带相位和频率反馈环路的GNSS弱信号跟踪技术研究
Phase-and-rate Feedback Loops for Weak GNSS Signals Tracking
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摘要: 从频率反馈锁相环和相位-频率反馈锁相环的环路噪声转移函数出发,分析预检测积分时间和等效噪声带宽的乘积与环路稳定性的关系;提出了针对软件接收机和硬件接收机的相位-频率反馈环路实现方式;通过对实际信号的测试表明,当接收信号的载噪比在15dB×Hz左右时,使用长预检测积分时间的相位-频率反馈锁相环可以稳定工作,且跟踪性能优于频率反馈锁相环。Abstract: With the transfer function of rate-only feedback loop and phase-and-rate feedback loop,the relationship between loop stability and the product of pre-correlation time and equivalent noise bandwidth will be analyzed.Then realizable phase-and-rate feedback loops for software and hardware receivers will be introduced.Finally,some tracking results of real signals will be given.Simulation results show that software receivers perform well with phase-and-rate feedback loops and longer pre-correlation time when carrier-to-noise ratio(CNR) of received signals is approach to 15 dB×Hz.