Abstract: A keyless entry system allows operation of door locks, a trunk lid lock, a glove box lid lock, a steering lock device or so forth without mechanical keys. The keyless entry system includes electrically disconnected transmitter and a controller. The controller is connected to operate the devices. The transmitter is adapted to send a present code-indicative radio signal to the controller, which then compares the code contained in the radio signal from the transmitter with a preset code. The controller is provided with a dual-antenna system which ensures clear data transmission between the transmitter and the controller. The dual-antenna system includes at least a pair of antennas oriented essentially perpendicular to each other.

Abstract: A method for detecting an encoded radio signal involves comparing the received signal amplitude with a predetermined threshold amplitude. The difference between the received signal-component amplitude and the noise-component amplitude is derived and used to adjust the threshold amplitude. By adjustng the threshold amplitude depending upon the difference between the signal-component amplitude and the noise-component amplitude, mis-detection which could occur otherwise when the reception amplitude of the noise component is relatively high or the reception amplitude of the signal component is relatively low can be successfully and satisfactorily avoided.

Abstract: A keyless entry system allows fully automatic operation of a door lock device of an automotive vehicle. The system recognizes the presence and absence of an authorized user and automatically locks or unlocks the vehicle door lock device according to the presence or absence of the authorized user. The keyless entry system is provided with a controller mounted on a vehicle and designed to periodically generate a radio demand signal and transmit same at regular intervals. A radio code signal transmitter is normally in a stand-by state in which it is ready to transmit a radio code signal indicative of a preset code in response to the radio demand signal. The radio code signal transmitter is of a pocket-portable size for convenient transport by an authorized user. The radio signal transmission between the controller and the radio code signal transmitter is performed within a predetermined distance range around the vehicle.

Abstract: An antenna for an automotive keyless entry system can ensure radio-wave transmission between a transmitter and a controller and can be conveniently mounted on a vehicle body. The antenna for an automotive keyless entry system, has a first planar antenna loop, and a second antenna loop disposed within the first antenna loop and lying in the plane thereof. The axis of the second antenna loop is substantially perpendicular to the axis of the first antenna loop. The first and second antenna loops form an antenna assembly which can be conveniently mounted on the vehicle body as, for example, within a door mirror of the vehicle.

Abstract: A keyless entry system can lock and unlock an automotive vehicle door, a trunk lid, a glove box and/or a steering column without an ignition key. The system comprises a transmitter producing a radio signal indicative of a preset unique code, and a controller receiving the radio signal and performing desired locking or unlocking operation when the code from the transmitter matches a preset code. A manual switch is provided to order the transmitter to transmit the code-indicative radio signal to the controller. The transmitter encloses a battery acting as a power source. A battery checker is provided to produce an alarm when the battery voltage becomes lower than a predetermined voltage.

Abstract: An improved positioning system for a vehicle is shown. In the system, when radio wave can be received from only one satellite, the current position of the vehicle is computed based on a pair of navigational data, which are brought by radio wave received at the current time and by radio wave received at an earlier time.

Abstract: A keyless entry system can lock and unlock an automotive vehicle door, a trunk lid, a glove box and/or a steering column without an ignition key. The system comprises a transmitter producing a radio signal indicative of a preset unique code, and a controller receiving the radio signal and performing desired locking or unlocking operation when the code from the transmitter matches a preset code. A manual switch is provided to order the transmitter to transmit the code-indicative radio signal to the controller. The controller is disabled when a preselected vehicle condition is detected, for example the ACC or ON position of an ignition switch or the presence of an ignition key in an ignition key hole.

Abstract: A keyless entry system for an automotive vehicle allows operation of a vehicle device or devices without the need for an ignition key or other mechanical keys. A user can simply depress a single push-button or operate another suitable type of switch to activate the system and operate the desired vehicle device to the desired position. The system generally comprises a pocket-portable radio signal transmitter and a controller mounted on the vehicle and associated with the vehicle device. The transmitter has a small, long-life battery and the controller receives electric power from the vehicle battery. Power conservation for both the transmitter and the controller is achieved by activating them for limited periods in response to operation of the manual switch.

Abstract: A keyless entry system allows operation of various vehicle devices including a door lock without using a mechanical key, such as an ignition key. The system comprises a wireless, portable transmitter adapted to produce a radio signal indicative of a unique code preset in the transmitter, and a controller mounted on the vehicle and associated with the vehicle devices. The controller has a preset code to compare with the unique code indicative in the radio signal transmitted from the transmitter. The controller also detects impending or accomplished locking of the transmitter in the vehicle and produces an alarm and subsequently disables the keyless entry system unless the transmitter is removed from the vehicle within a given period of time after the alarm is given.

Abstract: A keyless entry system can lock and unlock an automotive vehicle door, a trunk lid, a glove box and/or a steering column without an ignition key. The system comprises a transmitter producing a radio signal indicative of a preset unique code, and a controller receiving the radio signal and performing desired locking or unlocking operation when the code from the transmitter matches a preset code. A manual switch is provided to order the transmitter to transmit the code-indicative radio signal to the controller. The transmitter encloses a battery acting as a power source. Locking the transmitter in the vehicle is detected by detecting that the code signal level remains substantially unchanged for a given period of time after the vehicle is locked. In such cases, an alarm is produced to remind the driver to remove the transmitter from the vehicle cabin by operating the manual switch to open the door.