Abstract: An antenna device includes a ground plate which is a flat plate-shaped conductor member, an opposing conductive plate which is a flat plate-shaped conductor member installed at a predetermined distance from the ground plate and is electrically connected to a power supply line, and a plurality of short-circuit pins for electrically connecting the opposing conductive plate and the ground plate. One end of a plurality of short-circuit pins extends to a conductive plate plane, which is a plane including the opposing conductive plate, and the other end of the plurality of short-circuit pins extends to the ground plate plane, which is a plane including the ground plate. One or more of the plurality of short-circuit pins connect the opposing conductive plate and the ground plate.

Abstract: In a wireless communication system, a portable device transmits a first signal spread based on a reference period indicated by a synchronization signal transmitted from an in-vehicle device and transmits a second signal spread based on an operation by a user. The in-vehicle device sets a search period based on a variation range in a delay time from when the synchronization signal is transmitted to when the spread first signal is transmitted and sets a residual period that starts at an ending point of the search period and ends at an ending point of the reference period when a starting point of the reference period is set at a starting point of the search period. When the in-vehicle device fails in a synchronous acquisition for the search period, the in-vehicle device performs a synchronous acquisition process for the residual period.

Abstract: A receiving device for spread spectrum communication includes a phase determining unit and a data demodulating unit. The receiving device receives a signal spread and modulated with first spreading code. The phase determining unit calculates a cross correlation between the received signal and a second spreading code and determines a phase P(0) of the received signal based on the cross correlation. The data demodulating unit synchronizes the phase P(0) and the first spreading code and despreads and demodulates the received signal with the first spreading code. The number of components in each of the first spreading code and the second spreading code is an integer greater than or equal to 2.

Abstract: When a demodulated signal of a radio signal in Ch1 transmitted from a TPMS transmitter is acquired, a control IC controls the frequency of a signal inputted from a PLL circuit to a mixer into a frequency for converting a TPMS radio signal into an intermediate frequency signal of a specific frequency. When the demodulated signal of the radio signal transmitted from a portable unit through two frequency channels is acquired, the control IC determines a channel whose state of communication is favorable from between Ch2 and Ch3, and controls the signal frequency for conversion into a frequency for converting a keyless radio signal in the determined channel into an intermediate frequency signal.

Abstract: When a vehicle door locking operation is conducted, an in-vehicle device checks the vehicle compartment to determine whether a mobile unit exists in the vehicle compartment. When the in-vehicle device receives a response from the mobile unit indicating its presence in the compartment, the in-vehicle device receives a response from the mobile unit, prohibits the door from locking, and activates a buzzer. The mobile unit thus can be prevented from being locked in the vehicle compartment. When the mobile unit receives the search signal, it sounds its buzzer, thereby making it possible to further indicate its location within the compartment.

Abstract: In a wireless communication system, a portable device transmits a first signal spread based on a reference period indicated by a synchronization signal transmitted from an in-vehicle device and transmits a second signal spread based on an operation by a user. The in-vehicle device sets a search period based on a variation range in a delay time from when the synchronization signal is transmitted to when the spread first signal is transmitted and sets a residual period that starts at an ending point of the search period and ends at an ending point of the reference period when a starting point of the reference period is set at a starting point of the search period. When the in-vehicle device fails in a synchronous acquisition for the search period, the in-vehicle device performs a synchronous acquisition process for the residual period.

Abstract: A receiver for spread spectrum communication includes a receiver for receiving a wireless signal, a demodulator for demodulating the wireless signal into a spread spectrum signal, a correlation value calculator for calculating a correlation value between the spread spectrum signal and a spreading code having a predetermined number of chips, a synchronization detector for detecting a synchronization point between the spread spectrum signal and the spread signal based on the correlation value, a despreading device for despreading the spread spectrum signal based on the synchronization point, a noise level detector for detecting a noise level of the wireless signal, and a code number setting device for determining the number of chips of the spreading code in such a manner that there is a positive correlation between the noise level and the number of code portions.

Abstract: A receiving device for spread spectrum communication includes a phase determining unit and a data demodulating unit. The receiving device receives a signal spread and modulated with first spreading code. The phase determining unit calculates a cross correlation between the received signal and a second spreading code and determines a phase P(0) of the received signal based on the cross correlation. The data demodulating unit synchronizes the phase P (0) and the first spreading code and despreads and demodulates the received signal with the first spreading code. The number of components in each of the first spreading code and the second spreading code is an integer greater than or equal to 2.

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: When a door locking operation is conducted in a vehicle, an in-vehicle device executes a vehicle compartment checking to check whether a mobile unit exists in the vehicle compartment. When the in-vehicle device receives a response from the mobile unit, the in-vehicle device transmits a search signal to the mobile unit, prohibits the door locking, and activates a buzzer, etc. The mobile unit can be prevented from being blocked in a vehicle compartment. When the mobile unit receives the search signal, it blows the buzzer, thereby making it possible to indicate the location of its existence.

Abstract: A mobile unit for an electronic key system includes an LF receiver unit that receives a radio signal transmitted from an in-vehicle device by an electric wave of an LF band, a UHF transmitter unit that transmits a radio signal to the in-vehicle unit by an electric wave of a UHF band. The mobile unit also includes a UHF receiver unit that receives a search signal transmitted from another mobile unit by an electric wave of the UHF band, and a buzzer that notifies outside existence thereof when the search signal is received by the UHF receiver unit. The UHF transmitter unit can transmit the search signal to the mobile unit in addition to the radio signal to the in-vehicle device.

Abstract: A smart portable device transmits a keyless radio signal for a keyless entry system by two frequency channels. In an integrated tuner, a control IC determines a frequency channel having a better communication state, and controls a frequency of a signal that is input to a mixer from a PLL circuit to a frequency for converting the keyless radio signal of the determined frequency channel into an intermediate frequency signal. This configuration makes it possible to share a circuit for receiving the keyless radio signals of those two frequency channels, and to receive the keyless radio signal of the frequency channel having the better communication state to surely conduct communication.

Abstract: When a demodulated signal of a radio signal in Ch1 transmitted from a TPMS transmitter is acquired, a control IC controls the frequency of a signal inputted from a PLL circuit to a mixer into a frequency for converting a TPMS radio signal into an intermediate frequency signal of a specific frequency. When the demodulated signal of the radio signal transmitted from a portable unit through two frequency channels is acquired, the control IC determines a channel whose state of communication is favorable from between Ch2 and Ch3, and controls the signal frequency for conversion into a frequency for converting a keyless radio signal in the determined channel into an intermediate frequency signal.