WO2024041865A1

WO2024041865A1 - Cognitive radar for unambiguously measuring the speed

Info

Publication number: WO2024041865A1
Application number: PCT/EP2023/071547
Authority: WO
Inventors: Hector Andres GONZALEZ DIAZ; Chen Liu; Bernhard VOGGINGER; Matthias LOHRMANN; Sebastian Hoeppner; Christian Georg Mayr
Original assignee: Spinncloud Systems Gmbh
Priority date: 2022-08-23
Filing date: 2023-08-03
Publication date: 2024-02-29
Also published as: DE102022121301A1

Abstract

Various aspects of the invention provide a method (200) for dynamically resolving the speed ambiguity of a target in a radar system, the method (200) including: using (210) a first radar detection method for detecting a target, wherein the first radar detection method has a first maximum unique speed; dynamically determining (220) whether an actual speed of the target is greater than the first maximum unique speed; and in the case where the actual speed of the target is greater than the first maximum unique speed, using (230) a second radar detection method for detecting the target, wherein the second radar detection method has a second maximum unique speed and wherein the second maximum unique speed is greater than the first maximum unique speed.

Description

Cognitive radar for clearly measuring speed

Various aspects relate to a radar system adapted to resolve speed ambiguity and a corresponding method (e.g., a method for resolving speed ambiguity in a radar system).

In general, radar (in English “Radio Detection and Ranging”) is a type of detection system based on the emission and reception of electromagnetic waves to detect objects. Radar systems have a wide range of applications, e.g. for tracking aircraft or ships, measuring ocean properties, supporting autonomous driving and the like. A radar system can provide various information about an object, such as the distance at which the object is, the speed of movement, or the angular position. Among the possible types of radar systems, high-density “multiple-input-multiple-output” (MIMO) radar systems have become extremely popular in industry and research in recent years because they enable fine angular isolation of objects. The development of radar systems that are set up for MIMO applications is therefore of great interest for the further development of vehicles with autonomous driving functions.

However, the simultaneous emission of frequency-modulated continuous waves (FMCW) by multiple transmitters requires modulation techniques that ensure orthogonality. All common modulation methods for full-bandwidth transmission, such as time division multiplexing (TDM) or code division multiplexing (CDM), combine groups of consecutive chirps to achieve the contribution of the entire MIMO -Arrays to use. Such group-wise processing limits the frequency of repetition of identical codes and thus reduces the maximum unique speed that can be detected. For example, a typical FMCW (77 GHz) automotive radar using CDM or TDM with a six-transmitter MIMO configuration has an 83% reduction in its maximum unique speed compared to a single-transmitter system. Since modern 4D radars (visual, for determining distance, relative speed, azimuth angle and elevation angle) usually have a large number of transmitters, the situation in the automotive field is even worse and particularly dangerous because the speed Faster vehicles are incorrectly folded into the cyclic ambiguity region can be made, giving the impression that fast cars are moving at a slower speed or even in the opposite direction.

Various aspects of the present disclosure relate to a method of radar detection adapted to respond dynamically to fast-moving targets so that accurate detection of the target's speed can be ensured. The radar acquisition procedure is designed to reactively adjust the radar acquisition parameters when it determines that the speed of the target cannot be clearly determined with the parameters currently in use. This cognitive approach allows the radar system to adapt to its environment, optimizing performance based on the current scenario.

In a preferred configuration, the radar detection method may include dynamically switching from radar detection parameters that provide high angular resolution but a relatively low maximum unique speed to other radar detection parameters that provide lower angular resolution but a higher maximum unique speed. A dynamic compromise between the angular resolution and the maximum unique speed can thus be adjusted reactively depending on the current scenario, extending the speed range if necessary.

The approach described herein provides an online adjustment mechanism that allows the maximum Doppler range to be extended as needed. Unlike traditional velocity ambiguity resolution approaches, the strategy described herein does not require active application of ambiguity resolution methods when the target is not moving ambiguously, resulting in low processing overhead. Traditional methods that require little effort in applying ambiguity resolution techniques either have poor performance (e.g. when inferring velocity from the

As of the status change), are not applicable in the MIMO domain or have shifted the effort to the processing domain (e.g. in a complex multi-band approach). The approach described herein thus provides a solution to the problem of velocity ambiguity in radar detection without compromising the overall performance of the radar system and without requiring complex and resource-intensive processing.

According to various aspects, there is provided a method for resolving target ambiguity in a radar system, the method comprising: using a first radar detection method to detect a target, the first Radar detection method comprising transmitting a first plurality of transmit signals via a plurality of transmit antennas and receiving a first plurality of reflected signals via a plurality of receive antennas, the first radar detection method having a first maximum unique velocity (and in some aspects a first angular resolution); dynamically determining whether an actual speed of the target is greater than the first maximum unique speed; and in the event that the actual speed of the target is greater than the first maximum unique speed, using a second radar detection method to detect the target, the second radar detection method comprising transmitting a second plurality of transmit signals using the plurality of transmit antennas and receiving a second one a plurality of reflected signals by means of the plurality of receiving antennas, wherein the second radar detection method has a second maximum unique speed, the second maximum unique speed being greater than the first maximum unique speed (and in some aspects, the second radar detection method has a second angular resolution, which is smaller than the first angular resolution, or the second radar detection method is not used at all to determine angular information).

According to various aspects, a radar device for resolving target ambiguity may be provided, the radar device comprising: a plurality of transmit ports configured to be coupled to a plurality of transmit antennas; a plurality of receiving ports configured to be coupled to a plurality of receiving antennas; and a processing circuit configured to: control transmission of a first plurality of transmission signals via the plurality of transmission ports to provide a first radar detection method of a target, the transmission signals of the first plurality of transmission signals being configured to have a first maximum unique speed (and , in some aspects, to provide a first angular resolution); determining whether an actual speed of the target is greater than the first maximum unique speed based on a plurality of reflected signals received at the plurality of receive ports; and in the event that the actual speed of the target is greater than the first maximum unique speed, dynamically controlling transmission of a second plurality of transmit signals via the plurality of transmit ports to provide a second radar detection method of the target, wherein transmit signals of the second plurality of transmit signals are configured to provide a second maximum unique velocity (and, in some aspects, a second angular resolution); where the second maximum unique speed is greater than the first maximum unique speed (and the second angular resolution is smaller than the first angular resolution).

The method and apparatus may thus enable dynamic adjustment of the transmit signals used for radar detection to increase the maximum unique velocity in response to a target moving too quickly for the current Doppler range. As an exemplary application, the radar system described herein may be installed (e.g., retrofitted) into a vehicle, e.g., a vehicle with at least partially autonomous driving capabilities.

According to various aspects, the approach proposed herein can be implemented in a MIMO radar system, which is a type of radar system for which the problem of target velocity ambiguity is particularly relevant. In addition, it has been found that the capabilities of a MIMO radar system can be used to adjust the broadcast signals to enable simple but reliable ambiguity detection (see for example FIG.4A and FIG.4B). Therefore, without limiting generality, some aspects of the present description relate to MIMO radar systems. However, it is understood that the approach described herein may in principle also be applicable to other types of radar systems, e.g. to a SIMO (Single-Input Multiple-Output) radar system.

Various aspects relate to a method for determining whether the measured speed of a target is unique and a processing circuit (eg, an ambiguity detector) configured to make such a determination. Illustratively, various aspects relate to an approach that makes it possible to determine in a simple but efficient manner whether the radar detection parameters should be (temporarily) adjusted in order to detect a fast-moving target. The method for determining the speed ambiguity may be based on taking a plurality of individual measurements of the speed of the target, the individual measurements having different maximum unique speeds, and determining whether the measured values of the speed converge to a same value or diverge. If the measured values diverge, this is an indication that the target is moving at a speed that cannot be clearly determined with the current parameters and an adjustment to the radar detection parameters may be triggered. The method for detecting the ambiguities can therefore be based on directly determining whether a speed ambiguity exists, without using complex post-processing techniques. According to various aspects, a method for dynamically determining an ambiguity associated with radar detection of a target may be provided, the method comprising: transmitting a plurality of sets of transmit signals, the sets of transmit signals being configured of the plurality of sets of transmit signals to provide an equal velocity resolution with respect to each other and a different maximum unique velocity with respect to each other; determining a respective value for a measured speed of the target for each set of transmission signals; and determining whether an actual speed of the target is greater than a predetermined maximum unique speed as a function of the values of the measured speed of the target.

In a preferred configuration, the method may include using at least three sets of broadcast signals (illustratively, at least three sub-frames) to determine the presence of ambiguity in radar detection. In particular, each sub-frame may include a plurality of blocks of broadcast signals, and the numbers of blocks in the various sub-frames may be coprime (in other words, relatively prime) with respect to each other. A block of broadcast signals can have multiple spatial codes, e.g. B. several chirp signals that are emitted using different transmitting antennas and are coded so that they are orthogonal. It has been found that the configuration with at least three sub-frames and coprime numbers of blocks enables a direct but reliable and accurate determination of whether the speed of the target can be uniquely determined. It was clearly determined that the individual speed values measured using at least three different sub-frames only converge to the same value if the speed of the target can be clearly determined (clearly the value to which the measured values converge is then the true one speed of the target).

Therefore, configuring at least three different sub-frames provides a time and resource efficient strategy for determining the presence of velocity ambiguity in radar detection. Therefore, without loss of generality, some of the aspects in the present description relate to ambiguity detection using at least three different sub-frames. However, it is understood that the approach described here is in principle also applicable for other signal types, e.g. with a different number of sub-frames, with numbers of blocks that are not coprime, etc. Exemplary embodiments are shown in the figures and are explained in more detail below.

Show it

Figure 1 A shows a radar system in a schematic view, according to various aspects;

Figure 1B shows a transmission circuit in a schematic view, according to various aspects;

Figure IC shows a receiving circuit in a schematic view, according to various aspects;

Figure ID shows a transmission signal comprising a plurality of chirp signals in a schematic view, according to various aspects;

Figure 2A is a schematic flowchart of a method for operating a radar system, according to various aspects;

Figure 2B and Figure 2C each show a plurality of transmission signals in a schematic view, according to various aspects;

Figure 3A and Figure 3B show a processing circuit in a schematic view, according to various aspects;

Figure 3C shows a radar system in a schematic view, according to various aspects;

Figure 4A is a schematic flow diagram of a method for determining ambiguity associated with radar detection of a target, according to various aspects;

Figure 4B shows a plurality of sets of transmission signals in a schematic view, according to various aspects;

Figure 5A is a schematic flowchart of a method for operating a radar system, according to various aspects; and Figures 5B, 5C and 5D are each a diagram illustrating experimental results of radar detection according to various aspects.

In the following detailed description, reference is made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be used and structural or logical changes may be made without departing from the scope of the present invention. It is to be understood that the features of the various exemplary embodiments described herein may be combined with one another unless specifically stated otherwise. The following description is therefore not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

FIG.1A shows a radar system 100 in a schematic view according to various aspects. In general, the radar system 100 may include a plurality of antennas 102 and a radar device 104 coupled to the antennas 102 and configured to control the transmission and reception of radar signals using the antennas 102. The plurality of antennas 102 may include one or more transmit antennas 106 and one or more receive antennas 108. The one or more transmitting antennas 106 may be intended for transmitting radar signals and the receiving antennas 108 may be intended for receiving radar signals. A radar signal transmitted from a transmitting antenna 106 may be referred to herein as a transmitted signal, and a radar signal received at a receiving antenna 108 may be referred to herein as a received signal or reflected signal.

In the exemplary configuration in FIG. 1A, the radar system 100 has a plurality of transmit antennas 106 (e.g. four transmit antennas 106) and a plurality of receive antennas 108 (e.g. four receive antennas). The radar system 100 in FIG. 1A can thus be set up for MIMO radar detection, e.g. the radar system 100 can be a MIMO radar system. However, it should be understood that the aspects described with respect to the radar system 100 may apply in a corresponding manner to another configuration of the radar system 100, e.g. a configuration with a single transmitting antenna 106 or a configuration with a number of transmitting antennas 106 that differ from the Number of receiving antennas 108 differs.

The general operating principle of radar detection is well known in the art. A brief overview is provided herein to introduce the aspects relevant to this disclosure. In general, the radar detection can show that electromagnetic waves (e.g. radio waves) are emitted towards a scene and electromagnetic waves are received that are reflected back to the radar system 100. Processing the reflected electromagnetic waves that the radar system receives allows it to provide an understanding of the scene.

Referring to the configuration of FIG. 1A, the radar system 100 may be configured to transmit a plurality of transmit signals 110 (via the plurality of transmit antennas 106) and to receive a plurality of reflected signals 112 (via the plurality of receive antennas 108). A reflected signal 112 can be understood as a transmit signal 110 that is reflected from a target 114 back to the radar system 100. Within the scope of the present disclosure, the transmission signals used for detection of the target, e.g. a measurement of the speed of the target, may be referred to as a frame.

As used herein, the term "target" may be used to describe any type of entity that can be detected by radar detection. A "target" can be an object that is within the field of view of a radar system and is capable of reflecting electromagnetic waves in the direction of the radar system. Clearly, a “target” can be an object that is in the field of view of a radar system. As an example, a "target" may be a vehicle (as shown in FIG. 1A), a human, an animal, a structure, a facility, a traffic sign, a building, or the like. In general, a "target" can be referred to as a "moving target" if the target is not stationary, for example if the target's speed is not 0 m/s. As an example convention, the target (radial) velocity may be negative if the target is moving toward the radar system or positive if the target is moving away from the radar system.

Processing the reflected signals 112 received from the radar system 100 enables the determination of various properties of the target 114, such as its distance from the radar system 100 (also referred to as its range), its radial velocity, and its angular position (with respect to the radar system 100), e.g., the angular position both in both horizontal and vertical directions (illustrated by the azimuth and elevation angles). Determination of the characteristics of the target 114 may be based on the frequency and phase variations of the transmitted signals 110 caused by reflection from the target 114, as is known in the art. The characteristics of the radar detection, such as the maximum detectable distance, the maximum detectable speed, the angular resolution, etc., depend on the characteristics of the radar system 100 (e.g., hardware or software limitations) and on the Properties of the transmission signals 110, as is known from the art and will be described in more detail below.

In various aspects, the radar device 104 may include a transmitting circuit 116, a receiving circuit 118, a waveform generator 120, and a processing circuit 122. It is understood that the representation of the radar device 104 in FIG. 1A may be simplified for the purpose of illustrating the principles of the proposed approach, and that the radar device 104 may include additional components relative to those shown. It is also understood that the functions of the components shown separately in FIG.1A may be performed by a single component with equivalent functions, and that the functions performed by a single component in FIG.1A may be performed by two or more separate components with equivalent functions functions can be carried out. In addition, the transmitting circuit 116, the receiving circuit 118, the waveform generator 120 and/or the processing circuit 122 may be configured to perform the respective operations in an analog and/or digital manner.

The transmit circuit 116 may be configured to perform signal processing in preparation for transmitting a transmit signal 110, for example, the transmit circuit 116 may be configured to perform signal amplification, frequency selection, digital-to-analog conversion, and the like. The transmit circuit 116 may be coupled to the transmit antennas 106 via one or more transmit ports 124 of the radar device 104. In the configuration in FIG. 1A, the radar device 104 may have a plurality of transmit ports 124, e.g. one for each transmit antenna 106. A transmit port 124 may be an output port configured to be coupled to a respective transmit antenna 106. The transmit circuit 116 may be a high-frequency front end, e.g. a TX front end, of the radar device 104. A transmitting antenna 106 with associated transmitting circuit 116 can also be referred to as a transmitter.

The receiving circuit 118 can be set up to carry out signal processing of the reflected signals 112 received on the radar system 100, for example the receiving circuit 118 can be set up to carry out signal amplification, frequency selection, analog-to-digital conversion and the like. The receiving circuit 118 may be coupled to the receiving antennas 118 by means of one or more receiving ports 126 of the radar device 104. In the configuration in FIG. 1A, the radar device 104 may include a plurality of receive ports 126, eg, one for each receive antenna 108. A receive port 126 may be an input port configured with a respective receiving antenna 108 to be coupled. The receiving circuit 118 may be a radio frequency front end, for example an RX front end, of the radar device 104. A receiving antenna 108 with associated receiving circuit 118 can also be referred to as a receiver.

The waveform generator 120 can be set up to generate the transmission signals 110 and to provide the generated transmission signals 110 to the transmission circuit 116 for transmission by means of the transmission antennas 106. Clearly, the waveform generator 120 can be set up to generate a waveform signal 132 (e.g. a plurality of waveform signals) with the desired characteristics, e.g. in terms of frequency, phase, duration, etc., and to provide the waveform signal(s) to the transmitter circuit 116 for transmission. A waveform signal 132 may be an analog signal, such as a voltage, that has the desired characteristics to be provided in the transmit signal(s) 110. In various aspects, the waveform generator 120 may be a ramp generator, for example configured to generate a frequency ramp for a transmit signal 110 (see also FIG. ID). Illustratively, the waveform generator 120 can be a frequency synthesizer.

The processing circuit 122 can be set up to control the operation of the radar device 104, for example to control the operation of the transmitting circuit 116 (by means of a corresponding control signal 134), the receiving circuit 118 and the waveform generator 120. In particular, the processing circuit 122 can be set up to receive a measurement signal 136 from the receiving circuit 118 and for processing the measurement signal 136 to determine the properties of the target 114 (e.g. distance, speed, angle, etc.). A measurement signal 136 may correspond to a reflected signal 112 after processing in the receiving circuit 118. As an example, a measurement signal 136 may be a reflected signal 112 that has been converted into a digital signal. In various aspects, processing circuitry 122 may be a digital front end of radar device 104. Clearly, the processing circuit 122 can be set up to perform digital signal processing (DSP). In some aspects, the measurement signal 136 may be or include a plurality of measurement signals, e.g. one for each receiving antenna 108.

The characteristics of the transmit signals 110 can be selected according to the desired radar detection strategy. In the present disclosure, particular reference is made to the case where the transmission signals 110 are frequency modulated continuous wave (FMCW). This configuration has been shown to provide a simple and efficient implementation of the ones described herein Strategy enables. However, it is understood that this strategy can also be used in a corresponding manner for other types of radar detection, for example for continuous wave radar or pulse-Doppler radar.

FIG.1B and FIG.1C show possible configurations of the transmitting circuit 116 and the receiving circuit 118 in a schematic view according to various aspects. The configurations in FIG.1B and FIG. ICs can enable a simple but efficient implementation of the cognitive approach described herein. However, it is understood that other configurations of the transmission circuit 116 and/or the reception circuit 118 can also be provided in order to carry out the respective signal processing. It is also understood that the signal processing in the transmit circuit 116 and the receive circuit 118 may be performed using analog components and/or in a digital manner.

In various aspects, as shown in FIG. 1B, the transmit circuit 116 may include a phase shift circuit 140 and a signal amplification circuit 142. The phase shift circuit 140 can be set up to effect a shift in the phase of the (respective) transmission signal 110. Clearly, the phase shift circuit 140 can be set up to generate a phase shift for the waveform signal 132 received at the transmission circuit 116. It is understood that the phase shift circuit 140 additionally or alternatively can be set up as a time delay circuit that is set up to provide a time delay of a transmission signal 110. In an exemplary implementation, the phase shift circuit 140 can have a phase shifter 154, for example a phase shifter with switchable delay lines. The signal amplification circuit 142 may be arranged downstream of the phase shift circuit 140 and may be configured to amplify a signal level of the transmitted signal 110, for example, it may be configured to increase an amplitude of the transmitted signal 110. As an example, the signal amplification circuit 142 may include a power amplifier 156.

In general, the transmit circuit 116 may include one or more signal processing circuits 138, for example a signal processing circuit 138 for each transmit antenna 106 of the radar system 100. A signal processing circuit 138 may be coupled to a respective transmit port 124 and configured to perform signal processing of a signal transmitted via this transmit port 124 Transmit signals 110. Considering the MIMO configuration of FIG. 1A, the transmit circuit 116 may include a plurality of signal processing circuits 138, each of which includes a phase shift circuit 140 and a Signal amplification circuit 142. A signal processing circuit 138 may also be referred to herein as a transmit slice (TX slice) or transmit chain (TX chain). In the MIMO configuration, the radar device 104 (illustratively, the transmit circuit 116) may thus include a plurality of phase shifters (one for each transmit antenna 106).

In various aspects, the transmit circuit 116 may be configured (e.g., controlled) to provide different phase shifts for transmit signals 110 that are transmitted using different transmit ports 124 (and different transmit antennas 106). The different phase shifts (or different time delays) can cause encoding of the transmission signals 110, as described in more detail below. In this regard, the processing circuit 122 may be configured to control the phase shift circuit(s) 140 to provide a predetermined phase profile (also referred to herein as a phase pattern) for the transmit signals 110. For example, the processing circuit 122 may be configured to control the plurality of phase shifters (via corresponding control signals 134) according to a predetermined coding scheme.

According to various aspects, as shown in FIG. As shown in IC, the receiving circuit 118 may include a signal amplification circuit 146, a frequency shifting circuit 148, a signal filtering circuit 150, and a signal conversion circuit 152. In general, the receiving circuit 118 may be configured to receive a reflected signal 112 at the receiving port(s) 126 and to provide a measurement signal 136 as an output signal to the processing circuit 122.

The signal amplification circuit 146 may be configured to amplify a signal level of a reflected signal 112 received at a receive port 126, e.g., the signal amplification circuit 146 may be configured to increase an amplitude of the reflected signal 112. As an example, the signal amplification circuit 146 may include a low noise amplifier 158 .

The frequency shift circuit 148 may be configured to shift a frequency of the reflected signal 112 (in other words, to shift or convert). The receiving circuit 118 may be configured to receive the transmitted waveform (waveform signal 132) from the waveform generator 120. The frequency shifting circuit 148 may be configured to combine (in other words, mix) the transmitted waveform and the received waveform with each other. The frequency shift circuit 148 can be clearly seen be configured to combine a transmitted signal 110 with a corresponding reflected signal 112. The resulting signal may have an instantaneous frequency that is equal to the difference in the instantaneous frequencies of the combined signals and a phase that is equal to the difference in the phases of the combined signals. The frequency shift circuit 148 can thus provide a resulting signal at a frequency suitable for processing in the processing circuit 122. As an example, the frequency shift circuit 148 may include a mixer 160, such as an IQ mixer or a normal mixer.

The signal filtering circuit 150 may be configured to filter the components of the resulting signal that lie outside a predetermined frequency range. The signal filtering circuit 150 may thus be configured to pass only those components of the resulting signal that have a predetermined frequency. As an example, the signal filtering circuit 150 may include a bandpass filter or a low-pass filter 162.

The signal conversion circuit 152 may be configured to convert the resulting (filtered) signal into a format that enables processing in the processing circuit 122. For example, the signal conversion circuit 152 may be configured to convert the resulting (analog) signal into a digital signal, which is then supplied to the processing circuit 122. As an example, the signal conversion circuit 152 may include an analog-to-digital converter 164 (ADC) or a plurality of analog-to-digital converters (e.g. 2x ADC in the case of an IQ signal).

In general, the receiving circuit 116 may include one or more signal processing circuits 144, e.g., a signal processing circuit 144 for each receiving antenna 108 of the radar system 100. A signal processing circuit 144 may be coupled to a respective receiving port 126 and configured to perform signal processing of a reflected signal received at this receiving port 126 112. Given the MIMO configuration of FIG. 1A, the receiving circuit 118 may include a plurality of signal processing circuits 144 (eg, four signal processing circuits 144), each including a signal amplification circuit 146, a frequency shift circuit 148, a signal filtering circuit 150, and a signal conversion circuit 152. A signal processing circuit 144 may also be referred to herein as a receive slice (RX slice) or receive chain (RX chain). FIG. 1D shows a diagram 128 that schematically represents a transmit signal 110 according to various aspects. The transmission signal 110 is represented in terms of frequency (f) over time (t).

In various aspects, a transmit signal 110 may include one or more chirp signals 130, e.g., a plurality of chirp signals 130. A chirp signal 130 may be a signal whose frequency increases linearly with time, e.g., a chirp signal 130 be a sinusoid with a frequency that increases linearly from a start frequency to an end frequency. A chirp signal may also be referred to herein as a wobble signal or simply as a chirp. In various aspects, a transmit signal 110 may thus be a frequency modulated continuous wave signal having one or more chirps (e.g., a plurality of chirps).

A chirp signal 130 can be characterized by several properties, for example by the starting frequency f _c , the bandwidth B (illustratively, the frequency range that the chirp signal covers), the duration of the ramp T _c (also referred to as the chirp time) , the idle time Ti (also called the inter-chirp duration) and the slope S, which defines the rise of the chirp signal. As example values for radar applications, a chirp signal 130 may have a starting frequency f _c in the range of 30 MHz to 300 GHz, a bandwidth B in the range of 500 MHz to 5 GHz, and a duration T _c in the range of 1 ps (1 microsecond) to 500 ps (500 microseconds). The slope S (in Hz/s) can be determined by dividing the bandwidth by the duration. With reference to the configuration in FIG. 1A, the waveform generator 120 may be configured to generate the chirps 130, for example, the waveform generator 120 may be configured to generate the frequency ramps to be transmitted.

Chirp signals 130 are often used in radar detection because they allow the range of a target 114 to be easily determined. Briefly, a chirp signal 130 is emitted by means of a transmitting antenna 106, reflected back by the target 114 and received as a reflected signal 112 at a receiving antenna 108. The transmitted chirp signal and the received chirp signal are combined with each other, for example in the frequency shift circuit(s) 148 of the reception circuit 118. Taking the chirps into account, the frequency of the resulting signal can thus be constant over time and represent the distance, in which target 114 is located. In various aspects, the resulting signal may be an intermediate frequency (IF) signal.

The frequency of the resulting signal (and correspondingly the frequency of the measurement signal 136) can be expressed as S*2*d/c, where S is the slope of the chirp signal, d the distance of the target and c is the speed of light. The processing circuit 122 may thus be configured to determine (eg, calculate) the distance of a target as a function of the frequency of the measurement signal 136, for example by means of a Fourier transform (FT) of the measurement signal, such as a fast Fourier transform Fourier transform, FFT), also known as 1D FFT or distance FFT, or another frequency analysis method. Clearly, the position of a peak in the frequency range, e.g. in the FFT spectrum, can be an indication of the distance at which the target is located. The frequency of the measurement signal 136 increases as the distance to the target 114 increases.

The use of multiple chirp signals 130 allows the speed of the target 114 to be determined. This determination is based on the property that the phase of an intermediate frequency signal is very sensitive to small changes in the position of the target 114. Therefore, if a plurality of chirp signals 130 are emitted, the corresponding measurement signals (e.g. the corresponding peaks resulting from the FFT) have a different phase. The phase difference measured between two consecutive measurement signals corresponds to the movement of the target and can be used to determine its speed.

The processing circuit 122 can therefore be set up to determine (eg to calculate) the speed of a target 114 as a function of the phase of the measurement signal, for example by means of a further Fourier transformation (FT), such as a further fast Fourier transformation (FFT), which also is called 2D-FFT or Doppler FFT. The (radial) velocity of the target can be estimated from the measured phase as v = ( *A(p)/(4*7t*(T _c +Ti)), where Acp is the phase difference between peaks in the 2D FFT, associated with consecutive chirps. To determine the velocity of more than one target 114, a sequence of evenly spaced chirps 130 may be used, e.g., a sequence having a number N of chirps with N greater than 2.

The use of multiple receiving antennas 108 enables the angular position of a target 114 to be determined. Clearly, the arrival angle of a reflected signal 112 can be determined by using multiple receiving antennas 108. The determination of the angle is based on the property that a reflected signal 112 travels different distances in order to be received by receiving antennas 108 arranged at a distance from one another. For example, at a first receiving antenna 108 that is a distance h away from a second receiving antenna 108, a reflected signal that arrives at an angle 9 travels an additional distance h*sin(9) in order to reach the second receiving antenna 108 . The additional distance influences the phase of the corresponding measurement signal. For example, such additional distance causes a phase change in the peaks of the 2D FFT, and the phase change can be used to determine the angle of arrival. The processing circuit 122 can therefore be set up to determine the angle of a target (visually its angular position with respect to the radar system 100) as a function of the phases of the measurement signals that are associated with different receiving antennas 108, for example by means of the MUSIC (Multiple Signal Classification) method, or by means of a further Fourier transformation (FT) of the measurement signal, such as a further fast Fourier transformation (FFT), which is also referred to as 3D FFT or angular FFT. The 3D FFT can clearly be understood as an FFT that is carried out via the receiving antennas 108. To determine the angle of more than one target 114, a number M of receiving antennas 108 with M greater than 2 can be used.

The determination of distance, speed and angle can be implemented according to any suitable configuration of a radar system 100. As an example, a SIMO radar, e.g. a radar system with a single transmitting antenna 106 and a plurality of receiving antennas 108, may be suitable for such a determination. However, the angular resolution of a SIMO radar can be limited. A cost-effective approach to increasing angular resolution is in a so-called MIMO configuration, in which a radar system has a plurality of transmit antennas and a plurality of receive antennas, as shown in FIG.1A.

The use of a plurality of transmit antennas 106 results in an additional phase shift in the reflected signals 112 received at the receive antennas 108. The additional phase shift is due to the distance between the transmitting antennas 106 and to the additional distance that the transmitting signals 110 emitted by the various transmitting antennas 106 travel. The use of a plurality of transmit antennas 106 thus increases the number of peaks that can be distinguished in the 3D FFT and accordingly increases the angular resolution.

An important aspect of MIMO radar detection is that the reflected signals 112 received at the receiving antennas 108 should be distinguished and associated with the corresponding transmit antenna 106. The radar system 100 may therefore be configured to transmit a plurality of transmission signals 110 that are configured to enable a separation (illustratively, an assignment) of the received reflected signals 112, for example transmission signals 110 that are orthogonal to one another. Clearly, the transmission signals 110 can be coded in such a way that the reflected signals 112 are clearly one corresponding transmitting antenna 106 can be assigned. There are various ways to ensure such separation, however the use of multi-transmitter detection schemes (SIMO or MIMO) places a limit on the maximum speed that can be detected.

When measuring the speed of a target, given the above considerations, the associated phase measurement is only clear if the phase difference between successive chirp signals (illustratively, successive measurement signals) is within ±180°. This limit corresponds to a phase change between two consecutive chirps of less than 7t, so the maximum speed that can be uniquely detected is given by vmax = X/(4*(Tc+Ti). A higher maximum speed can therefore be used of closely spaced chirps.

This requirement is in contrast to a MIMO approach in which the transmission of distinguishable broadcast signals 110 results in increased transmission duration (taking into account the durations of the individual chirps as well as the idle time Ti between successive chirps) to enable appropriate encoding of the broadcast signals 110 . A contribution from the entire group is clearly taken into account, so that the maximum speed is limited by the distance between homogeneous codes. The reduction in unique Doppler range as a result of MIMO modulation techniques in modern dense arrays is a long-standing problem in the radar scene. Several solutions have been proposed, but they have various disadvantages.

An example of this is the application of the Chinese Remainder Theorem (CRT) to MIMO radars. The CRT uses different measurements of the same objects measured with different chirp configurations. However, a disadvantage of this approach is the high susceptibility to measurement deviations, which can lead to divergence in the CRT expansion. In this context, the so-called Density based Spatial Clustering of Applications with Noise (DBSCAN) and its improved version EDBSCAN were proposed to solve the problems related to measurement mismatch. However, these methods lead to a high processing effort. Another "lightweight" method, based on distance measurements across multiple images, has low processing overhead but also poor performance. Other methods for resolving the ambiguity rely on different hypotheses for the phase shift of the velocity or on taking into account the Doppler induced phase shift between chirps from different transmitters to determine the true speed. However, such approaches require complex post-processing of the individual signals, even in cases where this would not be necessary because the target moves in the clearly detectable speed range. Finally, complex multi-band configurations with short chirps can be used to avoid the use of complex methods by increasing the chirp repetition interval. However, this approach introduces additional signal processing to recover the full bandwidth covered by shorter chirps, requiring non-standard FFT accelerators to account for the multiband considerations.

Other conventional approaches are described in the following references. The publication US 2019/0011547 Al describes a system that combines frames with different maximum, unique speed limits. The system can selectively decide which frame to use depending on the speed of the ego vehicle, resulting in an optimized dynamic range of speed. This approach differs significantly from the strategy described herein because, according to the strategy described herein, the internal detection modes are dynamically selected based on the behavior of the target and not the ego vehicle. US 10,775 489 B2 describes the simultaneous operation of two radar ICs, namely master and slave, the purpose of which is to emit overlapping chirps, which are further combined to increase speed measurement capabilities. This approach differs from the approach described herein because the two modes operate simultaneously and are not triggered reactively to a cognitive paradigm. Smith et al. in “Experiments with cognitive radar” (IEEE International Workshop on Computational Advances in MultiSensor Adaptive Processing (CAMSAP)) describes the development of on-algorithms for cognitive radar devices in general and provides a specific example for speed measurement. Despite incorporating cognitive principles in a pulse radar to adjust the maximum unique velocity scale tracked in a particle filter, Smith's system has no method for determining whether the target is moving ambiguously. It assumes that the goal starts from zero and is pursued from there. EP 3 339 880 A1 presents a reinforcement learning approach for adapting certain signal parameters and waveforms based on certain performance indicators. This paper describes a cognitive radar, but only indicators based on Doppler resolution, among other performance parameters, are considered. The publication KR 10-1993855 describes a pulse radar (not FMCW) for aircraft that optimizes its altitude and pulse repetition frequency to avoid interference and blind zones and to continuously track the range and Doppler of a target if it is known in advance. In contrast to the approach described herein, the system of this reference does not have a dynamic mechanism to determine whether a target's velocity is ambiguous. It assumes that the true speed is known beforehand or that the target is moving from zero.

Various aspects of the present disclosure are based on the recognition that dynamic adjustment of the radar detection parameters (e.g., the parameters of the transmission signals) makes it possible to respond to the presence of a fast-moving target in the scene, thereby ensuring reliable detection without complex Hardware or time-consuming processing techniques are required. In particular, various aspects of the present disclosure rely on dynamically determining whether the speed of a target is too high to be clearly determined and dynamically adjusting radar detection parameters to provide the Doppler range for detecting such a fast-moving target to expand the goal.

2A shows a schematic flowchart of a method 200 for operating a radar system, for example for operating a MIMO radar system (for example for operating the radar system 100). The method 200 can be understood as a method for resolving the velocity ambiguity of targets in a radar system. In various aspects, a processing circuit of a radar system (e.g., processing circuit 122) may be configured to perform method 200.

In general, the method 200 may include adjusting the radar detection parameters depending on the speed of a target, e.g., the method 200 may include changing one or more signal characteristics of broadcast signals used for radar detection to the maximum unique Increase speed as a function of the target's actual speed.

In the present disclosure, the term "maximum unique speed" may describe the maximum speed (e.g. of a target) that can be uniquely detected using a radar detection method (e.g. using broadcast signals with certain characteristics). The term "maximum unique velocity" can thus describe the maximum velocity that a target can have in order to be correctly recognized, e.g. without its velocity being folded in the cyclic region of the Doppler phase. Clearly, the “maximum unique speed” can be the upper limit of a speed range in which a Radar detection method can correctly determine the speed of the target. As an example, a "maximum unique velocity" may describe the maximum velocity that causes a phase shift within ±180° in the phase of the peaks of the 2D FFT of a radar measurement. The “maximum unique speed” may also be referred to herein as the “maximum uniquely detectable speed”.

As previously mentioned, depending on the convention chosen, a target can have a positive or negative velocity depending on the direction of movement in relation to the radar system. Accordingly, the maximum unique speed may have a positive value when dealing with targets moving in a first direction (e.g. away from the radar system) or a negative value when dealing with targets moving in a second direction (e.g. towards the radar system). The aspects described here in relation to a "maximum unique velocity" can therefore apply correspondingly to a "unique velocity range", that is, a range from a negative "maximum unique velocity" to a positive "maximum unique velocity" (from -Vmax to +v _ma x).

The term "angular resolution" can describe the smallest angular difference that can be resolved using a radar detection method. Similarly, the term "velocity resolution" can describe the smallest difference in speed that can be resolved using a radar detection method.

The radar detection parameters that can be adjusted include all suitable parameters that can influence the maximum clearly detectable speed using radar detection. As an example, the radar detection parameters may include one or more signal characteristics of the transmitted signals that may be controlled using software or hardware. The one or more signal properties of the transmission signal(s) may have any suitable properties that may influence the maximum clearly detectable speed. As examples particularly suitable for implementing the strategy described herein, the one or more signal characteristics of the transmit signal(s) may include a phase, a frequency, a bandwidth, a chirp time, an idle time, a number of chirps - Signals, a phase of the chirp signal(s) and/or a coding of the chirp signal(s). Two examples of radar detection methods with different maximum unique speeds are presented below (see FIG.2B and FIG.2C). These two example radar detection methods have proven to be a time and resource efficient implementation of the dynamic approach described herein. However, it is understood that other radar detection methods also exist (e.g. with other signal properties) are possible as long as the reactive increase in the maximum unique speed is guaranteed.

In various aspects, the method 200 in 210 may include using a first radar detection method to detect a target, e.g., using a first radar detection method to determine the speed of the target (and other characteristics such as range, angle, etc.). Illustratively, the method 200 may include performing radar detection using first radar detection parameters, e.g. using one or more first transmission signals with first signal properties (and receiving one or more corresponding reflected signals). Considering a MIMO configuration, the first radar detection method may include transmitting a first plurality of transmit signals using a plurality of transmit antennas and receiving a first plurality of reflected signals using a plurality of receive antennas. In this context, the processing circuitry of the radar system may be configured to control the transmission of the first plurality of transmission signals to provide (e.g., implement or perform) the first radar detection method.

The first radar detection method may have a first maximum unique speed. Clearly, the first radar detection parameters (e.g. the first transmission signal(s)) can provide (e.g. define) a first maximum speed that can be clearly detected using the first radar detection method. In some aspects, the first radar detection method may have a first angular resolution. For example, the first radar detection method may have a relatively high angular resolution and a relatively low maximum unique velocity, e.g., the first radar detection method may be a Hi-res Angle Mode (HAM). The use of a radar detection method with high angular resolution is particularly important in heavy traffic, where a vehicle should be able to distinguish the different road users with high precision.

The method 200 may further include, in 220, determining (dynamically) whether an actual speed of the target is greater than the first maximum unique speed. Illustratively, the method 200 may include determining (during operation and not in post-processing) whether the first radar detection method is capable of providing a clear measurement of the actual speed of the target. In some aspects, the determination may be performed using the first plurality of broadcast signals (see also FIG.4A to FIG.4B), for example using first transmission signals that are set up to enable a direct determination of whether the actual speed of the target is greater than the first maximum unique speed. A method for ambiguity detection will be described in further detail with reference to FIG.4A to FIG.4B. In this context, the processing circuit of the radar system can be set up to carry out such a determination. In various aspects, the processing circuitry may include an ambiguity detector (see also FIG.3A and FIG.3B) configured for this purpose. The determination can be based on the reflected signals that are received on the radar system (eg on the majority of the receiving antennas).

The term "actual speed" may be used herein to describe the (radial) speed at which the target is moving. The "actual speed" can thus be the speed that the target actually has in the physical world. The term "actual speed" can therefore be used to describe the speed of the target regardless of radar detection. In this context, the term “measured speed” can be used to describe the speed of the target as determined (e.g. calculated or estimated) using radar detection. Ideally, the "measured speed" should be substantially the same as the "actual speed". However, as described above, there may be factors that influence the measurement, so that in some cases the "actual speed" cannot be clearly determined, so that in these cases the "measured speed" is no longer representative of the "actual speed " is. The "actual speed" may also be referred to herein as the "true speed".

In various aspects, determining whether the actual speed of the target is greater than the maximum unique speed may include determining whether the actual speed of the target is outside the unique speed range. For example, the method 200 in 220 may include determining whether an absolute value of the actual speed of the target is greater than an absolute value of the maximum unique speed of the radar detection method used.

In this context, it should be noted that the method 200 in 220 includes determining whether the actual speed of the target has been incorrectly determined, even if the radar detection method produces a measured speed result that is within the unique speed range. For example, the method 200 may include determining whether the from The measured speed provided by the radar detection method can be trusted. In other words, the method 200 may include determining (eg, estimating) whether the value of the speed measured using the (first) radar detection method correctly represents the actual speed of the target or whether the value of the speed measured using the (first) radar detection method incorrectly represents the cyclic Doppler phase region is folded. In general, determining whether the actual speed of the target is greater than the maximum unique speed can be understood as determining whether the measured speed correctly represents the actual speed, e.g. this can be understood as providing a confidence level for the measured speed is determined and that it is determined whether the (first) radar detection method correctly measures the actual speed of the target based on the confidence level.

The method 200 may further include, in 230, using a second radar detection method to acquire the target if the actual speed of the target is greater than the first maximum unique speed, e.g., using a second radar detection method to detect the target Determine the speed (and other characteristics) of the target. Illustratively, the method 200 may include radar detection using second radar detection parameters, e.g. using one or more second transmit signals with second signal properties (and receiving one or more corresponding reflected signals). Considering a MIMO configuration, the second radar detection method may include transmitting a second plurality of transmit signals using the plurality of transmit antennas and receiving a second plurality of reflected signals using the plurality of receive antennas. In this context, the processing circuit of the radar system may be configured to control the transmission of the second plurality of transmission signals to provide the second radar detection method.

The second radar detection method may have a second maximum unique speed that is greater than the first maximum unique speed. Clearly, the second radar detection parameters (e.g. the second transmission signal(s)) can specify (e.g. define) a second maximum unique speed that is greater than the maximum speed (e.g. in absolute value) that is unique using the first radar detection method can be captured. In other words, the second transmission signals can be set up so that they enable a clear measurement of the speed of the target over a larger speed range. In some aspects, the second radar detection method may have a second angular resolution that is smaller than the first angular resolution. For example, the second radar detection method may have a relatively low angular resolution and a relatively high maximum unique velocity, e.g., the second radar detection method may be a Hi-max Doppler Mode (HDM). The use of a radar detection method with a high maximum unique speed is particularly relevant in a traffic scenario with a fast-moving target, e.g. a fast-moving vehicle, which would otherwise be incorrectly detected and thus pose a safety risk. According to various aspects, the HDM can be triggered by the ambiguity detector to temporarily increase the maximum detectable speed. In some aspects, the second radar detection method may be configured to provide no angle information at all (i.e., the second radar detection method is used only to measure speed).

To illustrate, the method 200 may include switching between a first mode with higher angular resolution but smaller speed range and a second mode with lower angular resolution but larger speed range based on ambiguity in the speed determination in the first mode. The terms "relatively high/low", "higher", "lower", and the like may be used herein to compare the characteristics of different radar detection methods (e.g., the first radar detection method and the second radar detection method). The speed of the target can be determined by processing the reflected signals, for example as described above with respect to FIG.1A and FIG.1B.

In various aspects, the method 200 may include continuing to use the first radar detection method to acquire the target when the actual speed of the target is less than the first maximum unique speed. The actual speed of the target is thus within the unique speed range of the first radar detection method. Illustratively, the method 200 may include that the first radar detection parameters (e.g. the first transmission signals) are maintained if it is determined that the first radar detection method can clearly detect the speed of the target.

In various aspects, the method 200 may include switching back to the first radar detection method after using the second radar detection method to resolve the target ambiguity. Clearly, the method 200 can use the second Radar detection method to determine the (actual) speed of the target, and then switching back to the first radar detection method. As an example, the method 200 may include sending a frame using the second radar detection parameters and then switching back to the first radar detection parameters. This configuration can allow focusing on providing high angular resolution while expanding the speed range only for the time required to detect the target. In this context, the processing circuit of the radar system may be configured to control (eg, cause) the transmission of the first plurality of transmission signals after the (actual) speed of the target has been determined using the second radar detection method.

The actual speed of the target measured by the second radar detection method may be stored, for example in a memory device of the processing circuit (e.g. in a tracking filter), before switching back to the first radar detection method. In some aspects, if the actual speed of the target has already been tracked and stored in the device, the processing circuit may forego performing the second radar detection process, thereby saving resources.

FIG.2B and FIG.2C each show an exemplary configuration of first transmission signals 240 and second transmission signals 250 in a schematic view according to various aspects. FIG.2B and FIG.2C clearly show a possible configuration for carrying out radar detection methods with different maximum unique speeds (and different angular resolutions). The configurations in FIG.2B and FIG.2C have been found to provide a flexible and resource efficient approach to implementing the reactive strategy described herein. However, it is understood that other configurations for the transmission signals can also be provided.

According to various aspects, the first transmission signals 240 may be configured to enable a transmission signal to be associated (eg, assigned) to the respective transmission antenna by means of which the transmission signal was transmitted. As an example, the first transmission signals that are transmitted using different transmission antennas can be orthogonal to one another, for example, a first transmission signal that is transmitted via a first antenna Txi can be orthogonal to a second signal that is transmitted via a second antenna Tx2 be orthogonal to a third signal transmitted by a third antenna Txs, etc. The term "orthogonal" with respect to a plurality of signals may be used herein as generally understood in the art to indicate that an inner product between the signals is zero. The orthogonality between two signals can be given in time, phase and/or frequency. In the present disclosure, reference is made in particular to the case in which the transmission signals are phase-orthogonal. It has been shown that this configuration enables efficient use of the resources of a radar system. However, it is understood that other orthogonality schemes can also be provided.

As an example, the first radar detection method may include sending the first transmission signals according to a time division multiplexing method or according to a code division multiplexing method. In a preferred configuration, the first radar detection method may include transmitting the first transmission signals according to a Binary Phase Modulation (BPM) method as shown in FIG. 2B. Binary phase modulation is a special case of code multiplexing that ensures high angular resolution without reducing the signal-to-noise ratio (SNR) of the transmission. In general, CDM allows all transmitters (illustratively, the transmit antennas and associated transmit circuits) to be left on during the two modes, ensuring efficient use of available resources.

In a preferred configuration, the first transmit signals may include a first plurality of chirp signals 242. Illustratively, the first plurality of transmit signals may include a first plurality of sequences of chirp signals, and each sequence may be associated with a respective transmit antenna. A sequence of chirp signals can have a plurality of chirp signals (e.g. at equal time intervals) that are emitted using a respective transmitting antenna. In the exemplary configuration in FIG. 2B, the first transmission signals 240 can have four sequences 244-1 to 244-4 of chirp signals 242 with four transmission antennas TXI-TX4.

The chirp signals 242 of sequences associated with different transmit antennas can be encoded to ensure orthogonality, for example according to the BPM approach. As shown in FIG. 2B, the sequences may have chirp signals 242 with different phases (+1 may represent a phase of 0, and -1 may represent a phase of TI (Pi), as an example). Clearly, the first plurality of transmission signals can have at least a first sequence 244-1 of chirp signals 242 and a second sequence 244-2 of chirp signals 242, and at least one (first) chirp signal 242 of the first sequence 244-1 a different phase (e.g with a difference of ±180°) with respect to at least one (second) chirp signal 242 of the second sequence 244-2. The coding of the chirp signals can provide that the chirp signals emitted using different antennas encode different sequences of +1 and/or -1, so that the reflected signals can be distinguished on the receiver side.

In general, the first plurality of transmission signals may comprise a plurality of transmission signal blocks (e.g. a block consisting of the spatial codes Sa, Sb, Sc, Sd in FIG. 2B). In general, a block of transmit signals may include a plurality of chirp signals 242, each chirp signal 242 being transmitted using a respective transmit antenna. Clearly, a block of transmission signals can have the chirp signals 242, which are transmitted simultaneously using different transmission antennas. The plurality of chirp signals 242 that are emitted by all transmit antennas within a chirp period is also referred to as a spatial code (e.g. Sa in FIG. 2B). The chirp signals 242 within a block may be encoded in a manner that enables separation at the receiver side, e.g. the chirp signals 242 within a block may be encoded according to a phase profile that enables the association of the chirp signal 242 with the respective transmit antenna , have different phases. In various aspects, a block of transmit signals may be a block of chirp signals (e.g., each transmitted using a respective transmit antenna).

A block of transmit signals can therefore have a plurality of spatial codes (e.g. Sa to Sd in FIG. 2B). Each spatial code may have a plurality of chirp signals 242, each chirp signal 242 being transmitted using a corresponding transmit antenna (within the same time period). The chirp signals 242 of different spatial codes are encoded to enable separation of the spatial codes, e.g., they are encoded to provide orthogonality between the spatial codes. For example, as shown in FIG. 2B, the phases of the chirp signals of different spatial codes are encoded (in a block) according to different phase patterns to provide orthogonality between the different spatial codes. For example, the phases of the chirp signals of different spatial codes can be encoded (in a block) according to a Hadamard matrix.

A block of transmitted signals may thus have a first spatial code with a first phase pattern, a second spatial code with a second phase pattern, a third spatial code with a third phase pattern, etc. Each phase pattern can be different from every other phase pattern in the block. The first phase pattern may be different from the second phase pattern, etc. In the example configuration in FIG.2B, a block may have four spatial codes, but it is understood that in general a block may have any suitable number of (orthogonal) spatial codes (e.g., depending on the number of transmit antennas). The first transmission signals 240 can have any number of blocks. A preferred configuration that enables direct evaluation of the ambiguity is explained in more detail with reference to FIG.4A and FIG.4B. A block can have a block duration TB.

In various aspects, the codes associated with different transmit antennas may be statistically unconnected, e.g., the (first) phase of the first chirp signal and the (second) phase of the second chirp signal may be statistically unconnected. As an example that provides an efficient solution for transmitting orthogonal signals, the first plurality of transmit signals (e.g., the sequences of chirp signals) may be encoded according to a Hadamard code. Clearly, the spatial codes that are encoded in the phases of the chirp signals emitted by various transmitting antennas can be selected according to a Hadamard matrix. The phase of the chirps for each transmitting antenna is determined by the binary value of the code. In various aspects, apart from the initial phase shift, all transmit antennas may transmit identical frequency chirps derived from a common reference. The two statistically unrelated phase codes (0 and 7t) ensure individual orthogonality, and the Hadamard coding between transmitters establishes group orthogonality.

With respect to the first radar detection method, the processing circuit of the radar system may be configured to control the transmission of the first plurality of transmission signals such that the transmission signals transmitted by means of different transmission antennas are orthogonal to each other in phase. Clearly, the processing circuit can be set up to control the phase shifters of the transmit circuit in such a way that different phase shifts are imposed on the chirp signals of different sequences (e.g. according to Hadamard coding).

The use of (first) transmit signals 240, which can be separated at the receiver side, ensures high angular resolution, but at the expense of the maximum speed that can be clearly detected, as described above. For chirp signals, encoding increases the chirp repetition interval. The chirp repeat interval can be the time required to transmit a complete code. With a plurality of NTX transmitting antennas, TX, the chirp repetition interval can be TB = NTX*(TI+TC) in the case of coded chirp signals. This can be, for example, the chirp repetition interval Atnwi of the HAM mode, which is used as the first radar acquisition mode. In this context, the maximum unique velocity can be given by v _m ax,HAM = ±X/(4* Atnwi) and is thus relatively low due to the long chirp repetition interval. Illustratively, the chirp repetition interval can be the duration of the repetition of the same code. The chirp repetition interval may, in some aspects, be the block duration.

The second transmit signals 250 may be configured to provide a greater maximum unique speed compared to the first transmit signals 240, for example at the expense of angular resolution. In the exemplary configuration in FIG. 2C, the second transmit signals 250 may include a second plurality of chirp signals 252. The (second) chirp repetition interval of the second plurality of chirp signals 252 may be smaller than the (first) chirp repetition interval of the first plurality of chirp signals 242. The reduced chirp repetition interval increases the maximum unique speed.

In an exemplary configuration, the chirp signals of the second transmit signals 250 may have an equal phase with respect to one another. Clearly, the second transmission signals 250 can have a second plurality of sequences of chirp signals 252-1 to 252-4, with the chirp signals 252 having the same phase within a sequence and also with respect to the chirp signals 252 in another sequence can have. The second radar detection method can therefore have a redundant transmission of chirp signals 252, for example sending chirp signals that do not have phase coding. In this configuration, the chirp repetition interval may simply be the time interval between adjacent chirp signals 252, ie TB = Ti+Tc. This can be, for example, the chirp repetition interval AtHDM of the HDM mode used as the second radar acquisition mode. In this context, the maximum unique speed can be given by v _m ax,HDM = ±X/(4* Atumi) =NTX* Vmax,HAM. The maximum unique speed is then increased by the factor NTX (the number of transmitting antennas) compared to the first radar detection method. Illustratively, in the second mode (HDM), all transmitters are active across all chirps to maintain a high SNR and they share a constant phase to reduce the chirp repetition interval. Angular resolution is traded for a higher maximum speed range in this mode.

With respect to the second radar detection method, the processing circuit of the radar system may be configured to control the transmission of the second plurality of transmission signals such that the transmission signals transmitted using different transmission antennas have the same phase with respect to each other. It can be clearly seen Processing circuit can be set up to control the phase shifter of the transmission circuit in such a way that the chirp signals of different sequences have the same phase shift.

More generally, the chirp signals of the second transmission signals 250 may have a different phase pattern than the phase patterns of the chirp signals of the first transmission signals 240. The phase pattern of the chirp signals of the second transmission signals 250 may be set up (e.g. selected) in such a way that that a greater maximum unique speed (and a lower angular resolution) is achieved. Clearly, the phase pattern of the chirp signals of the second transmission signals 250 can be set up to provide a smaller chirp repetition interval compared to the chirp signals of the first transmission signal 240. In the exemplary configuration in FIG. 2C, the chirp signals may have a phase pattern with the same phase for each chirp signal, but it is understood that other phase patterns may also be provided as long as a greater maximum unique speed is provided.

Thus, the method 200 may include switching to a redundant mode when the target moves ambiguously. Redundant mode can have the transmission of the same frame in all chirps, reducing the time between homogeneous chirps. In various aspects, the chirp signals 242 of the first transmit signals 240 and the chirp signals 252 of the second transmit signals 250 may have the same characteristics (e.g., same bandwidth, starting frequency, slope, etc.) and differ only in phase profile, such that switching between the modes can be carried out in a simple and resource-efficient manner. Reconfiguration of the chirp profiles can be performed during ongoing frames using software or via a general purpose input output (GPIO) provided by the processing circuitry in self-contained application-specific integrated circuits. Application Specific Integrated Circuit”, ASIC).

In contrast to the traditional strategies that apply complex methods to resolve velocity ambiguity independently of the ambiguous movement of the target, the approach described herein provides online evaluation (e.g. using an online ambiguity detector) that dynamically configures of a second set of phase profiles to reduce the chirp repetition interval and temporarily increase the unique Doppler range. FIG.3A and FIG.3B show a processing circuit 300 for use in a radar system in a schematic view according to various aspects. The processing circuit 300 may be configured to perform the dynamic adjustment described herein (eg, to perform the method 200). The processing circuit 300 may thus be an exemplary configuration of the processing circuit 122 of the radar system 100. FIG.3B shows a possible implementation of the processing circuit 300.

In various aspects, the processing circuit 300 may include an ambiguity detection circuit 302 configured to determine whether an ambiguity exists in the speed measurement and a target detection circuit 304 configured to determine various characteristics of the target. The operation of the processing circuit 300 may be implemented using hardware components (e.g., dedicated circuits such as general-purpose circuits, field programmable gate arrays, application-specific integrated circuits, etc.) and/or using software (e.g., on a general-purpose processor). In various aspects, the processing circuit 300 may include a CFAR accelerator to preprocess the measurement signals.

The operation of the ambiguity detection circuit 302 will be described in further detail with reference to FIG. 4A and FIG. 4B. In general, the ambiguity detection circuit 302 may be configured to receive a plurality of velocity measurements, illustratively a plurality of values of the target's measured velocity, and determine whether an ambiguity exists in the velocity measurements. In various aspects, as shown in FIG. 3B, the ambiguity detection circuit 302 may include an ambiguity detector 306 configured for such determination.

In general, the processing circuit 300 (e.g., the target detection circuit 304) may be configured to determine characteristics of the target such as distance, speed, angle, etc. based on the reflected signals received at the radar system (e.g., based on the measurement signals received from a receiving circuit). The type of processing may vary depending on the type of configuration of the radar system. The following discussion focuses on the MIMO configuration described in FIG. 1A, but it is to be understood that the aspects may apply in a corresponding manner to other types of radar detection.

The processing circuit 300 may include a range determination circuit 308 configured to determine the range of the target based on the reflected signals received on the radar system. As an example, the distance determination circuit 308 can be set up to determine the distance depending on the frequency of the reflected signals (eg depending on the frequency of the corresponding measurement signals), as explained with reference to FIG. 1 A. In various aspects, as shown in FIG. 3B, the range determination circuit 308 may include an ID-FFT circuit 310 configured to perform a fast Fourier transform of a measurement signal and determine the range of the target(s) as a function from the position of the peaks in the FFT spectrum.

The processing circuit 300 may include a speed detection circuit 312 configured to determine the speed of the target based on the reflected signals received at the radar system. As an example, the speed determination circuit 312 may be configured to determine the speed as a function of the phase of the reflected signals (e.g. as a function of the phase of the corresponding measurement signals), as explained with reference to FIG. 1A. In various aspects, as shown in FIG. 3B, the speed detection circuit 312 may include a 2D FFT circuit configured to perform a fast Fourier transform on the signal output from the distance detection circuit 308 and to determine the speed of the target(s). Targets depending on the phase difference between the peaks in the FFT spectrum.

In various aspects, the processing circuit 300 may include a plurality of processing paths, each associated with a respective radar detection method. Referring to the method 200 of Figure 2, the processing circuit 300 may include a first processing path 313a associated with the first radar detection method and a second processing path 313b associated with the second radar detection method. Clearly, each processing path 313a, 313b can be set up to process the measurement signals obtained with the respective radar detection method. A processing path 313a, 313b can thus be adapted to the special properties of the transmission signals of the respective radar detection method. Such a configuration thus enables flexible processing that ensures efficient use of computing resources.

The different radar detection methods can handle different sizes of a radar cube, so that the speed determination can be carried out in different ways. A radar cube can be three-dimensional Be data structure, with the samples of the reflected signal for a single chirp along a first axis, reflected signals from other chirps along a second axis, and reflected signals associated with different receiving antennas along a third axis. Clearly, a radar cube can have three dimensions: in the first dimension, the cube can have a plurality of analog-digital converted samples of an IF signal within a chirp; in the second dimension, the cube may have a repeat from the first dimension for all chirps of a broadcast sequence; and in the third dimension, the cube may have a repetition of the first and second dimensions for all receiving antennas.

The use of transmit signals encoded to enable separation at the receiver side in the first radar detection method provides that the results of the 1D-FFT can be divided into a plurality of groups depending on the spatial code to which they belong (e.g. four groups corresponding to the four spatial codes, as in the exemplary configuration in FIG.2B). In this scenario, the 2D FFT can be applied to each of the groups separately to obtain the velocity estimate. The first processing path 313a may thus comprise a plurality of 2D FFT circuits 314 (or subcircuits) (as shown in FIG. 3B), e.g. one 2D FFT circuit per transmit antenna of the radar system. Each 2D FFT circuit 314 can thus perform a fast Fourier transform on the distance measurements provided by the respective group. In the second radar detection method (e.g. with transmit signals set up as in FIG. 2C) such separation is not provided, so that the 2D-FFT is applied to the results of the 1D-FFT as a whole (illustratively to all chirps in a frame). can be. Thus, the second processing path may include a single 2D FFT circuit 316 (as shown in FIG. 3B).

In various aspects, the processing circuit 300 may include a switching element 318 (eg, a multiplexer) configured to enable processing along a processing path 313a, 313b according to the current ambiguity scenario. The switching element 318 may be configured to dynamically switch between the first processing path 313a or the second processing path 313b depending on the speed of the target. Illustratively, the switching element 318 can be set up to selectively direct a measurement signal to the first processing path 313a if the speed of the target is less than the first maximum unique speed, or to the second processing path 313b if the speed of the target is greater than that first maximum unique speed. In various aspects, the ambiguity detection circuit 302 (eg, the ambiguity detector) may be configured be for providing a control signal to the switching element 318 to dynamically select a processing path 313a, 313b based on the ambiguity detection.

The processing circuit 300 may include a target detection circuit 319 configured to identify a target (or a plurality of targets) based on the reflected signals received at the radar system. As an example, the target detection circuit 319 may be configured to determine an angular position of a target as a function of the phase of the reflected signals (e.g. as a function of the phase of the corresponding measurement signals), as explained with reference to FIG. 1A.

In various aspects, as shown in FIG. 3B, the target detection circuit 319 may include a target detection circuit 320 configured to find potential targets, a decoder 322 configured to decode the measurement signal(s), and a 3D FFT circuit 324 configured to perform a fast Fourier transform on the signal output from the velocity detection circuit 312 and to determine the angle of the target(s) depending on the phase difference between the peaks in the FFT Spectrum. For example, after applying phase correction to the range Doppler maps originating from each receiver path (in other words, from each measurement signal), the maps are decoded to isolate the contribution of each transmit antenna versus each receive antenna. As a further example, the target detection circuit 319 can be set up to determine angle information using the MUSIC (Multiple Signal Classification) method.

In an exemplary configuration, the processing circuit 300 may include an FFT accelerator or core to perform the range, Doppler, and angle calculations, and the processing circuit 300 may include a general purpose processor to perform the ambiguity detection, target detection, (Hadamard) Implement decoding steps, clustering algorithms, tracking, etc.

FIG.3C shows a radar system 350 in a schematic view according to various aspects. The radar system 350 may be an exemplary configuration of the radar system 100 and may include a processing circuit 300 (set up as in FIG. 3B), a transmit circuit 116 (set up as in FIG. 1B), and a receive circuit 118 (set up as in FIG. IC).

FIG.4A shows a schematic flowchart of a method 400 for dynamically determining a speed ambiguity associated with radar detection of a target is associated. The method 400 may be part of the method 200 described with respect to FIG. 2A, e.g., as part of the determination in 220. In various aspects, a processing circuit of a radar system (e.g., the processing circuit 122, 300) may be configured to perform the method 400.

In general, the method 400 may include taking a plurality of direct measurements of the target's velocity and determining whether the velocity can be uniquely determined based on the measured values (e.g., based on whether the measured values converge or diverge).

The method 400 may include, at 410, transmitting a plurality of sets of transmit signals (e.g., using the plurality of transmit antennas). A set of transmit signals may include a plurality of transmit signals (e.g., each transmitted via a respective transmit antenna) used for a speed measurement, illustratively a plurality of transmit signals whose reflections are processed together to derive a value for a measured speed of the target. A set of transmission signals may include the transmission signals that are transmitted simultaneously (in other words, simultaneously) by means of the plurality of transmission antennas of a radar system. To illustrate, a set of broadcast signals may be a sub-frame. In this context, the processing circuit of the radar system can control the transmission of the plurality of transmission signals. A set of transmission signals may also be referred to herein as a group of transmission signals.

The transmission signals of the sets of transmission signals can be set up such that the sets of transmission signals have the same speed resolution and a different maximum unique speed. This configuration thus enables a plurality of measurements covering slightly different speed ranges while maintaining the same resolution. Various aspects of the present disclosure are based on the recognition that such a configuration of broadcast signals enables a direct yet accurate assessment of whether the actual speed of the target can be clearly determined. The angular resolution of the sets of transmission signals can be freely selected; for example, the sets of transmission signals can be set up in such a way that the sets of transmission signals have the same angular resolution.

It can clearly be determined that the actual speed of the target can be clearly determined if the majority of measurements provide the same or essentially the same result. On the other hand, it can be stated that the The actual speed of the target cannot be clearly determined if the majority of measurements give diverging results.

In a preferred configuration, which has proven to be very accurate for ambiguity detection, each set of transmit signals may comprise a plurality of transmit signal blocks (illustratively a plurality of coded chirp signals transmitted by different transmit antennas during the block duration TB in FIG. 2B ), and the numbers of transmission signal blocks in the transmission signal sets are coprime to each other. The coprime numbers of blocks ensure a clear convergence of the measured speeds only if the actual speed of the target can be clearly determined.

In a preferred configuration, at least three sets of broadcast signals (at least three heterogeneous sub-frames) may be used for ambiguity detection, as shown in FIG. 4B. A first set 440-1 of transmit signals may include a first number NI of blocks 442 of chirp signals, a second set 440-2 of transmit signals may include a second number N2 of blocks 442 of chirp signals, and a third set 440- 3 of transmit signals may include a third number N3 of blocks 442 of chirp signals. The first number of blocks NI, the second number of blocks N2 and the third number of blocks N3 can be coprime to each other. As a numerical example, the at least three sets of broadcast signals may include 27, 35, and 44 blocks of broadcast signals, respectively. It is understood that the indication first, second, third does not imply a chronological order of the transmission signal blocks. Clearly, the sets of transmission signals can be sent out one after the other, but the order in which the sets with different numbers of blocks are sent out can be freely chosen.

In other words, each set of transmit signals may include a plurality of sequences of chirp signals, each sequence being transmitted using a respective transmit antenna. The sequences within a set of broadcast signals may have the same number of chirped signals, and the numbers of blocks belonging to different sets may be coprime with respect to each other.

In various aspects, the transmission signals of the sets of transmission signals may be encoded to provide orthogonality between the transmission signals transmitted using different transmission antennas. Clearly, the transmission signals emitted by different transmission antennas can be orthogonal to one another within a set. In a preferred configuration, orthogonality may be provided by encoding the phase of the chirp signals, e.g. as in relation to FIG.2B described. In each set of transmission signals, the chirp signals can be encoded in different sequences according to a different phase profile, e.g. in each set a first chirp signal of a first sequence can have a different phase than a second chirp signal of a second sequence, etc. According to In various aspects, in each set of transmit signals, the chirp signals within each block may have a phase encoded according to a Hadamard code (eg, according to a Hadamard matrix). As with reference to FIG. 2B, each block 442 may include a plurality of spatial codes. The spatial codes can be coded so that they are orthogonal, for example the spatial codes can be coded according to Hadamard coding.

In various aspects, ambiguity detection may be part of the initially used (first) radar detection method, e.g., the high angular resolution, relatively low maximum unique velocity radar detection method. Illustratively, the sets of transmission signals may be transmitted as part of the first radar detection process and used to determine the speed of the target as part of the first radar detection process. This configuration provides a resource-efficient approach that combines speed detection and ambiguity detection. In such a configuration, the (first) plurality of transmission signals transmitted using the plurality of transmission antennas as part of the first radar detection method may include the plurality of sets of transmission signals (e.g. at least three sets of transmission signals).

The method 400 may include, at 420, determining a respective value for a measured speed of the target for each set of transmit signals. Illustratively, the method 400 may include receiving a plurality of sets of reflected signals, each set of reflected signals associated with a set of transmitted signals, and determining a respective value for a measured speed of the target by processing the set of reflected signals, e.g. as described above. As an example, the method 400 may include determining the value of the measured velocity as a function of the phase of the measurement signal associated with the set of transmit signals. In this context, the processing circuit of the radar system (e.g. its ambiguity detector) can perform such a determination, e.g. based on the results of the 2D FFT.

The method 400 may include, at 430, determining whether an actual speed of the target is greater than a predefined maximum unique speed as a function of the values of the measured speed of the target. In connection with the method 200, the predefined maximum unique Speed be the first maximum unique speed of the first radar detection method. Illustratively, the method 400 in 430 may include determining whether the values of the measured speed of the target correctly represent the actual speed of the target. For example, the method 400 may include determining a confidence value for the measured speeds and determining, based on the confidence value, whether the measured speed values of the target correctly represent the actual speed of the target.

Determining 430 may include comparing the measured target speed values with each other and determining, based on the comparison result, whether the actual speed is greater than the predetermined maximum unique speed (e.g., greater than the first maximum unique speed). As an example, determining 430 may include determining that the actual speed of the target is less than the predetermined maximum unique speed if the measured values (from different sets) are equal to each other. In this case, the measured values correspond to the actual speed of the target. On the other hand, the method includes determining that the actual speed of the target is greater than the predetermined maximum unique speed if the measured values differ from each other (diverge). Due to the cyclic phase variation of the IF signal across chirps, the (e.g. three) convolved velocities only agree when the target's velocity is not ambiguous. In contrast to other methods, such as CRT, the ambiguity detection does not need to be extended to a range of assumed velocities, but rather only summarizes individual measurements that come directly from the (e.g. three) sub-frames.

As another example, determining 430 may include determining (eg, calculating) a difference between the measured target speed values associated with the different sets of transmit signals (eg, a plurality of differences between pairs of sets). Determining 430 may further include determining that the actual speed of the target is greater than the predetermined maximum unique speed if the difference (eg, the largest difference among the plurality of differences) is greater than a predetermined threshold difference. This configuration allows non-idealities that may occur during a measurement to be taken into account. To detect the match with some flexibility and tolerate bin mismatches that occur in real radar sensors, DBSCAN or another method for clustering the convolutional velocities can be used. In various aspects, the method 400 may include determining whether the actual speed of the target is greater than the maximum unique speed of the set of broadcast signals associated with the lowest maximum unique speed among the sets of broadcast signals. As already mentioned, the sets of broadcast signals can have different unique speeds (e.g. depending on the number of blocks). The target can move uniquely if it is moving uniquely for the set of transmit signals with the lowest maximum unique speed. The speed limits of such a partial image define the speed limits for the clear detection of the target. In various aspects, the set of broadcast signals that has the fewest number of blocks may have the lowest maximum unique speed.

FIG.5A shows a schematic flowchart of a method 500 for resolving target ambiguities in a radar system. Method 500 may be an exemplary implementation of the strategy described herein, e.g., considering methods 200 and 400 described in FIG. 2A and FIG. 4A. FIG. 5B, FIG. 5C and FIG. 5D show diagrams of experimental results showing the Demonstrate application of the strategy described herein.

The method 500 may include carrying out a first radar detection method (HAM) by sending out a plurality of sets of transmission signals, e.g. at least three heterogeneous sub-frames 502-1, 502-2, 502-3, with numbers of blocks that are coprime to each other. In the proposed HAM, the three heterogeneous sub-frames have different unique velocity ranges while providing the same velocity resolution so that they can capture the convolved Doppler phase of a target from three different perspectives. According to various aspects, the numbers of Hadamard blocks for each heterogeneous sub-frame can be chosen to be coprime (e.g. NI, N2, N3) to ensure unique convergence.

The method 500 may include performing processing (eg, BPM digital signal processing) on the reflected signals associated with each subframe to determine the respective values 504-1, 504-2, 504-3 for the measured speed of the target. The method 500 may further include, at 506, determining whether an ambiguity has been detected. The ambiguity detector can be triggered when the three convolved velocities present in each sub-frame for a single target was detected, are not grouped within the speed limits of the shortest sub-frame.

If no ambiguity is detected, the method 500 may proceed to the next three heterogeneous subframes to acquire the next target or to continue acquiring the same target. If an ambiguity is detected, the method 500 may include determining at 508 whether the true speed has already been tracked (e.g., stored). If the true speed has already been detected, the method 500 can move on to the next three heterogeneous sub-frames. If the true speed has not already been tracked, the method 500 may include switching to the second radar detection method by sending out a redundant frame 512 and performing redundant digital signal processing to determine the true speed 514 of the target.

The method 500 may then include, at 516, tracking (e.g., storing) the actual speed of the target (e.g., in a tracking filter) and then, at 518, reconfiguring the chirp profile according to Hadamard encoding, thereby returning to the first radar detection method.

The working principle of the cognitive radar has been validated in both synthetic scenarios and a real scenario.

The synthetic scenario consists of two targets located 22 and 15 meters from the radar, with an angle of +10° and -10°, moving with a constant radial velocity vl and v2, respectively. The speed v2 has a fixed value of -3.28 m/s in all test cases, while the speed vl varies from -30 m/s to +30 m/s in steps of 0.2 m/s. Each speed set is treated in a separate experimental run.

The normal operation of the cognitive radar occurs by switching between the heterogeneous sub-frames. Ambiguity detection is accomplished by identifying the region where the three measured velocities do not agree and thus maintaining a high logic value at the output of the ambiguity detector, as shown in section 532 of diagram 530 in FIG. 5B. The output of the ambiguity detector is zero only if the object moves within the unique boundaries of sub-image 1.

The output of the detector in FIG.5B triggers a switch between the HAM and the HDM, whose maximum unique speed increases by a factor of NTX is as described above. Diagram 540 in FIG. 5C shows the recovered velocity in the HDM versus the folded velocity measured in the HAM. Figure 5C also shows that the two measured velocities in the two modes only agree when the object moves within the boundaries of the shortest sub-frame.

Diagram 550 in FIG.5D refers to a real experiment conducted with a robotic car moving in front of the radar device. The robot car starts at a negative speed as it approaches the radar device and changes direction at approximately frame 17. After this frame, the target begins to move away from the radar device. The three sub-frames (A, B and C) in HAM are used to determine the exact point in time at which the velocity becomes ambiguous. In contrast to the synthetic experiments, the real recordings are influenced by interference, which can lead to deviations between the measured velocities in the three sub-frames. Despite these discrepancies, the bottom diagram 552 in FIG. 5D shows how the detector detects the ambiguity and triggers the redundant sub-frame D, which captures the true speed that follows the robot car's turning pattern. After detecting the speed and registering it in the tracking filter, the system switches to HAM.

In various aspects, a computer program product may be provided, the computer program product having instructions that, when executed by a computer, cause the computer to perform one of the methods described herein (e.g., methods 200, 400, 500).

Various examples are described below that relate to what has been described and shown above (e.g. to the method 200, 400, 500 or to the radar device 104).

Example 1 is a method for resolving the speed ambiguity of a target in a radar system, the method comprising: using a first radar detection method to detect a target, the first radar detection method comprising transmitting a first plurality of transmit signals using a plurality of transmit antennas and receiving a first A plurality of reflected signals by means of a plurality of receiving antennas, the first radar detection method having a first maximum unique speed; determining whether an actual speed of the target is greater than the first maximum unique speed; and in the case that the target's actual speed is greater than the first maximum unique speed, using a second radar detection method for detecting the target, the second radar detection method comprising transmitting a second plurality of transmission signals by means of the plurality of transmission antennas and receiving a second plurality of reflected signals by means of the plurality of reception antennas, the second radar detection method having a second maximum unique speed, and wherein the second maximum unique speed is greater than the first maximum unique speed.

In Example 2, the method according to Example 1 may optionally further comprise that the first radar detection method has a first angular resolution, that the second radar detection method has a second angular resolution, and that the second angular resolution is smaller than the first angular resolution.

In Example 3, the method according to Example 1 or 2 may optionally further comprise determining whether the actual speed of the target is greater than the first maximum unique speed comprising: transmitting, by means of the plurality of transmit antennas, a plurality of sets of transmit signals , wherein the sets of transmit signals of the plurality of sets of transmit signals are arranged to provide an equal speed resolution with respect to one another and to provide a different maximum unique speed with respect to one another; determining a respective value for a measured speed of the target based on respective reflected signals associated with the sets of transmitted signals; and determining whether an actual speed of the target is greater than the first maximum unique speed as a function of the values of the measured speed of the target.

In Example 4, the method according to Example 3 may optionally further include determining whether the actual speed of the target is greater than the first maximum unique speed comprising: comparing the determined values for the measured speed of the target with each other; and determining whether the actual speed of the target is greater than the first maximum unique speed based on a result of the comparison.

In Example 5, the method according to Example 3 or 4 may optionally further comprise that the first plurality of transmission signals associated with the first radar detection method comprises the plurality of sets of transmission signal sets. In Example 6, the method according to any one of Examples 3 to 5 may optionally further comprise determining whether the actual speed of the target is greater than the first maximum unique speed: determining whether the actual speed of the target is greater than that maximum unique speed of the set of broadcast signals, which defines the lowest maximum unique speed among the sets of broadcast signals.

In Example 7, the method according to one of Examples 3 to 6 may optionally further comprise that each set of transmission signals has a plurality of transmission signal blocks, that each transmission signal block has a plurality of chirp signals, each chirp signal in a transmission signal block using a respective one Transmitting antenna of the plurality of transmitting antennas is transmitted, that the chirp signals in each transmitting signal block are encoded according to a plurality of spatial codes, and that a number of transmitting signal blocks in one set of transmitting signals are coprime with respect to a number of transmitting signal blocks in another set of transmitting signals is.

In Example 8, the method according to Example 7 may optionally further comprise that each set of transmit signals has a plurality of sequences of chirp signals, that each sequence of chirp signals is transmitted by means of a respective transmit antenna of the plurality of transmit antennas, and that the sequences of chirp signals are set up to be orthogonal with respect to each other.

In Example 9, the method according to Example 7 or 8 may optionally further include determining whether the actual speed of the target is greater than the first maximum unique speed: determining whether the actual speed of the target is greater than the maximum unique speed Speed of the set of transmission signals that has the fewest number of transmission signal blocks among the sets of transmission signals.

In Example 10, the method according to one of Examples 3 to 9 may optionally further comprise that the plurality of sets of transmission signals comprises at least a first set of transmission signals, a second set of transmission signals and a third set of transmission signals, that the first set of transmission signals a first number of transmission signal blocks, the second set of transmission signals has a second number of transmission signal blocks and the third set of transmission signals has a third number of transmission signal blocks, and that the first number of transmission signal blocks, the second number of transmission signal blocks and the third number of transmission signal blocks are coprime to each other. In Example 11, the method according to one of Examples 1 to 10 can optionally further comprise that the first plurality of transmission signals has a first plurality of chirp signals with a first chirp repetition interval, that the second plurality of transmission signals has a second plurality of chirp signals Signals with a second chirp repetition interval, and that the second chirp repetition interval is smaller than the first chirp repetition interval.

In Example 12, the method according to Example 11 may optionally further comprise that the first plurality of chirp signals have at least a first spatial code with a first phase pattern and a second spatial code with a second phase pattern, the first phase pattern and the second phase pattern being different from each other are different, and that the chirp signals of the second plurality of chirp signals have a different phase pattern compared to the first phase pattern and the second phase pattern, the different phase pattern being arranged such that the second chirp repetition interval is smaller than the first Chirp repeat interval.

Example 13 is a computer program product comprising instructions that, when the program is executed by a computer, cause it to carry out the method according to any of Examples 1 to 12.

Example 14 is a method for detecting a speed ambiguity of a radar detection of a target, the method comprising: transmitting a plurality of sets of transmission signals, the sets of transmission signals of the plurality of sets of transmission signals being arranged to have an equal speed resolution with respect to one another provide and provide a different maximum unique speed with respect to each other, determining a respective value for a measured speed of the target for each set of transmit signals; and determining whether an actual speed of the target is greater than a predetermined maximum unique speed as a function of the values of the measured speed of the target. In some aspects, the predetermined maximum unique speed may be the maximum speed that can be uniquely measured using the plurality of sets of transmission signals, e.g., the smallest maximum speed among the maximum speeds that can be uniquely measured using the plurality of sets of transmission signals.

In Example 15, the method according to Example 14 may optionally further comprise that each set of transmit signals has a plurality of transmit signal blocks, each transmit signal block has a plurality of chirp signals, each chirp signal in a transmission signal block is transmitted by means of a respective transmission antenna of the plurality of transmission antennas, that the chirp signals in each transmission signal block are encoded according to a plurality of spatial codes, and that a number of transmission signal blocks in a set of transmission signals is related to a number of transmission signal blocks in one other set of transmission signals is coprime.

In Example 16, the method of Example 15 may optionally further include determining whether the actual speed of the target is greater than the predetermined maximum unique speed: determining whether the actual speed of the target is greater than the maximum unique speed of the Set of transmission signals that has the smallest number of transmission signal blocks among the sets of transmission signals.

In Example 17, the method according to one of Examples 14 to 16 may optionally further comprise that each set of transmission signals has a plurality of sequences of chirp signals, that each sequence of chirp signals is transmitted by means of a respective transmission antenna of a plurality of transmission antennas, and that the sequences of chirp signals are arranged to be orthogonal with respect to each other.

In Example 18, the method according to one of Examples 14 to 17 may optionally further comprise that the plurality of sets of transmission signals comprises at least a first set of transmission signals, a second set of transmission signals and a third set of transmission signals, that the first set of transmission signals a first number of transmission signal blocks, the second set of transmission signals has a second number of transmission signal blocks and the third set of transmission signals has a third number of transmission signal blocks, and that the first number of transmission signal blocks, the second number of transmission signal blocks and the third number of transmission signal blocks are coprime to each other.

In Example 19, the method according to any one of Examples 14 to 18 may optionally further include determining whether the actual speed of the target is greater than the predetermined maximum unique speed comprising: comparing the determined values for the measured speed of the target with each other; and determining whether the actual speed of the target is greater than the predetermined maximum unique speed based on a result of the comparison.

In Example 20, the method according to any one of Examples 14 to 19 may optionally further comprise transmitting the plurality of sets of transmission signals: transmitting the plurality of sets of transmission signals using a plurality of transmission antennas. In Example 21, the method according to any one of Examples 14 to 20 may optionally further include determining whether the actual speed of the target is greater than the predetermined maximum unique speed: determining whether the actual speed of the target is greater than that maximum unique speed of the set of broadcast signals, which defines the lowest maximum unique speed among the sets of broadcast signals. Illustratively, the predetermined maximum unique speed may be the maximum unique speed of the set of transmission signals, which defines the lowest maximum unique speed among the sets of transmission signals.

Example 22 is a computer program product comprising instructions that, when the program is executed by a computer, cause it to carry out the method according to any of Examples 14 to 21.

Example 23 is a radar device for resolving the speed ambiguity of a target in a radar system, the radar device comprising: a plurality of transmit ports configured to be coupled to a plurality of transmit antennas; a plurality of receiving ports configured to be coupled to a plurality of receiving antennas; and a processing circuit configured to: control transmission of a first plurality of transmit signals via the plurality of transmit ports to provide a first radar detection method for a target, the first plurality of transmit signals configured to provide a first maximum unique speed; determining, based on a plurality of reflected signals received at the plurality of receiving ports, whether an actual speed of the target is greater than the first maximum unique speed; and in the event that the actual speed of the target is greater than the first maximum unique speed, dynamically controlling transmission of a second plurality of transmit signals via the plurality of transmit ports to provide a second radar detection method of the target, wherein the second plurality of transmit signals is established is to provide a second maximum unique speed; where the second maximum unique speed is greater than the first maximum unique speed.

In Example 24, the radar device according to Example 23 may optionally further comprise that the processing circuit has a first processing path associated with the first radar detection method and a second processing path associated with the second radar detection method, and wherein the Processing circuit has a switching element configured to enable processing along the first processing path or the second processing path, depending on whether the actual speed of the target is greater than the first maximum unique speed.

In Example 25, the radar device according to Examples 23 or 24 may optionally have one or more features of the method according to one of Examples 1 to 12 or 14 to 21.

Example 26 is a method for resolving the speed ambiguity of a target in a radar system, the method comprising: transmitting at least three sets of transmit signals using a plurality of transmit antennas, the at least three sets of transmit signals being arranged to have an equal speed resolution with respect to each other and a different maximum unique speed with respect to each other, each set of transmit signals having a plurality of transmit signal blocks, each block of transmit signals having a plurality of chirp signals, each chirp signal in a block by means of a respective one Transmitting antenna of the plurality of transmitting antennas is transmitted, wherein the chirp signals in each block are encoded according to a plurality of spatial codes, and wherein a number of blocks of transmitting signals in a set of transmitting signals is coprime with respect to a number of blocks of transmitting signals in another set of broadcast signals; determining a respective value for a measured speed of the target for each set of transmission signals; determining, as a function of the values of the measured speed of the target, whether an actual speed of the target is greater than the maximum unique speed of the set of transmit signals that defines the smallest maximum unique speed among the at least three sets of transmit signals; and in the event that the actual speed of the target is greater than such maximum unique speed, transmitting a second plurality of transmit signals via the plurality of transmit antennas, the transmit signals of the second plurality of transmit signals comprising a second plurality of chirp signals, and wherein the chirp signals of the second plurality of chirp signals have an equal phase with respect to one another.

In Example 27, the method according to Example 26 may optionally have one or more features of the method according to any of Examples 1 to 12 or 14 to 21.

Example 28 is a method for resolving the velocity ambiguity of a target in a radar system, the method comprising: transmitting of at least three sets of transmission signals by means of a plurality of transmission antennas, the at least three sets of transmission signals being arranged to have an equal speed resolution with respect to one another and a different maximum unique speed with respect to one another, each set of transmission signals having a plurality of Transmission signal blocks, each block of transmission signals having a plurality of chirp signals, each chirp signal in a block being transmitted by means of a respective transmission antenna of the plurality of transmission antennas, the chirp signals in each block being encoded according to a plurality of spatial codes are, and wherein a number of blocks of transmission signals in one set of transmission signals is coprime with respect to a number of blocks of transmission signals in another set of transmission signals; determining a respective value for a measured speed of the target for each set of transmission signals; determining, as a function of the values of the measured speed of the target, whether an actual speed of the target is greater than the maximum unique speed of the set of transmit signals that defines the smallest maximum unique speed among the at least three sets of transmit signals; and in the event that the actual speed of the target is greater than such maximum unique speed, transmitting a second plurality of transmit signals via the plurality of transmit antennas, the transmit signals of the second plurality of transmit signals comprising a second plurality of chirp signals, and wherein the chirp signals of the second plurality of chirp signals have an equal phase with respect to one another.

In Example 29, the method according to Example 28 may optionally have one or more features of the method according to any of Examples 1 to 12 or 14 to 21.

The foregoing description has been given by way of example only, and those skilled in the art will understand that changes may be made without departing from the broader scope of the invention as set forth in the claims. The description and drawings are therefore to be understood in an illustrative rather than a restrictive sense.

It is understood that the implementations of the methods described in detail herein are demonstrative in nature and are therefore understood to be capable of being implemented in a corresponding device. It is also understood that implementations of devices described in detail herein are understood to be suitable for being implemented as a corresponding method. It is therefore understood that a device that is described in detail herein Method corresponds, may have one or more components that are set up to carry out each aspect of the associated method.

All acronyms defined in the description above also apply to all claims contained herein.

Claims

Patent claims

1. Method (200) for resolving the speed ambiguity of a target in a radar system, the method (200) comprising:

Using (210) a first radar detection method to detect a target, the first radar detection method comprising transmitting a first plurality of transmit signals using a plurality of transmit antennas and receiving a first plurality of reflected signals using a plurality of receive antennas, the first radar detection method comprising a first has maximum unique speed;

determining (220) whether an actual speed of the target is greater than the first maximum unique speed; and in the event that the actual speed of the target is greater than the first maximum unique speed, using (230) a second radar detection method to detect the target, the second radar detection method comprising transmitting a second plurality of transmit signals using the plurality of transmit antennas, and the Receiving a second plurality of reflected signals by means of the plurality of receiving antennas, wherein the second radar detection method has a second maximum unique speed, and wherein the second maximum unique speed is greater than the first maximum unique speed.

2. The method (200) of claim 1, wherein the first radar detection method has a first angular resolution, the second radar detection method has a second angular resolution, and wherein the second angular resolution is smaller than the first angular resolution.

3. The method (200) of claim 1, wherein determining (220) whether the actual speed of the target is greater than the first maximum unique speed comprises:

Transmitting, by means of the plurality of transmission antennas, a plurality of sets of transmission signals, the sets of transmission signals of the plurality of sets of transmission signals being set up to have the same provide speed resolution with respect to each other and provide a different maximum unique speed with respect to each other;

determining a respective value for a measured speed of the target based on respective reflected signals associated with the sets of transmitted signals; and

Determine whether an actual speed of the target is greater than the first maximum unique speed as a function of the values of the measured speed of the target. The method (200) of claim 3, wherein determining (220) whether the actual speed of the target is greater than the first maximum unique speed comprises:

Comparing the determined values for the measured speed of the target with each other; and

Determine whether the target's actual speed is greater than the first maximum unique speed based on a result of the comparison. The method (200) of claim 3, wherein the first plurality of transmit signals associated with the first radar detection method comprises the plurality of sets of transmit signal sets. The method (200) of claim 3, wherein determining (220) whether the actual speed of the target is greater than the first maximum unique speed comprises:

Determine whether the actual speed of the target is greater than the maximum unique speed of the set of transmit signals, which defines the lowest maximum unique speed among the sets of transmit signals. The method (200) of claim 3, wherein each set of transmit signals comprises a plurality of transmit signal blocks, each transmit signal block comprises a plurality of chirp signals, each chirp signal in a transmit signal block being transmitted by means of a respective transmit antenna of the plurality of transmit antennas, wherein the chirp signals in each transmission signal block are encoded according to a plurality of spatial codes, and wherein a number of transmission signal blocks in one set of transmission signals is coprime with respect to a number of transmission signal blocks in another set of transmission signals.

8. The method (200) according to claim 7, wherein each set of transmit signals comprises a plurality of sequences of chirp signals, each sequence of chirp signals being transmitted by means of a respective transmit antenna of the plurality of transmit antennas, and wherein the sequences of chirp signals Signals are set up such that they are orthogonal with respect to each other.

9. The method (200) of claim 7, wherein determining (220) whether the actual speed of the target is greater than the first maximum unique speed comprises:

Determine whether the actual speed of the target is greater than the maximum unique speed of the set of transmit signals that has the fewest number of transmit signal blocks among the sets of transmit signals.

10. The method (200) according to claim 3, wherein the plurality of sets of transmission signals comprises at least a first set of transmission signals, a second set of transmission signals and a third set of transmission signals, the first set of transmission signals comprising a first number of transmission signal blocks, the second set of transmission signals has a second number of transmission signal blocks and the third set of transmission signals has a third number of transmission signal blocks, and wherein the first number of transmission signal blocks, the second number of transmission signal blocks and the third number of transmission signal blocks are coprime to one another.

11. The method (200) according to claim 1, wherein the first plurality of transmission signals comprises a first plurality of chirp signals with a first chirp repetition interval, wherein the second plurality of transmission signals comprises a second plurality of chirp signals with a second chirp repetition interval and wherein the second chirp repetition interval is smaller than the first chirp repetition interval. The method (200) of claim 11, wherein the first plurality of chirp signals comprises at least a first spatial code having a first phase pattern and a second spatial code having a second phase pattern, the first phase pattern and the second phase pattern being different from each other, and wherein the chirp signals of the second plurality of chirp signals have a different phase pattern compared to the first phase pattern and the second phase pattern, the other phase pattern being set such that the second chirp repetition interval is smaller than the first chirp repetition interval. Method (400) for detecting an ambiguity in a radar detection of a target, the method comprising:

Sending (10) a plurality of sets of transmission signals, the sets of transmission signals of the plurality of sets of transmission signals being set up to provide an equal speed resolution with respect to one another and to provide a different maximum unique speed with respect to one another,

determining (420) a respective value for a measured speed of the target for each set of transmission signals; and

determining (430) whether an actual speed of the target is greater than a predetermined maximum unique speed as a function of the values of the measured speed of the target. The method (400) of claim 13, wherein each set of transmit signals comprises a plurality of transmit signal blocks, each transmit signal block comprises a plurality of chirp signals, each chirp signal in a transmit signal block being transmitted by means of a respective transmit antenna of the plurality of transmit antennas, wherein the chirp signals in each transmit signal block are encoded according to a plurality of spatial codes, and wherein a number of transmit signal blocks in one set of transmit signals is coprime with respect to a number of transmit signal blocks in another set of transmit signals. Method (400) according to claim 14, wherein determining (220) whether the actual speed of the target is greater than the predetermined maximum unique speed comprises:

Determine whether the actual speed of the target is greater than the maximum unique speed of the set of transmit signals that has the fewest number of transmit signal blocks among the sets of transmit signals. The method (400) of claim 13, wherein each set of transmit signals comprises a plurality of sequences of chirp signals, each sequence of chirp signals being transmitted by means of a respective transmit antenna of a plurality of transmit antennas, and wherein the sequences of chirp signals are such are set up so that they are orthogonal with respect to each other. The method (400) according to claim 13, wherein the plurality of sets of transmission signals comprises at least a first set of transmission signals, a second set of transmission signals and a third set of transmission signals, the first set of transmission signals comprising a first number of transmission signal blocks, the second Set of transmission signals has a second number of transmission signal blocks and the third set of transmission signals has a third number of transmission signal blocks, and wherein the first number of transmission signal blocks, the second number of transmission signal blocks and the third number of transmission signal blocks are coprime to one another. The method (400) of claim 13, wherein determining (430) whether the actual speed of the target is greater than the predetermined maximum unique speed comprises:

Determine whether the actual speed of the target is greater than the predetermined maximum unique speed based on a result of the comparison. Radar device (104) for resolving the speed ambiguity of a target in a radar system, the radar device (104) comprising: a plurality of transmit ports (124) configured to be coupled to a plurality of transmit antennas (106); a plurality of receive ports (126) configured to be coupled to a plurality of receive antennas (108); and a processing circuit (122, 300) set up to:

Controlling transmission of a first plurality of transmission signals (110, 240) via the plurality of transmission ports (124) to provide a first radar detection method for a target (114), the first plurality of transmission signals (110, 240) being set up, a first to provide maximum unique speed;

determining, based on a plurality of reflected signals (112) received at the plurality of receive ports (126), whether an actual speed of the target (114) is greater than the first maximum unique speed; and in the event that the actual speed of the target (114) is greater than the first maximum unique speed, dynamically controlling transmission of a second plurality of transmit signals (110, 250) via the plurality of transmit ports (124) to a second radar detection method of the target (114), the second plurality of transmit signals (250) being configured to provide a second maximum unique speed; where the second maximum unique speed is greater than the first maximum unique speed. The radar device (104) according to claim 19, wherein the processing circuit (122, 300) has a first processing path (313a) associated with the first radar detection method and a second processing path (313b) associated with the second radar detection method, and wherein the processing circuit (122, 300) has a switching element (318) which is set up to enable processing along the first processing path (313a) or the second processing path (313b), depending on whether the actual speed of the target (114) is greater is as the first maximum unique speed.