Tire inner pressure measurement system

A tire inner pressure measurement system comprising:

• a detector that detects the inner pressure of a tire and an acquisition apparatus that acquires data regarding the inner pressure of the tire detected by the detector, wherein
• the detector comprises:
• a resonance circuit that includes:
• a capacitive sensor having capacitance changed according to a change in an inter-electrode distance by the inner pressure of the tire;
• and a detection-side antenna unit formed by a coil, the coil being obtained by winding a conductive wire around a coil material, the antenna unit being connected to the capacitive sensor,
• the acquisition apparatus comprises:
• an acquisition-side antenna unit that is formed by a coil obtained by winding a conductive wire around a coil material, that generates electromotive force in the detection-side antenna unit by electromagnetic induction, and that acquires resonant waveforms of the resonance circuit including the capacitive sensor charged by the electromotive force and the detection-side antenna unit;
• a driving unit that applies electromotive force to the detection-side antenna unit;
• a signal amplification unit that amplifies the resonant waveforms;
• a division unit that divides a predetermined number of waveforms among the amplified resonant waveforms;
• a conversion unit that converts a period from rise to fall of a waveform obtained by dividing the waveforms into a voltage value;
• and
• a pressure calculation unit that calculates the inner pressure of the tire based on the voltage value converted by the conversion unit.