一种运用相位差测量标签距离的方法

A Method of Measuring Tag Distance by using Phase Difference

提出一种利用相位差计算标签距离的新方法。该方法利用无源标签的读写信号在传输过程中产生的相位差与时间的关系,计算出信号在传输中所需要的时间,从而求解得到所要测量的距离。首先对MATLAB建立的仿真模型进行理论验证,然后进行1个波长内和超过1个波长的实验验证,并计算出测距误差。实验结果表明：1个波长内的测距相对误差在6%之内;超过1个波长时,距离越短,测量精度越高,在918~924 MHz这段频率内的测距相对误差在10%之内。

In the application of passive RFID tag,a new method of calculating tag distance by utilizing phase difference was proposed. The relationship of the time and phase difference which was produced by the read-write signal of the passive tags in the process of transmission is of great use to calculate the time required by the signal in the transmission,so as to measure the distance. Frist the simulation model was established in MATLAB for theoretical validation of this phase difference method,then real experiments were used to the verification. The range error was calculated for the reader-tag distance below one wavelength and more than one wavelength in the theoretical simulation and experiments. The experimental results showed that the relative range errors were less than 6% for distance below one wavelength. For the reader-tag distance more than one wavelength,the shorter was the distance,the higher was the measuring accuracy,and the relative range errors were less than 10% in the range of 918 ~ 924 MHz.