GNSS数字中频信号再量化方法

GNSS抗干扰技术需要采用高位A/D量化，而现有接收机往往采用低位A/D量化，即在抗干扰前后采用不同A/D量化位数。为了不改变GNSS接收机的现有结构，因此需要研究如何将高位量化数字信号转换为低位量化数字信号。针对传统直接截取法带来信噪比损耗的问题，本文提出了一种基于自适应门限的GNSS数字中频信号再量化方法，该方法通过转换后低位信号的最佳概率分布即高斯分布不断调整再量化门限值，根据该门限值对高位数字信号进行再量化。本文理论分析并仿真比较了传统截取法和新方法再量化损耗，结果表明新方法具有更小的再量化损耗，并且针对本文提出的再量化方法对卫星信号进行捕获仿真，证明了该方法真实可行。

Re-quantization Method for Intermediate-Frequency Digital GNSS Signal

High bit A/D quantization is used in the interference suppression technology, while the low bit A/D quantization is applied in the existing global navigation satellite system (GNSS) receivers, so different number of A/D quantization bits should be applied before and after the anti-interference process. In order not to change the existing structure of the GNSS receiver, it is necessary to study how to convert the high bit digital signal into low bit digital signal. Aiming at the signal-to-noise ratio (SNR) loss caused by re-quantization, this paper proposes a re-quantization method based on adaptive thresholds. High bit intermediate frequency digital signal re-quantized according to the adaptive thresholds, and the adaptive thresholds are adjusted by the best probability distribution, which is the Gaussian distribution, of the low bit quantitative results. According to theoretical analysis and simulation, the new method has less re-quantization loss compared with the traditional interception method. Also, the simulation of GNSS signal acquisition using the new re-quantization method demonstrates that the method is actually possible and reliable.