DE102019201843A1 - Suppression of reflections in phase modulated radars - Google Patents

Abstract

Device (200) comprising a processor (201) designed to correlate a phase code with a received radar signal (S) sampled according to sampling times (A1, A2, A3, A4) and a shift (δ) of sampling times (A1 , A2, A3, A4) in such a way that a correlation power (| f (Δt) |) is minimized in a predetermined distance range ([Δt, Δt]).

Description

TECHNICAL AREA

The present disclosure relates to a method and a radar system for suppressing reflections in phase modulated radars.

TECHNICAL BACKGROUND

Radar technology (“Radio Detection and Ranging”) refers to devices, methods and systems for locating and recognizing objects on the basis of electromagnetic waves in the radio frequency range. The radar sends an electromagnetic signal and receives echoes from objects. Radar technology can be used, for example, to determine a position by evaluating transit times and, taking into account frequency signal changes (Doppler effect), the relative speed of an object.

The radar technology is used in a vehicle, for example. Vehicles use radar signals to determine the position and speed of objects such as other road users or obstacles.

Proceeding from this, the invention is based on the object of providing a radar system or a corresponding antenna module in which the behavior of the radar system is optimized.

This object is achieved by the device according to claim 1 and the method according to claim 10. Further advantageous embodiments of the invention emerge from the subclaims and the following description of preferred exemplary embodiments of the present invention.

The exemplary embodiments show a device which comprises a processor which is designed to correlate a phase code with a received radar signal sampled according to sampling times and to determine a shift of sampling times in such a way that a correlation power is minimized in a predetermined distance range.

The processor can, for example, be a computing unit such as a central processing unit (CPU) that executes program instructions.

The received radar signal can be generated, for example, by a phase-modulated continuous wave radar technology. With phase-modulated continuous wave radar technology, phase encodings (often + -180 °) are modulated onto a high-frequency signal, transmitted and correlated with the code used in the receiver. The correlation has a maximum at those points where the shift of the reference code corresponds to the signal propagation time to a target and thus to the distance. With other shifts, however, the correlation result could not be zero, but proportional to the amplitude of the maximum, see e.g. m-sequences ("Maximum Length Sequences"), so that interference occurs over the entire distance range. These disturbances can prevent the detection of targets with a small radar backscatter cross section or at a great distance. With the FMCW radar there is a similar problem (suppression of reflections from the bumper), which is solved by a high-pass filter. This is not possible with the PMCWRadar because there is no connection between the baseband frequency and the signal propagation time.

To suppress strong reflections (for example, a bumper that is always at the same distance), the sampling times are therefore shifted so that they fall on the zero crossings of a received radar signal with a certain signal propagation time. Individual sequences can, for example, consist of approx. 256 or approx. 512 Sampling points exist.

Shifting the sampling times in such a way that a correlation power is minimized in a predetermined distance range results in an optimized shift. This optimization of the sampling times is preferably carried out in a calibration phase of the sensor. After the calibration, the optimized shift of the sampling times is saved and used for subsequent measurements.

If the shift of the sampling times is optimized in such a way that a correlation power is minimized in the predetermined distance range, the sampling times fall on the zero crossings of the digitized received radar signal, so that interference in a received radar signal can be suppressed.

The predetermined distance range is preferably selected in such a way that it does not contain any reflections from objects (), except for reflections from an interfering object. The distance range can be determined by the processor or it can be specified manually with knowledge of the surroundings during the calibration process.

The processor is preferably designed to minimize the shifting of sampling times within a transmission pulse duration.

According to an exemplary embodiment, the device further comprises an analog-to-digital converter, wherein the analog-to-digital converter converts the phase code into a digital signal.

Furthermore, the device comprises an analog-digital converter, the analog-digital converter being designed to sample the received radar signal with the shift in sampling times.

The processor is preferably designed to determine the correlation performance on the basis of a correlation between the digitized received radar signal and the digitized phase code.

Instead of shifting the sampling times between successive measurements, this can also be carried out in a single measurement with greater computational effort. If the signal is sampled (usually given) in compliance with the sampling theorem, this can be represented for the entire time range. In this way, after calculating additional points in time, the most favorable sampling grid can be selected.

The received radar signal is preferably generated by means of phase-modulated continuous wave radar technology.

The exemplary embodiments also disclose a vehicle that comprises a device, the device comprising a processor which is designed to correlate a phase code with a sampled received radar signal according to sampling times and to determine a shift of sampling times in such a way that a correlation power in a predetermined Distance range is minimized. The vehicle can be, for example, a car, a truck, an electric vehicle, or the like. In particular, the device according to the invention can be used in an assistance system of such a vehicle. The vehicle can in particular be an autonomous or partially autonomous vehicle.

The exemplary embodiments also disclose a method in which a phase code is correlated with a sampled received radar signal according to sampling times and a shift in sampling times is determined so that a correlation performance is minimized in a predetermined distance range.

• 1 eine Hüllkurve einer phasenkodierten Wellenform eines PMCW-Radars in einem Zeitbereich zeigt;
• 2 ein Blockdiagramm zeigt, das eine beispielhafte Konfiguration eines erfindungsgemäßen Radarsystems darstellt;
• 3 ein exemplarisches Blockdiagramm des vom PN-Generator erzeugten Phasencodes zeigt;
• 4 exemplarische Abtastzeitpunkte des Analog-Digital-Wandlers 208 zeigt, der ein demoduliertes Empfangsradarsignal digital-wandelt;
• 5 ein Flussdiagramm eines Prozesses zum Bestimmen der optimalen Verschiebung der Abtastzeitpunkte zeigt;
• 6 zeigt, wie der Entfernungsbereichs für die Kalibrierung ausgewählt wird; und
• 7 ein Blockdiagramm zeigt, das schematisch die Konfiguration eines Fahrzeugs mit einem Radarsystem gemäß einem Ausführungsbeispiel der vorliegenden Erfindung darstellt.

Embodiments will now be described by way of example and with reference to the accompanying drawings, in which:

• 1 Figure 9 shows an envelope of a phase encoded waveform of a PMCW radar in a time domain;
• 2 Fig. 3 is a block diagram showing an exemplary configuration of a radar system according to the present invention;
• 3 Figure 11 shows an exemplary block diagram of the phase code generated by the PN generator;
• 4th exemplary sampling times of the analog-digital converter 208 shows that digital-converts a demodulated received radar signal;
• 5 Figure 3 shows a flow chart of a process for determining the optimal shift in sampling times;
• 6 shows how to select the distance range for calibration; and
• 7th FIG. 13 is a block diagram schematically showing the configuration of a vehicle having a radar system according to an embodiment of the present invention.

1 FIG. 10 shows an envelope of a phase-encoded waveform of a PMCW radar in a time domain. The phase-encoded waveform has seven sections S1 , S2 , S3 , S4 , S5 , S6 and S7 . Every sub-area S1 , S2 , S3 , S4 , S5 , S6 and S7 is a corresponding phase code ( 0 , 1 ) assigned. Is the live code 0 ( S1 , S4 , S6 , S7 ), the phase-coded wave is transmitted with a phase of 0 ° and is the phase code 1 ( S2 , S3 , S5 ), the phase-coded wave is transmitted with a phase of 180 °. The sub-areas ("Pulse") S1 , S2 , S3 , S4 , S5 , S6 and S7 have the same transmission pulse duration T , whereby the sub-areas are based on a base signal (not in 1 shown), which has a high frequency and an amplitude of 150mV to -150 mV, can be modulated. Due to the band limitation, the transitions between 0 and 1 do not have a rectangular shape, but follow a sine-like curve. The band limit is z. B. required due to frequency regulations or can arise from the bandwidth of the antennas. An additional safety spectrum can be used to ensure that the band limitation has a sinusoidal profile.

2 Fig. 13 is a block diagram showing an exemplary configuration of a radar system according to the invention. The radar system 200 includes a radar control unit 201 , a PN generator 202 , a modulator 203 , a transmitting antenna 204 , an analog-to-digital converter (ADC) 205 , a generator 206 , a correlator 207 , an analog-to-digital converter (ADC) 208 , an amplifier 209 , a demodulator 210 and a receiving antenna 211 and a delay element 212 . The Radar system 200 is a phase-modulated continuous wave (PMCW) radar system (phase-modulated continuous wave radar). The PMCW radar uses phase encodings, as in 1 shown, modulated on a high-frequency base signal, transmitted and correlated in the receiver with the code used. In the embodiment of 2 becomes a correlator though 207 shown, but as an alternative, several parallel correlators can also be provided in order to correlate several distances at the same time.

The PN generator 202 generates a phase code (reference code) which is sent to the modulator 203 is forwarded. The modulator 203 also receives a base signal at a high frequency from the generator 206 and mixes the signal with the phase code. The mixed signal (phase-encoded waveform) is sent to the transmitting antenna 204 transmitted to send the mixed signal (phase encoded waveform) to an object (target). The transmitted radar signal is reflected from the object and from the receiving antenna 211 receive. The received signal is matched with the signal from the generator 206 on the demodulator 210 and demodulated by the amplifier 209 reinforced. The demodulated signal is sent by the analog-to-digital converter 208 at different sampling times ( A1 , ..., A4 in 4th ) scanned. The sampling times of the analog-digital converter 208 are from the radar control unit 201 determined via a shift parameter δ and possibly with knowledge of the phase code. The process for determining the displacement parameter δ is under the description of FIG 5 explained in more detail. The other analog-to-digital converter 205 converts the phase code into a digital signal. The delay element 212 shifts the digitized phase code in time, the radar control unit 201 specifies the size of the time shift Δt. At the correlator 207 the sampled demodulated signal is correlated with the time-shifted (Δt) digitized phase code. The correlation has a maximum at those points where the shift of the phase code (reference code) corresponds to the signal propagation time to a target.

The present embodiment is not limited to a specific number of antennas. An antenna arrangement with antenna arrays with a plurality of transmitting and receiving antennas is preferably used.

3 Fig. 3 shows an exemplary block diagram of the PN generator 202 generated phase codes. The phase code is a binary code that consists of a sequence of 1 and 0. In this embodiment the phase code is "0110100". However, the embodiment is not limited to the phase code, but a different configuration of the phase code can be used, such as Braker code, Frank code or other codes known to those skilled in the art.

4th shows exemplary sampling times of the analog-digital converter 208 that scans ("digitally converts") a demodulated received radar signal. As in 1 a phase encoded waveform has seven pulses S1 , S2 , S3 , S4 , S5 , S6 and S7 on, taking each pulse S1 , S2 , S3 , S4 , S5 , S6 and S7 a corresponding phase code ( 0 , 1 ) assigned. Is the live code 0 ( S1 , S4 , S6 , S7 ), the phase-coded wave is transmitted with a phase of 0 ° and is the phase code 1 ( S2 , S3 , S5 ), the phase-coded wave is transmitted with a phase of 180 °. The pulse S1 , S2 , S3 , S4 , S5 , S6 and S7 have the same transmission pulse duration T , whereby the sub-areas are based on a base signal (not in 1 shown), which has a high frequency and an amplitude of 150mV to -150 mV, can be modulated. The transitions between 0 and 1 due to the band limitation do not have a rectangular shape, but follow a sine-like curve. The phase encoded waveform is made with sampling times A1 , A2 , A3 , A4 , A5 and A6 scanned. In the embodiment of 4th are the sampling times A1 , A2 , A3 and A4 however, with knowledge of the phase code, selected such that the sampling times are as spaced from one another as the zero crossings of the previously known phase code. The sampling times A1 , A2 , A3 and A4 are optimized by optimizing the displacement parameter ( δ in 2 ) placed in the zero crossings of the signal curve (see step 51 in 5 or. 6 ). Because the sampling times A1 , A2 , A3 and A4 are placed in the zero crossings of the signal curve, the received power or the correlation power can be reduced (cf. 6 ). The sampling times A5 and A6 do not fall on zero crossings, so that their correlation performance fluctuates only slightly due to a shift in the sampling times. As a result, their correlation performance increases significantly (up to approx. 6 dB) relative to the interference object.

The sampling times A1 to A6 are chosen equidistantly according to a sampling rate, the sampling rate corresponding to the frequency with which the phase code is modulated onto the baseband signal. This has the advantage that the analog-digital converter does not need any knowledge of the phase code, but has the disadvantage that the radar received signal is sampled even after the sampling times have been optimized at points where no zero crossings of the radar received signal are to be expected, namely at of the phase code on which no bit change takes place.

5 FIG. 13 shows a flow diagram of a process for determining the optimal shift in the sampling times as provided by the radar control unit 201 in 2 is carried out in a calibration phase. In step S50 a distance range [Δt ₁ , Δt ₂ ] is selected. The selected distance range [Δt ₁ , Δt ₂ ] is preferably selected so that no objects or objects with low reflection are contained in the distance range [Δt ₁ , Δt ₂ ], except for the object (object of no interest) for which the distance is specified is like this in 6 is shown and described.

wobei T die Sendepulsdauer ist, δ ∈ [0, T[ die Verschiebung der Abtastzeitpunkte innerhalb des Verschiebungsbereichs [0, T[ ist, ${\displaystyle {\int }_{\mathrm{\Delta }t1}^{\mathrm{\Delta }t2}{\left|f^{\left(\delta \right)}\left(\mathrm{\Delta }t\right)\right|}^{2}d\mathrm{\Delta }t}$

die Korrelationsleistung zwischen einem digitalisierten Phasencode und dem abgetasteten demodulierten Empfangsradarsignal innerhalb des Entfernungsbereichs [Δt₁, Δt₂ ] ist und min bedeutet, dass die optimale Verschiebung bestimmt wird, bei der die Korrelationsleistung ${\displaystyle {\int }_{\mathrm{\Delta }\text{t1}}^{\mathrm{\Delta }\text{t2}}{\left|f^{\left(\delta \right)}\left(\mathrm{\Delta }t\right)\right|}^{2}d\mathrm{\Delta }t}$

minimal ist.In step S51 the optimal shift (δ ^opt ) of the sampling times is determined. According to this exemplary embodiment, the shift is determined using the following equation: $${\delta }^{Opt}=mi{n}_{\delta \in [\mathrm{0,}T[}{\displaystyle {\int }_{\mathrm{<figure-callout\; id="1"\; label="\Delta \; t"\; filenames="DE102019201843A1\_0007.png,DE102019201843A1\_0009.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}t1}^{\mathrm{<figure-callout\; id="2"\; label="\Delta \; t"\; filenames="DE102019201843A1\_0013.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}t2}{\left|f^{\left(\delta \right)}\left(\mathrm{\Delta }t\right)\right|}^{2}d\mathrm{\Delta }t}$$

where T is the transmission pulse duration, δ ∈ [0, T [is the shift of the sampling times within the shift range [0, T [, ${\displaystyle {\int }_{\mathrm{<figure-callout\; id="1"\; label="\Delta \; t"\; filenames="DE102019201843A1\_0007.png,DE102019201843A1\_0009.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}t1}^{\mathrm{<figure-callout\; id="2"\; label="\Delta \; t"\; filenames="DE102019201843A1\_0013.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}t2}{\left|f^{\left(\delta \right)}\left(\mathrm{\Delta }t\right)\right|}^{2}d\mathrm{\Delta }t}$

the correlation power between a digitized phase code and the sampled demodulated received radar signal is within the distance range [Δt ₁ , Δt ₂ ] and min means that the optimum shift is determined at which the correlation power ${\displaystyle {\int }_{\mathrm{\Delta }\text{t1}}^{\mathrm{\Delta }\text{t2}}{\left|f^{\left(\delta \right)}\left(\mathrm{\Delta }t\right)\right|}^{2}d\mathrm{\Delta }t}$

is minimal.

Instead of shifting the sampling times between successive measurements, this can also be carried out in a single measurement with a high sampling rate due to a higher computational effort. The sampling rate is chosen to be higher than the pulse frequency of the phase code. If, for example, the sampling rate is chosen so that it corresponds to ten times the pulse frequency of the phase code, then correlation powers for ten different displacement parameters δ can be determined with one measurement. If the signal is sampled in compliance with the sampling theorem, which is usually the case, this can be represented for the entire time range. In this way, after calculating additional points in time, the most favorable sampling grid can be selected.

6 shows how the distance range [Δt ₁ , Δt ₂ ] in step 50 of the 5 is selected for calibration. With PMCW radar (Phase-Modulated Continuous Wave), phase encodings (often + -180 °) are modulated onto a high-frequency signal, transmitted and correlated with the code used in the receiver. The correlation f has a maximum at those points where the shift of the reference code corresponds to the signal propagation time or distance to a target. In 6 a signal maximum can be seen at a distance that corresponds to a reflection of an interfering object such as a bumper of the vehicle equipped with the radar sensor, which is always at the same distance. For other shifts, Δt is the correlation amplitude f however, not zero, but proportional to the amplitude of the maximum (see, for example, m-sequences or “Maximum Length Sequences”), so that interference occurs over the entire distance range. These disturbances can prevent the detection of target objects with little reflection (ie with a small radar backscatter cross section or at a great distance). In order to suppress strong reflections, such as those of an annoying bumper that is always at the same distance, the sampling times are therefore as in 5 described shifted so that they fall on the zero crossings of the receiving radar signal of the interfering object. With the optimal shift δ ^{opt of} the sampling times, the strong reflections are suppressed compared to the non-optimized case (cf. f ^(δopt) compared to f ^(δ) ). A suppression Δf of the received radar signal of approx. 5 dB can be achieved with the method.

In a non-optimized case (f ^(δ) ), the power of the interfering object, which is noticeable in the entire distance range, suppresses the signal-to-noise ratio of a reflection from a target object (SNR1). In an optimized case (f ^(δopt) ) the power of the interfering object is suppressed and thus the signal-to-noise ratio of a reflection of a target object (SNR2) is increased. The signal-to-noise ratio (SNR2) in an optimized case (f ^(δopt) ) is ^therefore greater than the signal-to-noise ratio (SNR1) in a non-optimized case (f ^(δ) ). Therefore, reflection of a target object with a small amplitude can be more reliably detected.

In the calibration phase, the distance range [Δt ₁ , Δt ₂ ] is preferably selected so that no objects or objects with low reflection are contained in the distance range [Δt ₁ , Δt ₂ ], apart from the reflection signal of the interfering object (object of no interest) Distance is given (e.g. bumper that is always at the same distance). This is z. B. proceed by a detection, z. B. by CFAR (Constant False Alarm Rate) guaranteed.

7th FIG. 13 is a block diagram schematically showing the configuration of a vehicle having a radar system according to an embodiment of the present invention. The vehicle according to this exemplary embodiment is controlled by a human driver or is a vehicle that can operate in road traffic wholly or partially without the influence of a human driver. With autonomous driving, this takes over Control system of the vehicle completely or largely the role of the driver. Autonomous (or semi-autonomous) vehicles can use various sensors to perceive their surroundings, determine their position and that of other road users from the information obtained, and use the vehicle's control system and navigation software to navigate to the destination and act accordingly in traffic.

The vehicle 600 includes a radar system 200 and a central control unit 610 (ECU 4th ). Radar data is from the radar system 200 recorded and for example to the central control unit 610 (ECU 4th ) transfer. Furthermore, the optimal displacement ( δ ^opt ) the sampling times are determined (see 5 ). In the case of a vehicle, for example, the bumper of the vehicle can be in front of the radar system 200 generate a high reflection of a radar signal. Since the bumper of the vehicle is typically not an object of interest, the reflected radar signal from the bumper can cause a great deal of interference. These disturbances can prevent the detection of targets with a small radar backscatter cross section or at a great distance. To suppress this interference, the sampling times are shifted so that they fall on the zero crossings of the demodulated received radar signal that is generated by the bumper. This is possible by considering a distance range after the correlation which contains no targets or only weak targets and therein the correlation performance is minimized by shifting the sampling times in successive measurements (see 5 ). Since a bumper is always at the same distance or it changes only slightly while driving, the sampling times only need to be adjusted occasionally. The central control unit 610 (ECU 4th ) is designed to receive the radar data from the radar system 200 to receive and process the radar data. The radar data include information such as the time shift between transmitted and received radar beams and the Doppler frequency. Based on the time difference, a distance between the vehicles becomes 600 and an object is determined and a relative movement is determined by the Doppler frequency.

The vehicle 600 also includes multiple electronic components that communicate via a vehicle communication network 613 are interconnected. The vehicle communication network 613 For example, a standard vehicle communication network installed in the vehicle, such as a CAN bus (controller area network), a LIN bus (local interconnect network), an Ethernet-based LAN bus (local area network), a MOST bus, an LVDS -Bus or the like.

In the in 7th The example shown includes the vehicle 600 also a control unit 601 (ECU 1 ) that controls a steering system. The steering system refers to the components that enable directional control of the vehicle. The vehicle 600 further comprises a control unit 602 (ECU 2 ) that controls a braking system. The braking system refers to the components that enable the vehicle to brake. The vehicle 600 further comprises a control unit 603 (ECU 3 ) that controls a drive train. The drive train refers to the drive components of the vehicle. The powertrain may include an engine, a transmission, a drive / propeller shaft, a differential, and a final drive. The control units 601 , 602 and 603 can also receive vehicle operating parameters from the above-mentioned vehicle subsystems, which these record using one or more vehicle sensors. Vehicle sensors are preferably those sensors that detect a state of the vehicle or a state of vehicle parts, in particular their state of movement. The sensors may include a vehicle speed sensor, a yaw rate sensor, an acceleration sensor, a steering wheel angle sensor, a vehicle load sensor, temperature sensors, pressure sensors, and the like. For example, sensors can also be arranged along the brake line in order to output signals which indicate the brake fluid pressure at various points along the hydraulic brake line. Other sensors in the vicinity of the wheel can be provided which detect the wheel speed and the brake pressure applied to the wheel. The central control unit 610 controls one or more vehicle subsystems while the vehicle is in operation 600 is operated, namely the braking system 602 , the steering system 601 and the drive system 603 . The control unit 610 for example via the vehicle communication network 613 with the corresponding control units 601 , 602 and 603 communicate.

The vehicle 600 further comprises one or more sensors 606 that are designed for environmental monitoring. With the other sensor units 606 For example, it can be a lidar system, ultrasonic sensors, ToF cameras or other units. These additional sensor units receive data from a distance and speed measurement 606 recorded and for example to the central control unit 610 transfer. Based on the data from these sensors 606 becomes a distance between the vehicle 600 and one or more objects are determined.

The vehicle 600 also includes a GPS / position sensor unit 607 . The GPS / position sensor unit 607 enables the absolute position of the autonomous vehicle to be determined 600 with respect to a geodetic reference system (earth coordinates). The position sensor can be, for example, a gyro sensor or the like which reacts to accelerations, rotational movements or changes in position.

The functionality described in this description can be implemented as integrated circuit logic, e.g. on a chip. Unless otherwise specified, the functionality described can also be implemented using software. Insofar as the embodiments described above are implemented at least partially with the aid of software-controlled processors, a computer program for providing such a software control and a corresponding storage medium are also regarded as aspects of the present disclosure.

List of reference symbols

200

Radar system

201

Radar control unit

202

PN generator

203

modulator

204

Transmitting antenna

205

Analog-to-digital converter

206

generator

207

Correlator

208

Analog-to-digital converter

209

amplifier

210

Demodulator

211

Receiving antenna

212

Delay element

600

vehicle

601

Steering system (ECU 1)

602

Braking system (ECU2)

606

Sensors

607

GPS / position sensor unit

610

Central control unit

613

Vehicle communication network

A1, A2, A3, A4

Sampling times

S1, S2, S3, S4, S5, S6, S7

Pulses of the phase code

[Δt ₁ , Δt ₂ ]

Distance range

T

Transmission pulse duration

S.

Radar reception signal

δ

Shifting the sampling times

δ ^opt

optimal shifting of the sampling times

Δt

Running time (or distance)

f

Correlation function

Correlation performance

Claims (10)

Device (200) comprising a processor (201) designed to correlate a phase code with a received radar signal (S) sampled according to sampling times (A1, A2, A3, A4) and a shift (δ) of sampling times (A1 , A2, A3, A4) in such a way that a correlation power (| f ^(δ) (Δt) | ² ) is minimized in a predetermined distance range ([Δt ₁ , Δt ₂ ]). Device (200) after Claim 1 , wherein the predetermined distance range ([Δt ₁ , Δt ₂ ]) is selected so that it does not contain any reflections from objects with little reflection, except for reflections from an interfering object. Device (200) according to one of the preceding claims, wherein the processor (201) is designed to minimize the shift (δ) of sampling times (A1, A2, A3, A4) within a transmission pulse duration ([0, T [). Device (200) according to one of the preceding claims, wherein the device (200) further comprises an analog-digital converter (208) which is designed to convert the received radar signal (S) with the shift (δ) of sampling times (A1, A2 , A3, A4). Device (200) after Claim 4 , wherein the processor (201) is designed to determine the correlation power (| f ^(δ) (Δt) | ² ) on the basis of a correlation (f ^(δ) ) between the sampled received radar signal (S) and the digitized phase code. Device (200) according to one of the preceding claims, wherein the processor (201) for this purpose is designed to determine the shift (δ) of the sampling times (A1, A2, A3, A4) according to the following formula $${\delta }^{Opt}=mi{n}_{\delta \in [\mathrm{0,}T[}{\displaystyle {\int }_{\mathrm{\Delta }t1}^{\mathrm{\Delta }t2}{\left|f^{\left(\delta \right)}\left(\mathrm{\Delta }t\right)\right|}^{2}d\mathrm{\Delta }t}$$

where T is the transmission pulse duration, δ ∈ [0, T [is the shift of the sampling time (A1, A2, A3, A4) within the shift range [0, T [, ${\displaystyle {\int }_{\mathrm{\Delta }t1}^{\mathrm{\Delta }t2}{\left|f^{\left(\delta \right)}\left(\mathrm{\Delta }t\right)\right|}^{2}d\mathrm{\Delta }t}$

the correlation power between the phase code and the sampled received radar signal is within the range range [Δt ₁ , Δt ₂ ] and δ ^{opt is} that shift at which the correlation power is minimal. Device (200) according to one of the preceding claims, wherein the processor (201) is designed to carry out the optimization of the shift (δ) of the sampling times (A1, A2, A3, A4)) in a single measurement. Device (200) according to one of the preceding claims, wherein the received radar signal (S) is generated by means of phase-modulated continuous wave radar technology. A vehicle (600) comprising an apparatus (200) according to any one of the preceding claims. Method in which a phase code is correlated with a received radar signal (S) sampled according to sampling times (A1, A2, A3, A4) and a shift (δ ^opt ) of sampling times (A1, A2, A3, A4) is determined so that a Correlation power (| f ^(δ) (Δt) | ² ) is minimized in a predetermined distance range ([Δt ₁ , Δt ₂ ]).

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