连续波干扰下卫星导航信号的ADC量化损耗分析

地球表面接收到的卫星导航信号强度通常远低于环境热噪声,并且其所处电磁环境越来越复杂,人们越来越关心在干扰环境下导航接收机的工作性能。模数转换器(ADC)作为数字式导航接收机中射频通道与基带处理的中间环节,其量化造成的有用信号损耗直接影响着接收机的整体性能。对于连续波干扰(CWI)与热噪声环境下ADC量化对卫星导航信号的影响,现有文献大多是基于数值模拟实验寻找答案,缺少理论推导。通过概率统计理论深入研究了在CWI干扰环境下任意位数(bits)ADC均匀量化对接收机相关信干噪比的影响,得出了明确的量化后信干噪比表达式,并给出近似最优的ADC量化门限选取法则。通过数学推导和仿真分析得出结论,在没有辅助抗干扰手段和采用均匀量化的情况下,2 bit的ADC量化即可达到最大的输出信干噪比。

The Effect of ADC on GNSS Signal in Continuous Wave Interference

With the application of satellite navigation becoming more and more widely, increasingly complex electromagnetic environment needs to be dealt with. The performance of navigation receivers in interference scenarios has got more and more attention. As the bridge between radio frequency channel and baseband processor, ADC directly impacts the overall performance of GNSS receivers through its quantization loss on useful signal. The ADC quantization loss on the post-correlation signal-to-noise ratio has been researched mostly based on simulation or experiment. In this paper, the quantization loss is theoretically derived, when the input interference is a continuous wave (CWI). A near-optimal quantization interval criterion is given with analyzing the minimize quantization loss. It is concluded that 2 bits ADC quantization can achieve the maximum post-correlation SINR in the uniform quantization case, when there is no other anti-jamming means.