DE102020003146A1 - Radar-based master-slave data transmission method and system for carrying out a data transmission method - Google Patents

Abstract

Radar-based master-slave data transmission method and system for carrying out a data transmission method, with a first participant acting as a master executing a transmission 1 of data in a first method step, - executing a determination 2 of the distance of objects in a second method step, - in a third Method step executes a reception 3 of data and fourth method step executes a waiting 4, in particular is inactive with regard to the sending and receiving of radar, and the second participant acting as slave executes receiving 3 of data in the first method step - in the second Method step carries out a waiting 4, - carries out a sending 1 of data in the third method step - and carries out a determination 2 of the removal of objects in the fourth method step.

Description

The invention relates to a radar-based master-slave data transmission method and system for carrying out a data transmission method.

It is generally known that distances from objects can be determined by means of radar sensors.

From the US 8 130 680 B1 The closest prior art is a timing method for a pulsed communication system.

From the US 2014/0 232 588 A1 a high-resolution, actively reflective radio frequency system is known.

From the US 2017/0 023 663 A1 a feedback technique for synchronizing a radar oscillator signal is known.

From the U.S. 5,731,781 A a continuous broadband precision radar is known.

From the US 2018/0 115 409 A1 a timing for an IC is known.

From the US 7 978 610 B1 a method for asynchronous transmission of communication data is known.

From the DE 10 2007 035 131 A1 a device for determining a train sequence is known.

From the US 2014/0 321 586 A1 a system for high-speed synchronization is known.

From the US 2014/0 320 335 A1 a personal radar is known.

From the US 2016/0 077 204 A1 a classification of the accuracy of measurements is known.

From the US 2009/0 045 997 A1 a communication method using pulsed radar radiation is known.

From the US 2009/0 275 288 A1 a radio frequency communication method is known.

The invention is therefore based on the object of developing a device and a method, wherein
According to the invention, the object is achieved in the radar-based master-slave data transmission method according to the features specified in claim 1 and in the system according to the features specified in claim 14.

• - in einem ersten Verfahrensschritt ein Senden von Daten ausführt,
• - in einem zweiten Verfahrensschritt eine Bestimmung der Entfernung von Objekten ausführt,
• - in einem dritten Verfahrensschritt einen Empfang von Daten ausführt
• - und vierten Verfahrensschritt ein Warten ausführt, insbesondere also bezüglich des Sendens und Empfangens von Radar inaktiv ist,

und der als Slave fungierende zweite Teilnehmer

• - im ersten Verfahrensschritt ein Empfangen von Daten ausführt,
• - im zweiten Verfahrensschritt ein Warten ausführt,
• - im dritten Verfahrensschritt ein Senden von Daten ausführt
• - und im vierten Verfahrensschritt eine Bestimmung der Entfernung von Objekten ausführt.

Important features of the invention in the radar-based master-slave data transmission method are that in the radar-based master-slave data transmission method, a first participant acting as a master

• - sends data in a first process step,
• - carries out a determination of the distance from objects in a second process step,
• - carries out a reception of data in a third method step
• - and fourth method step carries out a wait, in particular is inactive with regard to the sending and receiving of radar,

and the second participant acting as slave

• - receives data in the first process step,
• - carries out a wait in the second process step,
• - sends data in the third step
• and, in the fourth method step, determines the distance from objects.

The advantage here is that in the second method step for determining the distance of objects by means of radar sensors, a radar signal can be transmitted, the frequency of which increases, and the signal received by the radar sensor is fed to a mixer with the transmitted signal, so that information about the distance is obtained from the output signal of the mixer is determinable. In the first method step, however, a particularly digital data stream is frequency-modulated onto a radar signal, so that the data stream can be transmitted to a second participant by means of the frequency-modulated radar signal.

Since the method steps are carried out one after the other, a master-slave data transmission method can be carried out if it is specified that the master is active first and then the slave. The slave waits for the activity of the master until it becomes active after the end of the time window for activity of the master.

During the activity of the respective participant, data transmission or distance determination can be carried out serially and / or successively. The other participant is then passive or only set to receive.

In an advantageous embodiment, the sequence formed from the first, second, third and fourth method step is repeated executed. The advantage here is that both data transmission and distance determination can be carried out repeatedly and thus the task of distance determination and the task of data transmission can be carried out by one and the same participants.

In an advantageous embodiment, the second method step follows the first method step in time, the third method step follows the second method step in time, and the fourth method step follows the third method step in time. The advantage here is that the time windows for data transmission of both participants are spaced apart in time by time windows for determining the distance.

In an advantageous embodiment, the first, second, third and fourth method steps are not carried out one after the other in the order in which they are numbered. The advantage here is that the order can be adapted to the respective requirements.

In an advantageous embodiment, the master sends out a frequency-modulated radar signal in the first method step, in particular a radar signal which is frequency-modulated with a data stream to be transmitted,
in particular that consists of a sequence of signal sections which each have either the frequency f0 or the frequency f1. The advantage here is that modulation can be carried out in a simple manner.

In an advantageous embodiment, in the second method step, the master sends out at least one radar signal, the frequency of which increases linearly with time. The advantage here is that the distance can be determined in a simple manner.

In an advantageous embodiment, in the third method step, the master generates a radar signal with a constant frequency for mixing with a signal received from the master,
in particular, the low-pass filtered output signal of the mixer having the data stream sent by the slave. The advantage here is that the data stream can be decoded in a simple manner without any special effort.

In an advantageous embodiment, the slave transmits a frequency-modulated radar signal in the third method step, in particular the slave transmits a radar signal frequency-modulated with a data stream to be transmitted,
in particular that consists of a sequence of signal sections which each have either the frequency f0 or the frequency f1. The advantage here is that the data stream can be modulated in a simple manner. The frequencies f0 and f1 are different from one another, in particular they are not the same.

In an advantageous embodiment, in the fourth method step, the slave transmits at least one radar signal, the frequency of which increases linearly with time. The advantage here is that the distance determination can be carried out in a simple manner.

In an advantageous embodiment, the slave generates a radar signal with a constant frequency in the first process step for mixing with a signal received from the master,
in particular, the low-pass filtered output signal of the mixer having the data stream sent by the master. The advantage here is that data transmission can be easily implemented.

In an advantageous embodiment, the data stream has a data telegram which has a data field following a synchronization frame,
wherein the synchronization frame has a number n of equal bits directly following one another in time,
whereby a stuffing bit is transmitted in the data field after a number (n-1) reduced by one of equal bits directly following one another in time. The advantage here is that the synchronization frame is clearly differentiated from the data field.

wobei z die Werte des abgetasteten insbesondere tiefpassgefilterten Ausgangssignals des Mischers und g_0 die Rechteckfunktion ist,
und dass eine zweite Korrelation, insbesondere eine diskrete Kreuzkorrelation, des insbesondere tiefpassgefilterten Ausgangssignals des Mischers mit dem komplex konjugierten Signal des Rechtecksignals gebildet wird, insbesondere gemäß $$C_1\left(i\right)={\displaystyle \sum _{n:=-le{n}_{bit}+1}^{\text{o}}z\left(n+i\right)\cdot g\underset{0}{\overset{*}{}}\left(n\right)},$$

wobei g*_0 die komplex konjugierte Rechteckfunktion ist.In an advantageous embodiment, in particular to determine the respective bit of the data stream, a first correlation, in particular a discrete cross correlation, of the in particular low-pass filtered output signal of the mixer with a complex square-wave signal is formed,
especially according to $${\mathrm{C.}}_0\left(i\right)={\displaystyle \sum _{n:=-le{n}_{bit}+1}^{\text{O}}z\left(n+i\right)\cdot G_0\left(n\right)},$$

where z is the values of the sampled, in particular, low-pass filtered output signal of the mixer and g_0 is the rectangular function,
and that a second correlation, in particular a discrete cross-correlation, of the in particular low-pass filtered output signal of the mixer with the complex conjugate signal of the square-wave signal is formed, in particular according to $${\mathrm{C.}}_1\left(i\right)={\displaystyle \sum _{n:=-le{n}_{bit}+1}^{\text{O}}z\left(n+i\right)\cdot G\underset{0}{\overset{*}{}}\left(n\right)},$$

where g * _0 is the complex conjugate rectangular function.

The advantage here is that the transmitted bit can be determined by means of the square-wave signal and the formation of the correlation to this square-wave signal and its complex conjugate signal.

und als zweite Summe $$su{m}_{corr1}={\displaystyle \sum _{i=0}^{le{n}_{bit}}{C}_1\left(i\right)}$$

In an advantageous embodiment, a first sum of the first correlation and a second sum of the second correlation is determined and the transmitted respective bit is determined therefrom,
especially by being the first sum $$su{m}_{\text{corr0}}={\displaystyle \sum _{i=0}^{le{n}_{bit}}{\mathrm{C.}}_0\left(i\right)}$$

and as a second sum $$su{m}_{cOr\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="DE102020003146A1\_0014.png,DE102020003146A1\_0015.png"\; state="\{\{state\}\}">r</figure-callout>}1}={\displaystyle \sum _{i=0}^{le{n}_{bit}}{\mathrm{C.}}_1\left(i\right)}$$

Is formed and the transmitted bit is determined as LOW if sum_corr0 is larger in amount than sum_corr1, and the transmitted bit is determined as HIGH if sum_corr1 is larger in amount than sum_corr0. The advantage here is that the signal-to-noise ratio can be improved when recognizing the transmitted bit.

In an advantageous embodiment, the frequency of the square-wave signal is a quarter of the sampling frequency of the analog / digital converter when sampling the low-pass filtered output signal of the mixer,
in particular, the imaginary part of the complex square-wave signal being equal to the real part of the complex square-wave signal shifted by 90 °.

Important features of the system for carrying out a data transmission process are that the master is designed as a mobile part that can be moved on a moving surface of a system or is arranged stationary in the system, the slave being designed as a mobile part that can be moved on a moving surface of a system or is stationary in the system is arranged.

The advantage here is that the subscribers can be implemented as mobile parts which move automatically on the moving surface in order, for example, to fulfill intralogistic orders, that is to say pick up a load, transport it and then release it. Each mobile part can thus be equipped with a control system, in particular having a computer, and an electromotive traction drive. In addition, each of the mobile parts can be equipped with a radar sensor which, on the one hand, determines the distance to objects and, if necessary, their speed vector, so that collisions can be avoided. In addition, data can even be transmitted between the radar sensors of different mobile parts, the data transmission according to the invention being carried out alternately with the determination of the distance.

In an advantageous embodiment, the master has a radar sensor and the slave has a further radar sensor. The advantage here is that the method according to the invention can be carried out. This is because each radar sensor can be designed for sending and receiving, in particular with the same antenna.

Further advantages result from the subclaims. The invention is not restricted to the combination of features of the claims. For the person skilled in the art, there are further meaningful possible combinations of claims and / or individual claim features and / or features of the description and / or the figures, in particular from the task and / or the task posed by comparison with the prior art.

• In der 1 ist das erfindungsgemäße Radarbasierte Master-Slave-Datenübertragungsverfahren schematisch skizziert.
• In der 2 ist das dabei vorzugsweise verwendete Datentelegramm dargestellt.
• In der 3 ist ein komplexes Rechtecksignal g0(n) und sein komplex konjugiertes Rechtecksignal dargestellt.

The invention will now be explained in more detail with reference to schematic figures:

• In the 1 the inventive radar-based master-slave data transmission method is schematically sketched.
• In the 2 the data telegram that is preferably used is shown.
• In the 3 is a complex square wave signal g0 (n) and its complex conjugate square wave is shown.

As shown in the figures, a radar-based data transmission method is carried out between two participants.

The first participant is a mobile part or a stationary part. The second participant is also a mobile part or a part arranged in a stationary manner.

Each of the parts has a computer that controls a radar sensor. The radar sensor sends out radar radiation, the frequency of which depends on a control voltage that is specified by signal electronics that also include the computer.

Each of the radar sensors has a mixer to which the radar signal generated by it and received radar radiation is fed. The output signal of the mixer is fed to a filter which preferably has a low-pass or band-pass whose output signals encode the information received.

The sending participant, in particular the radar sensor of the sending participant, encodes the information to be transmitted, preferably on two different frequencies. This is carried out in a simple manner by a control voltage which uses a first voltage value for a LOW bit and a second voltage value for a HIGH bit. Thus, with the LOW bit, a radar signal with the frequency f0 is transmitted and with the HIGH bit, a radar signal with the frequency f1.

The receiving radar sensor, in particular the radar sensor of the receiving participant, generates a constant frequency, in particular the value of which is equal to the mean value of the two frequencies used by the transmitting radar sensor, and feeds this generated frequency together with the received signal to a mixer. The output signal thus has a frequency which equals the frequency difference to the mean value.

Since the amount of the frequency difference is the same for the HIGH and LOW bit, the phase position is detected.

The receiving radar sensor therefore provides the mixer with a signal with the frequency fc = (f0 + f1) / 2.

To detect the phase position, the filtered, in particular low-pass filtered, output signal of the mixer is fed to an A / D converter, i.e. an analog / digital converter, and converted into a digital data stream, the sampling frequency fs of the converter preferably being four times the difference frequency.

The output signal of the mixer is shown as a complex signal. It therefore has a real part and an imaginary part.

To determine the phase position and thus to determine the transmitted bit, two square-wave signals are generated, both of which are complex. The first is complex conjugate to the second. As the first of the two square-wave signals, g0 (n) is generated for this purpose, the frequency of which is four times the sampling frequency fs used by the A / D converter. In addition, the real part and also the imaginary part of the square wave signal g0 (n) symmetrical, i.e. its mean value is zero. As in 3 shown is the first sample in the 1st area, the second sample in the 2nd area, the third sample in the 3rd area and the fourth sample in the 4th area. The real part of the square wave signal g0 (n) is in the first and second area 1 and otherwise -1. The imaginary part is shifted in time by 90 °, i.e. a range, to the real part.

THE complex conjugate square wave signal g0 * (n) has the same real part as G0 (n). The imaginary part is shifted by -90 ° to the real part.

The preferably low-pass filtered output signal of the mixer has the sample values z (n).

Und andererseits die Korrelation, insbesondere also die diskrete Kreuzkorrelation, zwischen dem empfangenen Signal, insbesondere dem vorzugsweise tiefpassgefilterten Ausgangssignal, und dem komplex konjugierten Rechtecksignal g0*(n) gebildet: $$C_1\left(i\right)={\displaystyle \sum _{n:=-le{n}_{bit}+1}^{\text{o}}z\left(n+i\right)\cdot g\underset{0}{\overset{*}{}}\left(n\right)}$$

Wobei len_bit die Länge des Bits ist. Zur Verminderung von Rauschen werden die Summen $$su{m}_{\text{corr0}}={\displaystyle \sum _{i=0}^{le{n}_{bit}}{C}_0\left(i\right)}$$

$$su{m}_{corr1}={\displaystyle \sum _{i=0}^{le{n}_{bit}}{C}_1\left(i\right)}$$

gebildet und daraus das übertragene Bit erkannt, indem der die größere der beiden Summen das entsprechende Bit kennzeichnet.To determine the transmitted bit, on the one hand the correlation, in particular the discrete cross-correlation, between the received signal, in particular the preferably low-pass filtered output signal, of the mixer and the square wave signal is used g0 (n) educated: $${\mathrm{C.}}_0\left(i\right)={\displaystyle \sum _{n:=-le{n}_{bit}+1}^{\text{O}}z\left(n+i\right)\cdot G_0\left(n\right)}$$

And on the other hand, the correlation, in particular the discrete cross-correlation, between the received signal, in particular the preferably low-pass filtered output signal, and the complex conjugate square wave signal g0 * (n) is formed: $${\mathrm{C.}}_1\left(i\right)={\displaystyle \sum _{n:=-le{n}_{bit}+1}^{\text{O}}z\left(n+i\right)\cdot \mathrm{<figure-callout\; id="0"\; label="G"\; filenames="DE102020003146A1\_0015.png,DE102020003146A1\_0016.png"\; state="\{\{state\}\}">G</figure-callout>}\underset{0}{\overset{*}{}}\left(n\right)}$$

Where len _{bit is} the length of the bit. To reduce noise, the sums $$su{m}_{\text{corr0}}={\displaystyle \sum _{i=0}^{le{n}_{bit}}{\mathrm{C.}}_0\left(i\right)}$$

$$su{m}_{cOr\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="DE102020003146A1\_0014.png,DE102020003146A1\_0015.png"\; state="\{\{state\}\}">r</figure-callout>}1}={\displaystyle \sum _{i=0}^{le{n}_{bit}}{\mathrm{C.}}_1\left(i\right)}$$

and the transmitted bit is recognized from this by identifying the larger of the two sums for the corresponding bit.

gilt.A temporal symbol length of 1 / f_data is preferably used for data transmission, where f_data is the reciprocal of the symbol length. To fulfill the orthogonality, the frequencies f0 and f1 are selected in such a way that the amount of the difference (f0 - f1) equals an integral multiple of f_data, that is $$\left|f_0-{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="DE102020003146A1\_0014.png,DE102020003146A1\_0015.png"\; state="\{\{state\}\}">f</figure-callout>}}_1\right|=\Delta f=n*f_{data}$$

applies.

As in 2 shown, the data telegram has a synchronization frame 20th on which the transmitted data follows.

Since the synchronization frame 20th has six consecutive HIGH bits, is used in the transmitted data, i.e. in the synchronization frame 20th subsequent data field 23 , a stuffing bit 22nd inserted when five HIGH bits follow one another directly.

There are parity bits between the symbols of the data field 21st inserted.

In this way, error-free data transmission can be achieved.

According to the invention, a long-lasting sequence of directly successive HIGH bits is thus made possible during synchronization, because they are in the data field 23 inserted stuffing bits 22nd the distinction between synchronization frames 20th and data field 23 preserved.

As in 1 shown, the data is between the as master M. acting first participant and the slave S. transferring the founding subscriber alternately, with a distance determination being carried out between the respective time windows for data transmission.

In a first procedural step, the master leads M. a sending 1 from data; in a subsequent second procedural step, the master performs M. a determination 2 the removal of objects, in a subsequent third procedural step, the master performs M. a reception 3 of data and in a subsequent fourth procedural step, the master performs M. a wait 4th out. While waiting 4th is the master M. preferably inactive.

Accordingly, it leads as a slave S. Acting participants receive in the first procedural step 3 from data, in the second step a wait 4th , in the third process step a sending 1 of data and, in the fourth method step, a determination 2 the removal of objects.

The process, comprising the first, second, third and fourth method step, is carried out repeatedly.

The duration of each of the method steps is preferably the same. Since each of the two participants has a time base, in particular a clock, both participants know the time of the start of a respective method step after the synchronization has been carried out. The synchronization is updated every time a data telegram is transmitted.

In determining 2 the distance from objects, the participant sends a radar signal, the frequency of which increases linearly over time. The signal received by the subscriber, in particular the signal reflected from objects located at a distance, is in turn mixed with the transmitted signal so that the low-pass filtered output signal of the mixer represents the distance. In particular, the frequency of the low-pass filtered output signal encodes the distance.

Thus, in the first method step, the master m sends a radar signal which is a sequence of signal sections which each have either the frequency f0 or the frequency f1. In the second step, the master sends M. a radar signal whose frequency increases linearly with time. In the third process step, the master generates M. a radar signal at a constant frequency for mixing with the signal it receives. The fourth step is the master M. inactive. The slave works in accordance with the respective process steps 1 corresponding.

In further exemplary embodiments according to the invention, a method step is additionally inserted between the other four method steps, in which a distance is determined 2 is inserted. As an alternative or in addition, different time lengths of the method steps can also be carried out if the corresponding timing scheme is stored in a respective memory for both participants.

List of reference symbols

1

Sending data

2

Determining the distance from objects

3

Receiving data

4th

Waiting

20th

Sync frame, especially synchronization frame

21st

Parity bit

22nd

Stuffing bit

23

Data field

g0 (n)

complex square wave signal

Go * (n)

complex conjugate square wave

M.

master

S.

Slave

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 8130680 B1 [0003]
• US 20140232588 A1 [0004]
• US 20170023663 A1 [0005]
• US 5731781 A [0006]
• US 20180115409 A1 [0007]
• US 7978610 B1 [0008]
• DE 102007035131 A1 [0009]
• US 20140321586 A1 [0010]
• US 20140320335 A1 [0011]
• US 20160077204 A1 [0012]
• US 20090045997 A1 [0013]
• US 20090275288 A1 [0014]

Claims (15)

Radar-based master-slave data transmission method, characterized in that a first participant acting as a master (M) - carries out a transmission 1 of data in a first process step, - carries out a determination 2 of the distance to objects in a second process step, - in a third Method step carries out a reception 3 of data - and the fourth method step carries out a wait 4, i.e. is inactive in particular with regard to the sending and receiving of radar, and that the second participant acting as slave (S) carries out a reception 3 of data in the first method step, - carries out a waiting 4 in the second method step, - carries out a sending 1 of data in the third method step - and carries out a determination 2 of the distance of objects in the fourth method step. Data transfer method according to Claim 1 , characterized in that the sequence formed from the first, second, third and fourth method step is carried out repeatedly. Data transmission method according to one of the preceding claims, characterized in that the second method step chronologically follows the first method step, the third method step chronologically follows the second method step and the fourth method step chronologically follows the third method step, or that the first, second, third and fourth method step chronologically not in the order of their numbering. Data transmission method according to one of the preceding claims, characterized in that the master (M) transmits a frequency-modulated radar signal in the first method step, in particular a radar signal which is frequency-modulated with a data stream to be transmitted, in particular which consists of a sequence of signal sections, each of which either has the frequency f0 or have the frequency f1. Data transmission method according to one of the preceding claims, characterized in that in the second method step the master (M) sends out at least one radar signal, the frequency of which increases linearly with time. Data transmission method according to one of the preceding claims, characterized in that in the third method step the master (M) generates a radar signal with a constant frequency for mixing with a signal received from the master (M), in particular wherein the low-pass filtered output signal of the mixer corresponds to that of the slave (S ) has sent data stream. Data transmission method according to one of the preceding claims, characterized in that the slave (S) transmits a frequency-modulated radar signal in the third method step, in particular transmits a radar signal which is frequency-modulated with a data stream to be transmitted, in particular which consists of a sequence of signal sections, each of which either has the frequency f0 or have the frequency f1. Data transmission method according to one of the preceding claims, characterized in that in the fourth method step the slave (S) sends out at least one radar signal, the frequency of which increases linearly with time. Data transmission method according to one of the preceding claims, characterized in that in the first method step the slave (S) generates a radar signal with a constant frequency for mixing with a signal received from the master (M), in particular wherein the low-pass filtered output signal of the mixer corresponds to that of the master (M ) has sent data stream. Data transmission method according to one of the preceding claims, characterized in that the data stream has a data telegram which has a data field following a synchronization frame, the synchronization frame having a number n of equal bits immediately following one another in time, with each in the data field a stuffing bit is transmitted after a number (n-1) reduced by one of equal bits directly following one another in time. Data transmission method according to one of the preceding claims, characterized in that in particular for determining the respective bit of the data stream a first correlation, in particular a discrete cross-correlation, of the in particular low-pass filtered output signal of the mixer is formed with a complex square-wave signal, in particular according to FIG $${\mathrm{C.}}_0\left(i\right)={\displaystyle \sum _{n:=-le{n}_{bit}+1}^{\text{O}}z\left(n+i\right)\cdot G_0\left(n\right)},$$

where z is the values of the sampled, in particular, low-pass filtered output signal of the mixer and g_0 is the rectangular function, and that a second correlation, in particular a discrete cross-correlation, of the in particular low-pass filtered output signal of the mixer with the complex conjugate signal of the rectangular signal is formed, in particular according to $${\mathrm{C.}}_1\left(i\right)={\displaystyle \sum _{n:=-le{n}_{bit}+1}^{\text{O}}z\left(n+i\right)\cdot G\underset{0}{\overset{*}{}}\left(n\right)},$$

where g * _0 is the complex conjugate rectangular function. Data transmission method according to one of the preceding claims, characterized in that a first sum of the first correlation and a second sum of the second correlation is determined and the transmitted bit is determined therefrom, in particular as the first sum $$su{m}_{\text{corr0}}={\displaystyle \sum _{i=0}^{le{n}_{bit}}{\mathrm{C.}}_0\left(\text{i}\right)}$$

and as a second sum $$su{m}_{\text{corr1}}={\displaystyle \sum _{i=0}^{le{n}_{bit}}{\mathrm{C.}}_1\left(\text{i}\right)}$$

is formed and the transmitted bit is determined as LOW if sum_corr0 is larger than sum_corr1 in terms of amount, and the transmitted bit is determined as HIGH if sum_corr1 is larger than sum_corr0 in terms of amount. Data transmission method according to one of the preceding claims, characterized in that the frequency of the square-wave signal is a quarter of the sampling frequency of the analog / digital converter when sampling the low-pass filtered output signal of the mixer, in particular where the imaginary part of the complex square-wave signal is the real part of the complex square-wave signal shifted by 90 ° equals. System for carrying out a data transmission method according to one of the preceding claims, characterized in that the master (M) is designed as a mobile part which can be moved on a moving surface of a system or is arranged stationary in the system, the slave (S) being arranged on a moving surface of a system movable mobile part is executed or is arranged stationary in the system. System according to one of the preceding claims, characterized in that the master (M) has a radar sensor and the slave (S) has a further radar sensor.

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