| 摘要 |
A transponder includes an antenna, a modulation/demodulation unit (diode) that modulates and demodulates signals received and transmitted from and to a controller, a pressure resonator including a first piezoelectric single-crystal resonating element and a pressure sensor. The resonance frequency of the pressure resonator changes in accordance with a change in tire pressure, and a reference resonator includes a second piezoelectric single-crystal resonating element and a capacitor, where the resonance frequency of the reference resonator is unaffected by the change in tire pressure. The first and second piezoelectric single-crystal resonating elements are integrally formed on a single-crystal piece. The controller transmits a signal for resonating the pressure resonator and the reference resonator, receives signals modulated with the resonance frequencies of the pressure resonator and the reference resonator, and computes a measured value in accordance with the resonance frequencies of the two resonators retrieved from the received signals.
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