DE10012113A1 - Data transmission and/or distance measurement between base unit and mobile key unit of access authorization monitoring system involves modulating carrier signal with identification signal - Google Patents

Data transmission and/or distance measurement between base unit and mobile key unit of access authorization monitoring system involves modulating carrier signal with identification signal

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Publication number
DE10012113A1
DE10012113A1 DE2000112113 DE10012113A DE10012113A1 DE 10012113 A1 DE10012113 A1 DE 10012113A1 DE 2000112113 DE2000112113 DE 2000112113 DE 10012113 A DE10012113 A DE 10012113A DE 10012113 A1 DE10012113 A1 DE 10012113A1
Authority
DE
Germany
Prior art keywords
signal
unit
frequency
characterized
distance
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.)
Ceased
Application number
DE2000112113
Other languages
German (de)
Inventor
Martin Dr Vossiek
Patric Dr Heide
Richard Roskosch
Johannes Ilg
Klaus Dr Hofbeck
Wolfgang Piesch
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.)
Continental Automotive GmbH
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
Priority to DE2000112113 priority Critical patent/DE10012113A1/en
Publication of DE10012113A1 publication Critical patent/DE10012113A1/en
Application status is Ceased legal-status Critical

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60RVEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R25/00Fittings or systems for preventing or indicating unauthorised use or theft of vehicles
    • B60R25/20Means to switch the anti-theft system on or off
    • B60R25/24Means to switch the anti-theft system on or off using electronic identifiers containing a code not memorised by the user
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/003Transmission of data between radar, sonar or lidar systems and remote stations
    • GPHYSICS
    • G08SIGNALLING
    • G08CTRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C17/00Arrangements for transmitting signals characterised by the use of a wireless electrical link
    • G08C17/02Arrangements for transmitting signals characterised by the use of a wireless electrical link using a radio link
    • GPHYSICS
    • G07CHECKING-DEVICES
    • G07CTIME 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
    • G07C2209/00Indexing scheme relating to groups G07C9/00 - G07C9/38
    • G07C2209/60Indexing scheme relating to groups G07C9/00174 - G07C9/00944
    • G07C2209/63Comprising locating means for detecting the position of the data carrier, i.e. within the vehicle or within a certain distance from the vehicle
    • GPHYSICS
    • G07CHECKING-DEVICES
    • G07CTIME 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
    • G07C9/00Individual registration on entry or exit
    • G07C9/00174Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C9/00309Electronically 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

Abstract

The invention relates to a method and a device for transmitting data or for measuring the distance between a base unit and a mobile key unit of an access authorization control system, in particular for motor vehicles. To increase the security of the data transmission or the distance measurement, a high-frequency identification signal is modulated or added to the transmitted signal (data transmission) or the "reflected" signal (distance measurement). In the unit receiving the signal, this is checked for the presence of the high-frequency identification signal in addition to evaluating the data or evaluating the distance. The data are only recognized as permissible or the evaluation with regard to the distance is only carried out or the result thereof is recognized as permissible if the identification signal in the received signal agrees sufficiently with target information stored in the receiving unit.

Description

The invention relates to a method for data transmission between a base unit and a mobile key of an access authorization control system, in particular for motor vehicles, with the features of the preamble of Claim 1 and a method for determining the Ab stands of a basic unit with the characteristics of the generic term of claim 2 and one in particular for implementation access authorization control systems suitable for this method tem with the features of the preamble of the claim 12th

Access authorization control systems are becoming increasingly common use in motor vehicles and can, for example, as Locking system access to the motor vehicle in question enable or prevent or use the motor vehicle stuff by activating or deactivating an immobilizer block or unlock.

A basic distinction is made between access authorization accounts troll systems between active and passive systems. In at In the cases, the system consists of one or more bases units provided for example in the motor vehicle are, and one or more key units by the authorized drivers. With an ak Access authorization control system is a triggering one Action required which is the required communication between the base unit (s) and each Triggers key unit. This can be, for example to press a key on the key unit o that of operating a door blade of the motor vehicle. At  a purely passive access authorization control system preferably continually tried by the base unit with to communicate with a key entity with the aim of following successful communication, especially the transfer a correct code for the base unit, a corresponding one appropriate action (for example, the locking system disable or one or more locks automatically open) if the key unit is within a be agreed minimum distance to the base unit. The sys tem can also be designed so that an action only then is triggered if in addition to the condition of the sub an action is triggered if the minimum distance is exceeded, for example, a door handle is operated.

Especially with passive access authorization control systems It must be guaranteed with a high degree of certainty that the actually authorized key unit within a predetermined distance from the respective motor vehicle or from the base unit or units provided in the motor vehicle finds. Unauthorized interference in communication from outside eating by unauthorized persons should, if possible high security can be excluded.

This applies not only when determining the distance between between the basic unit or units and the relevant unit Key unit, but also in communication between the base unit or units and the relevant key unit. Here too, the highest possible security of the Communication channel can be guaranteed to unauthorized Avoid interference, such as deactivating the immobilizer re, if there is a key unit within the correct distance, but the key unit only has authorization to deactivate the locking system, but not to deactivate the immobilizer.

The invention is therefore based on the object of a method ren for data transmission and / or distance measurement between  a base unit and a mobile key unit Access authorization control system, especially for strength vehicles, which provide a high level of security in the Determination of the distance or the data transmission compared unauthorized external interventions by not calculating persons / key units. Furthermore is the object of the invention, an access calculation creation control system, which in particular for Realization of this method is suitable.

The invention solves this problem with the features of Pa Claims 1 and 2 or 12.

The invention is based on the knowledge that a Method for data transmission, in which one with a relative low frequency signal modulated carrier signal use who is protected against manipulation from outside that can be transmitted with the low frequency Signal modulated carrier signal past one or more agreed or predeterminable temporal positions high-frequency identification signal modulated or added becomes. With the addition of a high-frequency detection signals is understood to mean that this identification signal in Pauses in the modulated modulation with the low-frequency signal gersignals is inserted. Such breaks can for example wise with an amplitude modulation with a modulation degree of 100%.

Because usual receivers who are on such a thing with a never derfrequenten signal modulated carrier signal are the frequency band (of the modulati onssignals) or not for other reasons suitable for receiving a high-frequency modulation signal are, the identification signal is not when trying to listen co-recorded.  

Since the respective receiving unit (base unit or key seleinheit) the received signal for establishing the identity of the sending unit for the presence of the identification sig nals and its correspondence with a target quality checked, it is possible in this way, predetermined Akti only trigger or certain signals generate if by checking the identification signal actual authorization of the unit sending the signal is confirmed.

The communication channel is not opposed in this way a basic eavesdropping is assured, however, with great Security can be guaranteed that is not on a relative basis simple way and with simple means of the received Unit signals are faked, the safety critical Trigger actions.

The provision of such a high-frequency identification signal is not only to secure a data transmission route suitable, but can also be used to secure a distance measurement method for determining the distance of a mobile Key unit can be used by a base unit.

The measurement of the Distance by known radar measurement technology, with a from a sending unit (preferably base unit) generated radar signal from the other unit (preferred wise key unit) to which the distance is determined should, as an active or passive backscatter signal or as active response signal derived from the received radar signal nal is "reflected". The "reflected" signal is like around which the high-frequency identification signal is modulated or out added. In this way it can emit the radar signal de unit the reflected received signal to the presence be the identification signal and its correspondence with the Check the target condition. In the case of a positive Exam result can be assumed with a very high degree of certainty  be that the "reflected" signal from a actually entitled entity. The certain Ab stand can only be determined in this way for the case that an identification signal has been recognized or an already be In this case, the correct distance value can be defined as permissible be kidneyed. This will make the pretend a little Distance, which then determines the triggering in the further process ter actions can be avoided with high certainty the.

When using the distance method according to the invention determination can be the radar signal and / or backscatter or Response signal simultaneously a low-frequency signal aufmo be dulated so that the transmission path for the Ra Darsignal simultaneously for the transmission of data or one Codes can be used by the receiving unit Information about the nature of the high-frequency Ken supply signal.

To further improve the security of data transmission the high-frequency Ken a complex modulation scheme and / or a Have code. Furthermore, the modulation scheme and / or the code and / or the one or more agreed temporal positions of the identification signal with the low-frequency signal in a predetermined context stand.

The low-frequency signal can be a digital one Act signal. The predetermined connection with the module tion scheme and / or the code and / or the one or the Several cryptological positions can be a cryptological addition be related.

This further improves security bar that the signal energy of the identification signal is below the Noise wave of common receivers, especially not as correlation receivers  trained recipient. The Detec In this case, the identification signal is preferably used through the use of a correlation receiver. This mitit establishes a degree of correlation between the received signal ( preferably a certain time segment of the emp catch signal) and be in the receiving unit knew target identification signal. If the determined exceeds Degree of correlation a predetermined threshold, so the emp caught signal as permissible or as from an authorized Unit originating signal detected.

The threshold for the degree of correlation can depend on the Receiving power of the received signal can be determined.

As a radar signal for the method according to the invention level measurement is particularly suitable for a modulated carrier gerwelle, the distance measurement by comparing the information contained in the modulation and that in the passive or active "reflected" signal or in the response signal ent corresponding information is held.

The modulation can further increase the security of the Distance measurement after each distance measurement or after each a regular or irregular number of distances measurements are changed. This way eavesdropping of the measurement channel and using the information for the pre fool a wrong reflected signal the next time Measuring process practically impossible.

The modulation can be changed when using the FMCW Procedure by changing the repetition rate and / or The frequency ramp is steep when using the FSCW procedure by changing the size of the Fre steps or when using the pulse compression method rens by changing the time bandwidth product. The change The respective sizes can of course be within  predetermined limits, preferably random or pseudo-random lig.

The access authorization control system according to the invention includes at least one base unit in the usual way at least one mobile key unit, each of these one units has a transmitting and receiving unit. In at least a unit, which signals with safety-critical data sends, or which a radar signal re for distance measurement inflected, a high-frequency modulation unit is provided hen a signal to be sent on one or more predetermined or predeterminable temporal positions high-frequency identification signal modulated or added.

The target quality of the high-frequency identification signal and the one or more positions are also each the transmitted signal receiving unit known. For this can either be a corresponding one in the receiving unit Algorithm and / or the time course of the ID signal. There is one in the receiving unit Detector unit provided to determine the Identi the receiving unit acts on the existing signal the identity signal and its agreement with checks the target quality.

The sending and receiving unit of the On sending the signal Unit can be active or passive in a manner known per se Backscatter unit to be formed.

One unit (base unit and / or key unit) can both a radar signal transmitting and receiving unit as well a transmitter and receiver unit for low-frequency signals exhibit.

In one embodiment, each of the communicating Units have a radar signal transmitting and receiving unit so that a distance measurement is carried out in each unit  can be. One unit each (preferably the Key unit) can then be the result of the performed distance measurement, preferably coded, to the other Unit (preferably the base unit) transfer. This can then the transferred measurement result with the result of the distance measurement performed by her and that (from her he Define the mean) measurement result as permissible only if the deviations of the distance values within predetermined Tolerances.

Further embodiments of the invention result from the Dependent claims.

At this point it is expressly pointed out that the features of the present invention regarding the changes modulation of the (transmitted) radar signal and all other related features already for taken an improvement in the security of the data bearing or the distance measurement, even if in this Case on the additional use of a high frequency Ken voltage signal in the transmitted signal or "reflected" signal is waived.

In the same way, an improvement in security can already be achieved unit of data transmission or distance measurement independent of using a high frequency identification signal or egg ner changing modulation of the radar signal achieved if there is one in each of the two communicating units Radar signal transmission and reception unit is provided, so that a distance measurement was carried out in both units can and in the manner described above that of one measurement result (coded) to each because another unit is being transferred and this is the two Measurement results for the existence of permissible deviations checked.  

The invention is illustrated below with reference to the drawing illustrated embodiments explained in more detail. In the drawing show:

Fig. 1 is a schematic block diagram of a base unit and a mobile key unit of an access authorization control system according to the inven tion;

Figure 2 shows the temporal course of the entire modulation signal (low-frequency and high-frequency portion) of the "reflected" signal from the key unit;

Fig. 3 is a schematic block diagram of a second embodiment of an access authorization control system and

Fig. 4 is a schematic block diagram of a base unit or key unit of a further embodiment of an access authorization control system according to the invention.

The access authorization control system shown schematically in FIG. 1 comprises a base unit 3 and a key unit 5 . A plurality of base units 3 can also be provided in a motor vehicle, for example in order to be able to determine the exact position of a key unit relative to the vehicle in addition to a distance measurement. The entire access authorization control system 1 can also comprise a plurality of key units 5 , the key units being able to differ in terms of their authorization to trigger certain actions.

The base unit 3 shown in FIG. 1 is designed such that a measurement of the distance between the base unit 3 and the key unit 5 can be carried out according to the FMCW radar principle. For this purpose, the base unit comprises a frequency-tunable oscillator 7 (VCO), a high-frequency amplifier 9 (VB), a receiver / mixer unit 11 (trx-mix), an antenna 13 (AB), a filter 15 (FLT), an ana log / Digital converter 17 (A / D), a microprocessor unit 19 (mPB) and a digital / analog converter 21 (D / A).

The microprocessor unit 19 uses the digital / analog converter 21 to generate a voltage curve v (t) with which the frequency-tunable oscillator 7 is controlled. In the FMCW method used here, the voltage curve v (t) has a sawtooth curve, so that the output signal of the frequency-detunable oscillator 7 represents a frequency-modulated carrier wave, the frequency within a predetermined time segment in each case continuously and linearly from a minimum value Frequency increases to a maximum value of the frequency. The output signal of the frequency-detunable oscillator 7 passes via the receiver / mixer unit 11 essentially unchanged to the antenna 13 and is emitted by the latter as a radar transmission signal. The key unit 5 shown in FIG. 1 is designed as an active backscatter unit. The signal sent by the base unit 3 is received by the antenna 23 (AIR) of the key unit 5 and fed to a high-frequency amplifier 25 (VI). This amplifies the received signal and feeds it to a mixer unit 27 .

The key unit 5 further comprises a high-frequency modulation unit 29 (HMG) and a microprocessor unit 31 (mPI). The microprocessor unit 31 controls the high-frequency modulation unit 29 . In this way, the output signal of the RF amplifier 25 is profiled aufmodu means of the mixer unit 27, a radio frequency identification signal. If, instead of an additional modulation of the received signal, a signal modulated with a high-frequency identification signal is to be added to it in signal pauses, a corresponding transmission unit can be provided in the key unit 5 , the output signal (modulated or unmodulated carrier wave) with the curve h (t ) of the high-frequency identification signal is modulated.

The received signal changed in this way is fed to the transmitting antenna 33 (AIT) and radiated by the latter. Of course, measures known per se can be used instead of the receiving antenna 23 and the transmitting antenna 33 to use a single antenna.

The "reflected" signal emitted by the transmitting antenna 33 is received by the antenna 13 of the base unit 3 and supplied to the receiver / mixer unit 11 . In this, the receiver signal is mixed with the output signal of the Hochfrequenzver amplifier 9 and fed to the filter 15 . The filter 15 cuts the output signal of the receiver / mixer unit 11 to the baseband of the relatively low frequency modulation by the signal v (t) or n (t) of a code transmitter 35 (PNG) in the key unit 5 (see below). .

The analog / digitally converted output signal of the filter 15 by means of the analog / digital converter 17 is supplied to the microprocessor unit 19 . This evaluates the signal in the sense of a distance measurement. For this purpose, the signal mixed in the base band is subjected to a Fast Fourier Transform (FFT). The resulting spectrum is analyzed with regard to its spectral components. Those spectral lines that result from the reflection of the transmission signal at the respective key unit are identified by evaluating the modulation information (known to the base unit) in the FFT spectrum. The distance can then be determined from the frequency of the relevant spectral line (s), where the distance is essentially proportional to the frequency of the relevant spectral line (s) or proportional to the frequency of the spectral line shifted by a certain amount .

Furthermore, part of the received power supplied by the antenna 13 of the base unit 3 is fed to a mixer unit 39 by means of a directional coupler 37 . This Mi shear unit 39 is further supplied with the output signal of a high-frequency modulation unit 41 (HMG) provided in the base unit 3 . The high-frequency modulation unit 41 is controlled by the microprocessor unit 19 and generates the same high-frequency identification signal h (t) as the high-frequency modulation unit 29 in the key unit 5 . The timing of the generation of the signal h (t) is determined by the micro processor unit 19 from the course of the demodulated signal Emp fang, which the microprocessor unit 19 is supplied from the analog / digital converter 17th For this purpose, as already explained above, a code transmitter 35 is provided in the key unit 5 , whose relatively low-frequency output signal n (t) drives the switchable high-frequency amplifier 25 . In this way, the output signal of the high-frequency amplifier 25 receives a low-frequency digital amp modulation. The microprocessor unit 31 in the key unit 5 controls on the one hand the code transmitter 35 and on the other hand the high-frequency modulation unit 29 , so that in this way a coupling of the low-frequency modulation signal n (t) and the high-frequency identification signal h (t) can be ensured. In other words, depending on the code n (t), an identification signal h (t) is generated which has a very specific temporal position or several temporal positions in relation to the signal n (t) and / or its course likewise with the respective one Code can be linked.

The nature of the identification signal h (t) and its coupling between the low-frequency modulation signal n (t) is known in the same way to the microprocessor unit 19 in the base unit 3 . This ensures that the micro processor unit 19, the high-frequency modulation unit 41 of the base unit 3 depending on the received signal, which also contains the low-frequency modulation signal n (t) (this signal is of course also included in the output signal of the analog / digital converter 17 ), so that the output signal h (t) of the high-frequency modulation unit 41 has the same (target) nature with respect to the low-frequency modulation signal n (t) as the signal h (t) at the output of the high frequency - Modulation unit 29 with respect to the low-frequency modulation signal n (t) at the output of the code transmitter 35 in the key unit 5 . The (target) quality includes both the course of the signal h (t) and its temporal position in relation to the low-frequency modulation signal n (t).

The output signal of the mixer unit 39 is fed to a correlation filter 43 (KFLT), which can be designed, for example, as a low-pass filter. The size (example voltage) of the output signal of the correlation filter 43 is thus a measure of the correspondence of the radar signal "reflected" by the key unit 5 and received by the base unit 3 , in particular with regard to the presence and the correspondence of the course of the high-frequency identification signal h (t) with a target course known in the unit 3 unit .

To check whether there is sufficient agreement between the two signals, the output signal of the correlation filter 43 is fed to a comparator 45 (K) which compares the output signal with a fixed or predeterminable threshold. If the threshold is exceeded, this fact is understood as "identification signal identified", with the effect that the microprocessor unit 19 recognizes the distance value between the base unit 3 and the key unit 5 that it determines as correct or permissible. If the threshold is not exceeded, the determined distance is rejected as inadmissible. In this case, further actions such as the release of the locking system or individual locks of the locking system or the release of the immobilizer are blocked.

The threshold from which the comparator 45 generates a “positive” or a “negative” output signal can, as shown in FIG. 1, be defined by the microprocessor unit 19 and transferred to the comparator 45 . In particular, the threshold can be determined by the microprocessor unit 19 as a function of the power of the received signal or as a function of the power of the signal supplied to the microprocessor unit 19 . In particular, low threshold values can be defined for low reception powers and higher threshold values for high reception powers.

As explained above, in the embodiment shown in FIG. 1 of the access authorization control system 1 in the key unit the "reflected" signal is modulated from time to time (possibly in addition to the normal code) the high-frequency identification signal. The timing of this modulation and the modulation code are preferably coupled to the low-frequency code of the code transmitter 35 according to a cryptological principle, this coupling being ensured by the microprocessor unit 31 . The base unit 3 receives the "reflected" signal from the key unit 5 and evaluates it with respect to the distance between the two units and with respect to the low-frequency code. Based on the detected code sequence, the high-frequency modulation unit 41 is loaded in the base unit 3 by the microporo processor unit 19 with the correct correlation code. The received signal is then mixed with the high-frequency correlation code at a point in time which is also derived from the detected low-frequency code sequence. The degree of correlation between the expected code and the received code is determined with the correlation filter 43 , which can be designed, for example, as a low-pass filter. If the degree of correlation exceeds a certain threshold, which is realized with the comparator 45 , the key unit is accepted as "valid". If there is an insufficient correlation, the signal of the key unit 5 is rejected. As already explained, the level of the threshold is determined as a function of the received signal, in particular from the level of the signal of the low-frequency code, and is adapted by the processor unit 19 to suit the situation.

Instead of this relatively complex method, there is of course also the possibility of modulating the high-frequency identification signal h (t) in the key unit 5 without a complicated cryptological coupling with a low-frequency modulation signal n (t). In the base unit 3 , it is then only determined whether the high-frequency identification signal is contained in the received signal "reflected" by the key unit 5 at any given time.

Also, for further simplification, the high-frequency modulation signal h (t) can always have the same nature and cannot be varied, for example with regard to the curve shape or the code, depending on the course of the low-frequency signal n (t). The 1 realized basic principle of using a hochfrequen th identification signal in the embodiment of Fig. Can of course also, in conjunction with any types of modulation of the radar signal USAGE be det.

At this point it should be noted that the entire modulation signal shown in Fig. 2 includes both the low-frequency modulation signal n (t) and the high-frequency identification signal h (t) and can thus be understood as the sum of these two modulation signals, even if the In an embodiment of a key unit 5 shown in FIG. 1, the modulation of the signal received with the antenna 23 with the two signals h (t) and n (t) takes place in two successive steps in different components.

As can be seen from FIG. 2, the high-frequency identification signal h (t) has a relatively complex profile and consists, on the one hand, of “pulses” of different widths, each of which can also have a different pulse shape and a different distance from one another.

Of course, any desired modulation method can also be used for impressing the signals shown in FIG. 2 onto the received signal in the key unit 5 . It is only necessary to ensure that the signal sent and the signal received by the base unit 3 can be correctly demodulated.

In a departure from the representation in FIG. 2, the high-frequency identification signal h (t) does not of course have to have essentially the same amplitude as the low-frequency signal n (t). Rather, as already stated, the signal energy of the identification signal can be selected in a single time or frequency window in such a way that it lies below half the noise threshold of conventional detectors or in the signal level is so significantly below the low-frequency code that the dynamics of conventional detectors for detection both signals are not sufficient (spread spectrum method). The presence of such a modulated signal can then, as shown in FIG. 1, only be reliably detected with a correlation receiver, to which the underlying code is known.

Fig. 3 shows a further embodiment of an access authorization control system in which a possibility is provided in the base unit 3 to change the modulation in the FMCW radar method used from measurement process to measurement process or regularly or irregularly after a specific number of measurement processes. For this purpose, the microprocessor unit 19 controls the digital / analog converter 21 in such a way that a voltage curve v (t) which drives the frequency-tunable oscillator 7 results, which generates a high-frequency signal at the output of the frequency-tunable oscillator 7 , the frequency of which varies between one Minimum frequency and a maximum frequency changes. The temporal dependence of the frequency is shown in the diagram shown in FIG. 3 for the exemplary profiles M1, M2 and M3.

This basic principle of modulation of the emitted radar signal changed from distance measurement process to distance measurement process can of course not only be used in connection with the FMCW method used in FIG. 3, but practically with any radar method which includes a modulation of the transmitted signal, for example also with FSCW Process or in pulse compression processes. In the latter case, the time-bandwidth product is changed regularly or irregularly.

This additional measure leads to further improvements security of an access authorization control system against unauthorized external interference.

As shown in Fig. 3, this way of improving security can also be used regardless of the use of a high-frequency identification signal. In this case, the correlation detector unit 47 contained in the base unit according to FIG. 1 can be dispensed with. In the same way, use of a mixer 27 and a high-frequency modulation unit 29 , as shown in FIG. 1 in connection with the key unit 1 , can of course be dispensed with. In this case, the illustration according to FIG. 3 then results.

Of course, the access authorization control system according to FIG. 3 can be expanded by adding the aforementioned components to a system which realizes both the possibility of using a high-frequency signal and the use of a modulation of the radar signal that changes from measurement process to measurement process .

Even in the embodiment of a unit for data transmission or measurement of the distance between a base unit and a key unit shown in FIG. 4, the components that are necessary for reliably recognizing the permissibility of the transmitted data or the measurement result have been omitted, that is, on the components of the correlation detector unit 47 (cf. base unit 3 in FIG. 1) and on the components for generating and modulating the high-frequency identification signal h (t) in a key unit, that is, on those in FIG. 2 in Connection with the key unit shown components 27 and 29 . When using a unit according to FIG. 4 both in the base unit and in the key unit, a distance measurement can be carried out in each of these units. If the correlation detector unit 47 and a mixer unit 27 and a high-frequency modulation unit 29 are additionally used in the unit in FIG. 4, this measurement result can be determined with even greater certainty compared to the method described below.

Even with the embodiment shown in FIG. 4, however, there is an improvement in security against external interventions by, for example, transmitting the result determined in the key unit for the distance between the two units, preferably in coded form, to the base unit. The base unit can then check whether the distance measurement result determined by it matches the distance result transmitted by the key unit with sufficient accuracy. If this is not the case, the measurement result can be rejected as inadmissible. Further actions can then be blocked.

In the embodiment according to FIG. 4, the measurement result can be transmitted between the units by means of a communication module 49 (BKE), which enables data to be sent and received. The communication module 49 can be designed in any way.

Otherwise, the unit for distance measurement and data transmission shown in FIG. 4 comprises the components of the base unit in FIG. 3 and the components of the key unit 5 shown in this figure. The processor unit 31 of the key unit 5 can be dispensed with, since its function, like the function of the microprocessor unit 19 of the base unit 3 , can be taken over by a single microprocessor unit 19 '.

The measurement processes and the communication can take place in the embodiment according to FIG. 4 in different frequency bands, in time division multiplexing or with uncorrelated signals. In addition, the use of several antennas can be dispensed with if the different signals are separated using switches or filters. Furthermore, the distance measuring unit can be able to generate communication signals, for example by designing the high-frequency amplifier 9 as a switchable amplifier, to which a further data signal d (t) generated by the microprocessor unit 19 'is supplied. This is then modulated onto the output signal of the frequency-detunable amplifier 7 and can be detected by the respective receiving unit in the same way as was described above for the detection of the code signal or low-frequency correlation signals n (t).

In the event that the distance measuring unit can generate and detect communication signals, it is of course possible to dispense with the communication module 49 shown in FIG. 4.

In the same way, communication can of course take place via the backscatter module of the unit shown in FIG. 4. For this purpose, only the code transmitter 35 must be controlled by the microprocessor unit 19 'in such a way that it can not only send a fixed code, but the desired data. This signal can then be received as described above.

Claims (18)

1. Method for data transmission between a base unit and a mobile key unit of an access authorization control system, in particular for motor vehicles,
  • a) in which a carrier signal is modulated with a low-frequency signal (n (t)) and is transmitted from the transmitting unit ( 3 ; 5 ) to the receiving unit ( 5 ; 3 ) and is demodulated therein,
characterized by
  • a) that with the low-frequency signal (n (t)) modulated carrier signal in the transmitting unit ( 3 ; 5 ) at one or more predetermined or pre-determinable positions in time a high-frequency identification signal (h (t)) is modulated or added ,
  • b) the respective receiving unit ( 5 ; 3 ) also knowing the target condition of the high-frequency identification signal (h (t)) and the one or more temporal positions,
  • c) that in the respective receiving unit ( 5 ; 3 ) to determine the identity of the sending unit ( 3 ; 5 ) the received signal is checked for the presence of the identification signal (h (t)) and its correspondence with the target condition and
  • d) that the demodulated low-frequency signal (n (t)) is only recognized as permissible if a positive test result has been determined.
2. Method for determining the distance between a base unit and a mobile key unit of an access authorization control system, in particular for motor vehicles,
  • a) in which a radar signal is generated and transmitted in at least one of the two units ( 3 ; 5 ),
  • b) in which an active or passive backscatter signal or an active response signal derived from the received signal is generated by the other unit ( 5 ; 3 ) when the radar signal is received, which has the distance information contained in the received radar signal, and
  • c) in which the backscatter signal or the response signal is received by the unit transmitting the radar signal ( 3 ; 5 ) and evaluated in the sense of determining the distance,
characterized,
  • a) that a high-frequency identification signal (h (t)) is modulated or added to the backscatter signal or the response signal at one or more predetermined or predeterminable temporal positions,
  • b) the unit transmitting the radar signal ( 3 ; 5 ) also being aware of the desired nature of the high-frequency signal (h (t)) and the one or more temporal positions,
  • c) that in the unit ( 3 ; 5 ) transmitting the radar signal, the received backscatter signal or response signal is checked for the presence of the identification signal (h (t)) and its correspondence with its target condition, and
  • d) that the distance is only detected or that a determined result for the distance was only recognized as being reliable.
3. The method according to claim 2, characterized in that the radar signal and / or the backscatter or response signal modulates a low-frequency signal (n (t)) becomes.
4. The method according to any one of the preceding claims characterized by that the high-frequency identification sig nal (h (t)) a complex modulation scheme and / or one Has code.
5. The method according to any one of the preceding claims characterized in that the modulation scheme and / or the code and / or the one or more predetermined th temporal positions of the identification signal with the low frequency signal in a predetermined combination slope.
6. The method according to claim 5, characterized in that the low frequency signal is a digital signal and that the predetermined relationship with the modulation scheme and / or the code and / or the one or more a predetermined cryptological positions is related.
7. The method according to any one of the preceding claims, characterized in that the signal energy of the identification signal (h (t)) is below the noise threshold of conventional receivers, in particular receivers not designed as correlation receivers, and that the identification signal in the respective receiving unit ( 5 ; 3 ) is detected by means of a correlation detector unit ( 47 ).
8. The method according to claim 7, characterized in that the threshold for the degree of correlation between one that Identification signal (h (t)) comprising part of the received signal nals and the target identification signal depending on the Emp power of the received signal or the received level of the low-frequency signal (n (t)) is determined.
9. The method according to any one of claims 2 to 8, characterized ge indicates that the radar signal is a modulated Trä gerfrequency, the distance measurement by ei comparison of the information contained in the modulation tion and the passively or actively reflected signal o the corresponding informa contained in the response signal tion is carried out.
10. The method according to claim 9, characterized in that the modulation after each distance measurement or after because of a regular or irregular number of Distance measurements is changed.
11. The method according to claim 10, characterized in that the repetition rate when using the FMCW method and / or the slope of the frequency ramp when in use of the FSCW method, the size of the frequency steps or when using the pulse compression method, the time Bandwidth product within specified limits at random, is changed.
12. Access authorization control system, in particular for motor vehicles, which in particular implements the method according to one of the preceding claims,
  • a) with a base unit ( 3 ) and at least one mobile key unit ( 5 ), each unit ( 3 ; 5 ) having a transmitting and receiving unit,
characterized,
  • a) that in at least one unit ( 5 ) the transmission and reception unit in question comprises a radio-frequency modulation unit ( 29 ) which transmits a radio-frequency identification signal (h (t)) to a signal to be transmitted at one or more predetermined o or the predetermined time positions modulated o which is added
  • b) the unit receiving the transmitted signal ( 3 ) also the target condition of the high-frequency identification signal (h (t)) and the one or the several temporal positions are known,
  • c) that in the respective receiving unit ( 3 ) there is a detector unit ( 47 ) which, to determine the identity of the sending unit, the received signal for the presence of the identification signal (h (t)) and its correspondence with the target Checks texture.
13. Access authorization control system according to claim 12, characterized in that in the at least one unit the transmission and reception unit in question comprises, in addition to the high-frequency modulation unit ( 29 ), a low-frequency modulation unit ( 25 ) which modulates the signal to be transmitted with a digital data signal .
14. Access authorization control system according to claim 12 or 13, characterized in that in the at least one unit ( 5 ) the respective transmitting and receiving unit is designed as an active or passive backscatter unit.
15. Access authorization control system according to one of claims 12 to 14, characterized in that the detector unit ( 47 ) is designed as a correlation detector unit, which has a degree of correlation between the desired condition of the identification signal (h (t)) and the received signal in the received signal contained identification signal that the detector unit ( 47 ) compares the degree of correlation with a predetermined threshold and, if the threshold is exceeded, identifies the unit ( 3 ) transmitting the received signal as a permissible source of information.
16. Access authorization control system according to one of claims 12 to 15, characterized in that in the detector unit ( 47 ) having unit ( 3 ) the transmitting and receiving unit is designed as a radar signal transmitting and receiving unit or in addition to the transmitting and receiving unit a radar signal transmitting and Empfangsein is integrated provided, wherein the radar signal transmission and reception unit which, or the response signal at least produced a unit (5) from that of the at least one unit (5) passively or actively reflected signal (Backscattersignal) which also contains the identification signal, evaluates it in the sense of a distance measurement and only defines the result of the distance measurement as permissible or determines the result of the distance measurement only if the detector unit ( 47 ) simultaneously produces a positive result when checking the identification signal (h (t) ) delivers.
17. Access authorization control system according to claim 16, characterized in that a radar signal transmitting and receiving unit is provided both in the base unit ( 3 ) and in each key unit ( 5 ), that the key unit ( 5 ) has a distance value determined by it Base unit ( 3 ) sends and this compares the distance value transmitted by it from the key unit ( 5 ) and defines it as permissible only if the deviations of the distance values lie within predetermined tolerances.
18. Access authorization control system according to claim 16 or 17, characterized in that the radar signal transmission and receiving unit according to the FMCW, FSCW or the pulse comm compression process works and that when using the FMCW method the repetition rate and / or the slope the frequency ramp, when using the FSCW method the Size of the frequency steps or when using the pulse compression process the time-bandwidth product inside change half of predetermined limits, preferably randomly is changed.
DE2000112113 2000-03-13 2000-03-13 Data transmission and/or distance measurement between base unit and mobile key unit of access authorization monitoring system involves modulating carrier signal with identification signal Ceased DE10012113A1 (en)

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FR0103210A FR2807556B1 (en) 2000-03-13 2001-03-09 Method and device for transmitting data between a base unit and a mobile key unit of an access control device, in particular for a motor vehicle

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DE10209855A1 (en) * 2002-03-06 2003-09-25 Siemens Ag Security device against unauthorized access to an object or against unauthorized use of an object and method for operating the security device
WO2003081516A1 (en) * 2002-03-21 2003-10-02 Siemens Aktiengesellschaft Identification system for verifying an authorisation for access to an object, or use of an object, in particular a motor vehicle
WO2004059561A1 (en) * 2002-12-20 2004-07-15 Siemens Aktiengesellschaft Method for enabling data transmission between a read/write device and at least one mobile data memory
DE10300778A1 (en) * 2003-01-11 2004-07-22 Leopold Kostal Gmbh & Co Kg Tire pressure monitoring device for a motor vehicle
DE10310157A1 (en) * 2003-03-07 2004-09-23 Siemens Ag Operating access control system for object, especially vehicle, involves evaluating polling and response signals to determine distance between base station and code sender using up, down chirp ramps
DE10310155A1 (en) * 2003-03-07 2004-09-23 Siemens Ag Access control system, especially for vehicle, has transmitter in polling station that emits high frequency polling signal containing frequency modulated ramps, code sender, response signal receiver
EP1570146A1 (en) * 2002-11-19 2005-09-07 Australian Arrow Pty. Ltd. Passive entry system
WO2006018355A1 (en) * 2004-08-10 2006-02-23 Siemens Aktiengesellschaft Method for measuring a distance in a wireless carrier frequency communication system, and carrier frequency communication system for carrying out said method
EP1672385A1 (en) * 2004-12-20 2006-06-21 Siemens Aktiengesellschaft Production and processing plant with a transponder device
EP1672386A1 (en) * 2004-12-20 2006-06-21 Siemens Aktiengesellschaft Continuous wave radarsystem for distance measurements and data transmission
WO2006100167A1 (en) * 2005-03-21 2006-09-28 Robert Bosch Gmbh Method and device for measuring distance and relative speed of a plurality of objects
DE102005061660A1 (en) * 2005-12-22 2007-06-28 Giesecke & Devrient Gmbh Portable data carrier with active contactless interface
DE102013223157A1 (en) 2013-11-13 2015-05-28 Robert Bosch Gmbh Radar system for a vehicle
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DE10202282B4 (en) * 2002-01-22 2005-05-04 Siemens Ag Method for determining data carriers located in the access area of a request unit of an access control system
DE10202282A1 (en) * 2002-01-22 2003-07-31 Siemens Ag Method for detection of data carriers within range of an interrogation unit, e.g. for controlling access to a motor vehicle, whereby carriers are assigned a response time slot to prevent collisions and speed access authentication
DE10209855A1 (en) * 2002-03-06 2003-09-25 Siemens Ag Security device against unauthorized access to an object or against unauthorized use of an object and method for operating the security device
WO2003081516A1 (en) * 2002-03-21 2003-10-02 Siemens Aktiengesellschaft Identification system for verifying an authorisation for access to an object, or use of an object, in particular a motor vehicle
DE10212648A1 (en) * 2002-03-21 2003-10-09 Siemens Ag Identification system for proving authorization to access or use an object, in particular a motor vehicle
DE10212648B4 (en) * 2002-03-21 2006-04-13 Siemens Ag Identification system for proving authorization for access to an object or the use of an object, in particular a motor vehicle
EP1570146A1 (en) * 2002-11-19 2005-09-07 Australian Arrow Pty. Ltd. Passive entry system
EP1570146A4 (en) * 2002-11-19 2008-04-23 Australian Arrow Pty Ltd Passive entry system
WO2004059561A1 (en) * 2002-12-20 2004-07-15 Siemens Aktiengesellschaft Method for enabling data transmission between a read/write device and at least one mobile data memory
DE10300778A1 (en) * 2003-01-11 2004-07-22 Leopold Kostal Gmbh & Co Kg Tire pressure monitoring device for a motor vehicle
DE10310157B4 (en) * 2003-03-07 2008-07-31 Siemens Ag Method and device for eliminating oscillator drift in an access control system
DE10310155A1 (en) * 2003-03-07 2004-09-23 Siemens Ag Access control system, especially for vehicle, has transmitter in polling station that emits high frequency polling signal containing frequency modulated ramps, code sender, response signal receiver
DE10310157A1 (en) * 2003-03-07 2004-09-23 Siemens Ag Operating access control system for object, especially vehicle, involves evaluating polling and response signals to determine distance between base station and code sender using up, down chirp ramps
DE10310155B4 (en) * 2003-03-07 2008-07-31 Siemens Ag Access control system for an object, in particular for a motor vehicle, and method for operating an access control system
WO2006018355A1 (en) * 2004-08-10 2006-02-23 Siemens Aktiengesellschaft Method for measuring a distance in a wireless carrier frequency communication system, and carrier frequency communication system for carrying out said method
EP1672385A1 (en) * 2004-12-20 2006-06-21 Siemens Aktiengesellschaft Production and processing plant with a transponder device
EP1672386A1 (en) * 2004-12-20 2006-06-21 Siemens Aktiengesellschaft Continuous wave radarsystem for distance measurements and data transmission
WO2006100167A1 (en) * 2005-03-21 2006-09-28 Robert Bosch Gmbh Method and device for measuring distance and relative speed of a plurality of objects
US7714771B2 (en) * 2005-03-21 2010-05-11 Robert Bosch Gmbh Method and device for measuring the distance and relative speed of multiple objects
DE102005061660A1 (en) * 2005-12-22 2007-06-28 Giesecke & Devrient Gmbh Portable data carrier with active contactless interface
DE102013223157A1 (en) 2013-11-13 2015-05-28 Robert Bosch Gmbh Radar system for a vehicle
WO2017144349A1 (en) * 2016-02-26 2017-08-31 Huf Hülsbeck & Fürst Gmbh & Co. Kg Method for an activation of at least one safety function of a safety system of a vehicle
DE102018209233A1 (en) * 2018-06-11 2019-12-12 Siemens Aktiengesellschaft Device and method for detecting a drift and / or a change in position of radar systems

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