GNSS接收机采样率的选择及对相关器输出的影响

GNSS Receiver's Sampling Rate Selection and Its Impact on Correlator's Output

卫星导航系统数字接收机的开发首先要考虑采样率的设计,采样率的选择对接收机的运行、跟踪精度以及基带数字处理速度有着重要影响。首先研究了外差式和低中频2种射频前端结构下输出的中频信号的形式和中频频率选取原则,接着针对这2种中频信号分别设计了实/复数信号的抗混叠带通采样率;通过仿真讨论分别得到了采样率的选取与伪码速率、相关器间隔的关系,及其对相关器输出与跟踪性能的影响;最后综合各种因素给出了采样率的选取策略。

The development of the digital receiver of global navigation satellite system （GNSS） should take into ac- count the design of the sampling rate because its selection has an important impact on the operation and tracking ac- curacy of the receiver and on the digital processing speed of baseband signal. This paper studies the forms and fre- quency selection principles of intermediate frequency （IF） signal output by heterodyne and low-IF radio frequency （RF） front-end structure. It then designs the anti-aliasing bandpass sampling rates of real/complex signals for the two forms of IF signals respectively. Finally, it presents the sampling rate selection strategy by taking various factors into account. The simulation results, given in Fig.6 through 8, and their discussion show preliminarily that sampling rate, PN code rate and correlator spacing do have impact on the output of the correlator and the tracking performance of the GNSS.