Tag communication device and tag communication method

摘要

To improve communication between tags by causing a mobile object having a RFID tag attached to transmit an interrogating wave only when moving in a communication range to reduce power consumption and prevent occurrence of tag confusion. By acquiring two Doppler signals from 2-frequency transmission waves (CW) with different frequencies and respective reflected waves and detecting phase difference from the Doppler signals, a cargo (21A) is detected to be moving in the communication range (A). Only when the movement is detected, a reader-writer (1A) transmits the interrogating wave (RW).