GPS多径信号的自适应滤波估计方法

 研究全球定位系统(GPS)多径信号估计的问题。通过分析自适应滤波器的原理,建立了数字中频信号处理的数学模型,提出一种用自适应滤波实现GPS多径幅度、码相位和载波相位估计的方法。该方法采用不同延迟的伪随机序列对信号进行解扩、解调和累加,得到了作为期望信号的系列自适应滤波相关值。对该方法与其他3种方法进行了理论上的分析比较,得出本方法具有信噪比高、自适应滤波性能好、带有码相位信息和不存在载波模糊度问题等优点。根据各种滤波器算法的特点和本应用的需求,给出了选用递归最小二乘算法实现的方法。通过计算机仿真,验证了提出的方法能够在14 dB的信噪比下,以1个采样间隔的时间延迟分辨率和0.005周的载波相位估计精度估计出GPS L1的多径信号。

GPS Multipath Signal Estimation Method Utilizing Adaptive Filtering

This article studies global positioning systems (GPS) multipath signal estimation. Through analyzing the principle of adaptive filters, a model is built of processing the intermediate frequency signals, and a new multipath signal estimation method is proposed utilizing the adaptive filters which can realize the estimation of amplitude, code phases and carrier phase. The scheme takes a series of correlation values for the desired signal of the adaptive filter which are obtained from dispreading, demodulation and accumulation using pseudo-range random noise codes with different latencies. A theoretical comparison with three other possible schemes demonstrates that the scheme possesses high signal-to-noise ratio (SNR) with good performance as well as code phase estimation information with no carrier phase ambiguity. According to the characteristics of various adaptive algorithms and the demands of the application, a recursive least-squares algorithm is adopted. Simulations show that the method can estimate the multipath signals of GPS L1 with code delay resolution of one sampling interval and carrier phase precision of 0.005 cycle at a SNR of 14 dB.