混频器和滤波器非线性效应对MWC系统的影响

Analysis of the influence of non-lineartiy effects of mixer and filter on MWC system

近年来提出的调制宽带转换器欠奈奎斯特采样系统,可以在远低于奈奎斯特频率下无失真采样宽带稀疏多频带信号。但是实际系统中混频器和低通滤波器非线性效应的影响会导致重构的信号存在失真。利用Rapp模型在理论上分析了器件的非线性效应造成信号重构误差的原因,并通过仿真实验,分析了非线性效应对支撑集重构概率的影响以及通道数和输入信噪比在降低系统误差上的作用。仿真结果表明,器件的非线性效应会降低系统的重构性能;提高通道数和输入信噪比可以提高支撑集重构概率,改善系统的性能。

In recent years, the sub nyquist sampling system of modulated wideband converter （MWC） is proposed, and it could take sample of wideband sparse multiband signal without distoration far below the nyquist frequency. But in the actual system, the non-linearity effect of mixer and low pass filter can lead to the distortion of the reconstructed signal. The reason of signal reconstruction error caused by the non-linearity effects of the devices is analyzed theoretically by Rapp model. And through simulation experiment, the influence of the non-linearity effects on reconstruction probabilities of the support set and the effect of channel number and input SNR in reducing the system error are analyzed. The simulation results show that the non- linearity effects of the devices could decrease the reconstruction abilities of the system and it can increase recon- struction probabilities of the support set and improve the performance of the system by increasing the number of channels and input SNR.