For underwater acoustic positioning system based on measurement of time_delay, range ambiguity appears when pulse's propagating time is longer than its repetition period.
基于时延测量的水声跟踪定位系统，当信号传播时延大于脉冲重复周期时，就会出现距离模糊。
2
According to the given source and mathematic model of matching error, a algorithm for real time matching of GPS positioning results and digital maps is put forward.