EP0994998A1 - Anti-theft device for vehicule - Google Patents

Anti-theft device for vehicule

Info

Publication number
EP0994998A1
EP0994998A1 EP98928073A EP98928073A EP0994998A1 EP 0994998 A1 EP0994998 A1 EP 0994998A1 EP 98928073 A EP98928073 A EP 98928073A EP 98928073 A EP98928073 A EP 98928073A EP 0994998 A1 EP0994998 A1 EP 0994998A1
Authority
EP
European Patent Office
Prior art keywords
signal
antennas
motor vehicle
protection system
antenna
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98928073A
Other languages
German (de)
French (fr)
Inventor
Tilmann Seubert
Peter Gold
Ulrich Emmerling
Maximilian Löffler
Karl-Jürgen PETERS
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP0994998A1 publication Critical patent/EP0994998A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/0701—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips at least one of the integrated circuit chips comprising an arrangement for power management
    • G06K19/0712—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips at least one of the integrated circuit chips comprising an arrangement for power management the arrangement being capable of triggering distinct operating modes or functions dependent on the strength of an energy or interrogation field in the proximity of the record carrier
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R25/00—Fittings or systems for preventing or indicating unauthorised use or theft of vehicles
    • B60R25/20—Means to switch the anti-theft system on or off
    • B60R25/24—Means to switch the anti-theft system on or off using electronic identifiers containing a code not memorised by the user
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/0701—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips at least one of the integrated circuit chips comprising an arrangement for power management
    • G06K19/0707—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips at least one of the integrated circuit chips comprising an arrangement for power management the arrangement being capable of collecting energy from external energy sources, e.g. thermocouples, vibration, electromagnetic radiation
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C9/00309—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C2009/00753—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys
    • G07C2009/00769—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means
    • G07C2009/00793—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means by Hertzian waves

Definitions

  • the invention relates to an anti-theft system for a
  • Motor vehicle used to lock or unlock doors or to release an electronic immobilizer.
  • a known anti-theft system (DE 38 20 248 AI) has an antenna device in the driver's door. If a user wants to get into the vehicle, a question-answer dialog is triggered by actuating a release switch. Here, a question signal is sent from the antenna device in the vehicle to a transponder carried by the user. This sends an encrypted answer signal back if it receives the question signal. In the motor vehicle, the response signal is compared with an expected target signal and if the two match (successful authentication), the doors are locked or unlocked.
  • Such an antenna device in the motor vehicle is realized by two loop antennas that are perpendicular to one another.
  • the portable transponder happens to be positioned with its winding surface of its transponder coil in such a way that the winding surface is always still run parallel to the field lines of the magnetic field. Then the transponder coil is not or not sufficiently penetrated by the magnetic field, so that the interrogation signal is not received by the transponder or is received with an insufficient amplitude.
  • an antenna which consists of two loop antennas, which are arranged close together and in one plane.
  • the two loop antennas are controlled separately from one another, but out of phase with one another. This creates a spatially reciprocating magnetic field.
  • the winding surface of the transponder coil is not sufficiently penetrated by magnetic field lines of the magnetic field generated by the two frame antennas.
  • the two loop antennas cannot always be arranged close together. This is the case, for example, when one loop antenna is arranged in the front door and the other in the rear door. Then there is no - or only a slight - reciprocating magnetic field.
  • the invention is based on the problem of providing an anti-theft system for a motor vehicle in which signals are emitted from a vehicle-side transmitter such that they can be reliably received by a portable transponder in the vicinity of the motor vehicle, and this largely independently of the configuration of the Transponders.
  • At least two loop antennas are arranged separately from one another in the motor vehicle.
  • the loop antennas are operated under different conditions (which are determined by antenna parameters), whereby the interrogation signal is transmitted from each loop antenna in a separate transmission channel. If the question signal is received inadequately, no answer signal or an insufficient answer signal is sent back.
  • the antenna parameters are therefore changed so that the transmission of the query signal takes place again under different conditions.
  • the question signal is thus reliably and quickly transmitted several times from the motor vehicle to the transponder depending on transmission parameters. This increases the likelihood that the transponder will reliably receive a query signal. The transponder then sends back its response signal.
  • the antennas can be controlled with different antenna parameters, for each of which the returned response signal is evaluated.
  • the associated antenna parameter can be stored and used as a future antenna parameter for one or all antennas.
  • a distant signal can also be sent, in which the antenna parameter is constantly changed.
  • the optimum antenna parameter is determined by evaluating the response signal before the relevant information is then transmitted to the transponder with the antenna parameter determined in this way.
  • the antenna parameters can be saved so that they are available as start values for future transmissions.
  • the antenna parameters differ in frequency, power, and phase of the emitted signals and the selection of antennas transmitting at the same time.
  • the antennas are advantageously arranged in the doors of the motor vehicle.
  • the transponder is arranged in a housing similar to a chip card (smart card).
  • the theft protection system has a measuring antenna which is arranged, for example, on the transponder.
  • the question signals transmitted by the motor vehicle can be received and evaluated.
  • the question signals can be changed there until the question signals are received with the greatest strength.
  • vehicles at the vehicle manufacturer's end of the line can be initialized with optimal antenna parameters for the first time.
  • FIG. 1 a block diagram of a thief steel protection system according to the invention
  • FIG. 2 a block diagram of a transmitting and receiving unit in the motor vehicle of the anti-theft protection system according to FIG. 1
  • FIG. 3 a block diagram of a portable transponder of the anti-theft protection system according to FIG. 1,
  • FIG. 4 a flowchart for the method of authentication using the transponder
  • FIG. 5 directional characteristics of antennas of the theft protection system
  • FIGS. 6 and 7 magnetic field profiles in the motor vehicle, which are caused by the antennas of the theft protection system
  • FIG. 8 a block diagram for Initialize the anti-theft system.
  • An anti-theft system according to the invention for a motor vehicle 1 (FIG. 1) has a transmitting and receiving unit 2 in the motor vehicle 1.
  • the transmitting and receiving unit 2 transmits signals wirelessly via antennas 3 (cf. lightning-shaped arrows in FIG. 1), receives signals, evaluates them and controls relevant units in the motor vehicle 1.
  • the transmitting and receiving unit 2 does not have to be in one Housing can be arranged, but can be arranged distributed with the transmitter unit, the receiver unit and the evaluation unit over the motor vehicle, the units being connected to one another via data lines.
  • the transmitting and receiving unit 2 is connected to antennas 3 m from the side doors, at the rear / trunk, in the area of the tank, in the area of the bumpers or at other locations distributed over the body of the vehicle.
  • a question signal is transmitted via the antennas. If the question signal is received by a portable code transmitter or responder (portable transmitter and receiver device, which is referred to as transponder 5 below), then the latter sends back an answer signal.
  • a portable code transmitter or responder portable transmitter and receiver device, which is referred to as transponder 5 below
  • the response signal is received by one of the antennas 3 or another antenna in the motor vehicle and sent to the transmitting and receiving unit 2 as an evaluation unit.
  • the response signal is evaluated there.
  • the transmitting and receiving unit 2 is with door locks 6, control units or other electronic units in the
  • the transmitting and receiving unit 2 has a control unit which outputs control signals to the corresponding electronic units in the motor vehicle 1.
  • the question signal In order to initiate the question-answer dialogue between the motor vehicle 1 and the transponder 5, the question signal must first be drawn.
  • the transponder 5 can have a release switch (not shown key switch), when actuated a start signal is sent to the motor vehicle 1, whereupon the motor vehicle 1 sends out the question signal.
  • the release switch 4 can also be provided on the outside of the motor vehicle 1 in the vicinity of a door handle, the manual operation of which sends out the question signal.
  • a proximity switch can also be provided in the vehicle, which transmits the question signal when a person approaches.
  • the transmitting and receiving unit 2 can transmit the polling signal intermittently (Pollmg) and then wait for the answer signal. The intermittent transmission can take place via different antennas 3 under different transmission conditions.
  • the question signal is triggered is irrelevant to the invention.
  • the query signal requests a response signal from a portable transponder 5, by means of which the transponder 5 proves its authorization (authentication) and tells the motor vehicle 1 what is to be controlled in the motor vehicle.
  • the question signal is transmitted and transmitted so that an optimal coupling with the transponder is achieved.
  • the transmitting and receiving unit 2 has a computing unit 9 (microprocessor ⁇ P) which is used both as a control unit and unit as well as an evaluation unit.
  • the computing unit 9 controls the transmission and reception of signals and evaluates the received signals and controls other electronic units in the vehicle. For this purpose, it is connected to a transmitter 10 and a receiver 11, in which the signals are modulated or demodulated.
  • Each antenna 3 is connected to a transmitter 10 and a receiver 11.
  • the antennas 3 can both send and receive signals. The reception of signals is also possible via other antennas, not shown.
  • the computing unit 9 is connected via a data line 12 to the door locks 6, the immobilizer 7 or other control devices.
  • the transmitting and receiving unit 2 has memory units in which antenna parameters (parameter memory 14) and setpoints (setpoint memory 15) are stored.
  • the stored data can be stored in advance (during an initialization phase) or during operation in the memory units 14 and 15.
  • the transponder 5 (FIG. 3) is advantageously arranged on a credit card-sized card. It has a transmitter 16 and a receiver 17, which are connected to a transponder IC 18. User-specific code information protected against unauthorized access is stored in the transponder IC 18 or such is generated there with the aid of a mathematical algorithm. The code information is used to encrypt the response signal. The answer signal is then sent back if the question signal was previously received.
  • the transponder 5 has an antenna in the form of a coil (transponder coil 19).
  • the transponder coil 19 has a plurality of turns which are wound in one plane parallel to the top of the card and enclose a winding surface.
  • the windings can also be conductor tracks of a printed circuit board on which the transponder IC 18 as well as the transmitter 16 and the receiver 17 are then arranged as integrated components.
  • the authentication method is explained in more detail with reference to FIG. 4.
  • the method steps that take place in the transponder 5 are shown on the left side and the method steps that take place in the motor vehicle 1 are shown on the right side.
  • a question signal is transmitted from motor vehicle 1 via at least two antennas 3. If a question signal has been received by the transponder 5, the answer signal is sent back by the transponder 5. If the response signal is not received within a predetermined period of time, antenna parameters are changed, as explained in more detail below, and the question-answer dialog is carried out again.
  • the response signal is received, it is compared with a target signal (authentication). If the authentication was successful, door locks 6 are unlocked or the immobilizer 7 is released. If the authentication was unsuccessful, the authentication process is ended without any action. If necessary, an alarm can be triggered if an attempt has been made to carry out the authentication with an unauthorized transponder.
  • the at least two antennas 3 in the motor vehicle 1 are connected to The at least two antennas 3 in the motor vehicle 1
  • the antennas 3 are designed as loop antennas (several approximately rectangular or circular windings in one plane), electromagnetic fields (hereinafter referred to as magnetic fields) are generated which overlap with one another depending on the position of the antennas 3 (cf. Figure 5). A resulting magnetic field is created (hatched area in FIG. 5).
  • the antennas 3 are controlled with respect to one another with different transmission frequencies, different transmission powers and / or different phases. This changes the resulting magnetic field. Likewise, a change in the magnetic field can be achieved by changing the location of an antenna 3 or by selecting the antennas 3 to be controlled.
  • the transmitter and receiver unit 2 uses antenna parameters to determine the conditions under which the antennas 3 are controlled.
  • the question signal can be received with different strengths.
  • the transponder 5 is directed with its transponder coil 19 in such a way that the magnetic field lines of the generated magnetic field intersect the transponder coil 19 vertically (winding area perpendicular to the magnetic field lines), then it is known that the greatest voltage m of the transponder coil 19 is induced. The question signal is therefore optimally received.
  • the transponder coil 19 is oriented such that the magnetic field lines run parallel to the winding surface of the transponder coil 19, no voltage is induced in the transponder coil 19. The question signal is then not received, although the transponder 5 is sufficiently close to Motor vehicle 1 is located (the transponder 5 is within the range of the antennas 3).
  • a zero is taken when the intensity of the voltage induced in the transponder coil 19 is below a threshold value (for example 100 mV).
  • the positions of the zeros depend on various parameters, such as the position / orientation of the transponder coil 19 on the one hand and the location of the antennas 3 in the vehicle, the transmission power, the transmission frequency and / or the phase of activation with respect to two antennas 3 and the other Selection of which of the antennas 3 send the query signal.
  • the antennas 3 are controlled with different combinations of antenna parameters. This changes the power, the frequency and / or the phase of one antenna 3 with respect to another antenna 3. This results in many different magnetic fields which are dependent on the antenna parameters. Since the question signal is transmitted with the aid of a magnetic field, each combination and therefore each antenna parameter has its own transmission condition and thus its own transmission channel (and thus its own resulting magnetic field).
  • the transponder 5 with its transponder coil 19 is directed as optimally as possible to the magnetic field, systematically changing the antenna parameters (this results in changes in the resulting magnetic field) automatically results in the best possible conditions for the transmission of the question signal determined.
  • the response signal sent back by the transponder 5 is used to evaluate the best conditions.
  • a measuring device can be provided on the transponder 5, which measures the magnetic field present at the location of the transponder 5. evaluates and sends the measured values in a response signal to the transmitting and receiving unit 2.
  • the question signal with the information to be transmitted is transmitted as a function of a combination of antenna parameters via at least two antennas 3.
  • the information to be transmitted can first be transmitted with the antenna parameter "phase shift of 0 ° between antenna 3 in the driver's door and antenna 3 in the rear driver's door” (or on the body in the area of the rear seat if there is no door at the rear) become. Then the antenna parameter "phase shift ..” is changed so that a phase shift of 180 ° between the two antennas 3 is achieved.
  • phase shift of 180 ° creates clearly different conditions, so that a sufficiently large voltage m of the transponder coil 19 is certainly induced in at least one of the two resulting magnetic fields. If the induced voltage is above a threshold value, the response signal is then sent back. As soon as the response signal is received, the associated antenna parameter or the combination of antenna parameters is registered and stored in the parameter memory 14.
  • Antenna parameters are, for example, the transmission power, the transmission frequency, the phase between two antennas 3 or the selection of antennas 3.
  • the antenna parameter "1" means, for example, that the driver-side antenna 3 on the front door is activated for transmission.
  • the antenna parameter "125” means, for example, that this antenna 3 is operated at a transmission frequency of 125 kHz.
  • the antenna parameter "50” means, for example, that this antenna is operated at 50% of the maximum power.
  • the combination "1, 50, 125; 3, 100, 125" of the antenna parameters then means that the first antenna 3 transmits at 50% power and at 125 kHz, while the third antenna 3 transmits at 100% power and also at 125 kHz .
  • the question signal can also be divided into different blocks, each block being transmitted with a changed antenna parameter. This can take place within a predetermined period of time until the transponder 5 responds with its response signal. From this point on, the remaining blocks of the query signal can be transmitted with the combination of antenna parameters that was last transmitted. This results in a time saving in the transmission of the entire question signal, since the entire question signal does not have to be transmitted first and then the antenna parameters have to be changed.
  • the question signal can also have a distant signal which is emitted before the information actually to be transmitted.
  • the distant signal is changed each time it is transmitted, with different transmission conditions due to the antenna parameters, which are changed within a predetermined value range.
  • the transmitting and receiving unit 2 uses the distant signal to determine which combination of antenna parameters most effectively lead to a correct response signal. thereupon the actual information to be transmitted is transmitted with the query signal using this previously determined antenna parameter.
  • a code can also be assigned to each combination of antenna parameters. This key figure is sent out together with the information to be transmitted under different transmission conditions.
  • the transponder 5 generates an answer signal for each question signal, which also contains the identification number. By evaluating the characteristic number, the transmitting and receiving unit 2 then determines the antenna parameter combination in which the response signal is reliably reported back. This combination of antenna parameters can then be stored in the parameter memory 14 of the transmitting and receiving unit 2 as a starting value for future transmissions of the query signal.
  • the combination of antenna parameters determines with which antennas 3 a signal is transmitted under which conditions (frequency, power, phase). For example, a combination of antenna parameters can be used to determine that a signal is transmitted via antenna 3 in the driver's door at a frequency of 125 kHz, with 100% transmission power and a phase of 0 ° with respect to antenna 3 m from the passenger door becomes.
  • the antenna 3 m of the passenger door on the other hand, should only transmit a signal with 50% power.
  • the antennas 3 on the rear doors and in the trunk emit no signal or only signals with low power.
  • the antennas 3 are activated such that the question signal is transmitted essentially in the outside space outside the motor vehicle 1. If the user wants to start the engine, he first actuates the ignition switch 21 near the steering wheel (in conventional vehicles this is actuated by turning the ignition key in the ignition lock). If the transmitting and receiving unit 2 detects the actuation of the ignition switch 21, the antennas 3 are preferably actuated in such a way that the magnetic field essentially penetrates the interior (passenger compartment and / or trunk).
  • the targeted activation of the interior or the exterior is done by different antenna parameters, through which the antennas 3 are controlled. If, for example, two antennas 3 are controlled only on one side of the vehicle, the exterior space is essentially penetrated by a magnetic field (cf. FIG. 5). If, on the other hand, two opposite antennas 3 (for example in the driver's door and in the passenger's door) are controlled by the transmitting and receiving unit 2, a magnetic field essentially penetrates the interior (see FIGS. 6 and 7).
  • the interior is enforced differently. If, for example, two opposite antennas 3 are activated simultaneously in such a way that their magnetic fields in vehicle 1 are directed towards one another (180 ° phase shift with respect to one another), this mainly produces field lines which - coming from an antenna 3 in the footwell of the vehicle emerge distributed over the floor panel 22 and close back to the antenna 3 (FIG. 7).
  • the field lines inside the vehicle 1 run from one antenna 3 to another and via the floor panel 22 and the roof panel 23 back to the respective antenna 3 (FIG 6).
  • Antennas 3 can thus completely detect the interior of the vehicle 1, so that the transponder 5 also responds when it is arranged unfavorably to the antennas 3 inside the motor vehicle 1, for example on the floor.
  • the interior detection can work with significantly reduced performance.
  • the magnetic fields to the outside are shielded by the sheet metal of the doors or at least strongly dampened. It is thus largely ruled out that a transponder 5 is addressed in the exterior when the interior detection is operated with reduced power.
  • the antennas 3 in the front and rear doors have different outputs (this corresponds to a different antenna parameter in each case) ) acted upon. Whether the front or rear antenna 3 is controlled more can depend, for example, on whether the front or rear door handle is actuated when entering. According to the invention, various combinations of antenna parameters are used to control the antennas 3. In order to obtain a changed magnetic field (transmission channel), one or more antenna parameters can be changed step by step or continuously.
  • the anti-theft system can be used on different types of vehicles. Since the vehicles generally differ in their geometry, their level of equipment and their materials, each vehicle must be initialized at the end of the assembly line in an initialization phase (first saving the necessary data and comparing the anti-theft protection system in the vehicle).
  • portable measuring antennas 24 (FIG. 8) or located at the end of the band can be provided, which detect the magnetic fields emitted by the antennas 3 in the motor vehicle 1.
  • a transponder 5 having a measuring device can also serve as a portable measuring antenna. The strength of the magnetic field is measured in a known manner at the location of the measuring device.
  • the antennas 3 in the vehicle are controlled with many different antenna parameters.
  • the aim is that in the later operation of the motor vehicle 1, a magnetic transponder coil 19 assumed at a specific location is carried out in the vicinity of the vehicle with the greatest possible probability of reception.
  • the measuring antennas 24 are preferably arranged in the area where a transponder 5 is presumably located when the motor vehicle 1 gets in.
  • the measuring antennas 24 detect the magnetic field and pass it on to an evaluation unit, for example an external diagnostic device 25, for evaluating the measurement results. If a desired magnetic field strength is exceeded in the measuring antennas 24, the current combination of antenna parameters is found. These antenna parameters are then transmitted to the transmitting and receiving unit 2 in the motor vehicle 1 and there the parameter memory 14 is stored. For future transmissions of the interrogation signal during normal operation of motor vehicle 1, this combination of antenna parameters is then used as the initial values to control antennas 3. If the desired magnetic field strength is not reached (ie no response signal comes back), then the antenna parameters are changed until at least one threshold value for the magnetic field strength in the area of the transponder 5 is exceeded.
  • the diagnostic device 25 can scan through all possible antenna parameters in a measurement value field until the desired field strength is received at the measurement antenna 24.
  • Such an algorithm for running through all possible antenna parameters can be stored both in the diagnostic device 25 and in the transmitting and receiving unit 2.
  • An additional device can also be connected to the diagnostic device 25, in which this algorithm is stored and carried out if desired.
  • the various antenna parameters can be changed continuously (eg constant change in frequency or power) or also step by step within a specified value range. Individual antenna parameters can also be omitted and the optimal combination of antenna parameters can be determined from the measured magnetic field strengths.
  • One of the antennas 3 in the motor vehicle 1 can also be used as the measuring antenna 24.
  • an optimal combination of antenna parameters at the end of the band can be determined during the manufacture of the vehicle and can be stored in the parameter memory 14 in the vehicle.
  • the transmitting and receiving unit 2 begins to control the antennas 3 if in future a question-and-answer dialogue is to take place between the vehicle 1 and the transponder 5.
  • the antennas 3 are designed as coils, each of which is part of an RLC oscillation circuit.
  • a high-frequency oscillation (for example at 125 kHz) is excited by an oscillator in each resonant circuit.
  • the coil then generates a high-frequency magnetic field that, depending on the shape / design and location of the coil as well as the oscillation frequency and strength of the excitation current (power), has a range that depends on it and its own directional characteristic (see the two dashed areas in FIG. 5).
  • a transponder coil 19 If a transponder coil 19 is brought into the magnetic field, its winding surface is more or less penetrated by field lines of the magnetic field. Depending on the level of enforcement, a voltage is induced in the transponder coil 19.
  • the oscillation in the oscillating circuit is additionally modulated with a bar information (question signal)
  • this information is inductively transmitted from the antenna 3 to the transponder coil 19 by the magnetic field.
  • the range of the transmitted signals is very short in the case of inductive transmission and is about one to two meters.
  • the range is dependent on the transmission power and the frequency of the antennas 3 and the arrangement of the antennas 3 in the motor vehicle 1 dependent.
  • the range is also dependent on the phase of the control of two antennas 3 to one another. These dependencies are used in the invention in that the antennas 3 are controlled with the different antenna parameters.
  • the antenna parameters are stored in a table in the parameter memory 14 of the transmitting and receiving unit 2.
  • each antenna parameter is assigned a frequency (frequency to be set by the oscillator or a frequency divider), a power (control current of the resonant circuit), an antenna 3 or and a phase (with respect to a second antenna 3) with which an antenna 3 is controlled, assigned. All antenna parameters and their assigned values are determined during the development of the anti-theft system by testing on a model.
  • the query signal is transmitted at least via two antennas 3.
  • the antenna parameters determine which antennas 3 are used to transmit the query signal when they are first transmitted and which antennas 3 are used to transmit the query signals when they are next transmitted.
  • other antenna parameters determine under which conditions (frequency, power, phase) the respective antennas 3 are controlled.
  • Each combination of antenna parameters 3 thus causes its own transmission channel (magnetic field), to which the query signal is transmitted as a function of the antenna parameters.
  • the question signals contain a binary random number as information, which has a predetermined length of 32 bits, for example.
  • the random number is modulated and transmitted to the transponder 5. Only if the transponder 5 receives the complete random number, ie every 32 bits, does the question- signal received as correct.
  • the random number can be used to generate the response signal using a secret, cryptographic key.
  • user-specific or vehicle-specific binary data can also be used to encrypt the response signal.
  • control information with the random number can also be transmitted, by which it is then decided whether the doors or the immobilizer are to be controlled.
  • the same cryptographic key is used in the transmitting and receiving unit 2 in the motor vehicle 1 in order to calculate an expected target value from the random number and to store this in the target value memory 15. This setpoint is compared with the response signal received. If both at least largely agree, a control signal is generated with which the door locks 6 or the immobilizer 7 is actuated.
  • the term electronic immobilizer is to be understood as an electronic device in the motor vehicle 1, which allows the use of the motor vehicle 1 only with proven authorization (authentication).
  • the engine control unit for example, can serve as an immobilizer and only functions when the comparison between the response signal and the setpoint value results in agreement between the two.
  • An on / off switch in the ignition circuit or a check valve in the fuel circuit can also serve as an immobilizer.
  • Several control units can also be integrated into the immobilizer.

Abstract

The vehicle (1), such as equipped according to the invention, presents on its external face a plurality of loop antennas (3), through each of which an interrogation signal, which is dependent upon a transmission parameter, is sent to a transponder (5) under modified transmission conditions. The transmission parameter to which the transmission of a correct answer signal must correspond is stored as a starting value for future transmissions.

Description

Beschreibungdescription
Diebstahlschutzsystem für ein KraftfahrzeugAnti-theft system for a motor vehicle
Die Erfindung betrifft ein Diebstahlschutzsystem für einThe invention relates to an anti-theft system for a
Kraftfahrzeug, mit dem Türen ver- oder entriegelt werden oder eine elektronische Wegfahrsperre gelost wird.Motor vehicle used to lock or unlock doors or to release an electronic immobilizer.
Ein bekanntes Diebstahlschutzsystem (DE 38 20 248 AI) weist eine Antennenvorrichtung in der Fahrertur auf. Wenn ein Benutzer m das Fahrzeug einsteigen mochte, so wird durch Betatigen eines Ausloseschalters ein Frage-Antwort-Dialog ausgelost. Hierbei wird ein Fragesignal von der Antennenvorrichtung im Fahrzeug zu einem von dem Benutzer getragenen Trans- ponder gesendet. Dieser sendet ein verschlüsseltes Antwortsignal zurück, falls er das Fragesignal empfangt. Im Kraftfahrzeug wird das Antwortsignal mit einem erwarteten Sollsignal verglichen und wenn die beiden übereinstimmen (erfolgreiche Authentifikation) , so werden die Türen ver- oder entriegelt.A known anti-theft system (DE 38 20 248 AI) has an antenna device in the driver's door. If a user wants to get into the vehicle, a question-answer dialog is triggered by actuating a release switch. Here, a question signal is sent from the antenna device in the vehicle to a transponder carried by the user. This sends an encrypted answer signal back if it receives the question signal. In the motor vehicle, the response signal is compared with an expected target signal and if the two match (successful authentication), the doors are locked or unlocked.
Eine solche Antennenvorrichtung im Kraftfahrzeug ist durch zwei Rahmenantennen realisiert, die senkrecht zueinander stehen. Durch Steuern der beiden Antennen mit sinusförmigen Signalen werden elektromagnetische Felder erzeugt. Diese Felder induzieren m einer Transponderspule des Transponders eine Spannung. Damit die induzierte Spannung möglichst groß ist, müssen die Feldlinien in genügendem Maße die Transponderspule durchsetzen. Dies ist dann der Fall, wenn die Feldlinien des erzeugten Magnetfeld nicht m einer Ebene, sondern zumindest m zwei Ebenen verlaufen. Daher sind die beiden Rahmenantennen senkrecht zueinander angeordnet.Such an antenna device in the motor vehicle is realized by two loop antennas that are perpendicular to one another. By controlling the two antennas with sinusoidal signals, electromagnetic fields are generated. These fields induce a voltage in a transponder coil of the transponder. So that the induced voltage is as large as possible, the field lines must penetrate the transponder coil to a sufficient extent. This is the case if the field lines of the magnetic field generated do not run in one plane, but at least in two planes. Therefore, the two loop antennas are arranged perpendicular to each other.
Nun kann es jedoch vorkommen, daß der tragbare Transponder zufälligerweise mit seiner Windungsflache seiner Transponder- spule derart positioniert ist, daß die Windungsflache immer noch parallel zu den Feldlinien des Magnetfeldes verlaufen. Dann wird die Transponderspule nicht oder nicht genügend von dem Magnetfeld durchsetzt, so daß das Fragesignal von dem Transponder nicht oder mit zu geringer Amplitude empfangen wird.However, it can happen that the portable transponder happens to be positioned with its winding surface of its transponder coil in such a way that the winding surface is always still run parallel to the field lines of the magnetic field. Then the transponder coil is not or not sufficiently penetrated by the magnetic field, so that the interrogation signal is not received by the transponder or is received with an insufficient amplitude.
In einer nicht vorveröffentlichten Patentanmeldung (DE 195 42 441) wird daher eine Antenne vorgeschlagen, die aus zwei Rahmenantennen besteht, die dicht beieinander und in einer Ebene angeordnet sind. Um ein räumliches Magnetfeld zu erzeugen, werden die beiden Rahmenantennen getrennt voneinander, jedoch phasenverschoben zueinander gesteuert. Somit entsteht ein räumlich hin- und herbewegtes Magnetfeld. Auch hier kann es noch vorkommen, daß die Windungsfläche der Transponderspule nicht im genügendem Maße mit Magnetfeldlinien des von den beiden Rahmenantennen erzeugten Magnetfeldes durchsetzt wird.In an unpublished patent application (DE 195 42 441), an antenna is therefore proposed which consists of two loop antennas, which are arranged close together and in one plane. In order to generate a spatial magnetic field, the two loop antennas are controlled separately from one another, but out of phase with one another. This creates a spatially reciprocating magnetic field. Here too it can still happen that the winding surface of the transponder coil is not sufficiently penetrated by magnetic field lines of the magnetic field generated by the two frame antennas.
Außerdem können die beiden Rahmenantennen nicht immer dicht beieinander angeordnet werden. Dies ist beispielsweise dann der Fall, wenn die eine Rahmenantenne in der Vordertür und die andere in der Hintertür angeordnet ist. Dann entsteht kein - oder nur ein gering ausgeprägtes - hin- und herbewegtes Magnetfeld.In addition, the two loop antennas cannot always be arranged close together. This is the case, for example, when one loop antenna is arranged in the front door and the other in the rear door. Then there is no - or only a slight - reciprocating magnetic field.
Der Erfindung liegt das Problem zugrunde, ein Diebstahlschutzsystem für ein Kraftfahrzeug zu schaffen, bei dem Signale derart von einem fahrzeugseitigen Sender ausgesendet werden, daß sie zuverlässig von einem tragbaren Transponder in der Nähe des Kraftfahrzeugs empfangen werden können, und dies weitgehend unabhängig von der Ausgestaltung des Trans- ponders .The invention is based on the problem of providing an anti-theft system for a motor vehicle in which signals are emitted from a vehicle-side transmitter such that they can be reliably received by a portable transponder in the vicinity of the motor vehicle, and this largely independently of the configuration of the Transponders.
Dieses Problem wird erfindungsgemäß durch die Merkmale des Patentanspruchs 1 gelöst. Dabei sind zumindest zwei Rahmenantennen getrennt voneinander in dem Kraftfahrzeug angeordnet. Die Rahmenantennen werden dabei unter verschiedenen Bedingungen (die durch Antennenparametern festgelegt sind) betrieben, wodurch das Fragesignal von jeder Rahmenantenne jeweils in einem separaten Übertragungskanal ausgesendet wird. Wenn das Fragesignal ungenügend empfangen wird, so wird kein oder ein ungenügendes Antwortsignal zurückgesendet. Daher werden die Antennenparameter verändert, damit die Übertragung des Fragesignals nochmals unter anderen Bedingungen stattfindet. Somit wird das Fragesignal sicher und schnell abhängig von Übertragungsparametern mehrfach vom Kraftfahrzeug zu dem Transponder übertragen. Somit steigt die Wahrscheinlichkeit, daß der Transponder eine Fragesignal sicher empfängt. Der Transponder sendet dann sein Antwortsignal zurück.This problem is solved according to the invention by the features of patent claim 1. At least two loop antennas are arranged separately from one another in the motor vehicle. The loop antennas are operated under different conditions (which are determined by antenna parameters), whereby the interrogation signal is transmitted from each loop antenna in a separate transmission channel. If the question signal is received inadequately, no answer signal or an insufficient answer signal is sent back. The antenna parameters are therefore changed so that the transmission of the query signal takes place again under different conditions. The question signal is thus reliably and quickly transmitted several times from the motor vehicle to the transponder depending on transmission parameters. This increases the likelihood that the transponder will reliably receive a query signal. The transponder then sends back its response signal.
Vorteilhafte Ausgestaltungen der Erfindung sind durch die Unteransprüche gekennzeichnet. So können die Antennen mit verschiedenen Antennenparametern angesteuert werden, zu denen jeweils das zurückgesendete Antwortsignal ausgewertet wird.Advantageous embodiments of the invention are characterized by the subclaims. In this way, the antennas can be controlled with different antenna parameters, for each of which the returned response signal is evaluated.
Bei demjenigen Antwortsignal, bei dem die größte Übereinstimmung besteht, kann der dazugehörige Antennenparameter als zukünftiger Antennenparameter für eine oder alle Antennen gespeichert und verwendet werden.In the case of the response signal for which there is the greatest match, the associated antenna parameter can be stored and used as a future antenna parameter for one or all antennas.
Es kann auch ein Vorsignal ausgesendet werden, bei dem der Antennenparameter ständig geändert wird. Durch Auswerten des Antwortsignals wird der optimale Antennenparameter ermittelt, bevor dann mit dem so ermittelten Antennenparameter die maß- gebliche Information zu dem Transponder übertragen wird.A distant signal can also be sent, in which the antenna parameter is constantly changed. The optimum antenna parameter is determined by evaluating the response signal before the relevant information is then transmitted to the transponder with the antenna parameter determined in this way.
Die Antennenparameter können gespeichert werden, so daß sie für zukünftige Übertragungen als Startwerte zur Verfügung stehen. Die Antennenparameter unterscheiden sich in der Fre- quenz, der Leistung, der Phasenlage der ausgesendeten Signale und der Auswahl der gleichzeitig sendenden Antennen. Die Antennen sind vorteilhafterweise in den Türen des Kraftfahrzeugs angeordnet. Der Transponder hingegen ist in einem Gehäuse ähnlich einer Chipkarte (Smart Card) angeordnet.The antenna parameters can be saved so that they are available as start values for future transmissions. The antenna parameters differ in frequency, power, and phase of the emitted signals and the selection of antennas transmitting at the same time. The antennas are advantageously arranged in the doors of the motor vehicle. The transponder, however, is arranged in a housing similar to a chip card (smart card).
Vorteilhaft ist es, wenn das Diebstahlschutzsystem eine Meßantenne aufweist, die beispielsweise auf dem Transponder angeordnet ist. Mit dieser können die vom Kraftfahrzeug ausgesendeten Fragesignale empfangen und ausgewertet werden. Durch eine Rückmeldung an das Fahrzeug können dort die Fragesignale solange geändert werden, bis die Fragesignale mit größter Stärke empfangen werden. Auf diese Weise können Fahrzeuge am Bandende beim Fahrzeughersteller erstmalig mit optimalen Antennenparametern initialisiert werden.It is advantageous if the theft protection system has a measuring antenna which is arranged, for example, on the transponder. With this, the question signals transmitted by the motor vehicle can be received and evaluated. By feedback to the vehicle, the question signals can be changed there until the question signals are received with the greatest strength. In this way, vehicles at the vehicle manufacturer's end of the line can be initialized with optimal antenna parameters for the first time.
Ausführungsbeispiele der Erfindung werden im folgenden anhand der schematischen Zeichnungen näher erläutert. Es zeigen:Exemplary embodiments of the invention are explained in more detail below with reference to the schematic drawings. Show it:
Figur 1: ein Blockschaltbild eines erfindungsgemäßen Dieb- Stahlschutzsystems,FIG. 1: a block diagram of a thief steel protection system according to the invention,
Figur 2: ein Blockschaltbild einer Sende- und Empfangseinheit im Kraftfahrzeug des Diebstahlschutzsystems nach Figur 1, Figur 3: ein Blockschaltbild eines tragbaren Transponders des Diebstahlschutzsystems nach Figur 1,FIG. 2: a block diagram of a transmitting and receiving unit in the motor vehicle of the anti-theft protection system according to FIG. 1, FIG. 3: a block diagram of a portable transponder of the anti-theft protection system according to FIG. 1,
Figur 4: ein Ablauf iagramm zum Verfahren einer Authentifika- tion mit Hilfe des Transponders, Figur 5: Richtcharakteristika von Antennen des Diebstahlschutzsystems, Figuren 6 und 7: Magnetfeldverläufe im Kraftfahrzeug, die durch die Antennen des Diebstahlschutzsystems hervorgerufen werden und Figur 8: ein Blockschaltbild zum Initialisieren des Diebstahlschutzsystems . Ein erfindungsgemaßes Diebstahlschutzsystem für ein Kraftfahrzeug 1 (Figur 1) weist eine Sende- und Empfangseinheit 2 im Kraftfahrzeug 1 auf. Die Sende- und Empfangseinheit 2 sendet Signale über Antennen 3 drahtlos (vgl. blitzformige Pfei- le m Figur 1) aus, empfangt Signale, wertet diese aus und steuert betreffende Einheiten im Kraftfahrzeug 1. Die Sende- und Empfangseinheit 2 muß nicht in einem einzigen Gehäuse angeordnet sein, sondern kann jeweils mit der Sendeeinheit, der Empfangseinheit und der Auswerteeinheit über das Kraftfahr- zeug verteilt angeordnet sein, wobei die Einheiten über Da- tenleitungen miteinander verbunden sind.4: a flowchart for the method of authentication using the transponder, FIG. 5: directional characteristics of antennas of the theft protection system, FIGS. 6 and 7: magnetic field profiles in the motor vehicle, which are caused by the antennas of the theft protection system and FIG. 8: a block diagram for Initialize the anti-theft system. An anti-theft system according to the invention for a motor vehicle 1 (FIG. 1) has a transmitting and receiving unit 2 in the motor vehicle 1. The transmitting and receiving unit 2 transmits signals wirelessly via antennas 3 (cf. lightning-shaped arrows in FIG. 1), receives signals, evaluates them and controls relevant units in the motor vehicle 1. The transmitting and receiving unit 2 does not have to be in one Housing can be arranged, but can be arranged distributed with the transmitter unit, the receiver unit and the evaluation unit over the motor vehicle, the units being connected to one another via data lines.
Die Sende- und Empfangseinheit 2 ist mit Antennen 3 m den Seitenturen, am Heck/Kofferraum, in Bereich des Tanks, im Be- reich der Stoßfanger oder an sonstigen Stellen verteilt über die Karosserie des Fahrzeugs verbunden. Über die Antennen wird jeweils ein Fragesignal bei Betatigen eines Ausloseschalters 4 (vgl. Figur 2) ausgesendet. Falls das Fragesignal von einem tragbaren Codegeber oder Antwortgeber (tragbare Sende- und Empfangseinrichtung, die im folgenden als Transponder 5 bezeichnet wird) empfangen wird, so sendet dieser ein Antwortsignal zurück.The transmitting and receiving unit 2 is connected to antennas 3 m from the side doors, at the rear / trunk, in the area of the tank, in the area of the bumpers or at other locations distributed over the body of the vehicle. When the release switch 4 is actuated (see FIG. 2), a question signal is transmitted via the antennas. If the question signal is received by a portable code transmitter or responder (portable transmitter and receiver device, which is referred to as transponder 5 below), then the latter sends back an answer signal.
Das Antwortsignal wird von einer der Antennen 3 oder einer weiteren Antenne im Kraftfahrzeug empfangen und der Sende- und Empfangseinheit 2 als Auswerteeinheit zugeleitet. Dort wird das Antwortsignal ausgewertet.The response signal is received by one of the antennas 3 or another antenna in the motor vehicle and sent to the transmitting and receiving unit 2 as an evaluation unit. The response signal is evaluated there.
Die Sende- und Empfangseinheit 2 ist mit Türschlössern 6, Steuergeraten oder sonstigen elektronischen Einheiten imThe transmitting and receiving unit 2 is with door locks 6, control units or other electronic units in the
Kraftfahrzeug 1 über Datenleitungen verbunden. Wenn sich der Transponder 5 als berechtigt herausstellt (erfolgreiche Au- thentifikation) , so werden je nach Inhalt des Antwortsignals ein oder alle Türschlösser 6 ver- oder entriegelt, eine Weg- fahrsperre 7 gelost, das Innenlicht em-/ausgeschaltet , Fen- ster oder Schiebedach geöffnet/geschlossen, die Heizung ein- /ausgeschaltet, usw. Die Sende- und Empfangseinheit 2 weist hierzu eine Steuereinheit auf, die Steuersignale an die entsprechenden elektronischen Einheiten im Kraftfahrzeug 1 aus- gibt.Motor vehicle 1 connected via data lines. If the transponder 5 proves to be authorized (successful authentication), depending on the content of the response signal, one or all door locks 6 are locked or unlocked, an immobilizer 7 is released, the interior light is switched on / off, open or closed, the heating switched on / off, etc. For this purpose, the transmitting and receiving unit 2 has a control unit which outputs control signals to the corresponding electronic units in the motor vehicle 1.
Um den Frage-Antwort-Dialog zwischen dem Kraftfahrzeug 1 und dem Transponder 5 einzuleiten, muß das Fragesignal zunächst ausgelost werden. Hierzu kann entweder der Transponder 5 ei- nen Ausloseschalter (nicht dargestellter Tastschalter) aufweisen, bei dessen Betätigung ein Startsignal zu dem Kraftfahrzeug 1 gesendet wird, woraufhin das Kraftfahrzeug 1 das Fragesignal aussendet. Der Ausloseschalter 4 kann auch außen am Kraftfahrzeug 1 in der Nahe eines Türgriffs vorgesehen sein, bei dessen manueller Betätigung das Fragesignal ausgesendet wird. Im Fahrzeug kann auch ein Naherungsschalter vorgesehen sein, der das Fragesignal beim Annahern einer Person aussendet. Ebenso kann die Sende- und Empfangseinheit 2 das Fragesignal intermittierend (Pollmg) aussendet und daraufhin auf das Antwortsignal warten. Das intermittierende Aussenden kann dabei über verschiedenen Antennen 3 unter verschiedenen Sendebedingungen von statten gehen.In order to initiate the question-answer dialogue between the motor vehicle 1 and the transponder 5, the question signal must first be drawn. For this purpose, either the transponder 5 can have a release switch (not shown key switch), when actuated a start signal is sent to the motor vehicle 1, whereupon the motor vehicle 1 sends out the question signal. The release switch 4 can also be provided on the outside of the motor vehicle 1 in the vicinity of a door handle, the manual operation of which sends out the question signal. A proximity switch can also be provided in the vehicle, which transmits the question signal when a person approaches. Likewise, the transmitting and receiving unit 2 can transmit the polling signal intermittently (Pollmg) and then wait for the answer signal. The intermittent transmission can take place via different antennas 3 under different transmission conditions.
Für die Erfindung ist es jedoch unwesentlich, wie das Frage- signal ausgelost wird. Wesentlich ist hingegen, daß durch das Fragesignal ein Antwortsignal von einem tragbaren Transponder 5 angefordert wird, durch das der Transponder 5 seine Berechtigung nachweist (Authentifikation) und dem Kraftfahrzeug 1 mitteilt, was im Kraftfahrzeug zu steuern ist. Wesentlich ist auch, unter welchen Bedingungen das Fragesignal ausgesendet und übertragen wird, damit eine optimale Kopplung mit dem Transponder erreicht wird.How the question signal is triggered is irrelevant to the invention. On the other hand, it is essential that the query signal requests a response signal from a portable transponder 5, by means of which the transponder 5 proves its authorization (authentication) and tells the motor vehicle 1 what is to be controlled in the motor vehicle. It is also important under what conditions the question signal is transmitted and transmitted so that an optimal coupling with the transponder is achieved.
Die Sende- und Empfangseinheit 2 weist gemäß Figur 2 eine Re- chenemheit 9 (Mikroprozessor μP) auf, die sowohl als Steuer- einheit als auch als Auswerteeinheit dient. Durch die Recheneinheit 9 wird das Senden und Empfangen von Signalen gesteuert und die empfangenen Signale ausgewertet sowie weitere elektronische Einheiten im Fahrzeug gesteuert. Hierzu ist sie mit einem Sender 10 und einem Empfanger 11 verbunden, in denen die Signale moduliert bzw. demoduliert werden. Jede Antenne 3 ist jeweils mit einem Sender 10 und einem Empfanger 11 verbunden. Die Antennen 3 können sowohl Signale senden als auch welche empfangen. Der Empfang von Signale ist auch über andere, nicht dargestellte Antennen möglich.According to FIG. 2, the transmitting and receiving unit 2 has a computing unit 9 (microprocessor μP) which is used both as a control unit and unit as well as an evaluation unit. The computing unit 9 controls the transmission and reception of signals and evaluates the received signals and controls other electronic units in the vehicle. For this purpose, it is connected to a transmitter 10 and a receiver 11, in which the signals are modulated or demodulated. Each antenna 3 is connected to a transmitter 10 and a receiver 11. The antennas 3 can both send and receive signals. The reception of signals is also possible via other antennas, not shown.
Die Recheneinheit 9 ist über eine Datenleitung 12 mit den Türschlössern 6, der Wegfahrsperre 7 oder sonstigen Steuergeraten verbunden. Die Sende- und Empfangseinheit 2 weist Spei- cheremheiten auf, m denen Antennenparameter (Parameterspeicher 14) und Sollwerte (Sollwertspeicher 15) gespeichert sind. Die gespeicherten Daten können bereits vorab (wahrend einer Initialisierungsphase) oder auch wahrend des Betriebs m den Speichereinheiten 14 und 15 gespeichert werden.The computing unit 9 is connected via a data line 12 to the door locks 6, the immobilizer 7 or other control devices. The transmitting and receiving unit 2 has memory units in which antenna parameters (parameter memory 14) and setpoints (setpoint memory 15) are stored. The stored data can be stored in advance (during an initialization phase) or during operation in the memory units 14 and 15.
Der Transponder 5 (Figur 3) ist vorteilhafterweise auf einer scheckkartengroßen Karte angeordnet. Er weist einen Sender 16 und einen Empfanger 17 auf, die mit einem Transponder-IC 18 verbunden sind. In dem Transponder-IC 18 ist eine vor unbe- rechtigtem Zugriff geschützte, benutzerspezifische Codeinformation gespeichert oder es wird eine solche dort mit Hilfe eines mathematischen Algorithmus erzeugt. Die Codeinformation wird zum Verschlüsseln des Antwortsignals verwendet. Anschließend wird das Antwortsignal zurückgesendet, wenn zuvor das Fragesignal empfangen wurde.The transponder 5 (FIG. 3) is advantageously arranged on a credit card-sized card. It has a transmitter 16 and a receiver 17, which are connected to a transponder IC 18. User-specific code information protected against unauthorized access is stored in the transponder IC 18 or such is generated there with the aid of a mathematical algorithm. The code information is used to encrypt the response signal. The answer signal is then sent back if the question signal was previously received.
Zum Senden und zum Empfangen von Signalen weist der Transponder 5 eine Antenne m Form einer Spule (Transponderspule 19) auf. Die Transponderspule 19 weist mehrere Windungen auf, die in einer Ebene parallel zu der Kartenoberseite gewickelt sind und eine Windungsflache umschließen. Die Windungen können auch Leiterbahnen einer Leiterplatte sein, auf der dann auch das Transponder-IC 18 sowie der Sender 16 und der Empfanger 17 als integrierte Bauelemente angeordnet sind.For sending and receiving signals, the transponder 5 has an antenna in the form of a coil (transponder coil 19). The transponder coil 19 has a plurality of turns which are wound in one plane parallel to the top of the card and enclose a winding surface. The windings can also be conductor tracks of a printed circuit board on which the transponder IC 18 as well as the transmitter 16 and the receiver 17 are then arranged as integrated components.
Anhand der Figur 4 wird das Verfahren der Authentifikation naher erläutert. Dabei sind m der Figur 4 die Verfahrensschritte, die im Transponder 5 stattfinden, auf der linken Seite dargestellt und die Verfahrensschritte, die im Kraft- fahrzeug 1 stattfinden, auf der rechten Seite dargestellt.The authentication method is explained in more detail with reference to FIG. 4. In FIG. 4, the method steps that take place in the transponder 5 are shown on the left side and the method steps that take place in the motor vehicle 1 are shown on the right side.
Zunächst wird ein Fragesignal über zumindest zwei Antennen 3 vom Kraftfahrzeug 1 ausgesendet. Wenn ein Fragesignal vom Transponder 5 empfangen wurde, so wird das Antwortsignal vom Transponder 5 zurückgesendet. Wenn das Antwortsignal innerhalb einer vorgegebenen Zeitdauer nicht empfangen wird, so werden - wie weiter unten naher erläutert - Antennenparameter geändert und der Frage-Antwort-Dialog erneut durchgeführt.First of all, a question signal is transmitted from motor vehicle 1 via at least two antennas 3. If a question signal has been received by the transponder 5, the answer signal is sent back by the transponder 5. If the response signal is not received within a predetermined period of time, antenna parameters are changed, as explained in more detail below, and the question-answer dialog is carried out again.
Falls das Antwortsignal empfangen wurde, so wird es mit einem Sollsignal verglichen (Authentifikation) . Wenn die Authenti- fikation erfolgreich war, so werden Türschlösser 6 entriegelt oder die Wegfahrsperre 7 gelost. War die Authentifikation nicht erfolgreich, so ist das Verfahren der Authentifikation ohne irgendeine Aktion beendet. Gegebenenfalls kann Alarm ausgelost werden, falls der Versuch unternommen wurde, die Authentifikation mit einem nicht berechtigten Transponder durchzufuhren .If the response signal has been received, it is compared with a target signal (authentication). If the authentication was successful, door locks 6 are unlocked or the immobilizer 7 is released. If the authentication was unsuccessful, the authentication process is ended without any action. If necessary, an alarm can be triggered if an attempt has been made to carry out the authentication with an unauthorized transponder.
über zumindest zwei Antennen 3 im Kraftfahrzeug 1 wird dasThe at least two antennas 3 in the motor vehicle 1
Fragesignal ausgesendet. Da die Antennen 3 als Rahmenantennen (mehrere etwa rechteckformige oder kreisförmige Windungen m einer Ebene) ausgebildet sind, werden elektromagnetische Felder (im folgenden als Magnetfelder bezeichnet) erzeugt, die sich je nach Lage der Antennen 3 zueinander überlagern (vgl. Figur 5) . Es entsteht ein resultierendes Magnetfeld (schraffiert dargestellter Bereich m Figur 5).Question signal sent out. Since the antennas 3 are designed as loop antennas (several approximately rectangular or circular windings in one plane), electromagnetic fields (hereinafter referred to as magnetic fields) are generated which overlap with one another depending on the position of the antennas 3 (cf. Figure 5). A resulting magnetic field is created (hatched area in FIG. 5).
Die Antennen 3 werden mit unterschiedlicher Sendefrequenz, unterschiedlicher Sendeleistung und/oder unterschiedlicher Phase zueinander gesteuert. Dadurch ändert sich jeweils das resultierende Magnetfeld. Ebenso kann eine Veränderung des Magnetfeldes durch Verandern des Anbringungsorts einer Antenne 3 oder durch Auswahl der anzusteuernden Antennen 3 erzielt werden. Die Sende- und Empfangseinheit 2 legt dabei durch Antennenparameter fest, unter welchen Bedingungen die Antennen 3 angesteuert werden.The antennas 3 are controlled with respect to one another with different transmission frequencies, different transmission powers and / or different phases. This changes the resulting magnetic field. Likewise, a change in the magnetic field can be achieved by changing the location of an antenna 3 or by selecting the antennas 3 to be controlled. The transmitter and receiver unit 2 uses antenna parameters to determine the conditions under which the antennas 3 are controlled.
Wenn ein Benutzer in sein Kraftfahrzeug 1 einsteigen mochte und den Transponder 5 bei sich tragt, so muß er zunächst den Frage-Antwort-Dialog auslosen. Je nachdem, wo er den Transponder 5 tragt und wie dann die Transponderspule 19 mit ihrer Windungsflache im Bezug auf das von den Antennen 3 im Kraftfahrzeug 1 erzeugte Magnetfeld mit seinen Magnetfeldlinien gerichtet ist, kann das Fragesignal mit unterschiedlicher Starke empfangen werden.If a user wants to get into his motor vehicle 1 and carries the transponder 5 with him, he must first trigger the question-answer dialog. Depending on where he carries the transponder 5 and then how the transponder coil 19 with its winding surface is directed with respect to the magnetic field generated by the antennas 3 in the motor vehicle 1 with its magnetic field lines, the question signal can be received with different strengths.
Wenn der Transponder 5 mit seiner Transponderspule 19 derart gerichtet ist, daß die Magnetfeldlinien des erzeugten Magnet- feldes die Transponderspule 19 senkrecht schneiden (Windungsflache senkrecht zu den Magnetfeldlinien) , so wird bekanntlich die größte Spannung m der Transponderspule 19 induziert. Das Fragesignal wird also optimal empfangen.If the transponder 5 is directed with its transponder coil 19 in such a way that the magnetic field lines of the generated magnetic field intersect the transponder coil 19 vertically (winding area perpendicular to the magnetic field lines), then it is known that the greatest voltage m of the transponder coil 19 is induced. The question signal is therefore optimally received.
Ist die Transponderspule 19 jedoch so gerichtet, daß die Magnetfeldlinien parallel zur Windungsflache der Transponderspule 19 verlaufen, so wird keine Spannung in der Transponderspule 19 induziert. Das Fragesignal wird dann nicht empfangen, obwohl sich der Transponder 5 genügend nahe beim Kraftfahrzeug 1 befindet (der Transponder 5 ist innerhalb der Reichweite der Antennen 3).However, if the transponder coil 19 is oriented such that the magnetic field lines run parallel to the winding surface of the transponder coil 19, no voltage is induced in the transponder coil 19. The question signal is then not received, although the transponder 5 is sufficiently close to Motor vehicle 1 is located (the transponder 5 is within the range of the antennas 3).
Man spricht dann von einer Nullstelle. Eine Nullstelle wird dann eingenommen, wenn die Intensität der in der Transponderspule 19 induzierten Spannung unter einem Schwellwert (beispielsweise 100 mV) liegt. Die Lagen der Nullstellen hangen von verschiedenen Parametern ab, wie einerseits von der La- ge/Oπentierung der Transponderspule 19 und andererseits von dem Anbringungsort der Antennen 3 im Fahrzeug, der Sendeleistung, der Sendefrequenz und/oder Phase der Ansteuerung bezuglich zweier Antennen 3 sowie der Auswahl, welche der Antennen 3 das Fragesignal senden.One then speaks of a zero. A zero is taken when the intensity of the voltage induced in the transponder coil 19 is below a threshold value (for example 100 mV). The positions of the zeros depend on various parameters, such as the position / orientation of the transponder coil 19 on the one hand and the location of the antennas 3 in the vehicle, the transmission power, the transmission frequency and / or the phase of activation with respect to two antennas 3 and the other Selection of which of the antennas 3 send the query signal.
Um Nullstellen weitgehend zu vermeiden, werden die Antennen 3 mit unterschiedlichen Kombinationen von Antennenparametern angesteuert. Dadurch ändert sich die Leistung, die Frequenz und/oder die Phase einer Antenne 3 bezüglich einer anderen Antenne 3. Somit ergeben sich viele verschiedene, von den An- tennenparameter abhangige Magnetfelder. Da das Fragesignal mit Hilfe eines Magnetfelds übertragen wird, bewirkt jede Kombination und damit jeder Antennenparameter eine eigene Sendebedingung und somit einen eigenen Ubertragungskanal (und damit ein eigenes resultierendes Magnetfeld) .In order to largely avoid zeroing, the antennas 3 are controlled with different combinations of antenna parameters. This changes the power, the frequency and / or the phase of one antenna 3 with respect to another antenna 3. This results in many different magnetic fields which are dependent on the antenna parameters. Since the question signal is transmitted with the aid of a magnetic field, each combination and therefore each antenna parameter has its own transmission condition and thus its own transmission channel (and thus its own resulting magnetic field).
Damit der Benutzer nicht darauf achten muß, daß der Transponder 5 mit seiner Transponderspule 19 möglichst optimal zu dem Magnetfeld gerichtet ist, werden durch systematisches Andern der Antennenparameter (dies hat Änderungen des resultierenden Magnetfelds zur Folge) automatisch die möglichst besten Bedingungen für die Übertragung des Fragesignals ermittelt. Zur Auswertung der besten Bedingungen wird das von dem Transponder 5 zurückgesendete Antwortsignal verwendet. Ebenso kann auf dem Transponder 5 eine Meßeinrichtung vorgesehen sein, die das am Ort des Transponders 5 vorliegende Magnetfeld aus- wertet und die Meßwerte in einem Antwortsignal an die Sende- und Empfangseinheit 2 sendet.So that the user does not have to pay attention that the transponder 5 with its transponder coil 19 is directed as optimally as possible to the magnetic field, systematically changing the antenna parameters (this results in changes in the resulting magnetic field) automatically results in the best possible conditions for the transmission of the question signal determined. The response signal sent back by the transponder 5 is used to evaluate the best conditions. Likewise, a measuring device can be provided on the transponder 5, which measures the magnetic field present at the location of the transponder 5. evaluates and sends the measured values in a response signal to the transmitting and receiving unit 2.
Nachdem der Ausloseschalter 4 betätigt wurde, wird das Frage- signal mit der zu übertragenden Information abhangig von einer Kombination von Antennenparametern über zumindest zwei Antennen 3 ausgesendet. Beispielsweise kann die zu übertragende Information zunächst mit dem Antennenparameter "Phasenverschiebung von 0° zwischen der Antenne 3 in der Fahrertur und der Antenne 3 in der hinteren fahrerseitigen Tur" (oder an der Karosserie im Bereich des Rucksitzes, falls keine Tur hinten vorhanden ist) ausgesendet werden. Anschließend wird der Antennenparameter "Phasenverschiebung .." so geändert, daß eine Phasenverschiebung von 180° zwischen den beiden An- tennen 3 erzielt wird.After the trigger switch 4 has been actuated, the question signal with the information to be transmitted is transmitted as a function of a combination of antenna parameters via at least two antennas 3. For example, the information to be transmitted can first be transmitted with the antenna parameter "phase shift of 0 ° between antenna 3 in the driver's door and antenna 3 in the rear driver's door" (or on the body in the area of the rear seat if there is no door at the rear) become. Then the antenna parameter "phase shift .." is changed so that a phase shift of 180 ° between the two antennas 3 is achieved.
Durch die Phasenverschiebung von 180° werden deutlich unterschiedliche Verhaltnisse geschaffen, so daß bei zumindest einer der beiden resultierenden Magnetfelder sicher eine genu- gend große Spannung m der Transponderspule 19 induziert wird. Falls die induzierte Spannung über einem Schwellwert liegt, so wird daraufhin das Antwortsignal zurückgesendet. Sobald das Antwortsignal empfangen wird, wird der dazugehörige Antennenparameter oder die Kombination von Antennenparame- tern registriert und in den Parameterspeicher 14 gespeichert.The phase shift of 180 ° creates clearly different conditions, so that a sufficiently large voltage m of the transponder coil 19 is certainly induced in at least one of the two resulting magnetic fields. If the induced voltage is above a threshold value, the response signal is then sent back. As soon as the response signal is received, the associated antenna parameter or the combination of antenna parameters is registered and stored in the parameter memory 14.
Für die Authentifikation genügt es, wenn ein gültiges und berechtigtes Antwortsignal empfangen wird. Zum Einstellen von guten Ubertragungsverhaltnissen werden jedoch mehrere Ant- wortsignale benotigt, die jeweils durch unterschiedliche Sen- deverhaltnisse/Ubertragungskanale (abhangig von den Antennenparametern) hervorgerufen werden.For authentication, it is sufficient if a valid and authorized response signal is received. To set good transmission conditions, however, several response signals are required, each of which is caused by different transmission conditions / transmission channels (depending on the antenna parameters).
Es kann dabei nicht nur ein Antennenparameter, sondern mehre- re Antennenparameter (daher auch Kombination von Antennenpa- rametern) geändert werden. Antennenparameter sind beispielsweise die Sendeleistung, die Sendefrequenz, die Phase zwischen zwei Antennen 3 oder die Auswahl von Antennen 3. Der Antennenparameter "1" bedeutet beispielsweise, daß die fah- rerseitige Antenne 3 an der Vordertur zum Senden angesteuert wird. Der Antennenparameter "125" bedeutet beispielsweise, daß diese Antenne 3 mit einer Sendefrequenz von 125 kHz betrieben wird. Der Antennenparameter "50" bedeutet beispielsweise, daß diese Antenne bei 50% der maximalen Leistung be- trieben wird. Die Kombination "1, 50, 125; 3, 100, 125" der Antennenparameter bedeutet dann, daß die erste Antenne 3 mit 50% Leistung und bei 125 kHz sendet, wahrend die dritte Antenne 3 mit 100% Leistung und ebenfalls bei 125 kHz sendet.Not only one antenna parameter, but several antenna parameters (therefore also a combination of antenna parameters) can be changed. Antenna parameters are, for example, the transmission power, the transmission frequency, the phase between two antennas 3 or the selection of antennas 3. The antenna parameter "1" means, for example, that the driver-side antenna 3 on the front door is activated for transmission. The antenna parameter "125" means, for example, that this antenna 3 is operated at a transmission frequency of 125 kHz. The antenna parameter "50" means, for example, that this antenna is operated at 50% of the maximum power. The combination "1, 50, 125; 3, 100, 125" of the antenna parameters then means that the first antenna 3 transmits at 50% power and at 125 kHz, while the third antenna 3 transmits at 100% power and also at 125 kHz .
Das Fragesignal kann auch in verschiedene Blocke unterteilt werden, wobei jeder Block mit einem veränderten Antennenparameter ausgesendet wird. Dies kann innerhalb einer vorgegebenen Zeitdauer solange geschehen, bis der Transponder 5 mit seinem Antwortsignal antwortet. Von diesem Zeitpunkt an kon- nen die restlichen Blocke des Fragesignals mit der zuletzt ausgesendeten Kombination von Antennenparametern ausgesendet werden. Dadurch erhalt man einen Zeitgewinn bei der Übertragung des gesamten Fragesignals, da nicht zuerst das gesamte Fragesignal ausgesendet und dann der Antennenparameter gean- dert werden muß.The question signal can also be divided into different blocks, each block being transmitted with a changed antenna parameter. This can take place within a predetermined period of time until the transponder 5 responds with its response signal. From this point on, the remaining blocks of the query signal can be transmitted with the combination of antenna parameters that was last transmitted. This results in a time saving in the transmission of the entire question signal, since the entire question signal does not have to be transmitted first and then the antenna parameters have to be changed.
Das Fragesignal kann auch ein Vorsignal aufweisen, das vor der eigentlich zu übertragenden Information ausgesendet wird. Das Vorsignal wird bei jedem Aussenden geändert, und zwar mit unterschiedlichen Sendebedingungen bedingt durch die Antennenparameter, die innerhalb eines vorgegebenen Wertebereichs geändert werden. Durch die Ruckmeldung über das Antwortsignal ermittelt die Sende- und Empfangseinheit 2 anhand des Vorsignals, welche Kombination von Antennenparametern am wirkungs- vollsten zu einem korrekten Antwortsignal fuhren. Daraufhin wird die eigentliche zu übertragende Information m dem Fragesignal m t diesem zuvor ermittelten Antennenparameter ausgesendet .The question signal can also have a distant signal which is emitted before the information actually to be transmitted. The distant signal is changed each time it is transmitted, with different transmission conditions due to the antenna parameters, which are changed within a predetermined value range. By means of the acknowledgment of the response signal, the transmitting and receiving unit 2 uses the distant signal to determine which combination of antenna parameters most effectively lead to a correct response signal. thereupon the actual information to be transmitted is transmitted with the query signal using this previously determined antenna parameter.
Jeder Kombination von Antennenparametern kann auch eine Kennzahl zugewiesen werden. Diese Kennzahl wird zusammen mit der zu übertragenden Information bei unterschiedlichen Sendebedingungen ausgesendet. Der Transponder 5 erzeugt zu jedem Fragesignal ein Antwortsignal, m dem ebenfalls die Kennzahl enthalten ist. Durch Auswerten der Kennzahl stellt dann die Sende- und Empfangseinheit 2 fest, bei welcher Antennenpara- meterkombmation das Antwortsignal sicher zuruckgemeldet wird. Diese Kombination von Antennenparametern kann dann für zukunftige Übertragungen des Fragesignals in dem Parameter- Speicher 14 der Sende- und Empfangseinheit 2 als Startwert abgespeichert werden.A code can also be assigned to each combination of antenna parameters. This key figure is sent out together with the information to be transmitted under different transmission conditions. The transponder 5 generates an answer signal for each question signal, which also contains the identification number. By evaluating the characteristic number, the transmitting and receiving unit 2 then determines the antenna parameter combination in which the response signal is reliably reported back. This combination of antenna parameters can then be stored in the parameter memory 14 of the transmitting and receiving unit 2 as a starting value for future transmissions of the query signal.
Es muß nicht die gesamte Kombination von Antennenparametern mit Kennzahlen ausgesendet werden. Es genügt eine Untermenge oder eine geeignete Auswahl der Kombination auszusenden, so daß die optimale Kombination von Antennenparametern aus dieser Untermenge ermittelt werden kann. Dadurch laßt sich die Dauer des Vorsignals reduzieren, so daß der Vorgang der Authentifikation schneller vonstatten gehen kann.It is not necessary to send out the entire combination of antenna parameters with key figures. It is sufficient to send out a subset or a suitable selection of the combination so that the optimal combination of antenna parameters can be determined from this subset. This allows the duration of the distant signal to be reduced, so that the authentication process can be carried out more quickly.
Die Kombination von Antennenparametern bestimmt, mit welchen Antennen 3 unter welchen Bedingungen (Frequenz, Leistung, Phase) ein Signal ausgesendet wird. So kann durch eine Kombination von Antennenparametern beispielsweise festgelegt wer- den, daß ein Signal über die Antenne 3 in der Fahrertur bei einer Frequenz von 125 kHz, bei 100% Sendeleistung und einer Phase von 0° in Bezug auf die Antenne 3 m der Beifahrertur ausgesendet wird. Die Antenne 3 m der Beifahrertur dagegen soll nur ein Signal mit 50% Leistung aussenden. Ebenso sollen die Antennen 3 an den Hintertüren und am Kofferraum kein Signal oder nur Signale mit geringer Leistung aussenden.The combination of antenna parameters determines with which antennas 3 a signal is transmitted under which conditions (frequency, power, phase). For example, a combination of antenna parameters can be used to determine that a signal is transmitted via antenna 3 in the driver's door at a frequency of 125 kHz, with 100% transmission power and a phase of 0 ° with respect to antenna 3 m from the passenger door becomes. The antenna 3 m of the passenger door, on the other hand, should only transmit a signal with 50% power. Likewise, the antennas 3 on the rear doors and in the trunk emit no signal or only signals with low power.
Wenn das Fahrzeug zunächst verriegelt ist, so werden die An- tennen 3 so angesteuert, daß das Fragesignal im wesentlichen in dem Außenraum außerhalb des Kraftfahrzeugs 1 gesendet wird. Wenn der Benutzer den Motor starten mochte, so betätigt er zunächst den Zundschalter 21 in der Nahe des Lenkrades (bei herkömmlichen Fahrzeugen wird dieser durch Drehen des Zündschlüssels im Zündschloß betätigt) . Erkennt die Sende- und Empfangseinheit 2 das Betatigen des Zundschalters 21, so werden die Antennen 3 vorzugsweise derart angesteuert, daß im wesentlichen der Innenraum (Fahrgastraum und/oder Kofferraum) von dem Magnetfeld durchsetzt wird.If the vehicle is initially locked, the antennas 3 are activated such that the question signal is transmitted essentially in the outside space outside the motor vehicle 1. If the user wants to start the engine, he first actuates the ignition switch 21 near the steering wheel (in conventional vehicles this is actuated by turning the ignition key in the ignition lock). If the transmitting and receiving unit 2 detects the actuation of the ignition switch 21, the antennas 3 are preferably actuated in such a way that the magnetic field essentially penetrates the interior (passenger compartment and / or trunk).
Das gezielte Ansteuern des Innenraums oder des Außenraums geschieht durch unterschiedliche Antennenparameter, durch die die Antennen 3 gesteuert werden. Wenn beispielsweise zwei Antennen 3 nur auf einer Seite des Fahrzeugs angesteuert wer- den, so wird im wesentlichen der Außenraum mit einem Magnetfeld durchsetzt (vgl. Figur 5). Werden dagegen zwei gegenüberliegende Antennen 3 (beispielsweise in der Fahrertur und in der Beifahrertur) von der Sende- und Empfangseinheit 2 gesteuert, so wird im wesentlichen der Innenraum von einem Ma- gnetfeld durchsetzt (vgl. Figuren 6 und 7).The targeted activation of the interior or the exterior is done by different antenna parameters, through which the antennas 3 are controlled. If, for example, two antennas 3 are controlled only on one side of the vehicle, the exterior space is essentially penetrated by a magnetic field (cf. FIG. 5). If, on the other hand, two opposite antennas 3 (for example in the driver's door and in the passenger's door) are controlled by the transmitting and receiving unit 2, a magnetic field essentially penetrates the interior (see FIGS. 6 and 7).
Abhangig von der eingestellten Kombination der aktuellen Antennenparameter für die beiden anzusteuernden Antennen 3 in den Vorderturen wird der Innenraum unterschiedlich durch- setzt. Werden beispielsweise zwei gegenüberliegende Antennen 3 gleichzeitig derart angesteuert, daß ihre Magnetfelder im Fahrzeug 1 gegeneinander gerichtet sind (180° Phasenverschiebung zueinander) , so erzeugt dies hauptsachlich Feldlinien, die - von einer Antenne 3 kommend im Fußraum des Fahrzeugs verteilt über das Fußbodenblech 22 austreten und sich zurück zu der Antenne 3 wieder schließen (Figur 7).Depending on the set combination of the current antenna parameters for the two antennas 3 to be controlled in the front doors, the interior is enforced differently. If, for example, two opposite antennas 3 are activated simultaneously in such a way that their magnetic fields in vehicle 1 are directed towards one another (180 ° phase shift with respect to one another), this mainly produces field lines which - coming from an antenna 3 in the footwell of the vehicle emerge distributed over the floor panel 22 and close back to the antenna 3 (FIG. 7).
Wenn hingegen die beiden gegenüberliegenden Antennen 3 pha- sengleich (0° Phasenverschiebung) angesteuert werden, so verlaufen die Feldlinien im Innern des Fahrzeugs 1 von einer Antenne 3 zur anderen und über das Fußbodenblech 22 und das Dachblech 23 zurück zu der jeweiligen Antenne 3 (Figur 6) .If, on the other hand, the two opposite antennas 3 are driven in phase (0 ° phase shift), the field lines inside the vehicle 1 run from one antenna 3 to another and via the floor panel 22 and the roof panel 23 back to the respective antenna 3 (FIG 6).
Durch Variation der Phasenverschiebung zwischen den beidenBy varying the phase shift between the two
Antennen 3 kann somit der Innenraum des Fahrzeugs 1 vollständig erfaßt werden, so daß der Transponder 5 auch dann antwortet, wenn er ungünstig zu den Antennen 3 im Inneren des Kraftfahrzeugs 1 angeordnet ist, beispielsweise auf dem Fuß- boden.Antennas 3 can thus completely detect the interior of the vehicle 1, so that the transponder 5 also responds when it is arranged unfavorably to the antennas 3 inside the motor vehicle 1, for example on the floor.
Wenn die Antennen 3 auf der Innenverkleidung der Türen angeordnet sind, kann die Innenraumerkennung mit deutlich verminderter Leistung arbeiten. Die Magnetfelder nach außen werden durch das Blech der Türen abgeschirmt oder zumindest stark gedämpft. Somit wird weitgehend ausgeschlossen, daß ein Transponder 5 im Außenraum angesprochen wird, wenn die Innenraumerkennung mit verminderter Leistung betrieben wird.If the antennas 3 are arranged on the interior trim of the doors, the interior detection can work with significantly reduced performance. The magnetic fields to the outside are shielded by the sheet metal of the doors or at least strongly dampened. It is thus largely ruled out that a transponder 5 is addressed in the exterior when the interior detection is operated with reduced power.
Um jeweils den vorderen oder den hinteren Teil des Fahrgastraumes optimal mit dem Magnetfeld zu durchsetzen oder das Magnetfeld bevorzugt im hinteren oder vorderen Außenbereich zu erzeugen, werden die Antennen 3 in den vorderen und hinteren Türen mit unterschiedlichen Leistungen (dies entspricht je- weils einem anderen Antennenparameter) beaufschlagt. Ob die vordere oder die hintere Antenne 3 stärker angesteuert wird, kann beispielsweise davon abhängen, ob der vordere oder der hintere Türgriff beim Einsteigen betätigt wird. Zum Steuern der Antennen 3 werden erfmdungsgemaß verschiedene Kombinationen von Antennenparametern verwendet. Um ein verändertes Magnetfeld (Übertragungskanal) zu erhalten, kann einer oder zugleich auch mehrere Antennenparameter stufenwei- se oder stetig geändert werden.In order to optimally penetrate the front or the rear part of the passenger compartment with the magnetic field or to generate the magnetic field preferably in the rear or front outer area, the antennas 3 in the front and rear doors have different outputs (this corresponds to a different antenna parameter in each case) ) acted upon. Whether the front or rear antenna 3 is controlled more can depend, for example, on whether the front or rear door handle is actuated when entering. According to the invention, various combinations of antenna parameters are used to control the antennas 3. In order to obtain a changed magnetic field (transmission channel), one or more antenna parameters can be changed step by step or continuously.
Das Diebstahlschutzsystem kann bei unterschiedlichen Fahrzeugtypen eingesetzt werden. Da sich die Fahrzeuge in der Regel in ihrer Geometrie, ihren Ausstattungsgrad und ihren Werkstoffen unterscheiden, muß jedes Fahrzeug am Bandende in einer Initialisierungsphase zunächst initialisiert (erstmaliges Speichern notwendiger Daten und Abgleichen des Dieb- stahlschutzsystem im Fahrzeug) werden. Hierzu können tragbare oder am Bandende befindliche stationäre Meßantennen 24 (Figur 8) vorgesehen sein, die die von den Antennen 3 im Kraftfahrzeug 1 ausgesendeten Magnetfelder erfassen. Als tragbare Meßantenne kann auch ein Transponder 5 dienen, der eine Meßeinrichtung aufweist. Dabei wird die Starke des Magnetfeld am Ort der Meßeinrichtung auf bekannte Weise gemessen.The anti-theft system can be used on different types of vehicles. Since the vehicles generally differ in their geometry, their level of equipment and their materials, each vehicle must be initialized at the end of the assembly line in an initialization phase (first saving the necessary data and comparing the anti-theft protection system in the vehicle). For this purpose, portable measuring antennas 24 (FIG. 8) or located at the end of the band can be provided, which detect the magnetic fields emitted by the antennas 3 in the motor vehicle 1. A transponder 5 having a measuring device can also serve as a portable measuring antenna. The strength of the magnetic field is measured in a known manner at the location of the measuring device.
Die Antennen 3 im Fahrzeug werden dabei mit vielen unterschiedlichen Antennenparameter gesteuert. Ziel ist es, daß im spateren Betrieb des Kraftfahrzeugs 1 eine magnetische Durchdringung einer an einem bestimmten Ort angenommenen Transpon- derspule 19 im Nahbereich des Fahrzeugs mit möglichst großer Empfangswahrscheinlichkeit erfolgt .The antennas 3 in the vehicle are controlled with many different antenna parameters. The aim is that in the later operation of the motor vehicle 1, a magnetic transponder coil 19 assumed at a specific location is carried out in the vicinity of the vehicle with the greatest possible probability of reception.
Es wird mit einem Antennenparameter begonnen, mit dem m einem Entwicklungsmodell bei angenommenen Ort des Transponders 5 bereits gute Ergebnisse erzielt wurden. Die Meßantennen 24 sind vorzugsweise m dem Bereich angeordnet, wo sich vermutlich ein Transponder 5 beim Einsteigen m das Kraftfahrzeug 1 befindet. Die Meßantennen 24 erfassen das Magnetfeld und leiten es an eine Auswerteeinheit, z.B. ein externes Diagnosegerat 25, zur Auswertung der Meßergebnisse weiter. Wenn m den Meßantennen 24 ein gewünschte Magnetfeldstarke überschritten wird, so wird die aktuelle Kombination von Antennenparametern ausfindig gemacht. Diese Antennenparameter werden dann an die Sende- und Empfangseinheit 2 im Kraftfahrzeug 1 übertragen und dort m den Parameterspeicher 14 gespeichert. Für zukunftige Übertragungen des Fragesignals wahrend des Normalbetriebs des Kraftfahrzeugs 1 wird dann zunächst diese Kombination von Antennenparametern als Anfangswerte verwendet, um die Antennen 3 anzusteuern. Wird die gewünschte Magnetfeldstarke dabei nicht erreicht (d.h. kommt kein Antwortsignal zurück), so werden dann die Antennenparameter solange geändert, bis zu- mindest ein Schwellwert für die Magnetfeldstarke im Bereich des Transponders 5 überschritten wird.It starts with an antenna parameter with which good results have already been achieved in a development model assuming the location of the transponder 5. The measuring antennas 24 are preferably arranged in the area where a transponder 5 is presumably located when the motor vehicle 1 gets in. The measuring antennas 24 detect the magnetic field and pass it on to an evaluation unit, for example an external diagnostic device 25, for evaluating the measurement results. If a desired magnetic field strength is exceeded in the measuring antennas 24, the current combination of antenna parameters is found. These antenna parameters are then transmitted to the transmitting and receiving unit 2 in the motor vehicle 1 and there the parameter memory 14 is stored. For future transmissions of the interrogation signal during normal operation of motor vehicle 1, this combination of antenna parameters is then used as the initial values to control antennas 3. If the desired magnetic field strength is not reached (ie no response signal comes back), then the antenna parameters are changed until at least one threshold value for the magnetic field strength in the area of the transponder 5 is exceeded.
Bei der Initialisierung können durch das Diagnosegerat 25 alle möglichen Antennenparametern m einem Meßwertefeld durch- fahren werden, bis die gewünschte Feldstarke an der Meßantenne 24 empfangen wird.During the initialization, the diagnostic device 25 can scan through all possible antenna parameters in a measurement value field until the desired field strength is received at the measurement antenna 24.
Ein solcher Algorithmus zum Durchspielen aller möglichen Antennenparameter kann sowohl in dem Diagnosegerat 25 als auch in der Sende- und Empfangseinheit 2 gespeichert sein. Es kann auch ein zusätzliches Gerat an das Diagnosegerat 25 angeschlossen werden, in dem dieser Algorithmus gespeichert ist und bei Wunsch durchgeführt wird.Such an algorithm for running through all possible antenna parameters can be stored both in the diagnostic device 25 and in the transmitting and receiving unit 2. An additional device can also be connected to the diagnostic device 25, in which this algorithm is stored and carried out if desired.
Die verschiedenen Antennenparameter können dabei stetig (z.B. stetiges Andern der Frequenz oder Leistung) oder auch stufenweise innerhalb eines vorgegebenen Wertebereichs verändert werden. Es können auch einzelne Antennenparameter ausgelassen werden und aus den Meßwerten der optimale Kombination von An- tennenparametern aus den gemessenen Magnetfeldstarken ermittelt werden.The various antenna parameters can be changed continuously (eg constant change in frequency or power) or also step by step within a specified value range. Individual antenna parameters can also be omitted and the optimal combination of antenna parameters can be determined from the measured magnetic field strengths.
Als Meßantenne 24 kann auch eine der Antennen 3 im Kraftfahr- zeug 1 verwendet werden. Auf diese Weise kann eine optimale Kombination von Antennenparametern am Bandende bei der Fertigung des Fahrzeugs ermittelt und m dem Fahrzeug in dem Parameterspeicher 14 abgespeichert werden. Mit diesem Antennenparameter beginnt die Sende- und Empfangseinheit 2 die Antennen 3 zu steuern, wenn zukunftig ein Frage-Antwort-Dialog zwischen dem Fahrzeug 1 und dem Transponder 5 stattfindet soll.One of the antennas 3 in the motor vehicle 1 can also be used as the measuring antenna 24. In this way, an optimal combination of antenna parameters at the end of the band can be determined during the manufacture of the vehicle and can be stored in the parameter memory 14 in the vehicle. With this antenna parameter, the transmitting and receiving unit 2 begins to control the antennas 3 if in future a question-and-answer dialogue is to take place between the vehicle 1 and the transponder 5.
Die Antennen 3 sind als Spulen ausgebildet, die jeweils Teil eines RLC-Schwmgkreises sind. Durch einen Oszillator wird in jedem Schwingkreis eine hochfrequente Schwingung (beispielsweise bei 125 kHz) angeregt. Die Spule erzeugt dann ein hochfrequentes Magnetfeld, das je nach Form/Ausgestaltung und Anbringungsort der Spule sowie Schwingungsfrequenz und Starke des Anregestroms (Leistung) eine davon abhangige Reichweite und eine eigene Richtcharakteristik aufweist (vgl. die beiden gestrichelten Bereiche m Figur 5).The antennas 3 are designed as coils, each of which is part of an RLC oscillation circuit. A high-frequency oscillation (for example at 125 kHz) is excited by an oscillator in each resonant circuit. The coil then generates a high-frequency magnetic field that, depending on the shape / design and location of the coil as well as the oscillation frequency and strength of the excitation current (power), has a range that depends on it and its own directional characteristic (see the two dashed areas in FIG. 5).
Wenn eine Transponderspule 19 in das Magnetfeld hinein gebracht wird, dann wird deren Windungsflache mit Feldlinien des Magnetfeldes mehr oder weniger durchsetzt. Abhangig von der Hohe der Durchsetzung wird in der Transponderspule 19 eine Spannung induziert.If a transponder coil 19 is brought into the magnetic field, its winding surface is more or less penetrated by field lines of the magnetic field. Depending on the level of enforcement, a voltage is induced in the transponder coil 19.
Wenn der Schwingung in dem Schwingkreis zusätzlich eine bma- re Information (Fragesignal) aufmoduliert wird, so wird diese Information durch das Magnetfeld induktiv von der Antenne 3 zu der Transponderspule 19 übertragen. Die Reichweite der ausgesendeten Signale ist bei einer induktiven Übertragung jedoch sehr gering und betragt etwa ein bis zwei Meter. Die Reichweite ist jedoch von der Sendeleistung sowie der Sende- frequenz der Antennen 3 und der Anordnung der Antennen 3 im Kraftfahrzeug 1 abhangig. Ebenso ist die Reichweite von der Phase der Ansteuerung von zwei Antennen 3 zueinander abhangig. Diese Abhängigkeiten werden bei der Erfindung ausge- nutzt, indem die Antennen 3 mit den verschiedenen Antennenparametern gesteuert werden.If the oscillation in the oscillating circuit is additionally modulated with a bar information (question signal), this information is inductively transmitted from the antenna 3 to the transponder coil 19 by the magnetic field. However, the range of the transmitted signals is very short in the case of inductive transmission and is about one to two meters. However, the range is dependent on the transmission power and the frequency of the antennas 3 and the arrangement of the antennas 3 in the motor vehicle 1 dependent. The range is also dependent on the phase of the control of two antennas 3 to one another. These dependencies are used in the invention in that the antennas 3 are controlled with the different antenna parameters.
Die Antennenparameter sind in einer Tabelle in dem Parameterspeicher 14 der Sende- und Empfangseinheit 2 abgelegt. Jedem Antennenparameter wird in der Tabelle eine Frequenz (einzustellende Frequenz des Oszillators oder eines Frequenzteilers), eine Leistung (Steuerstrom des Schwingkreises), eine Antenne 3 oder und eine Phase (bezüglich einer zweiten Antenne 3), mit der jeweils eine Antenne 3 gesteuert wird, zu- geordnet. Alle Antennenparameter und ihre zugeordneten Werte werden bei der Entwicklung des Diebstahlschutzsystems durch Erprobung an einem Modell ermittelt.The antenna parameters are stored in a table in the parameter memory 14 of the transmitting and receiving unit 2. In the table, each antenna parameter is assigned a frequency (frequency to be set by the oscillator or a frequency divider), a power (control current of the resonant circuit), an antenna 3 or and a phase (with respect to a second antenna 3) with which an antenna 3 is controlled, assigned. All antenna parameters and their assigned values are determined during the development of the anti-theft system by testing on a model.
Bei dem erfindungsgemaßen Diebstahlschutzsystem wird das Fra- gesignal zumindest über zwei Antennen 3 ausgesendet. Durch die Antennenparameter wird festgelegt, über welche Antennen 3 das Fragesignal beim ersten Aussenden und über welche Antennen 3 das Fragesignal beim nächsten Aussenden ausgesendet wird. Außerdem wird durch andere Antennenparameter festge- legt, unter welchen Bedingungen (Frequenz, Leistung, Phase) die jeweiligen Antennen 3 gesteuert werden. Somit bewirkt jede Kombination von Antennenparametern 3 einen eigenen Uber- tragungskanal (Magnetfeld) , m dem das Fragesignal in Abhängigkeit von den Antennenparametern übertragen wird.In the theft protection system according to the invention, the query signal is transmitted at least via two antennas 3. The antenna parameters determine which antennas 3 are used to transmit the query signal when they are first transmitted and which antennas 3 are used to transmit the query signals when they are next transmitted. In addition, other antenna parameters determine under which conditions (frequency, power, phase) the respective antennas 3 are controlled. Each combination of antenna parameters 3 thus causes its own transmission channel (magnetic field), to which the query signal is transmitted as a function of the antenna parameters.
Die Fragesignal enthalten als Information eine binare Zufallszahl, die eine vorgegebene Lange von beispielsweise 32 Bit aufweist. Die Zufallszahl wird moduliert zu dem Transponder 5 übertragen. Nur wenn der Transponder 5 die vollständige Zufallszahl empfangt, d.h. alle 32 Bit, dann gilt das Frage- signal als korrekt empfangen. Die Zufallszahl kann dazu verwendet werden, das Antwortsignal mit Hilfe eines geheimen, kryptographischen Schlüssel zu erzeugen. Zusätzlich können auch benutzer- oder fahrzeugspezifische binare Daten zum Verschlüsseln des Antwortsignals verwendet werden. Abhangig vom Ort der Auslosung (Ausloseschalter 4 am Türgriff oder am Zündschloß) kann auch eine Steuerinformation mit der Zufallszahl übertragen werden, durch die dann entschieden wird, ob die Türen oder die Wegfahrsperre zu steuern sind.The question signals contain a binary random number as information, which has a predetermined length of 32 bits, for example. The random number is modulated and transmitted to the transponder 5. Only if the transponder 5 receives the complete random number, ie every 32 bits, does the question- signal received as correct. The random number can be used to generate the response signal using a secret, cryptographic key. In addition, user-specific or vehicle-specific binary data can also be used to encrypt the response signal. Depending on the location of the draw (release switch 4 on the door handle or on the ignition lock), control information with the random number can also be transmitted, by which it is then decided whether the doors or the immobilizer are to be controlled.
In der Sende- und Empfangseinheit 2 im Kraftfahrzeug 1 wird der gleiche kryptografische Schlüssel verwendet, um aus der Zufallszahl einen erwarteten Sollwert zu errechnen und diesen im Sollwertspeicher 15 abzuspeichern. Dieser Sollwert wird mit dem empfangenen Antwortsignal verglichen. Wenn beide zumindest weitgehend übereinstimmen, so wird ein Steuersignal erzeugt, mit dem die Türschlösser 6 oder die Wegfahrsperre 7 betätigt wird.The same cryptographic key is used in the transmitting and receiving unit 2 in the motor vehicle 1 in order to calculate an expected target value from the random number and to store this in the target value memory 15. This setpoint is compared with the response signal received. If both at least largely agree, a control signal is generated with which the door locks 6 or the immobilizer 7 is actuated.
Unter dem Begriff elektronische Wegfahrsperre ist ein elektronische Einrichtung im Kraftfahrzeug 1 zu verstehen, die das Benutzen des Kraftfahrzeugs 1 nur bei nachgewiesener Berechtigung (Authentifikation) erlaubt. Als Wegfahrsperre kann beispielsweise das Motorsteuergerat dienen, das seine Funkti- on nur aufnimmt, wenn der Vergleich zwischen dem Antwortsignal und dem Sollwert Übereinstimmung der beiden erbrachte. Ebenso kann ein Eιn-/Ausschalter im Zundkreis oder ein Sperrventil im Kraftstoffkreis als Wegfahrsperre dienen. Es können auch mehrere Steuergerat in die Wegfahrsperre eingebunden werden. The term electronic immobilizer is to be understood as an electronic device in the motor vehicle 1, which allows the use of the motor vehicle 1 only with proven authorization (authentication). The engine control unit, for example, can serve as an immobilizer and only functions when the comparison between the response signal and the setpoint value results in agreement between the two. An on / off switch in the ignition circuit or a check valve in the fuel circuit can also serve as an immobilizer. Several control units can also be integrated into the immobilizer.

Claims

Patentansprüche claims
1. Diebstahlschutzsystem für ein Kraftfahrzeug mit1. Theft protection system for a motor vehicle with
- einer in dem Kraftfahrzeug (1) angeordneten Sende- und Emp- fangseinheit (2), die mit zumindest zwei voneinander getrennt im Kraftfahrzeug (1) angeordneten Antennen (3) elektrisch verbunden ist, über die jeweils ein Fragesignal ausgesendet wird,a transmission and reception unit (2) arranged in the motor vehicle (1), which is electrically connected to at least two antennas (3) arranged separately from one another in the motor vehicle (1) and via which a query signal is transmitted in each case,
- einem Antwortgeber (5) , der ein Antwortsignal aussendet, wenn er das Fragesignal empfängt,- a responder (5) which sends out a response signal when it receives the question signal,
- einer Auswerteeinheit (9) in der Sende- und Empfangseinheit (3) , die das empfangene Antwortsignal auswertet und mit Sollwerten vergleicht, und mit- An evaluation unit (9) in the transmitting and receiving unit (3), which evaluates the received response signal and compares it with target values, and with
- einer in der Sende- und Empfangseinheit (2) angeordneten Steuereinheit (9), die ein Fragesignal zumindest zwei Antennen (3) abhängig jeweils von einer Kombination von Übertragungsparametern zuführt, wodurch das Fragesignal in Abhängigkeit von den Übertragungsparametern in zumindest zwei verschiedenen Übertragungskanälen übertragen wird, wobei die Übertragungsparameter in Abhängigkeit vom Antwortsignal verändert werden.- A control unit (9) arranged in the transmitting and receiving unit (2), which supplies a query signal to at least two antennas (3) depending on a combination of transmission parameters, whereby the query signal is transmitted as a function of the transmission parameters in at least two different transmission channels , the transmission parameters being changed as a function of the response signal.
2. Diebstahlschutzsystem nach Anspruch 1, dadurch gekennzeichnet, daß diejenigen Übertragungsparameter für zukünftige Übertragungen des Fragesignals zunächst verwendet werden, bei denen das zurückgesendete Antwortsignal zumindest weitgehend mit den Sollwerten übereinstimmt.2. Theft protection system according to claim 1, characterized in that those transmission parameters for future transmissions of the query signal are initially used, in which the returned response signal at least largely matches the target values.
3. Diebstahlschutzsystem nach Anspruch 1, dadurch gekenn- zeichnet, daß die Übertragungsparameter zeitweise solange verändert werden, bis das zurückgesendete Antwortsignal weitgehend mit den Sollwerten übereinstimmt.3. Theft protection system according to claim 1, characterized in that the transmission parameters are temporarily changed until the response signal returned largely corresponds to the target values.
4. Diebstahlschutzsystem nach einem der vorhergehenden An- Sprüche, dadurch gekennzeichnet, daß die Übertragungsparame- ter m einem Speicher (14) der Sende- und Empfangseinheit (2) gespeichert sind.4. Theft protection system according to one of the preceding claims, characterized in that the transmission parameters ter m a memory (14) of the transmitting and receiving unit (2) are stored.
5. Diebstahlschutzsystem nach einem der vorhergehenden An- spruche, dadurch gekennzeichnet, daß die Ubertragungsparame- ter die Sendefrequenz, die Sendeleistung, die Phasenlage oder die Auswahl von Antennen (3) , mit denen das Fragesignal ausgesendet wird, bestimmen.5. Theft protection system according to one of the preceding claims, characterized in that the transmission parameters determine the transmission frequency, the transmission power, the phase position or the selection of antennas (3) with which the query signal is transmitted.
6. Diebstahlschutzsystem nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Antennen (3) in Form von elektrischen Spulen m der Fahrertur, in der fahrerseiti- gen Hintertür, m der Seitenwand im Bereich des Rucksitzes, des Tanks oder der Stoßfanger oder an sonstigen Stellen m der Karosserie angeordnet sind.6. Theft protection system according to one of the preceding claims, characterized in that the antennas (3) in the form of electrical coils m the driver's door, in the driver's side rear door, m the side wall in the area of the back seat, the tank or the bumper or other Places m of the body are arranged.
7. Diebstahlschutzsystem nach Anspruch 6, dadurch gekennzeichnet, daß sowohl fahrerseitig als auch beifahrerseitig Antennen (3) an der Fahrzeugkarosserie befestigt sind.7. Theft protection system according to claim 6, characterized in that both the driver's side and the passenger's side antennas (3) are attached to the vehicle body.
8. Diebstahlschutzsystem nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Antwortgeber (5) in einem scheckkartenahnlichen Gehäuse angeordnet ist und eine oder mehrere Antennen (19) in Form von elektrischen Spulen aufweist.8. Theft protection system according to one of the preceding claims, characterized in that the answering device (5) is arranged in a credit card-like housing and has one or more antennas (19) in the form of electrical coils.
9. Diebstahlschutzsystem nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Ubertragungsparame- ter innerhalb eines vorgegebenen Bereichs stufenweise veran- dert werden und jeder Kombination von Ubertragungsparametern eine Kennzahl zugeordnet wird, die mit dem Fragesignal zu dem Antwortgeber gesendet wird, und der Antwortgeber zu jedem Fragesignal ein entsprechendes Antwortsignal zurücksendet, das die mit dem Fragesignal übermittelte Kennzahl enthalt, wenn das Fragesignal ordnungsgemäß empfangen wurde. 9. Theft protection system according to one of the preceding claims, characterized in that the transmission parameters are changed step by step within a predetermined range and each combination of transmission parameters is assigned a code number which is sent to the responder with the question signal, and the responder sends a corresponding response signal back to each question signal, which contains the code transmitted with the question signal if the question signal was received properly.
10. Diebstahlschutzsystem nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Sende- und Empfangseinheit (2) Antennen (3) nur auf der Fahrerseite oder nur auf der Beifahrerseite des Kraftfahrzeugs (1) ansteuert, wenn ein Fragesignal in einen Bereich außerhalb des Kraftfahrzeugs (1) gesendet werden soll und daß die Sende- und Empfangseinheit (2) Antennen (3) sowohl auf der Fahrerseite als auch auf der Beifahrerseite des Kraftfahrzeugs (1) ansteuert, wenn ein Fragesignal in das Fahrzeuginnere gesendet werden soll.10. Theft protection system according to one of the preceding claims, characterized in that the transmitting and receiving unit (2) antennas (3) only on the driver's side or only on the passenger's side of the motor vehicle (1) controls when a question signal in an area outside the motor vehicle (1) should be sent and that the transmitting and receiving unit (2) antennas (3) controls both on the driver side and on the passenger side of the motor vehicle (1) when a query signal is to be sent into the vehicle interior.
11. Diebstahlschutzsystem nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Transponder (5) eine Meßeinrichtung aufweist, mit der das Fragesignal in seiner Starke gemessen und ein Meßwert zurück zu der Sende- und Empfangseinheit (2) im Kraftfahrzeug gesendet wird sowie dort die zu dem gerade empfangenen Fragesignal zugehörigen Antennenparametern für zukunftige Übertragungen gespeichert werden. 11. Theft protection system according to one of the preceding claims, characterized in that the transponder (5) has a measuring device with which the question signal is measured in its strength and a measured value is sent back to the transmitting and receiving unit (2) in the motor vehicle and there the antenna parameters associated with the query signal just received are stored for future transmissions.
EP98928073A 1997-05-06 1998-03-25 Anti-theft device for vehicule Withdrawn EP0994998A1 (en)

Applications Claiming Priority (3)

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DE19718764 1997-05-06
DE1997118764 DE19718764C1 (en) 1997-05-06 1997-05-06 Theft protection system for motor vehicle
PCT/DE1998/000880 WO1998050652A1 (en) 1997-05-06 1998-03-25 Anti-theft device for vehicule

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EP0994998A1 true EP0994998A1 (en) 2000-04-26

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BR (1) BR9808744A (en)
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