Abstract:

In the complex urban environment such as tall buildings and trees,multipath error and non-line-of-sight(NLOS) signal error can't be modeled accurately,which badly affect the accuracy and usability of pedestrian GNSS navigation and positioning.This paper comparatively analyses the characteristics of multipath error and NLOS signal error at first,and then separates multipath error and NLOS signal error using double difference observation equation to analyze the influence on pseudo range,carrier phase and doppler of two kind error.By analysing the data measured by UBLOX-NEO-M8T single frequency navigation GNSS receiver beside tall buildings or trees,the results show that Doppler noise is significantly larger when C/N0 is small.For M8T navigation receiver,Doppler noise becomes larger when C/N0 is lower than 30 dBHz under Multi-path seriously affected environment.The relationship between Doppler noise and C/N0 is not obvious under NLOS seriously affected environment.Doppler noise is still significant when C/N0 is larger.Satellite signal is mainly affected by the multipath effect when the trees are obscured,which causes pseudo range error is between 10~150 m,and the impact on phase and Doppler is not obvious.Satellite signal is mainly affected by NLOS when tall buildings are obscured,which causes the same effect on pseudorange and carrier phase observations.The amount of the delay depends on the distance between the reflection point and the receiver,sometimes can reach a few hundred meters.Doppler observations also have a significant impact.

Key words: pedestrian navigation, multi-path, NLOS, single-frequency navigation receiver, city environment