BDS三频双差载波相位组合平滑伪距算法

Pseudo-Range Smoothing Algorithm Using BDS Triple-Frequency Double-Difference Carrier Phase Combination

针对现有的载波相位平滑伪距算法多基于GNSS双频观测值且在伪距平滑过程中易受电离层延迟累积干扰的问题,提出一种基于北斗三频观测值的载波相位平滑伪距算法。首先通过构建北斗三频优选线性组合,进一步削弱双差载波相位观测值的电离层延迟以及观测噪声;接着通过经典Hatch滤波平滑器,用优选三频双差载波相位观测值代替原始载波相位观测值对组合伪距观测值进行平滑,得到最终伪距平滑解用于伪距定位。最后采用0.004、14.4、61.7和131.6 km这4组不同基线长度的北斗三频实测数据对算法进行验证,给出了平滑前后伪距历元差对比图及算法对4组基线观测值的平滑率。结果表明,所提算法对短基线和中长基线三频观测值的平滑率均能达到90%以上。通过对4组基线条件下平滑效果进行比较分析,验证了本文中的理论推导及算法的有效性。

In order to solve the problem that the existing carrier phase smoothing pseudo-range algorithm is based on GNSS dual-frequency observation and is susceptible to cumulative interference of ionospheric delay in pseudo-range smoothing process, a carrier phase smoothing pseudo-range algorithm based on Beidou triple-frequency observation is proposed. The ionospheric delay and observed noise of the double-difference carrier phase observations are further attenuated by constructing a preferred linear combination of the Beidou triple-frequency observation, and then the original carrier phase observations are replaced by the preferred triple-frequency double-difference carrier phase observations by a classical Hatch filter smoother. The pseudo-range observations are smoothed to obtain a final pseudo-range smoothing solution for pseudo-range positioning. Finally, the algorithm is validated by four sets of triple-frequency measured data with different baseline lengths of 0.004 km, 14.4 km, 61.7 km and 131.6 km and the comparison chart of pseudo-range difference before and after smoothing and the smoothing efficiency of the algorithm on the observed values of the four groups of baselines are presented. The results show that the smoothing rate of the short-long and medium-long baseline triple-frequency observations can reach more than 90%. The comparison of the smoothing effects of the four sets of baseline conditions verifies the theoretical derivation and the effectiveness of the algorithm.