DE10310658B4 - Method and system for bidirectional data transmission and distance determination - Google Patents

Abstract

Method for bidirectional data transmission and distance determination between a first transceiver unit (10) and a second transceiver unit (20) placed remotely therefrom, characterized by the following steps:
the first and second transceiver units (10, 20) transmit and receive short pulses or wave packets with a respective carrier frequency (RF) in the same frequency range in the forward and backward channels (1, 11),
the transmission from the second to the first transmitting / receiving unit (20, 10) is synchronized in the second transmitting / receiving unit (20) with the transmission from the first to the second transmitting / receiving unit (10, 20), and
the distance determination is carried out in the first transmitting / receiving unit (10) on the basis of the signal propagation time of the transmission between the second and first transmitting / receiving unit (20, 10) by correlation of the pulses received in the first one with the corresponding ones in the first transmitting / receiving unit (10 ) carried out by the second transmitting / receiving unit (20) transmitting / receiving unit (10) pulses, wherein prior to the correlation of the second transmitting / receiving unit (20) received in the first transmitting / receiving unit pulses corresponding to the first in the first transmitting / receiving unit (10) generated pulses in the first transmitting / receiving unit (10) of an adjustable delay (.DELTA.T), which is a measure of the respective distance between the first and second transceiver unit (10, 20), wherein a correlation only takes place, if the distance between the first and second transceiver units (10, 20) corresponds to the set delay (ΔT).

Description

State of the art

The invention relates to a method and system for bidirectional data transmission and distance determination between a first transmitter / receiver unit and a second transmitter / receiver unit placed remotely therefrom.

In the field of access control systems, methods and systems are known which no longer require special handling of a door key. The key is recognized, for example, by radio communication between a vehicle unit and a transponder unit that embodies a key. For this communication, frequencies from the low frequency range to the gigahertz range come into question. A gigahertz access control system is in DE 199 02 185 A1 (Robert Bosch GmbH). From the US 2002/0008615 A1 An anti-theft system is already known, which has a transmitting and receiving unit in the motor vehicle. This sends out radar signals modulated in broadband and waits for echo signals. A code transmitter which receives a radar signal in turn sends back an additionally modulated and coded signal. An evaluation unit analyzes all received echo signals on the one hand according to an authorization of the code transmitter and on the other hand with regard to the distance between the code transmitter and the transmitting and receiving unit. A similar arrangement is also in the WO 02/064405 A1 disclosed.

The verification and recognition of valid communication partners can be done by exchanging cryptological data (key / lock principle). The distance determination between key and vehicle unit can be carried out in the low frequency range by magnetic fields or in the gigahertz range by a radar-based measurement.

Purpose and advantages of the invention

To ensure the functionality of the system, the distance between the vehicle unit and the transponder unit must be determined. On the other hand, a bidirectional data exchange between vehicle unit and transponder unit must be carried out. With temporal separation of distance determination and data transmission, the security of the system against intentional disturbances (misuse) and unintentional disturbances (several similar operating systems in the environment) is not always given.

It is therefore the object of the invention to provide a method and system for bidirectional data transmission and distance determination between a first transceiver unit and a second transceiver unit located remotely so that the distance between the vehicle unit and the transponder unit can be determined during the communication and the system is protected against intentional and unintentional disruptions. This object is solved by the features of the main claims.

• - die erste und zweite Sende/Empfangseinheit senden und empfangen im Hin- und Rückkanal kurze Impulse bzw. Wellenpakete mit einer Trägerfrequenz im selben Frequenzbereich,
• - die Übertragung von der zweiten zur ersten Sende/- Empfangseinheit wird in der zweiten Sende/Empfangseinheit mit der Übertragung von der ersten zur zweiten Sende/- Empfangseinheit synchronisiert, und
• - die Entfernungsbestimmung wird in der ersten Sende/- Empfangseinheit auf Grund der Signallaufzeit der Übertragung zwischen zweiter und erster Sende/- Empfangseinheit mittels Korrelation der in der ersten Sende/Empfangseinheit von der zweiten Sende/Empfangseinheit empfangenen Impulse mit den entsprechenden in der ersten Sende/Empfangseinheit erzeugten Impulsen ausgeführt.

According to a first essential aspect, a method for bidirectional data transmission and distance determination between a first transceiver unit and a second transceiver unit located remotely from the above task is characterized by the following steps:

• the first and second transceiver units transmit and receive short pulses or wave packets with a carrier frequency in the same frequency range in the forward and reverse channel,
• the transmission from the second to the first transmitting / receiving unit is synchronized in the second transmitting / receiving unit with the transmission from the first to the second transmitting / receiving unit, and
• the distance determination is carried out in the first transceiver on the basis of the signal propagation time of the transmission between the second and first transceiver by correlation of the pulses received in the first transceiver by the second transceiver with the corresponding one in the first transceiver. Receiving unit generated pulses executed.

According to a second essential aspect, a system according to the invention for bidirectional data transmission and distance determination between a first transceiver unit and a second transceiver unit located remote therefrom is characterized in that the first and second transceiver units comprise short pulses or wave packets transmit and receive at a carrier frequency in the same frequency range,
the second transmitting / receiving unit has a synchronization device for temporally synchronization of the pulse signal to be transmitted to the first transmitting / receiving unit with the pulse signal received by the latter and the first transmitting / receiving unit for determining the distance a correlation device for correlating the pulse signal received by the second transmitting / receiving unit with the corresponding one pulse signal generated in the first transceiver unit, wherein the correlation device has a delay element which has an adjustable, the distance between the first and second transmission / Receive unit corresponding delay time delays the pulse signal generated in the first transmitting / receiving unit to achieve the correlation.

• - die Sicherheit gegen unbeabsichtigte und beabsichtigte Störungen ist erhöht;
• - ein stromintensiver Gigahertzempfänger in der ersten Sende/Empfangseinheit, insbesondere im Kraftfahrzeug, muss nur kurzzeitig in Betrieb genommen werden, dadurch kann eine verbrauchsintensive Standby-Empfangsbereitschaft im Kraftfahrzeug entfallen;
• - im Transponder ist keine Echtzeitdatenverarbeitung der Empfangs- und Sendesignale für die Entfernungsbestimmung nötig;
• - für Austausch und Bearbeitung der Daten (Identifikation, Verschlüsselung und Entschlüsselung) können handelsübliche Prozessoren eingesetzt werden. Dadurch wird eine sinnvolle Realisierung des batteriebetriebenen Transponders erst ermöglicht.

The following advantages are achieved in particular with the method and system according to the invention:

• - the security against unintentional and intended disturbances is increased;
• a power-intensive gigahertz receiver in the first transmitting / receiving unit, in particular in the motor vehicle, only has to be put into operation for a short time, thereby eliminating a consumption-intensive standby readiness to stand in the motor vehicle;
• - In the transponder, no real-time data processing of the receive and transmit signals for the distance determination is necessary;
• - For the exchange and processing of data (identification, encryption and decryption) can be used commercially available processors. This makes a meaningful realization of the battery-powered transponder possible.

The primary field of application is the aforementioned application for access authorization in the motor vehicle sector. The system can also be used in other applications where access or access authorization is required.

The system and method of the invention will be explained in more detail in the following description, which is made with reference to the appended sole 1 describes an embodiment of a system according to the invention and its function.

embodiment

The block diagram in 1 shows on the right a first transmitting / receiving unit 10 and on the left a second transceiver unit 20 of the system according to the invention. The first send / receive unit 10 In particular, a vehicle unit and the second transceiver unit is a transponder unit. In the first send / receive unit 10 generates a first oscillator 101 a carrier frequency RF in the gigahertz range, eg 24 GHz, via a first power divider 106 a first high frequency switch 104 (Branch s11 ) and a second high frequency switch 107 (Branch s12 ) is supplied. A second oscillator 102 generates a pulse train of a predetermined pulse repetition frequency PRF (branch s13 ). This produces a first pulse shaper 103 suitable drive pulses for the first high-frequency switch 104 , The first high frequency switch 104 This generates short pulses (wave packets) in the gigahertz range, eg 24 GHz. By switching this pulse train on and off when applying modulation signals 112 to a control input 114 of the first pulse shaper 103 be over the first high frequency switch 104 generates modulated transmit pulses that a transmit antenna 11 the first transmitting / receiving unit 10 be supplied.

On the side of the second transceiver 20 This will be from a receiving antenna 22 received from the first transceiver 10 transmitted transmit pulse signal to a mixer (second mixer) 205 supplied and transmitted by this in the baseband (branch e22 ). The second send / receive unit 20 contains a third oscillator 201 whose oscillation is in the same frequency range as the oscillation of the first oscillator 101 , eg at 24 GHz. When receiving the third oscillator works 201 as a local oscillator. The third oscillator 201 the second transmitting / receiving unit 20 Radio frequency RF generated, eg at 24 GHz, is transmitted via a second power divider 206 the mixer 205 fed (signal LO in branch s22). The mixer output signal amplified by an amplifier is provided by an envelope demodulator 209 demodulated and is after filtering in a bandpass 210 at a data output as a demodulated data signal 211 to disposal.

It should be noted that a (wanted) slight frequency offset between that of the first oscillator 101 in the first transmitting / receiving unit 10 and the third oscillator 201 in the second transmitting / receiving unit 20 generated frequency is not relevant for envelope demodulation.

At the top, the transmission and reception process from the first transmission / reception unit to the second transmission / reception unit has been described via the path (I-link) designated I. The second transmitting / receiving unit transmits to received data recognized as valid 20 (the transponder) an answer over the way II (down link).

The second send / receive unit 20 contains a third high frequency switch 204 , About the third oscillator 201 , the circuit breaker 206 and the third high frequency switch 204 (Branch s21) short pulses (wave packets) in the said high-frequency range, in particular at 24 GHz generated. The temporal position of the second transceiver unit 20 transmitted pulses are applied to that of the first transceiver unit 10 received pulse signal synchronized. This is done by the second transmitter / receiver unit 20 received and from the mixer 205 down-mixed signal for controlling the transmission branch of the second transceiver unit 20 used. In a third pulse shaper 203 gets to that from the mixer 205 mixed signal processed accordingly. The output of the third pulse shaper 203 actuates the third high frequency switch 204 for a defined period of time. The third pulse shaper 203 contains a control input 214 so that through the third high-frequency switch 204 generated transmission pulses from a data signal 212 modulated and then the transmitting antenna 21 the second transmitting / receiving unit 20 be supplied.

In the receiving part of the first transmitting / receiving unit 10 are corresponding to the second oscillator 102 (PRF) generates synchronized wave packets (second pulse shaper 113 , second high frequency switch 107 , Path e13 ). The first send / receive unit 10 also contains a delay element 108 with one according to a distance range setting signal 114 adjustable delay time ΔT. In accordance with the set delay ΔT, the signal propagation time between the second transceiver unit becomes 20 and first transmitting / receiving unit 10 simulated. The in the delay element 108 The set delay is a direct measure of the distance between the two communication partners. At a distance corresponding to the delay time ΔT, a correlation of the pulse packets in the first mixer takes place 105 instead of. About a demodulator 109 and a low-pass filter at the mixer output can be the data contained in the received signal 111 be accepted (baseband receiver).

Is the second transceiver unit located? 20 in which by the delay time .DELTA.T at the delay element 108 Set distance range, the second from the second transmitter / receiver unit 20 (the transponder) emitted signals from the first transceiver unit 10 be received. Outside this range no reception is possible. Due to the width of the wave packets (pulses), the signal correlation in a certain distance range is possible. This results in a "distance cell".

By switching the delay time ΔT at the delay element 108 You can set different range cells. The delay time ΔT corresponds to the distance of the cell. The size of the cells is determined by the duration (pulse duration) of the wave packets.

In order that unwanted feedback, for example in the case of strong reflection, and the associated reception of one's own signals between the transmitter and receiver of the second transmitter / receiver unit can be avoided, a "dead time" is incorporated in the latter. This means that it is ensured that for the duration of a pulse transmission and for a defined period thereafter a renewed impulse triggering by the third pulse shaper 203 is prevented.

An advantage of the system described above is, for example, that the first to third oscillator in the first and second transceiver unit 10 . 20 do not have to work in phase synchronization with each other. It is also possible between the frequencies of the first oscillator 101 and the third oscillator 201 to choose a certain frequency offset. This allows the signals at the output of the mixer 105 the first transmitting / receiving unit 10 and at the exit of the mixer 205 the second transmitting / receiving unit 20 be removed in the intermediate frequency range (intermediate frequency receiver).

The second send / receive unit 20 can be operated clocked in a suitable manner, ie it wakes up only regularly for a short time and sends a short signal, if necessary, the first transmitting / receiving unit 10 to appeal. This receives the signal from the second transmitter / receiver unit 20 , she starts with the data exchange. The first send / receive unit 10 can be operated either permanently or clocked in a suitable manner. The first send / receive unit 10 and the second transmitting / receiving unit 20 can also be monostatic, ie be carried out with one antenna, in each case then transmitting and receiving antenna 11 . 12 the first transmitting / receiving unit to an antenna and the transmitting and receiving antenna 21 and 22 the second transmitting / receiving unit 20 are combined to form another antenna. For this purpose, the transmitting and receiving branches are each connected to the antenna, for example via a directional coupler.

Above, a method and a system for the bidirectional transmission of data and distance determination, in particular with regard to the application in the field of vehicles, in particular for access control systems in the automotive sector, has been described with reference to FIG. As already mentioned, however, the system can also be used in other applications where access or access authorization is required.

Claims (23)

Method for bidirectional data transmission and distance determination between a first transceiver unit (10) and a second transceiver unit (20) located remotely, characterized by the following steps: - transmitting and receiving the first and second transceiver units (10, 20) Forward and return channel (1,11) short pulses or wave packets with a respective carrier frequency (RF) in the same frequency range, - the transmission from the second to the first transceiver unit (20,10) is in the second transceiver unit (20) with the transfer of the synchronizing the first to the second transceiver unit (10, 20); and determining the distance in the first transceiver unit (10) based on the signal propagation time of the transmission between the second and first transceiver units (20, 10) by correlation in the first transceiver unit first received pulses with the corresponding in the first transmitting / receiving unit (10) from the second transmitting / receiving unit (20) transmitting / receiving unit (10) generated pulses, wherein prior to the correlation of the second transmitting / receiving unit (20) in the the first transmitter / receiver unit received pulses in the first transceiver unit (10) generated pulses in the first transceiver unit (10) of an adjustable delay (.DELTA.T) are subjected, which is a measure of the respective distance between the first and second transmission / Receiving unit (10, 20), wherein a correlation takes place only if the distance between the first and second transmitting / receiving unit (10, 20) corresponds to the set delay (ΔT). Method according to Claim 1 , characterized in that the respective carrier frequency (RF) in the microwave range between 2 GHz and 80 GHz. Method according to Claim 2 , characterized in that the carrier frequency (RF) of the second transmitting / receiving unit (20) has a small frequency offset with respect to that of the first transmitting / receiving unit (10). Method according to one of Claims 1 to 3 , characterized in that the first transceiver unit (10) in a vehicle, in particular motor vehicle, and the second transceiver unit (20) are installed in a transponder unit. Method according to one of Claims 1 to 4 , characterized in that the pulses in the first transmitting / receiving unit (10) are modulated by switching on and off with a data signal (112). Method according to one of Claims 1 to 5 , characterized in that the data signal received by the first transceiver unit (10) in the second transceiver unit (20) is transmitted to a baseband and envelope-demodulated. Method according to Claim 6 , characterized in that in the second transmitting / receiving unit (20) the synchronized transmission pulses are modulated by switching on and off with a data signal (212). Method according to Claim 1 , characterized in that the width of the pulses defines a specific distance range between the first and second transceiver units (10, 20) and thus a range cell within which the signals are received by the second transceiver unit (20). Method according to Claim 1 or 8th , characterized in that by switching the delay time (.DELTA.T) a number of range cells is specified. Method according to one of Claims 1 to 9 , characterized in that in the second transmitting / receiving unit (20) during a defined period of time after a previous pulse transmission a renewed pulse transmission is prevented. Method according to one of Claims 1 to 10 , characterized in that the second transceiver unit (20) is clocked operated so that it is regularly switched briefly from a sleep state to an active state in which then from the second transceiver unit (20) a short signal is sent, with which the first transmitting / receiving unit (10) is addressed to start the data exchange. System for bidirectional data transmission and distance determination between a first transceiver unit (10) and a second transceiver unit (20) located remotely, characterized in that the first and second transceiver units (10, 20) comprise short pulses or wave packets with one transmit and receive respective carrier frequency (RF) in the same frequency range, the second transmitting / receiving unit (20) comprises a synchronization device (203) for temporally synchronizing the pulse signal to be transmitted to the first transmitting / receiving unit (10) with the pulse signal received by the latter and the first Transmitting / Receiving unit (10) for determining the distance, a correlation device (105, 107, 108, 113) for correlating the pulse signal received from the second transceiver unit (20) with the corresponding pulse signal generated in the first transceiver unit (10), wherein the correlator comprises a delay element (108) that delays the pulse signal generated in the first transceiver unit (10) with an adjustable delay time (ΔT) corresponding to the distance between the first and second transceiver units (10, 20) to achieve the correlation, wherein a correlation takes place only when the distance between the first and second transceiver units (10, 20) corresponds to the set delay time (ΔT). 13. System after Claim 12 characterized in that the first transmitter / receiver unit (10) comprises a transmitter branch (s11, s13) having - a first oscillator (101) generating the predetermined carrier frequency (RF) - a second oscillator (102) having a pulse train of predetermined pulse repetition frequency (PRF), a first pulse shaper (103) which switches on and off the pulse train generated by the second oscillator (102) in accordance with first transmission data (112) and a high-frequency switch (104) connected to a control input at a control input Output of the first pulse shaper (103) is connected, at a high-frequency input from the first oscillator (101) generated carrier frequency (RF) receives and at its output with the first transmission data (112) modulated pulse signal a transmitting antenna (11) supplies and - a reception branch (e12, e13) comprising the correlation means including a receive mixer (105) connected to a receive antenna (12) and a demodulator (109, 110) which demodulates the data received from the second transmitting / receiving unit (20). System after Claim 12 or 13 characterized in that the second transceiver unit (20) has a reception branch (e22) with a second reception mixer (205) connected to a reception antenna (22) and a third oscillator (201), a third pulse shaper (203 ), which is connected on the input side to the second receiving mixer (205), and - a second demodulator (209, 210) for demodulating the data received from the first transmitting / receiving unit (10), the second receiving mixer (205) using the received signal from the third oscillator (201) generated carrier frequency in a baseband for subsequent demodulation, and a transmitting branch (s21) having - a high-frequency switch (204) connected to the third oscillator (201) and an output of the third pulse shaper (203) the output side is connected to a transmitting antenna (21), wherein the third pulse shaper (203) from the first transmitting / receiving unit (10) received and by the second Empfangsmiseher (205) processed in the baseband pulse signal processed according to a control input (214) supplied data signal (212) on and off, and thus by the third oscillator (201) generated carrier frequency (RF) in the high frequency switch (204) in synchronized Transmit pulses implemented. System after Claim 13 or 14 , characterized in that the carrier frequency (RF) in the microwave range between 2 GHz and 80 GHz. System after Claim 15 , characterized in that the carrier frequency (RF) of the second transmitting / receiving unit (20) has a small frequency offset with respect to that of the first transmitting / receiving unit (10). System according to one of Claims 12 to 16 , characterized in that the first transceiver unit (10) in a vehicle, in particular a motor vehicle, and the second transceiver unit (20) are installed in a transponder unit. System after Claim 12 , characterized in that the width of the pulses defines a specific distance range between the first and second transceiver units (10, 20) and thus a range cell within which the signals can be received by the second transceiver unit (20). System after Claim 18 , characterized in that a number of range cells can be predetermined by switching the delay time (ΔT). System according to one of Claims 12 to 19 characterized in that the second transceiver unit comprises means for preventing retransmission of pulses during a defined period of time after a previous pulse transmission. System according to one of Claims 12 to 20 , characterized in that the second transceiver unit (20) has a clock device which regularly switches the second transceiver unit (20) temporarily from a sleep state to an active state, the latter then sending out a short signal to the first transceiver / Reception unit (10) to start to exchange data. System according to one of Claims 12 to 21 , characterized in that the respective carrier frequencies generated by the first and third oscillators have a certain frequency offset in order to pick up the signals at the output of the first and second receiving mixer in an intermediate frequency range. Use of the system according to one of Claims 12 to 22 as an access control system in the automotive sector.

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