改进的基于四象限反正切函数的鉴别器算法

Improved discriminator algorithm based on four-quadrant arctangent function

为了解决GPS接收机载波跟踪环路中鉴别器算法运算量大的问题,提出了一种改进的锁相环和锁频环共用四象限反正切函数单元的鉴别器算法。环路通过共用的四象限反正切函数单元和校正函数,使得锁相环对导航数据跳变不敏感,锁频环能够克服频率调整模糊度。此外,还在加性高斯白噪声条件下通过仿真对鉴别器算法中的参数设置问题进行了讨论。理论分析对比和仿真实验表明:该改进的鉴别器算法不但具有良好的鉴相和鉴频能力,而且与传统鉴别器算法相比具有运算量小、复杂度低的特点,从而达到提高载波跟踪环路的运算速度,减少系统资源占用的目的。

In order to reduce the calculation load of a carrier tracking loop in a Glohal Positioning System （GPS） receiver, an improved discriminator algorithm based on four-quadrant arctangent function is proposed, which is shared by Phase-Locked Loop （PLL） and Frequency-Locked Loop （FLL） discriminators. The PLL discriminator is insensitive to the navigation message data. The FLL discriminator overcomes the frequency uncertainty by the shared four-quadrant arctangent function unit as well as correction functions. Furthermore, parameter setting of the discriminator algorithm is investigated with additive white Gaussian noise at various signal-to-noise ratios. Theoretical analysis comparison and simulation show that the improved algorithm not only has good discrimination capacity with the carrier phase and frequency, but also has the characteristics of small calculation load and low complexity. Therefore, carrier tracking loops can improve operational speed and occupy less system resources.