Method for processing radar signals of a radar system and radar system - Patents.com

Abstract

To provide a method for processing radar signals of a radar system including a plurality of antennas.SOLUTION: A method includes: processing a plurality of radar signals for determining a distance from a radar system to at least one target and velocity of the at least one target, thereby forming a plurality of processed radar signals, and receiving each radar signal of the plurality of radar signals by an associated antenna of the plurality of antennas; digitally beamforming the plurality of processed radar signals for at least one beam direction, thereby forming a plurality of beamformed radar signals; and summing the plurality of beamformed radar signals from the plurality of antennas per beam direction.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] Various embodiments relate generally to a method for processing radar signals in a radar system and to a radar system. [Background technology]

[0002] Prior art methods of processing radar signals may include beamforming the radar signal. Several beamforming methods are available, one of which is very well established: digital beamforming.

[0003] To beamform a radar signal, the portion of the signal coming from a particular direction can be digitally amplified. This can require two operations: the first operation allows the signal to be steered in a given direction, and the second operation allows the signal to be amplified.

[0004] Generating a beamforming signal may require two passes through the signal processing unit, where one pass can steer the beam and another pass can process the signal without the beam being steered.

[0005] Such a procedure, especially two passes, can be time consuming and not entirely optimal. Summary of the Invention [Means for solving the problem]

[0006] A method for processing radar signals for a radar system with multiple antennas is provided, which may include processing a plurality of radar signals to determine a range of at least one target from the radar system and a velocity of the at least one target, thereby forming a plurality of processed radar signals, where each radar signal of the plurality of radar signals is received by an associated antenna of the plurality of antennas, digitally beamforming the plurality of processed radar signals for at least one beam direction, thereby forming a plurality of beamformed radar signals, and summing the plurality of beamformed radar signals from the plurality of antennas for each beam direction.

[0007] In the drawings, like reference numerals generally refer to identical elements throughout the various views. The drawings are not necessarily drawn to scale; rather, emphasis has generally been placed on illustrating the principles of the invention. In the following description, various embodiments of the invention are described with reference to the following drawings: [Brief explanation of the drawings]

[0008] [Figure 1A] FIG. 1 shows an example layout of a vehicle to illustrate how radar signals are processed and the processed radar signals. [Figure 1B] FIG. 1 illustrates a beam-steered radar signal. [Figure 1C] FIG. 1 is a schematic diagram of a portion of a radar system according to the prior art; [Figure 1D] FIG. 1 is a schematic diagram of a portion of a radar system according to the prior art; [Figure 2A] FIG. 1 is a diagram that schematically illustrates a portion of a radar system in accordance with various embodiments. [Figure 2B] FIG. 1 is a diagram that schematically illustrates a portion of a radar system in accordance with various embodiments. [Figure 3] FIG. 1 illustrates a schematic diagram of a radar system in accordance with various embodiments. [Figure 4] 1 is a flowchart illustrating a method for processing a radar signal in a radar system in accordance with various embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following detailed description refers to the accompanying drawings, which show, by way of example, specific details and embodiments that enable the invention to be practiced.

[0010] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

[0011] Various aspects of the disclosure are provided for devices and for methods. It will be understood that essential features of the devices also apply to the methods, and vice versa. Therefore, for the sake of clarity, duplication of descriptions of such features has been omitted.

[0012] 1A shows, in the top diagram, an example arrangement of targets T1 and T2 (e.g., other automobiles) to be detected by a radar system operating within an object (in this case, an automobile) labeled RS, and in the bottom diagram, the processed radar signals of a first target T1 and a second target T2 are shown as normalized power versus range (where range is the distance from the radar system to the corresponding target) to illustrate how the radar signals of the radar system may be processed, for example, in a portion 100 of a radar system shown in FIG. 1C. The radar signals shown in FIG. 1A may be unsteered and may be similar or identical to the beam-steered radar signal for an angle of 0° (in other words, directly ahead of the object RS).

[0013] FIG. 1B shows beam-steered radar signals at five different beam steering angles: −40°, −25°, 0°, 25°, and 40°. These five angles are also shown in FIG. 1A. As can be seen in the beam-steered radar signals, two targets T1 and T2 are detected in all beam-steered signals, but the relative signal strengths of the two targets T1 and T2 may vary. For most beam steering angles, the normalized power of the radar signal reflected from the first target T1, which is the closer of the two targets T1 and T2, may be greater than the power at T2, and therefore may have its maximum absolute value at the beam steering angle corresponding to the 0° angle between the radar system RS and target T1. At a beam steering angle of −25°, corresponding to the direction toward the second target T2, the signal strength of the second target T2 reaches its maximum value, which is approximately equivalent to the magnitude at the first target T1. This allows the direction toward the first target T1 and the second target T2 to be detected.

[0014] Visually, digital beamsteering may involve combining radar signals received at multiple receivers in a manner that takes into account the relative phase delays introduced by targets that may be located in the direction of the desired steering angle.

[0015] FIG. 1C shows a schematic representation of a portion 100 of a radar system that can be configured to apply digital beam steering according to the prior art.

[0016] The radar system can be configured to coherently combine radar signals from multiple antennas, provided by an input array 102. The coherent combiner is shown in the upper branch and may include a beamformer 104, a complex windowing unit 106, a (fast) Fourier transformer 108, a coherent summation unit 110 (also called a cross-antenna summation unit) of the beamformed, windowed, and Fourier transformed signals from the multiple antennas, and a subsequent amplitude detection unit 112 (labeled "power unit").

[0017] The radar system can be further configured to non-coherently combine radar signals from multiple antennas provided by the input array 102. The non-coherent combiner is shown in the lower branch and may include a complex windowing unit 114, a (fast) Fourier transform unit 116, an amplitude detector 118 (labeled "power" because it is applied before summation, losing phase information and making the sum non-coherent), and a non-coherent summation of the absolute values ​​of the windowed and Fourier transformed signals from multiple antennas 120 (also referred to as a cross-antenna summation unit).

[0018] The coherent and non-coherent sums may be passed to a detection block 122 for target detection, for example, a detection block 122 configured to determine a constant false alarm rate (CFAR) of the processed signal and determine whether and where the processed signal exceeds the CFAR.

[0019] The beamforming described above requires two passes through the signal processing unit: one pass where the beam is steered (coherent integration in the upper branch) and one pass where the beam remains unsteered (incoherent integration in the lower branch).

[0020] 1D shows a schematic diagram of a portion 101 of the radar system portion 100 of FIG. 1C in greater detail. In particular, it shows how beamforming 104 and complex windowing 106 can be performed, and also shows the DBF function, which is the post-digital beamforming Fourier transform for a given beam steering angle direction (denoted by beam index b). b A formula for calculating (n) is presented, where the variables or symbols are explained in Table 1 below.

[0021] In particular, the first mathematical operation (MATH1) involves the window function coefficients w(k), which may differ for different samples but may be the same for different beam deflection angles and different antennas, and the antenna coefficients a(k), which may differ for different beam directions b and different antennas m, but may be the same for different samples. (b,m) Thus, the multiplier 134 may be a single complex multiplier 134 that includes both the "antenna coefficients multiplied by windowing" (a (b,m) ·w(k)) The multiplier 134 can be stored in memory, for example in a configuration RAM.

[0022] For each desired beam steering direction with beam index b, M × K (M antennas, K samples per antenna) storage may be required. Therefore, large memory may be required. For example, when M = 8 and K = 1024, a complex 32-bit configuration RAM size of 64 KiB may be required, which may exceed the size of a typical configuration RAM.

[0023] Furthermore, the M×K elements can be updated, for example by a CPU, between successive loops targeting different beam directions (different beam indices b), which can result in large update delays.

[0024] In various embodiments, a radar system and a method for processing radar signals from a radar system are provided that support the use of complex multiplication coefficients per antenna for coherent and non-coherent integration of radar signals, respectively.

[0025] In various embodiments, fixed digital beamforming (DBF) coefficients per antenna can be provided to enable beam steering per antenna.

[0026] In various embodiments, fine beamforming, eg, sample-by-sample beam steering, can be enabled by providing vector coefficients.

[0027] In various embodiments, the windowing coefficients w(k) and the antenna coefficients a (b,m) This allows for post-Fourier transform beamsteering, or in other words post-FFT beamsteering, which means that the beamsteering can be performed in parallel. In an exemplary embodiment, this can save up to 500 μs (out of 2.5 ms) per processing step.

[0028] FIG. 3 illustrates a radar system 300 according to various embodiments, FIG. 2A illustrates a schematic representation of a portion 200 of a radar system according to various embodiments, such as the embodiment of radar system 300 of FIG. 3, and FIG. 2B illustrates a schematic representation of a portion 201 of portion 200 of the radar system of FIG. 2A.

[0029] The following table provides an explanation of the symbols used in the formulas presented in Figures 1D, 2B and elsewhere in this document: [Table 1] is.

[0030] The radar system 300 includes a plurality of antennas 330 (e.g., M antennas, addressed m=0, . . . , M−1) and a plurality of radar signals x for determining the distance from the radar system 300 to at least one target and the velocity of at least one target. m and at least one processor 332 configured to process (k). To visualize the overall mode of operation, geometry, etc., Figure 1A can also be considered here.

[0031] In various embodiments, a plurality of processed radar signal DFTs N can be formed, where each radar signal of the plurality of radar signals can be received by an associated antenna of the plurality of antennas 330. In other words, one radar signal can be generated for each antenna 330. In various embodiments, multiple samples (e.g., K samples, addressed k=0,...,K-1) can be generated for each antenna 330.

[0032] The processor 332 further calculates a plurality of processed radar signals DFTs for at least one beam direction b, and optionally for a plurality of beam directions, e.g., D, addressed as b=0, . . . , D−1. N , and can be configured to digitally beamform (e.g., see 204 in FIGS. 2A and 2B ) the multiple beamformed radar signals from the multiple antennas 330, thereby forming multiple beamformed radar signals, and sum (e.g., see 210 in FIGS. 2A and 2B ) the multiple beamformed radar signals for each beam direction b. The result is a Fourier transform DBF of the digital beamformed radar signal for beam direction b (or for each of multiple beam directions b). b (n) can be.

[0033] Multiple radar signals x mThe processing of (k) may include at least one Fourier transform 208, such as an N-point Fourier transform and / or windowing process 206. The Fourier transform and / or windowing may be used to determine the range and / or Doppler velocity of the target. See Figures 2A and 2B for visualization.

[0034] The Fourier transform and / or windowing can be performed substantially as known in the art. For example, windowing can include multiplying each sample by a complex windowing coefficient w(k) specific to that sample. In various embodiments, windowing can be performed before the Fourier transform.

[0035] The digital beamforming 204 of the plurality of further processed radar signals includes the further processed radar signals of each antenna 330 being multiplied by antenna- and beam-specific complex multiplication coefficients a b,m This may involve multiplication with

[0036] In various embodiments, antenna and beam specific multiplication coefficients a b,m can be provided as a matrix having the number of antennas M as a first dimension and the number of beam directions D as a second dimension.

[0037] Summing 210 may include coherently summing multiple beamformed radar signals from multiple antennas 330 for each beam direction b.

[0038] In various embodiments, the beamformed radar signal summed for at least one beam direction (b) is calculated by the formula

number

number

[0039] In various embodiments, the beamforming 204 calculates the multiplication coefficients a on the fly from the windowed radar signal, which can be stored in the memory 236, for example, in a buffer. b,m This can be done before the sum by performing a complex multiplication with

[0040] Antenna- and beam-specific complex multiplication coefficient a b,m In various embodiments,

number

number

[0041] Therefore, the angle θ, which indicates the beam direction that receives the most weight in the beamformed radar signal, is calculated by the antenna- and beam-specific complex multiplication coefficient a b,m It can have an effect on.

[0042] The coherent sum, in various embodiments, can be

number

[0043] In various embodiments, summing may further include non-coherently summing multiple beamformed radar signals for each beam direction θ from multiple antennas 330. In the exemplary embodiment shown in Figure 2A, this can be performed in the lower branch. Beamforming 216 can be performed on the fly, prior to power determination and summation, from windowed radar signals that can be stored in memory 236, e.g., in a buffer.

[0044] The non-coherent summation, in various embodiments, can be

number

[0045] Antenna- and beam-specific multiplication factor c for noncoherent summation b,m In various embodiments,

number

number

[0046] In various embodiments, the processor 332 can be configured to perform non-coherent summation and coherent summation in parallel.

[0047] Thus, in various embodiments, one additional complex multiplier a b,m is supplied and processed in the section labeled "MATH2". b,m is the antenna factor a (b,m) and the window function processing w(k).

[0048] For comparison of the required memory space, using the same example as above (e.g., M = 8 antennas, K = 1024 samples, and windowing w(k), real 32 bits), 4 KiB (i.e., only about 1 / 16 of the memory required by the prior art) is required. (b,m) requires only 1 byte of storage space per antenna, or about 64 bytes in total.

[0049] In various embodiments, the antenna coefficient a (b,m) can be updated by the processor 332, e.g., a CPU, during execution between different beam loops, i.e., at different beam indices, or can be stored as a fixed configuration. The latter, in particular, increases execution speed but also reduces the antenna coefficient a b,m Due to the small size of the antenna, the antenna factor a (b,m) The update of can also be much faster than in the prior art.

[0050] In various embodiments, radar system 300 may further include at least one register (e.g., 64 bits) for each antenna 330. The at least one register may be included, for example, in a portion of radar system 300 where non-coherent integration (NCI), also referred to as an NCI module, is performed.

[0051] In various embodiments, both the coherently integrated radar signal and the non-coherently integrated radar signal can be provided to a detection block 122, which can be similar to or identical to detection blocks used in the prior art. The coherently integrated radar signal and the non-coherently integrated radar signal can be processed jointly to eliminate false detections, or in other words, to identify "real" targets.

[0052] FIG. 4 illustrates a flowchart 400 of a method for processing radar signals in a radar system according to various embodiments.

[0053] The method may include processing a plurality of radar signals to determine a distance from the radar system to at least one target and a velocity of the at least one target, thereby forming a plurality of processed radar signals, where each radar signal of the plurality of radar signals is received by an associated antenna of the plurality of antennas (410); digitally beamforming the plurality of processed radar signals for at least one beam direction, thereby forming a plurality of beamformed radar signals (420); and summing the plurality of beamformed radar signals from the plurality of antennas for each beam direction (430).

[0054] Various examples are given below.

[0055] Example 1 is a method for processing radar signals for a radar system with multiple antennas. The method may include processing the multiple radar signals to determine a distance from the radar system to at least one target and a velocity of the at least one target, thereby forming multiple processed radar signals, where each radar signal of the multiple radar signals is received by an associated antenna of the multiple antennas; digitally beamforming the multiple processed radar signals for at least one beam direction, thereby forming multiple beamformed radar signals; and summing the multiple beamformed radar signals from the multiple antennas for each beam direction.

[0056] In example 2, processing the plurality of radar signals includes performing a Fourier transform. The subject matter of Example 1 may optionally be included.

[0057] Example 3 may optionally include the subject matter of example 1 or 2, wherein processing the plurality of radar signals includes performing windowing.

[0058] Example 4 may optionally include the subject matter of Example 3, wherein each radar signal of the plurality of radar signals includes a plurality of samples, and wherein windowing includes multiplying each of the samples by a complex windowing coefficient specific to the sample.

[0059] Example 5 can optionally include the subject matter of Examples 2 and 3, in which windowing is applied before performing the Fourier transform.

[0060] Example 6 may optionally include the subject matter of any one of Examples 1 to 5, wherein at least one beam direction includes a plurality of beam directions.

[0061] Example 7 may optionally include the subject matter of any one of Examples 1 to 6, wherein digitally beamforming the plurality of further processed radar signals includes multiplying the further processed radar signal for each antenna by a complex multiplication coefficient specific to the antenna and the beam.

[0062] Example 8 may optionally include the subject matter of Example 7, in which the antenna- and beam-specific complex multiplication coefficients are provided as a matrix having the number of multiple antennas as a first dimension and the number of multiple beam directions as a second dimension.

[0063] Example 9 may optionally include the subject matter of any one of Examples 1 to 8, wherein the summing includes coherently summing multiple beamformed radar signals from multiple antennas for each beam direction.

[0064] In example 10, the beamformed radar signals summed for at least one direction (b) are calculated by the formula

number

number

number

number

[0065] In Example 11, the coherent sum is

number

[0066] Example 12 may optionally include the subject matter of any one of Examples 9 to 11, wherein the summing further includes non-coherently summing the multiple beamformed radar signals from the multiple antennas for each beam direction.

[0067] In Example 13, the non-coherent sum is

number

number

number

[0068] Example 14 may optionally include the subject matter of any one of Examples 9-11 and Example 12 or 13, in which non-coherent summing and coherent summing are performed in parallel.

[0069] Example 15 may optionally include the subject matter of any one of Examples 9 to 11, wherein the coherent sum is provided to a target detection algorithm that performs target detection and / or to a local maximum search algorithm that searches for a local maximum.

[0070] In a sixteenth embodiment, the non-coherent sum is provided to a target detection algorithm for performing target detection and / or to a local maximum search algorithm for searching for a local maximum. The subject matter of Examples 12 or 13 may optionally be included.

[0071] Example 17 may optionally include the subject matter of Examples 12 or 13, in which target detection and local maximum search are performed in parallel.

[0072] Example 18 is a radar system including a plurality of antennas and at least one processor, the processor configured to process a plurality of radar signals to determine a distance from the radar system to at least one target and a velocity of the at least one target, thereby forming a plurality of processed radar signals, where each radar signal of the plurality of radar signals is received by an associated antenna of the plurality of antennas, digitally beamforming the plurality of processed radar signals for at least one beam direction, thereby forming a plurality of beamformed radar signals, and summing the plurality of beamformed radar signals from the plurality of antennas for each beam direction.

[0073] Example 19 may optionally include the subject matter of example 18, wherein processing the plurality of radar signals includes a Fourier transform.

[0074] Example 20 may optionally include the subject matter of example 18 or 19, wherein the processing of the plurality of radar signals includes window function processing.

[0075] Example 21 may optionally include the subject matter of example 20, wherein each radar signal of the plurality of radar signals includes a plurality of samples, and wherein the windowing includes multiplying each of the samples by a complex windowing coefficient specific to the sample.

[0076] Example 22 may optionally include the subject matter of Examples 20 and 21, wherein the processor is further configured to apply a windowing function before the Fourier transform.

[0077] Example 23 may optionally include the subject matter of any one of Examples 18 to 22, wherein at least one beam direction includes a plurality of beam directions.

[0078] Example 24 may optionally include the subject matter of any one of Examples 18 to 23, wherein the digital beamforming of the plurality of further processed radar signals includes multiplying the further processed radar signals for each antenna by a complex multiplication coefficient specific to the antenna and the beam.

[0079] Example 25 may optionally include the subject matter of Example 24, in which the antenna- and beam-specific complex multiplication coefficients are provided as a matrix having the number of multiple antennas as a first dimension and the number of multiple beam directions as a second dimension.

[0080] Example 26 may optionally include the subject matter of any one of Examples 18 to 25, wherein the summation includes a coherent summation, per beam direction, of multiple beamformed radar signals from multiple antennas.

[0081] In Example 27, the processor further calculates the summed beamformed radar signal for at least one direction (b) according to the formula

number

number

number

number

[0082] In Example 28, the coherent sum is

number

[0083] Example 29 may optionally include the subject matter of example 27 or 28, wherein the summing further includes non-coherent summing, for each beam direction, of multiple beamformed radar signals from multiple antennas.

[0084] In Example 30, the non-coherent sum is

number

number

number

[0085] Example 31 may optionally include the subject matter of any one of Examples 26 to 28 and Example 29 or 30, wherein the processor is further configured to perform non-coherent summation and coherent summation in parallel.

[0086] While the invention has been particularly shown and described with reference to certain embodiments, it will be understood by those skilled in the art that various changes in form and detail in each embodiment can be made without departing from the spirit and scope of the invention as defined in the appended claims. The scope of the invention is therefore indicated by the appended claims, and all changes that come within the meaning and range of equivalents of such claims are therefore intended to be embraced.

Claims

1. 1. A method for processing radar signals for a radar system with multiple antennas, the method comprising: windowing and Fourier transforming a plurality of radar signals to determine a range from the radar system to at least one target and a velocity of the at least one target, thereby forming a plurality of processed radar signals, each radar signal of the plurality of radar signals being received by an associated antenna of the plurality of antennas; digitally beamforming the plurality of processed radar signals for at least one beam direction, thereby forming a plurality of beamformed radar signals; - coherently and / or non-coherently summing multiple beamformed radar signals from the multiple antennas for each beam direction; Including, The coherent sum is [Equation 1] and The noncoherent sum is [Equation 2] and c b,m are antenna- and beam-specific multiplication coefficients for the non-coherent summation. method.

2. each radar signal of the plurality of radar signals includes a plurality of samples; said windowing comprising multiplying each of said samples by a complex windowing coefficient specific to said sample; The method of claim 1.

3. The windowing is applied before the Fourier transform.

3. The method according to claim 1 or 2.

4. the at least one beam direction includes a plurality of beam directions; 4. The method according to any one of claims 1 to 3.

5. digitally beamforming the plurality of processed radar signals includes multiplying the processed radar signals for each of the antennas by a complex multiplication coefficient specific to the antenna and the beam; 5. The method according to any one of claims 1 to 4.

6. the antenna and beam specific complex multiplication coefficients are provided as a matrix having the number of the plurality of antennas as a first dimension and the number of the plurality of beam directions as a second dimension; The method of claim 4.

7. The beamformed radar signal summed for the at least one beam direction (b) is expressed by the formula [Equation 3] where b is the beam direction index, m is the antenna index, and a ｂ，ｍ is an antenna- and beam-specific complex multiplication coefficient, [Equation 4] where k is the sample index and X ｍ (n) is the complex window function w of antenna m for sample k ｍ (k) and the radar signal x of antenna m for sample k ｍ (k) is the Fourier transform (DFT) of the multiplication with [Equation 5] or [Equation 6] where d is the antenna pitch (wavelength), b=m, and hann() is the Hann window function.

7. The method according to any one of claims 1 to 6.

8. c ｂ，ｍ teeth, [Equation 7] or [Equation 8] where d is the antenna pitch (wavelength), b=m, and hann() is the Hann window function.

8. The method according to any one of claims 1 to 7.

9. the non-coherent summing and the coherent summing are performed in parallel.

9. The method according to any one of claims 1 to 8.

10. the coherent sum is fed to a target detection algorithm for performing target detection and / or to a local maximum search algorithm for searching for a local maximum; 10. The method according to any one of claims 1 to 9.

11. the non-coherent sum is fed to a target detection algorithm for performing target detection and / or to a local maximum search algorithm for searching for a local maximum; 11. The method according to any one of claims 1 to 10.

12. the target detection and the local maximum search are performed in parallel; 12. The method according to claim 10 or 11.

13. 1. A radar system, comprising: - a plurality of antennas; at least one processor; wherein the processor: windowing and Fourier transforming a plurality of radar signals to determine a range from the radar system to at least one target and a velocity of the at least one target, thereby forming a plurality of processed radar signals, each radar signal of the plurality of radar signals being received by an associated antenna of the plurality of antennas; digitally beamforming the plurality of processed radar signals for at least one beam direction, thereby forming a plurality of beamformed radar signals; Coherently and / or non-coherently summing multiple beamformed radar signals from the multiple antennas for each beam direction; It is structured as follows: The coherent sum is [Equation 9] and The noncoherent sum is [Equation 10] and c b,m are antenna- and beam-specific multiplication coefficients for the non-coherent summation. Radar system.

14. each radar signal of the plurality of radar signals includes a plurality of samples; said windowing comprising multiplying each of said samples by a sample-specific complex windowing coefficient; The radar system of claim 13.

15. the processor is further configured to apply the windowing function before the Fourier transform.

15. A radar system according to claim 13 or 14.

16. the at least one beam direction includes a plurality of beam directions; A radar system according to any one of claims 13 to 15.

17. digital beamforming of the plurality of processed radar signals includes multiplying the processed radar signals for each of the antennas by a complex multiplication coefficient specific to the antenna and the beam; A radar system according to any one of claims 13 to 16.

18. the antenna and beam specific complex multiplication coefficients are provided as a matrix having the number of the plurality of antennas as a first dimension and the number of the plurality of beam directions as a second dimension; 18. The radar system of claim 17.

19. The processor calculates the summed beamformed radar signal for the at least one beam direction (b) according to the formula: [0011] where b is the beam direction index, m is the antenna index, and a ｂ，ｍ is an antenna- and beam-specific complex multiplication coefficient, [0012] where k is the sample index and X ｍ (n) is the complex window function w of antenna m for sample k ｍ (k) and the radar signal x of antenna m for sample k ｍ (k) is the Fourier transform (DFT) of the multiplication with [0013] or [0014] where d is the antenna pitch (wavelength), b=m, and hann() is the Hann window function. A radar system according to any one of claims 13 to 18.

20. c ｂ，ｍ teeth, [Equation 15] or [0016] where d is the antenna pitch (wavelength), b=m, and hann() is the Hann window function. A radar system according to any one of claims 13 to 19.

21. the processor is further configured to perform the non-coherent summation and the coherent summation in parallel. A radar system according to any one of claims 13 to 20.

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