基于二阶采样和二次混频的全数字正交解调

The All Digital Quadrature Demodulator Based on Second-order Sampling and Secondary Mixing

在获取有采样时间差的数字I/Q信号过程中,二阶采样在采样频率、载频和采样时间差的选择上比一阶采样有更大的自由度。建立了单中频二阶采样正交解调模型,通过获取有采样时间差的数字复指数信号和利用二次混频技术,提出了一种新的采样频率与载频关系式,极大地拓展了二阶采样的采样频率、载频和采样时间差的选择范围,简化了ADC前端雷达系统设计和ADC采样过程。最后通过实验仿真与分析进行了验证。

Compared to the method based on the first order sampling, the method based on the second order sampling has more freedom in the selection of sampling rate, carrier frequency and the difference of sampling instant in the process of generating the digital I/Q components with different sampling instant. This paper proposes a single IF quadrature demodulation model and obtains a new relation between the sampling rate and the carrier frequency, via generating the digital complex exponential with different sampiing instant and using the secondary mixing. This relation expand the selection range of sampling rate, carrier frequency and the difference of sampling instant, and simplify the design of radar system in the front of ADC and the process of ADC. Finally, simulation and analysis are processed to verify our method.