Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
2000-07-03
2002-03-05
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
C701S024000, C701S032000, C701S033000, C701S036000, C340S993000, C340S995190, C340S983000, C340S990000, C340S426110, C340S572100, C340S870030, C340S573300, C342S450000, C342S457000, C342S357490, C342S357490, C455S073000, C455S066100, C455S431000, C455S422100, C375S219000, C375S220000, C375S221000, C370S320000, C370S335000, C370S342000, C370S441000
Reexamination Certificate
active
06353776
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a control system and method for controlling at least one function of an object, in which measures for preventing an unauthorized use or access to the object are taken. The invention also relates to an access control and driving authorization device for a motor vehicle.
Access control systems, immobilizer systems, or other control systems whose functions are enabled or controlled only when there is proven authorization of a code transmitter, for example, in the form of a Smart Card or an electronic key that is interrogated by wireless communication, are known for motor vehicles. See, for example, U.S. Pat. No. 4,763,121 to Tomoda et al. Usually, to accomplish this purpose, at least one base station with a transceiver unit, i.e., for controlling the access control or the immobilizer device, is disposed on or in the motor vehicle. In reaction to a triggering event, for example, the activation of a door handle or an ignition starter knob, an interrogation code signal is emitted at regular or irregular intervals. An authorized code transmitter, carried by the user and serving as a key, responds to the interrogation code signal with a response code signal. Such communication is also referred to as an interrogation/response dialog.
The base station checks the received response code signal in terms of its authorization, for example, by comparing a code information item contained in the response code signal with a stored reference code information item. If authorization is given, the desired function is carried out, for example, the motor vehicle doors are unlocked or the immobilizer is released.
In such a system, there may also be security problems, for example, as a result of unauthorized monitoring and deliberate modification of the wireless communication between the motor vehicle and the code transmitter. To solve these problems, there exists a device for controlling functions of an object, in particular, the access and driving authorization control for a motor vehicle. See, i.e., German Patent DE 196 32 025 C2. In the device, the length of the communication of the interrogation/response dialog is measured and is compared with a predefined maximum duration. However, the signal propagation times are very short in comparison with the computing times, with the result that prolonged signal propagation times are not evident. Therefore, the signal propagation times cannot be used as a protection against deliberate data modification by unauthorized parties.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a control system and method for controlling at least one function of an object and access control and driving authorization device for a motor vehicle that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that has an increased level of protection against unauthorized attempts at use, without requiring considerable interventions into the system, and that provides an improvement in comparison with unauthorized execution of the associated function.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a control system for controlling at least one function of an object, including a base station disposed at an object and having a transceiver unit with a transmitter unit formed to transmit an interrogation signal, a portable code transmitter formed to emit a response signal with a code information item in response to the interrogation signal, the base station checking an authorization of the code information item contained in the response signal and, in the case of an authorized response signal, the base station enabling an object-specific function, at least one of the base station and the code transmitter determining a time period between a transmission of at least one part of the interrogation signal and a reception of a part of the interrogation signal obtained in reaction to the interrogation signal, and comparing the time period with a predefined reference time period, the base station enabling the object-specific function only if the measured time period is shorter than the reference time period even if the code information item of the response signal is correct, an evaluation circuit in at least one of the code transmitter and the base station for evaluating the code information item, a transmitter antenna, and a bypass path through which parts of the interrogation signal are routed to the transmitter antenna, the bypass path bypassing the evaluation circuit.
In the invention, the time period between the transmission of marked parts of a transmit signal and the reception of these parts is determined in one of the units involved. For example, the system reaction time is measured in order to determine the distance between the code transmitter and the base station disposed at the object end. The measurement is preferably carried out in the base station for reasons associated with power technology, logic, or the system, but depending on the system configuration the code transmitter can also perform it.
When there is an unauthorized remote interrogation, the very much longer signal paths and the internal processing times of the intermediately connected signal amplifiers result in significantly longer processing times than in the case of an authorized code transmitter that is located near to the motor vehicle, and, thus, longer delays between the emission of the signal and the reception of the response signal. In such a case, the evaluation circuit measures the time period between the emission of the signal and the reception of at least one or more marked sections or parts of the signals, and compares these time periods. In the simplest case, the time period is compared with a previously defined reference time period that is sufficient for the signal to be received back from an authorized code transmitter located near to the motor vehicle, but is usually exceeded in the case of an unauthorized remote interrogation due to the above mentioned influences.
The base station is configured according to the invention such that it executes or enables the desired function only if at least the particularly characterized parts of the signals have been received within the predefined time period.
In order to eliminate internal time delays that are due to the system and cannot be calculated precisely—especially long time delays—and which are caused by the processing operations, necessary at the receiver end (for example, code transmitter end), which relate to the reception of an interrogation signal, the detection and evaluation of the interrogation signal, the generation/calculation of a response signal and its emission, the system component which generates the response signal (here the code transmitter) is preferably equipped with a bypass path through which at least a marked part of the received signal can be conducted directly to the transmitter (transmitting amplifier and/or antenna), bypassing the system component's own evaluation circuit, and thus transmitted back, virtually without delay, to the component that transmitted the signal.
The appropriate parts are reflected without delay, apart from the short group delay (transparent mode of the code transmitter). The delay between the emission and reception of a signal is then essentially only conditioned by propagation time so that a distance measurement takes place between the base station and the code transmitter. Additional analog or digital processing of the original signal would entail additional processing times that would be significantly longer than the signal propagation time in free space.
In accordance with another feature of the invention, there is provided at least one switch disposed in the bypass path and formed to selectively disconnect and connect the bypass path into the evaluation circuit.
The bypass path is preferably provided with a controllable switch so that the bypass path causes parts of the received si
Gold Peter
Röhrl Thomas
Greenberg Laurence A.
Lerner Herbert L.
Mancho Ronnie
Nguyen Tan
Siemens Aktiengesellschaft
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