| 摘要 |
<p>PROBLEM TO BE SOLVED: To exchange data in a simple constitution without using a semiconductor element of a high breakdown strength by generating a reference signal which is of the same frequency as the carrier wave of a received transmission signal and is phase-synchronized, and PSK-modulating a response data string with this reference signal for transmission from an antenna. SOLUTION: Various kinds of data are transmitted and received without contact between a read-writer and an IC card carried with by a user. An IC card modulating and demodulating circuit 5 takes part of energy received by the antenna 4 into a power supply circuit 19 to supply to the circuit 5 and a signal processing circuit. A carrier extractor 20 consisting of a PLL circuit generates a reference signal CK phase-synchronized with the carrier wave of a transmission signal. Based on this reference signal CK, a demodulator 22 detects transmission data D (R→C) to send to the signal processing circuit. A modulator 23 modulates the signal CK with a response data string D (C→R) to generate a response signal for transmission through a level adjuster 24 and the antenna 4.</p> |
