Comparing with the traditional phase - shifted laser range finder , the method could implement the ranging with multifrequency by using single modulated frequency . it could not only solve the contradiction of the range and the precision , but has high degree of accuracy and wide range , simplify the hardware design , and reduce the cost . this paper introduced the theory of phase distance measurement , analyzed various testing methods and expatiated the hardware and the software for the proposal system 与传统的相位法测距相比，本方法使用单调制频率实现了多频测距，有效地解决了相位法测距中测程与测量精度之间的矛盾，具有高精度、大量程、大噪声容限的特点，而且简化了硬件设计，降低了成本；其次在数据处理中采用数据加窗函数的方法，提高了方波信号的频谱分辨率，进而提高了测量的精度。
