基于北斗双星的被动定位算法研究

针对我国现有北斗双星定位系统主动定位存在的问题,提出了一种被动定位算法．该算法根据两颗同步卫星、用户配备的原子钟、高程设备等获得卫星到用户的时间及高程信息,首先将北斗系统的工作区域划分为若干网格,定义了费用函数．然后计算各网格的费用,将具有最小费用的网格及邻域作为下一次搜索的区域,再将该子区域进一步网格化后计算费用函数,经过多次迭代后就可将当前搜索的网格中心作为用户所在位置．最后用电子地图对三维搜索算法可行性进行了仿真,仿真考虑了网格划分方法和电离层误差对结果的影响．结果表明,该算法运算速度快,并且具有较高的定位精度,对现有北斗双星主动定位系统是一种可行的改进算法．

Passive Positioning Algorithm Based on Beidou Double-Star Positioning System

Being an active positioning system.China's Beidou Double-star Positioning System can- not achieve continuous and real-time positioning,and capacity of the system is limited as users consume system resources during positioning.In order to overcome these shortcomings,a passive positioning algorithm is proposed based on three-dimensional grid search.According to a newly defined cost function,as well as the data collected from the two synchronous satellites,atomic clock and altitude gauge carried by a user,passive positioning is fulfilled through the grid search algorithm. The operational area of Beidou system is first divided into some grids.Secondly,the grid with the lowest cost and its eight neighboring grids,i.e.sub-area,is chosen as the next search area.Thirdly, the sub-area is further divided into some sub-grids so as to calculate the cost of each sub-grid and find out the sub-grid with the lowest cost.This process repeats until the positioning accuracy is satisfactory or a predetermined iteration time is reached.At this point,the center of the current search grid is taken as the position of the user.During simulation,a digital map is used to validate the three-dimensional search algorithm.The influence of ionospheric error on positioning accurate is considered.Simulation results show that the method is fast and accurate enough for real-time posi- tioning,and that the number of partition grids greatly affects positioning accuracy and positioning time.It is a possible way to turn the active Beidou Double-star positioning system into a passive one.