多路径效应对GPS多普勒测速的影响

针对全球定位系统（GPS）多普勒观测值在城市环境中受多路径效应影响，从而导致测速误差大的问题，从多普勒频移产生的原理入手，通过运动学理论分析，构建了接收机、反射点与卫星整体运动与多普勒频移误差关系模型。模型分析结果表明:多普勒频移误差与卫星观测向量、反射点切线法向量、接收机运动速度及反射点运动速度有关。最后通过5种不同场景的GPS数据验证了所提模型的正确性。在多路径情况下，当接收机或反射点运动时，可能会导致巨大的测速误差，使得结果不具备可靠性。 

Multipath effects on velocity measurement from GPS Doppler observations

Global Positioning System (GPS) Doppler observation is affected by multipath, which leads to a huge error in velocity calculation. In response to this problem, starting from the causes of Doppler observations, through kinematic analysis, a model of the relationship between the overall motion of receiver, reflection point and the satellite, and the error of Doppler observations is constructed. The results show that: the error of Doppler observations is related to the satellite observation vector, the tangent normal vector of the reflection point, the speed of the receiver and the reflection point. The effectiveness of the proposed model is verified by the results in 5 different scenarios. When receiver and reflection point are moving, multipath may cause a huge error in velocity, which makes the velocity unreliable.