| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a radio communication system in which a plurality of interrogators simultaneously identifies a plurality of transponders. <P>SOLUTION: A communication system 1 is composed of an interrogator 10 and transponders 20 to 22, a main carrier FC1 is transmitted from the interrogator 10, a reflected wave f1 is returned from the transponder 20, a reflected wave f2 is returned from the transponder 21, and a reflected wave f3 is returned from the transponder 22. In each of the transponders 20 to 22, the received main carrier is secondarily modulated by using a sub carrier signal which is primarily modulated by an information signal, and the reflected waves f1 to f3 are returned. The frequency of the sub carrier signal is hopped differently for each transponder and in accordance with lower two bits of a transponder ID, a hopping start frequency is made different. Further, in accordance with a value of bits in transmission data, the hopping frequency is made different. <P>COPYRIGHT: (C)2004,JPO</p> |
