基于随机解调的软件无线电直接射频采样系统研究

Study of Direct RF Sampling System on Software Radio Based on Stochastic Demodulation

摘要:

针对高速信号采样系统因ADC模数转换器模拟输入带宽低而不能对频率较高的模拟信号直接进行A/D转换的瓶颈,结合某类高速信号高精度数据记录仪的研制,提出了一种基于随机解调的采样方式,并通过矩阵理论将随机解调采样转换为可进行矩阵计算的数学模型；该模型利用随机解调和抗混叠滤波器实现了低速ADC模数转换器对高速模拟信号的采集；同时,根据所建立的采样模型,提出了一种基于最小二乘的采样重构方法,并且对其重构误差进行了定量的分析；最后,通过仿真对基于随机解调的采样系统进行了验证,结果表明该采样系统实现了低速ADC模数转换器采样对高速信号的直接采样,且误差更优于单片ADC模数转换器采样误差。

Abstract:

The bottleneck of high-speed signals sampling system is that it cannot sample directly higher frequency signal because of lower analog input bandwidth of its ADC. In order to resolve this problem, a kind of sampling model based on stochastic demodulation is presented in combination with the development of a high-speed and high-precision data recorder, the stochastic demodulation sampling is then transformed into a mathematical model that can perform matrix calculation through matric theory. The model achieves the high-speed analog signal sampling with low-speed A / D converters by means of stochastic demodulation and anti-aliasing filter. According to the model of sampling, a reconstruction method of sampling based on least squares is proposed, and its reconstruction error is quantitatively analyzed. Finally, the sampling model is proved by simulation, it is showed that the sampling system is effective, the sampling error is better than that of a single ADC.