| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain an asynchronous communication system by a pulse gap signal in an RFID communication, which is capable of dealing with a change in carrier frequency and shortening a communication time without increasing a baud rate. <P>SOLUTION: Load modulation is performed by a VPM coding system in which a negative logical pulse signal is outputted for a Tg time as a pulse gap signal for the head of each data indicative of "1" and "0", an H level signal is outputted for a T1 time after the pulse gap signal in the case of "1" data, and the H level signal is outputted for a T0 time after the pulse gap signal in the case of "0" data. Also, in the interrogator side, this load modulation wave is demodulated to detect the VPM code, a signal subsequent to the pulse gap signal is read using the rise edge or the fall edge of the pulse gap signal of each VPM signal as a trigger, and the reference time, the T1 time and the T0 time are compared to detect the "1" data and the "0" data. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
