Abstract: Through a microcontroller, control signals are transferred to a transmitting and receiving unit or configuration data are transferred. Through the transmitting and receiving unit, in a first operating state transmission signals are issued, while controlling the control signals of the microcontroller. Upon a first specified event, the transmitting and receiving unit is switched to a second operating state through a one-time transfer of corresponding configuration data by the microcontroller. In the second operating state, the transmitting and receiving unit automatically transmits repeated transmission signals. The microcontroller immediately switches to a current-saving or non-current, inactive operating state after said microcontroller has switched the transmitting and receiving unit to the second operating state.

Abstract: An electric circuit for controlling the access and immobilizing a vehicle has a first antenna driver (12) for driving a first antenna (19) for emitting a signal (100) in the event of identification of an ID transmitter (3) for access control of a vehicle. A second antenna driver (24) is provided for driving a second antenna (21) for emitting a signal (104) in the event of identification of an ID transmitter (3) for the immobilizer of the vehicle. In addition, the electric circuit has a receiver device (14) for receiving a signal captured by an antenna (21) for the identification of an ID transmitter (3) for the immobilizer. The first antenna driver (12) and the receiver device (14) are commonly integrated into a semiconductor chip (1).

Abstract: The system has a uniform system architecture that is designed for an access authorization request both with and without the use of a transponder. Should a transponder be used, only a corresponding transponder must be fitted in the key that can interact with an immobilizer coil specially provided for this in a receiving unit of the motor vehicle. In this case, the corresponding system requirements have also already been taken into consideration in the system architecture. As a result, the different system requirements for access and right of use systems to a great extent provide flexibility.

Abstract: In a method for operating an electronic anti-theft system, data communication is effected between the control device and the key further to an access authorization request, whereby the control device unlocks the doors and deactivates an alarm system as a function of the data communication. The data communication for unlocking the doors and the data communication for disarming the alarm system are separate from each other. In this way, the mechanical unlocking of the doors can be initiated immediately after the data communication for unlocking the doors. The corresponding data communication for deactivating the alarm system is effected in parallel with this, whereby extensive cryptological data is exchanged between the control device and the key.

Abstract: In the device a controllable switch is built into the control device which enables the start authorization and by means of which the supply voltage with which this controllable switch is supplied can be switched off. To check a start authorization a diagnosis can be undertaken which is realized with known resistance elements in the voltage supply line between identification device holder and control device. This allows the voltage drops across the elements to be compared with the corresponding required values. Simple short circuiting of the starter or the ignition is thus no longer possible since this would be detected by the control device as a result of the changes in voltage drop. In addition a fault in the supply voltage or the feed lines can be definitively detected.

Abstract: A method, and a device for its implementation, for locating a transmitter and receiver device, are provided. At least one first transmitter and receiver device transmits a request with a predetermined transmission power, this request is received by at least one second transmitter and receiver device with a predetermined receiving power and after successful receipt the second transmitter and receiver device, of which there is at least one, transmits a response signal, with the response signal only being transmitted if the field strength of the transmitted signal in the position of the second transmitter and receiver device exceeds a specific threshold value or is within a threshold range and the threshold value or threshold range is predetermined by the first transmitter and receiver device by transmission to the second transmitter and receiver device.

Abstract: The transmitting and receiving station generates a interrogation code signal which is identical for all of the transponders. All of the transponders that receive the signal answer simultaneously at the same carrier frequency. In order to avoid signal collisions, the transponders are synchronized before and/or during the transmission of the response signals. As an alternative, each transponder is assigned a dedicated subcarrier frequency in addition to the main carrier frequency, which is the same for all of the transponders.

Abstract: A code signal generator (3) of a system for protecting against theft remains in the motor vehicle while it is not operating, this code signal generator (3) is disabled as soon as a door of the motor vehicle is opened and closed again and/or a security device (8, 9) is locked with another authorized code signal generator (3). The disabled code signal generator (3) is enabled again only if, after the opening of a door or after the unlocking of a locking device (8, 9), another code signal generator (3) in the vicinity outside the vehicle is recognized as authorized and a request signal which is triggered manually by the user for enabling the disabled code signal generator (3) is received by the control unit (1).

Abstract: In a method for operating an electronic anti-theft system, data communication is effected between the control device and the key further to an access authorization request, whereby the control device unlocks the doors and deactivates an alarm system as a function of the data communication. The data communication for unlocking the doors and the data communication for disarming the alarm system are separate from each other. In this way, the mechanical unlocking of the doors can be initiated immediately after the data communication for unlocking the doors. The corresponding data communication for deactivating the alarm system is effected in parallel with this, whereby extensive cryptological data is exchanged between the control device and the key.

Abstract: The system has a uniform system architecture that is designed for an access authorization request both with and without the use of a transponder. Should a transponder be used, only a corresponding transponder must be fitted in the key that can interact with an immobilizer coil specially provided for this in a receiving unit of the motor vehicle. In this case, the corresponding system requirements have also already been taken into consideration in the system architecture. As a result, the different system requirements for access and right of use systems to a great extent provide flexibility.

Abstract: In the device a controllable switch is built into the control device which enables the start authorization and by means of which the supply voltage with which this controllable switch is supplied can be switched off. To check a start authorization a diagnosis can be undertaken which is realized with known resistance elements in the voltage supply line between identification device holder and control device. This allows the voltage drops across the elements to be compared with the corresponding required values. Simple short circuiting of the starter or the ignition is thus no longer possible since this would be detected by the control device as a result of the changes in voltage drop. In addition a fault in the supply voltage or the feed lines can be definitively detected.

Abstract: A method of authenticating a first object to at least one further object, especially a vehicle to a key, is disclosed in which information is transmitted unidirectionally between the first object and at least one further object, the computation result is calculated from parts of the transmitted information in the receiving object in each case, the calculated computation result is compared with a computation result transmitted with the information, and only if these match is the sending object viewed as authenticated and the computation result declared invalid for further transmissions.

Abstract: A method, and a device for its implementation, for locating a transmitter and receiver device, are disclosed. At least one first transmitter and receiver device transmits a request with a predetermined transmission power, this request is received by at least one second transmitter and receiver device with a predetermined receiving power and after successful receipt the second transmitter and receiver device, of which there is at least one, transmits a response signal, with the response signal only being transmitted if the field strength of the transmitted signal in the position of the second transmitter and receiver device exceeds a specific threshold value or is within a threshold range and the threshold value or threshold range is predetermined by the first transmitter and receiver device by transmission to the second transmitter and receiver device.

Abstract: A code signal generator (3) of a system for protecting against theft remains in the motor vehicle while it is not operating, this code signal generator (3) is disabled as soon as a door of the motor vehicle is opened and closed again and/or a security device (8, 9) is locked with another authorized code signal generator (3). The disabled code signal generator (3) is enabled again only if, after the opening of a door or after the unlocking of a locking device (8, 9), another code signal generator (3) in the vicinity outside the vehicle is recognized as authorized and a request signal which is triggered manually by the user for enabling the disabled code signal generator (3) is received by the control unit (1).

Abstract: If a key (A) which is already assigned with authorization to a first object (A1) is placed in the vicinity of a second object (B), and this object (B) is placed in an initialization state, the data (X) of the key (A1) is written into the second object (B), or the data (Y) of the second object (B) is written into the key (A1). The key (A1) is then assigned with authorization to the second object (B). In this way, the key can be assigned to further objects (A, C) as authorized by means of an initialization.