Abstract: A sensor transceiver is kept in a state capable of receiving LF waves. Upon receiving LF waves indicating a start command from the vehicle-body system, the sensor transceiver is caused to be in a state capable of receiving RF waves accordingly. Upon receiving an instruction command from the vehicle-body system under the state capable of receiving RF waves, the sensor transceiver notifies the vehicle-body system of data on tire pressure.

Abstract: An electronic key system includes an in-vehicle unit mounted in a vehicle and a portable unit. When a user leaves the vehicle, the in-vehicle unit requests information on a relative position of the vehicle relative to a landmark object near the vehicle from a vehicle navigation device and transmits received relative position information to the portable unit. The portable unit stores the received relative position information, and notifies of the stored relative position information according to a user's operation.

Abstract: In an electronic key system for a vehicle, an in-vehicle unit transmits a request of response to a mobile unit together with information of a priority channel, and receives a response from the mobile unit by using the priority channel. If the response is not received successfully, the in-vehicle unit automatically changes and tries the transmission and reception again. If the response from the mobile unit is successfully received by using the changed channel, this channel is stored in a memory to be used as the priority channel in subsequent communications with the mobile unit.

Abstract: In a certification system, a smart security controller transmits to a portable terminal a designation request signal for which a response frequency is designated. In a case where any signal cannot be received within a preset allowable time period after the transmission of the designation request signal, the smart security controller transmits a designation request signal whose response frequency has been altered to a different frequency. The portable terminal selects the response frequency designated by the designation request signal, and transmits a reception response signal to the smart security controller at the selected response frequency. Accordingly, the response signal can be prevented from becoming unreceivable on account of the radio interference of the response signal.

Abstract: An on-board receiver device includes a receiver having two antennas and a controller for controlling operation of the receiver. A first input signal from a keyless entry system and a second input signal from a tire pressure monitoring system are wirelessly transmitted to the receiver. Two input signals have different frequencies from each other. One of the input signals is selected at a time and processed through the receiver to obtain a base band signal (data signal) included in the input signal. In this manner, two input signals can be handled in a single receiver device without causing confusion between two input signals.

Abstract: In a radio receiver integrated vehicular meter unit, a receiver circuit of the radio receiver is arranged on the side of a meter circuit board opposite to the side on which a CPU and a communication IC included in a meter circuit are mounted. The distance between the receiver circuit board and the CPU or the communication IC increases by the thickness of the meter circuit board. As a result, a receiver circuit formed on the receiver circuit board is less affected by noise caused by the CPU or the communication IC.

Abstract: When an acceleration sensor is used, it is attached to a measured object to detect an acceleration applied to the object. The acceleration sensor includes a package having at least one chamber. A sensor element is disposed in the chamber and has a portion which vibrates in response to the acceleration. Damping liquid is sealed within the package and has a quantity which allows the sensor element to be submerged in the damping liquid and which allows a predetermined quantity of gas to remain in the package. The gas absorbs a thermally-induced volume change of the damping liquid. In the absence of the acceleration, a gas bubble is prevented from separating from the gas. In addition, the gas bubble is prevented from staying in the chamber.