Development of Seamless Positioning System for Urban areas by Combining Satellite-based and Pseudolite-based Positioning Systems.

点击翻译按钮获取中文摘要

1.Prototype of pseudolite system including transmitter and receiver are developed. The transmitter is based on the existing GPS simulator, while the receiver was developed based on software except the receiving antenna and A/D converter. The software-based receiver enables to implement an algorithm to mitigate errors caused by multi-pass signal from the transmitter or the satellites. In addition, the software receiver was made open to researchers as a platform for further research.2.Using the prototype receiver, a method of mitigating the multi-pass errors. A number of correlators are implemented to compute the shape of the correlation peak, and with the detailed shape, direct signal and reflected signal are estimated and separated. Parameters describing the reflected signal is the delay, the ratio of signal strength and the phase difference. Through the experiment, it is demonstrated that the multi-path errors are mitigated using the actual reflected GPS signals.3.To estimate how much the positioning accuracy will be improved by the combination of pseudolites and the satellites, the simulation system, which was originally developed by the previous project, was improved to represent the reflection and the diffraction of the signal using the 3D urban data. In addition, by inputting the data into the software GPS receiver, we can estimate how much errors will be expected with a given distribution of pseudolites and satellites. It also demonstrated with the simulator that by removing the contaminated signal by the reflection, the positioning accuracy can be improved.