欠奈奎斯特采样在数字接收机中的应用

从理论上讲，为提高侦察接收机的截获概率，接收机的瞬时带宽必须足够宽。接收机的瞬时带宽决定于接收机的ADC采样速率。因此数字接收机必须具备高速的ADC采样速率。这样对接收机的ADC采样器件性能提出了更高的要求。将采样的方法应用于数字接收机中，可以在一定条件下降低采样速率，同时增加接收机的瞬时带宽。提出了一种基于延时和FFT技术的时域欠采样方法，并在阐述简单原理的基础上找出存在的问题及提出改进方案。重点分析了利用延时和非延时2路通道的相位差与入射信号频率之间的关系，进行信号频率的无模糊估计。基于目前硬件实现水平，数字接收机中采用这种欠采样方法是经济可行的方案。

Application of Sub-nyquist Sampling in Digital Receiver

Theoretically speaking, instantaneous band width of digital receivers must be wide enough in order to improve the probability of intercept. Instantaneous band width depends on sampling rate of ADC. So digital receivers must have a high speed AnalogDigitalConverter(ADC) and make high demands on the performance of ADC. Subnyquist sampling applied in digital receivers can reduce sampling rate of ADC and increase input band width of digital receivers under given conditions. A method of Subnyquist sampling based on time delay and FFT technique is presented in this paper, problems are pointed out, and new improved projects are presented. Especially, the paper discussed how to estimate the frequency of signal unambiguously according to the relation between the frequency of input signal and phasic difference between delay channel and nondelay channel. Because of the realization of hardware technique, Subnyquist sampling applied in digital receivers is an economy and feasible project at the present time.