| 摘要 |
A device (1) for detecting the presence of at least one between a first type of transponder (20) and a second type of transponder (21), operating respectively at a high-frequency and at a low-frequency. The device comprises a pulse generator (8), which is adapted to generate pulses (22) at a preset repetition frequency, a first resonator (4), which is tuned to a first resonance frequency and is connected to the pulse generator (8), so as to generate an oscillating signal (24, 25, 26) in response to the pulses (22), and a circuit (5) for measuring the amplitude of the oscillating signal (24, 25, 26) connected to the resonator (4). The first resonance frequency is lower than the pulse repetition frequency and the device comprises means (12) for detecting the presence of the first type of transponder (20) and of the second type of transponder (21). These means can also discriminate the first type of transponder (20) from the second type of transponder (21) on the basis of a respectively negative and positive variation of the amplitude of the oscillating signal (25, 26) with respect to the amplitude of the oscillating signal (24) in the absence of the transponders. |
