FPLL载波跟踪环仿真及高动态GPS信号测试

Simulation and Testing of FPLL Carrier Tracking Loops with High Dynamic GPS Signals

针对高动态环境下普通GPS接收机跟踪环路容易失锁的问题,考虑到锁频环动态性能好、锁相环跟踪精度高的特点,实现了二阶锁频环辅助三阶锁相环的载波跟踪环(FPLL)。根据FPLL结构原理和误差分析理论,提出了一种FPLL环路的码相位和载波相位精度分析方法。借助GPS软件接收机平台,在Matlab环境下仿真实现了FPLL载波跟踪环,并利用Spirent GSS7700仿真器采集高动态GPS模拟信号对FPLL环路进行了测试。测试结果和精度分析表明,在导航信号的载噪比为40dB-Hz,加速度为26g,加加速度为9g/s的条件下,该高动态跟踪环路能够达到码相位1.31m(1σ),载波相位为4.24×10-3 m/s(1σ)的跟踪精度。

The conventional tracking loops in GPS receivers usually lose locked high dynamic signals. Thus, to achieve better FLL performance in dynamic situations and higher PLL measurement accuracy, we implemented a second order FLL in an assisted third order PLL （FPLL） based carrier tracking loop. These methods were employed to analyze the measurement accuracy FPLL of code and carrier phases, and implemented on our software receiver platform with Matlab. FPLL was tested using the data collected through Spirent GSS7700 simulator. The results show that the average measurement accuracy for code the phase and carrier phase was 1.31 m （1σ） and 4. 24× 10^-3 m/s （1σ） , respectively, as the signals are around 40 dB/Hz of SNR （signal to noise ratio）, with 26 g of acceleration and 9 g/s of jerk.