| 摘要 |
PCT No. PCT/FR91/00026 Sec. 371 Date Aug. 22, 1991 Sec. 102(e) Date Aug. 22, 1991 PCT Filed Jan. 18, 1991 PCT Pub. No. WO91/11063 PCT Pub. Date Jul. 25, 1991.A device for the bi-directional transmission of data between a master system and a slave system uses a single transmission antenna and a single reception antenna each tuned to the same frequency; the master system comprises first data transmission circuits for transmitting first data to the slave system by modulating an electromagnetic signal at the frequency; detection circuits for detecting, during the transmission of the electromagnetic signal, variations in electrical characteristics of the master system induced by a modulation of the impedance of the slave system as a function of second data to be transmitted from the slave system to the master system; and restoring circuits for restoring the second data on the basis of the detected variations; and the slave system comprises reception circuits connected to the reception antenna for restoring the first data; a rectifier circuit connected across the reception antenna for rectifying an electrical signal induced in the reception antenna by the electromagnetic signal; a power supply circuit connected to the rectifier circuit for powering the circuits and the loads of the slave system with a DC voltage on the basis of energy from the rectified electrical signal; and a switching circuit connected in series between the rectifier circuit and the power supply circuit to modulate the real part of the impedance of the slave system between a high value and a low value when the switching circuit is driven in its opened and closed position by a control signal representative of the second data.
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