基于矢量频率锁定环的高动态GPS信号跟踪

研究了高动态环境下矢量跟踪算法在GPS接收机中的应用,提出了一种适合高动态环境的矢量频率跟踪算法。当接收机存在高动态时,与由其引起的多普勒频率的变化率相比,由卫星运动引起的多普勒频率的变化率非常小,多普勒频率的变化主要由接收机的动态引起。对各个通道来说接收机的速度与加速度等状态信息是共同的,因此利用矢量跟踪的方法从各个通道的量测数据中直接估计接收机的速度、加速度等状态,可以有比通常的标量跟踪更低的跟踪门限,而在相同的载噪比下,可以有比通常的标量跟踪更好的估计精度。给出了一种适合高动态环境的矢量频率锁定环(VFLL)的结构,详细分析了导航滤波器的系统转移方程与量测方程,讨论了导航滤波器的实现。利用非线性估计的方法代替鉴频器提取频率误差,提高矢量跟踪的性能。由于矢量跟踪的性能是与想定相关的,在典型的高动态情景下,根据具体的想定,利用仿真的方法分析了矢量频率锁定环的跟踪性能。仿真结果表明矢量跟踪在高动态环境下可以有比标量跟踪更好的优势,能很好地跟踪GPS接收机的高动态信号。

High Dynamic GPS Signals Tracking Based on Vector Frequency Lock Loop

The vector tracking algorithms was researched for the GPS receiver in the high dynamic circumstances,and a method of vector frequency tracking was proposed under the high dynamic situation.The VFLL method is based on the fact that the change ration of Doppler frequency is mainly decided by the dynamic of the receiver,compared with the dynamic of satellites being tracked.The state information,such as velocity,acceleration etc of the receiver for all channels are common,so these receiver’s states can be estimated from the measure value of all channels using the vector method.The major advantage of this method is that vector tracking can have lower threshold than scalar tracking,and the velocity estimation by all channels can be more accurate in the same carrier-to-noise density ratio(CNR).The VFLL architecture suiting to high dynamic circumstance was given,and the system dynamics equation and measure equation of the navigation processor were discussed in detail,the realization of the navigation processor was also discussed.To improve the performance of the VFLL,the nonlinear estimation method was used to replace the frequency discriminator.The performance of the VFLL was tested using simulation according to the high dynamic circumstance of the classical setting,because it was inherently scenario dependent.The tracking performance of vector tracking is much better than scalar tracking supported by the simulation.