection and frequency measurement abilities between the novel digital receiver and the traditional channelization digital receiver. The structure provides a theoretical basis for the physical implementation of the digital compressive receiver and the novel design concept with regard to wideband digital receivers.