Abstract: A dual frequency based Real Time Location System（RTLS） using passive Ultra-High Frequency Radio Frequency Identification（UHF-RFID） is presented in this paper. Compared with traditional RFID location systems which mostly use RSSI measurement, the proposed approach has the unique virtue of small bandwidth requirement and high estimation resolution. The dual frequency ranging principle is analyzed and the system is modeled in a simulation tool. Simulation results show that the estimation accuracy can be less than 0.5 m with I-Q relative mismatch under 0.08 and SNR at baseband above 21.5 dB.

Key words: Real Time Location System（RTLS）, passive Ultra-High Frequency Radio Frequency Identificatio（UHF-RFID）, dual frequency ranging principle, I-Q relative mismatch

摘要： 提出一种基于双频比相的无源超高频射频识别（UHF-RFID）实时定位系统（RTLS）。与传统射频识别定位系统相比，该方法带宽小，精度高。分析了双频比相测距原理在无源RFID系统中的适用性，通过理论计算得到非理想因素对测距精度的影响，并在Simulink平台上进行建模。仿真结果表明，I-Q相对失配度小于0.08，基带信噪比为21.5 dB时，系统定位精度可小于0.5 m。

关键词: 实时定位, 无源超高频射频识别, 双频比相测距, I-Q相对失配