Abstract: A tire air pressure monitoring system includes: a data acquisition unit that acquires tire air pressure data at each fixed detection period; a storage unit that stores newly acquired air pressure data P(0), and air pressure data P(1) to P(N) acquired 1 to N periods prior to the air pressure data P(0); a determination unit that determines a state in which air pressure has decreased, on the basis of air pressure data; and a communication unit that transmits a determination result of the determination unit to an external device, in which the determination unit compares each piece of the air pressure data P(1) to P(n) with the air pressure data P(0) to calculate decrease values, compares the decrease values with a preset first threshold value (th1), and determines that tire air pressure is decreasing when at least one decrease value is greater than or equal to the first threshold value.

Abstract: A receiving module selects frequencies to be used for data request signals from all channels if there is no channel prohibited from being used, and if there are channels prohibited from being used, the receiving module selects frequencies to be used for data request signals from channels other than the channels prohibited from being used. In the case failed in acceptance of measured data from a sensor module, the receiving module sets communication channels failed in acceptance of measured data predetermined times to prohibited channels from being used. In this manner, when the receiving module transmits the data request signals to the sensor module, frequencies of channels having jamming radio waves and the like could not be selected by the receiving module, thereby enabling the receiving module to select the frequencies of high probability in communication reception.

Abstract: A receiving module selects frequencies to be used for data request signals from all channels if there is no channel prohibited from being used, and if there are channels prohibited from being used, the receiving module selects frequencies to be used for data request signals from channels other than the channels prohibited from being used. In the case failed in acceptance of measured data from a sensor module, the receiving module sets communication channels failed in acceptance of measured data predetermined times to prohibited channels from being used. In this manner, when the receiving module transmits the data request signals to the sensor module, frequencies of channels having jamming radio waves and the like could not be selected by the receiving module, thereby enabling the receiving module to select the frequencies of high probability in communication reception.

Abstract: The present invention provides a tire/wheel assembly that ensure a proper function of a tire-information transmitter even in a severe use condition, installation and fixing devices for the tire-information transmitter which has a superior workability, and a method of mounting a tire-information transmitter in a simple manner. In a tire/wheel assembly in which the tire is mounted on the wheel, a ring-shaped elastic body equipped with a tire-information transmitter is provided along a periphery of the rim base of the rim of the wheel.