Abstract: A receiver includes two reception antennas, which receive a modulated wave (transmission signal) from each of transmitters, a selection circuit, which alternately selects one of the two reception antennas at a predetermined switching cycle to alternately obtain the modulated wave from the two reception antennas, and a demodulation section, which generates a demodulated signal by demodulating the modulated wave obtained at the selection circuit. The switching cycle is 27 ?s, which is 1/7.4 of the transmission time of data per symbol in the transmission signal from each transmitter, that is, 200 ?s. In other words, the modulated waves from the two reception antennas are alternately obtained at least seven times each while the data of one symbol is transmitted.

Abstract: A receiver 4 includes two reception antennas 11, which receive a modulated wave (transmission signal) from each of transmitters 3, a selection circuit 12, which alternately selects one of the two reception antennas 11 at a predetermined switching cycle to alternately obtain the modulated wave from the two reception antennas 11, and a demodulation section (15, 16), which generates a demodulated signal by demodulating the modulated wave obtained at the selection circuit 12. The switching cycle is 27 ?s, which is 1/7.4 of the transmission time of data per symbol in the transmission signal from each transmitter 3, that is, 200 ?s. In other words, the modulated waves from the two reception antennas 11 are alternately obtained at least seven times each while the data of one symbol is transmitted.

Abstract: A portable remote controller for a tire status detector, includes a portable casing, a transmission circuit disposed in the casing, a low-pass filter disposed at an output side of the transmission circuit for permitting a signal with a frequency of not more than the first frequency to pass through the low-pass filter, a receiving circuit disposed in the casing, a high-pass filter disposed at an input side of the receiving circuit for permitting a signal with a frequency of not less than the second frequency to pass through the high-pass filter, a ferrite bar antenna housed in the casing and having a ferrite bar wound with an antenna coil, the antenna coil having two terminals, one of which being connected to the ground and the other being connected in common to the low-pass and high-pass filers and a duplexer composed of the low-pass and high-pass filters. The ferrite bar antenna is used both for transmission of the long wave signals and for receipt of the ultra high frequency signals.

Abstract: A portable remote controller for a tire status detector, includes a portable casing, a transmission circuit disposed in the casing, a low-pass filter disposed at an output side of the transmission circuit for permitting a signal with a frequency of not more than the first frequency to pass through the low-pass filter, a receiving circuit disposed in the casing, a high-pass filter disposed at an input side of the receiving circuit for permitting a signal with a frequency of not less than the second frequency to pass through the high-pass filter, a ferrite bar antenna housed in the casing and having a ferrite bar wound with an antenna coil, the antenna coil having two terminals, one of which being connected to the ground and the other being connected in common to the low-pass and high-pass filers and a duplexer composed of the low-pass and high-pass filters. The ferrite bar antenna is used both for transmission of the long wave signals and for receipt of the ultra high frequency signals.