随机稀疏调频步进信号距离像抗混叠方法研究

An Anti-Range Aliasing Method for Random Sparse Chirp Frequency-Stepped Signal

传统步进频率波形不模糊距离窗大小受载频步进量制约,将会导致距离像混叠等问题.针对此问题,基于压缩感知理论,研究了一种随机稀疏调频步进信号距离像抗混叠方法.首先对子脉冲进行脉压(Dechirp)处理,将处理后的回波信号看作为具有等效带宽线性调频信号回波的量测数据;其次根据子脉冲随机发射方式构造相应的量测矩阵,得到随机稀疏调频步进信号的压缩感知重构模型,并采用压缩感知重构算法得到高分辨一维距离像.最后,对该方法不模糊距离窗大小进行了分析,并给出了影响不模糊距离窗大小的因素和参数设置原则.所研究方法通过将随机稀疏调频步进信号的距离像合成处理等效为LFM信号的距离像合成过程,既降低了载频步进量对不模糊距离窗大小的限制,克服了距离像混叠问题,又提高了距离像合成性能.仿真实验进一步验证了本文方法的有效性.

The ambiguity range of the traditional stepped-frequency waveform is decided by the frequency step,which result in range aliasing. To solve the above problem,a compressive sensing-based anti-range aliasing method for random sparse chirp frequency-stepped（ RSCFS） signal is proposed. In the method, the sub pluses are dechirped firstly. Then the echoes are treated as the measurement data of the equivalent bandwidth LFM signal. Secondly, the corresponding measurement matrix is constructed according to the random transmission mode of the sub pulses, and then the compressed sensing reconstruction model of the RSCFS signal is built. At the same time, the high resolution range profile can be obtained by the compressed sensing reconstruction algorithm. At last, the ambiguity range of the proposed method is analyzed, and the factors that influence the size of the ambiguity range and the parameter setting criteria are given. In this method, the range profile synthesis process of the RSCFS signal is regarded as the process of the equivalent bandwidth LFM signal. It can not only reduce the restriction of the carrier frequency step to ambiguity range, effectively overcome the range aliasing problem,but also improve the range profile synthetic performance. Simulation results show the effectiveness of the proposed method.