一种新的方法对北斗三频观测数据质量进行评估

A new method to assess the quality of Bei-Dou tri-band observation data

针对北斗导航系统的测距信号,特别是载波相位观测值的精确与否将直接影响其精密应用,因此本文通过伪距多路径误差和载波相位噪声两个方面对北斗三频观测数据质量进行分析。利用伪距载波相位组合法推导出三频信号的多径误差估计模型;并针对零基线双差法对载波相位观测值精度评估时,必须要求在同一个测站有两个相同型号的接收机对两颗卫星的三频观测数据的情况,提出利用无几何相位无电离层组合法,实现单个接收机对单个卫星接收到的三频载波相位观测值精度进行正确评估。通过实测数据验证,发现采用三频多路径估计模型对伪距多径误差估计精度高,且数据利用率高;伪距多路径误差以及卫星载波相位观测值精度均与卫星高度角成正比。当卫星高度角大于40°左右,载波相位观测值精度均在3 mm以内。

Since the ranging signal in Bei-Dou navigation system, particularly the accuracy of carrier phase observations will directly affect its precision applications. The quality of the tri-frequency observation data in Bei-Dou satellite system were analyzed from two aspects in this article, Muhipath error and carrier phase noise. The tri-band signals multipath error estimation model was deduced by using the pseudo-range carrier phase combination method. Since observations from two satellites use two identical receivers were necessary when the method of zero-baseline double-difference was used to assess the accuracy of carrier phase observations, the carrier phase noise estimation model was proposed by using the geometric-free phase method with observations received from one satellite use one receiver. Experimental results show that the accuracy using the tri-band model to estimate the multipath error is higher than using the dual model, and with a high utilization of data. pseudo-range multipath and carrier phase noise are proportional with satellite elevation angle. When the satellite elevation angle is greater than about 40°, the accuracy of carrier phase measurements is less than 3 mm.