Communications: electrical – Land vehicle alarms or indicators – Of burglary or unauthorized use
Reexamination Certificate
1999-10-12
2001-03-27
Hofsass, Jeffery A. (Department: 2736)
Communications: electrical
Land vehicle alarms or indicators
Of burglary or unauthorized use
C340S870030, C340S870030, C340S870030, C340S429000, C340S435000, C340S438000
Reexamination Certificate
active
06208239
ABSTRACT:
BACKGROUND OF THE INVENTION
With engine-driven vehicles, access authorization to the vehicle is subdivided into two separate processes: actual access to the vehicle on the one hand (closing/opening the vehicle by closing/opening the vehicle doors), and starting the vehicle on the other hand (the start process for the vehicle engine, initiated by operating the ignition lock).
Normally, access authorization to the vehicle is provided by mechanical means, that is, by means of a conventional car key. However, increasingly access authorization is also provided by electronic processes and techniques; in such cases, encoded signals will be transmitted between an electronic key and at least one transmission unit located in or on the vehicle (in particular, on the periphery of the vehicle). Thus, for example, encoded signals will be transmitted between an electronic key and a door lock for unlocking the door lock, and/or between a remote control unit and a drive control unit and/or an anti-theft device (a vehicle immobilizer) to release the drive control unit; following evaluation and verification of the signals, as well as meeting specific conditions if necessary, authorized access to the vehicle will be provided.
For these two separate access authorization processes—access to the vehicle on the one hand, and starting the vehicle on the other hand—different operator activities are usually required, as well as different conditions to be met: thus, for example, a vehicle may be started up only if the electronic key is located inside the vehicle; also, for safety reasons, it should only be possible to lock the vehicle doors if the electronic key is located outside the vehicle. Therefore, the two access authorization processes must be differentiated; to this end, the position of the electronic key needs to be determined—in particular, it must be possible to identify its position relative to the vehicle interior and exterior (“interior detection”).
OBJECT OF THE INVENTION
The invention is based on the task to state a procedure for providing access authorization to an engine-driven vehicle in accordance with the preamble of patent claim
1
wherein a reliable access authorization is provided in a simple fashion for authorized operators. In accordance with the invention, this task is solved by the features described in the characterizing clause of patent claim
1
.
Advantageous embodiments of the invention result from further patent claims.
SUMMARY OF THE INVENTION
With the process described here, if there is an operator request for the provision of access authorization to an engine-driven vehicle—that is, either for providing access to the vehicle by carrying out a locking or opening operation on the vehicle doors, or for providing vehicle startup by carrying out an engine start process,—a bidirectional signal transmission (bidirectional communication) between at least two (preferably, however, at least three) transmission units permanently mounted in or on the vehicle and the electronic key carried by the operator will be performed, during which transmission at least the signal run time for the bidirectionally transmitted signals between the respective transmission unit and the electronic key will be determined. The distance between the transmission units and the electronic key is obtained by evaluating this signal run time value, that is by determining the time difference between the vehicle signal, in particular the activation signal transmitted as a first vehicle signal at the start of the signal transmission (communication), transmitted by the respective transmission unit to the electronic key, and the key signal (echo signal) returned from the electronic key and received by the respective transmission unit; the evaluation of this signal run time measurement may be effected e.g. by means of a control unit connected with the transmission units. In order to suppress undesirable echo effects in the key signal (that is, in order to distinguish the desired echo signal from undesirable echo signals) it is possible to use various different methods: for example, the key signal returned from the electronic key to the respective transmission unit may be emitted only on expiry of a specific predefined delay time following reception of the vehicle signal, which delay time needs to be taken into appropriate account when measuring signal run time and determining the distance; or the desired echo signal can be characteristically “colored” (e.g. by a frequency offset between the frequency of the vehicle signal and the frequency of the key signal). As successive signal run time measurements are carried out between at least two (preferably at least three) transmission units, located in different positions on the vehicle, and the electronic key, the position of the latter may be determined by comparing and evaluating the signal run times of the key signals being received by the various different transmission units. In particular, limit values for the signal run time can be specified, e.g. for the maximum permissible signal run time (by specifying a maximum limit) and/or for reliable signal run time ranges (by specifying maximum and minimum limits) which will define the maximum permissible distance and/or reliable distance ranges for signal transmission (communication) between the electronic key and the transmission units or the vehicle; that is, the execution of the operator request (release of the process requested by the latter for the provision of access authorization) will be carried out only if there exists a specified distance range. On the one hand, this allows the permissible signal transmission distance to be limited (and, in consequence, the permissible distance of the operator from the vehicle for executing the operator request or for the provision of access authorization), and, on the other hand, this also allows a differentiation between the vehicle interior and the vehicle exterior (interior detection). In particular, different limit values for the signal run time and thus different permissible distance ranges may be specified for access to the vehicle and for vehicle startup, allowing simple adaptation to different vehicles and/or different vehicle types.
In connection with the signal transmission, and for determining the position of the electronic key, it is additionally possible to carry out also a (bidirectional) data transmission between the electronic key and the transmission units, e.g. for transmitting cryptological data (e.g. by means of challenge and response protocols) and/or data required for localisation (e.g. for identifying the respective transmission unit or for a transmission unit ID). Using these transmitted data, a verification of the electronic key can be effected, that is, the right of the operator for effecting access authorization can be checked.
The bidirectional signal transmission between the transmission units and the electronic key can be effected either by means of impulses or by means of continuous signals (cw process) using a suitable modulation, and by means of a suitable transmission principle (e.g. HF, IR, or ultrasound) preferably within the microwave range. The transmission signals from the transmission units and the electronic key, that is, the vehicle signal and the key signal can be emitted at the same transmission frequency (carrier frequency) or at different transmission frequencies, e.g. within the HF range in an ISM band having a transmission frequency of e.g. 2.4 GHz or 5.8 GHz. Here, for signal transmission, a high bandwidth of the transmission signals—necessary for high resolution time measurement—needs to be implemented (e.g. >10 MHz) in order to enable the required distance resolution for localizing the current position of the electronic key (of the authorized operator). The bidirectional signal transmission between the transmission units and the electronic key is effected at a high transmission rate, e.g. at a transmission rate in excess of 100 kBaud. In the case of an impulse type signal transmission, a suitable impulse modulation proces
Knepper Udo
Muller Karl-Heinz
Ulke Walter
Voss Wolfgang
Daimler-Chrysler AG
Hofsass Jeffery A.
Kunitz Norman N.
Nguyen Hung
Venable
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