radar device

Abstract

An interference signal processing unit (210) of a radar device (100) is configured to determine an interference range (Ri) in a sample signal (Ts); generate a modified sample signal (Ts2) by multiplying the sample signal by a reduction signal (Ti); convert the modified sample signal into a first frequency domain sample signal (Fs1) in a frequency domain; convert the reduction signal into a subtraction template signal (VFi1) in the frequency domain; calculate an evaluation value (Vs) based on the first frequency domain sample signal and the subtraction template signal to determine whether a partial signal of the first frequency domain sample signal is derived from a reflected wave of an object (OB); and generate an interference-removed signal (Ts4) such that a time domain signal of the partial signal determined based on the evaluation value to be derived from the reflected wave is contained in a corresponding range of the interference-removed signal.

Description

Technical Field

[0001] This disclosure relates to a radar device. Background Technology

[0002] Radar equipment measures an object based on a beat signal obtained by mixing a transmitted signal sent to the object as an electromagnetic wave with a received signal of the electromagnetic wave reflected by the object. Due to interference from transmitted signals from other radar equipment, interference components may appear in the beat signal. Techniques for removing such interference components set the amplitude to zero within the interference range containing the interference components and interpolate the interference range based on the true partial signal derived from the electromagnetic wave reflected from the object (see, for example, Patent Document 1). Patent Document 1 discloses determining the true partial signal based on the intensity of the partial signal.

[0003] Patent Document 1: WO 2020 / 120333 A1 Summary of the Invention

[0004] However, in cases where the true partial signal is determined solely based on intensity, as in Patent Document 1, setting the amplitude to zero within the interference range may lead to erroneous determination of the partial signal (so-called sidelobes). In such cases, the interference range cannot be properly interpolated, and the accuracy of target measurement by radar equipment may be reduced.

[0005] This disclosure may be provided by the following.

[0006] According to one aspect of this disclosure, a radar device includes: a transmitter configured to transmit a transmitted signal as an electromagnetic wave; a receiver configured to receive a reflected wave representing an electromagnetic wave reflected by an object as a received signal; a beat signal generator configured to generate a beat signal based on the transmitted signal and the received signal; a sample signal generator configured to generate a sample signal based on the beat signal, the sample signal being a digital signal in the time domain or time-frequency domain; and an interference signal processing unit configured to generate an interference-removed signal obtained by removing interference components from the sample signal. The interference signal processing unit includes: an interference range determination unit configured to determine an interference range representing the range in which the interference component is contained in the sample signal; a modified sample signal generator configured to generate a modified sample signal by multiplying the sample signal by a reduction signal used to reduce the signal strength in the interference range; a sample signal conversion unit configured to convert the modified sample signal into a first frequency domain sample signal in the frequency domain; a reduction signal conversion unit configured to convert the reduction signal into a subtraction template signal in the frequency domain; and an evaluation value calculator configured to calculate an evaluation value based on the first frequency domain sample signal and the subtraction template signal to determine whether a partial signal representing at least a portion of the first frequency domain sample signal is derived from the reflected wave. The interference signal processing unit generates the interference-removed signal such that a time-domain signal based on the partial signal (which is determined to be derived from the reflected wave based on the evaluation value) is included in a corresponding range corresponding to the interference range of the interference-removed signal.

[0007] Therefore, it is possible to determine whether a partial signal is a true partial signal derived from a reflected wave based on an evaluation value calculated from the first frequency domain sample signal and the subtraction template signal. This reduces the erroneous identification of sidelobes contained in the first frequency domain sample signal as true partial signals. Furthermore, compared to, for example, measuring an object based on a signal interpolated from a partial signal estimated solely by its intensity as a true partial signal, measuring the object based on interference-removed signals allows for high-precision object measurement. Attached Figure Description

[0008] Figure 1 This is an explanatory diagram showing a schematic configuration of a radar device according to a first embodiment;

[0009] Figure 2 This is an explanatory diagram showing a schematic configuration of the interference signal processing unit according to the first embodiment;

[0010] Figure 3 This is a flowchart of the interference signal processing in the first embodiment;

[0011] Figure 4 This is an explanatory diagram showing the sample signal and the modified sample signal;

[0012] Figure 5 This is an explanatory diagram showing the first subtraction signal;

[0013] Figure 6 This is an illustrative diagram showing a first example of a comparison signal;

[0014] Figure 7 This is an illustrative diagram showing a second example of a comparison signal;

[0015] Figure 8 This is an explanatory diagram showing an example of the evaluation value;

[0016] Figure 9 This is an explanatory diagram showing the second subtraction signal and the updated signal;

[0017] Figure 10 This is an explanatory diagram showing a schematic configuration of the interference signal processing unit according to the second embodiment;

[0018] Figure 11 This is a flowchart of the interference signal processing in the second embodiment;

[0019] Figure 12 This is an explanatory diagram illustrating a schematic configuration of the interference signal processing unit according to the third embodiment; and

[0020] Figure 13 This is a flowchart of the interference signal processing in the third embodiment. Specific Implementation

[0021] A. First Embodiment

[0022] Figure 1 The radar device 100 shown is mounted on a vehicle such as a car or a two-wheeled vehicle, and measures objects OB such as pedestrians, other vehicles, or obstacles on the road. Specifically, the radar device 100 measures the distance and angle between the host vehicle on which the radar device 100 is mounted and the object OB, and / or measures the relative speed of the object OB relative to the host vehicle. In this embodiment, the radar device 100 is configured as a millimeter-wave radar to measure the object OB using a Fast-Chirp Modulation (FCM) method. In another embodiment, the radar device 100 may be configured as a radar to measure the object OB using a Frequency Modulated Continuous Wave (FMCW) method.

[0023] like Figure 1 As shown, the radar device 100 includes a signal generator 101, a transmitter 102, a receiver 103, a beat signal generator 104, a sample signal generator 105, and a control device 200.

[0024] Signal generator 101 includes, for example, a voltage-controlled oscillator and generates a transmit signal Tw. In this embodiment, signal generator 101 continuously generates a linear frequency modulated (LFM) signal consisting of a steep up-chirp with a very high rate of increase as the transmit signal Tw. In another embodiment, for example, when radar device 100 measures target object OB using the FMCW method, signal generator 101 generates an LFM signal including up-chirp and down-chirp as the transmit signal Tw.

[0025] Transmitter 102 is configured to radiate the transmitted signal Tw as an electromagnetic wave Ew into space. Receiver 103 is configured to receive the electromagnetic wave Ew reflected by object OB as a received signal Dw. The electromagnetic wave Ew reflected by object OB is also referred to hereinafter as the reflected wave.

[0026] The beat signal generator 104 generates a beat signal Bw based on the transmitted signal Tw and the received signal Dw. In this embodiment, the beat signal generator 104 is configured as a mixer to mix the transmitted signal Tw and the received signal Dw to generate the beat signal Bw.

[0027] The sample signal generator 105 generates a sample signal Ts in the time domain or time-frequency domain based on the beat signal Bw. In this embodiment, the sample signal generator 105 generates a time-domain digital signal as the sample signal Ts based on the beat signal Bw. The sample signal generator 105 has a filter 106 and an analog-to-digital converter 107.

[0028] Filter 106 allows only the beat signal Bw2, which has a specific frequency band, to pass through the beat signal Bw. In this embodiment, filter 106 is configured as a low-pass filter. In another embodiment, filter 106 may be configured as, for example, a high-pass filter or a band-pass filter. Analog-to-digital converter (ADC) unit 107 converts the beat signal Bw2, which is an analog signal, into a sample signal Ts, which is a digital signal in the time domain.

[0029] The control device 200 is configured as a computer including a CPU, memory, and an input / output interface for signal input / output with external devices.

[0030] The control device 200 includes an interference signal processing unit 210 and a measurement processing unit 290. More specifically, in this embodiment, the interference signal processing unit 210 and the measurement processing unit 290 are functional units implemented by the CPU executing programs stored in the memory of the control device 200. In another embodiment, the interference signal processing unit 210 and the measurement processing unit 290 may be configured as devices separate from the control device 200, and they operate, for example, according to instructions from the CPU.

[0031] The interference signal processing unit 210 generates an interference-removed signal Ts4 based on the sample signal Ts. The interference-removed signal Ts4 corresponds to the signal obtained by removing the interference component Ci from the sample signal Ts. In this embodiment, the sample signal Ts is input to the interference signal processing unit 210 from the sample signal generator 105 via an input / output interface provided in the control device 200. The measurement processing unit 290 measures the object OB based on the generated interference-removed signal Ts4.

[0032] like Figure 2 As shown, the interference signal processing unit 210 includes an interference range determination unit 215, a modified sample signal generator 220, a sample signal conversion unit 225, a signal reduction conversion unit 230, and an evaluation value calculator 240. In this embodiment, the interference signal processing unit 210 has a peak extraction unit 235, a selection unit 244, an interpolation signal generator 265, an interpolator 270, and an update unit 275. In this embodiment, the evaluation value calculator 240 has a first subtraction signal generator 241, a comparison signal generator 242, and a calculation processing unit 243. The update unit 275 has a second subtraction signal generator 276 and an update processing unit 277. In this embodiment, each part of the interference signal processing unit 210 is configured as a functional part implemented by a program executed by the control device 200. In another embodiment, each part of the interference signal processing unit 210 may be implemented, for example, by hardware circuitry.

[0033] In this embodiment, the interference signal processing unit 210 executes... Figure 3 The interference signal processing shown generates the interference-removed signal Ts4. In this embodiment, interference signal processing is performed each time a sample signal Ts is input to the interference signal processing unit 210.

[0034] In step S105, the interference range determination unit 215 determines the interference range Ri. The interference component Ci is contained within the interference range Ri of the sample signal Ts. In this embodiment, the interference range Ri is determined as the time range in which the sample signal Ts contains the interference component Ci. Figure 4 The upper part shows an example of the spectrum of the sample signal Ts, where the horizontal axis represents time and the vertical axis represents amplitude. Figure 4 The upper part shows an example of the interference component Ci contained in the sample signal Ts and an example of the interference range Ri in the sample signal Ts. Such an interference component Ci is generated, for example, by an electromagnetic interference received signal Dw transmitted from a radar device different from radar device 100 (e.g., a radar device installed on another vehicle).

[0035] In step S105, the interference range determination unit 215 uses, for example, known techniques to determine the interference range Ri. More specifically, when the sample signal Ts includes an interference component Ci derived from an electromagnetic wave transmitted from another radar device, a linear frequency modulated signal is generated in the range of the interference component Ci, while a sinusoidal signal is generated in another range. The interference range determination unit 215 can determine the interference range Ri based on this waveform difference. Since the signal strength in the range containing the interference component Ci is generally higher than the signal strength in the other range, the interference range Ri can be determined based on this difference in signal strength.

[0036] exist Figure 3 In step S110, the modified sample signal generator 220 multiplies the sample signal Ts, which was identified for the interference range Ri in step S105, by a reduction signal Ti to generate the modified sample signal Ts2. The reduction signal Ti represents the signal used to reduce the signal strength of the interference range Ri. In this embodiment, in step S110, the modified sample signal generator 220 uses a reduction signal Ti with a rectangular waveform in the time domain, wherein the signal strength is zero in the range corresponding to the interference range Ri, and the signal strength is 1 in another range corresponding to an interference range Ri different from the sample signal Ts. Figure 4 The lower part shows an example of the spectrum of the modified sample signal Ts2 generated by multiplying the sample signal Ts by the reduced signal Ti. For example... Figure 4 As shown, in this embodiment, in step S110, the sample signal Ts is multiplied by the reduction signal Ti to generate the modified sample signal Ts2, wherein the signal strength is zero in the range Ri1 corresponding to the interference range Ri, and the signal strength in the other range is similar to that of the sample signal Ts.

[0037] exist Figure 3 In step S115, the sample signal conversion unit 225 converts the modified sample signal Ts2 generated in step S110 into a first frequency domain sample signal Fs1 in the frequency domain, thereby obtaining the first frequency domain sample signal Fs1. In this embodiment, in step S115, the sample signal conversion unit 225 multiplies the modified sample signal Ts2 by a window function and performs a Fourier transform on the signal multiplied by the window function to generate the first frequency domain sample signal Fs1. The window function in step S115 can be, for example, a general window function (Hamming window, Hanning window, Blackman window, etc.). The Fourier transform in step S115 can be, for example, a Discrete Fourier Transform (DFT) or a Fast Fourier Transform (FFT). Figure 5An example of the power spectrum of the first frequency domain sample signal Fs1 is shown, where the horizontal axis represents frequency and the vertical axis represents power.

[0038] In step S120, the signal reduction conversion unit 230 generates the subtraction template signal VFi1 by converting the reduced signal Ti into a subtraction template signal VFi1 in the frequency domain. In this embodiment, in step S120, the signal reduction conversion unit 230 generates the subtraction template signal VFi1 by performing a Fourier transform on the reduced signal Ti in the same manner as in step S115. The subtraction template signal VFi1 includes a main lobe and side lobes and has symmetry near zero frequency, similar to the Fourier transform of a general window function. The frequency range of the subtraction template signal VFi1 that includes at least the frequency with the maximum amplitude is also referred to as the first range or the second range. The second range may be the same frequency range as the first range or may be a different frequency range. However, the second range is preferably the same as or wider than the first range.

[0039] In step S125, the peak extraction unit 235 extracts at least one peak Ps included in the first frequency domain sample signal Fs1. In this embodiment, in step S125, the peak extraction unit 235 extracts the peak Ps containing the first frequency domain sample signal Fs1 whose indicated power value is equal to or greater than a predetermined value, and records the frequency position of the extracted peak Ps in the memory. Figure 5 An example of the peak Ps extracted in step S125 is shown, including the frequency range of the peak Ps extracted in step S125, also referred to as the peak range. In this embodiment, the peak range of each peak corresponds to half the width of each peak Ps. In another embodiment, the peak range may be narrower or wider than the range corresponding to half the width of the peak Ps. In another embodiment, for example, the peak Ps may be extracted in step S125 based on the absolute value of the signal.

[0040] exist Figure 3 In step S130, the peak extraction unit 235 determines whether the peak value Ps was extracted in step S125.

[0041] When it is determined in step S130 that the peak value Ps has been extracted, in steps S135 and S140, the evaluation value calculator 240 calculates the evaluation value Vs based on the first frequency domain sample signal Fs1 and the subtraction template signal VFi1. The evaluation value Vs represents the value used to determine whether a portion of the signal representing at least a part of the first frequency domain sample signal Fs1 is derived from the reflected wave. It should be noted that when a portion of the signal does not originate from the reflected wave, it means that the portion of the signal is generated by multiplying the subtracted signal Ti. The portion of the signal originating from the reflected wave is also referred to as the "true portion signal" below. In addition, the process of calculating the evaluation value Vs (e.g., steps S135 and S140 in this embodiment) is also called the "evaluation value calculation process".

[0042] In this embodiment, the evaluation value calculator 240 calculates an evaluation value Vs for each peak Ps extracted in step S125 to determine whether a portion of the signal within each peak range is a true portion of the signal. That is, in this embodiment, the portion of the signal within each peak range is the target for calculating the evaluation value Vs and the target for determination based on the evaluation value Vs. More specifically, one evaluation value Vs is calculated corresponding to one peak Ps, and the portion of the signal within the peak range of the peak Ps undergoes determination based on this evaluation value Vs. The portion of the signal to be determined based on the evaluation value Vs is also referred to below as the target portion of the signal.

[0043] In this embodiment, the evaluation value calculator 240 generates a comparison signal Cs in step S135. More specifically, the evaluation value calculator 240 first generates a first subtraction signal Ss1 in step S135. The first subtraction signal Ss1 is obtained by correcting the frequency position and frequency components (amplitude and phase) of the subtraction template signal VFi1 based on the frequency position and frequency components of the target partial signal, respectively, within a first range. In this embodiment, the first subtraction signal Ss1 has symmetry around the frequency position of the peak Ps corresponding to the target partial signal. In this embodiment, the first range corresponds to the entire frequency range of the subtraction template signal VFi1. Next, the evaluation value calculator 240 generates the comparison signal Cs by subtracting the first subtraction signal Ss1 from the first frequency domain sample signal Fs1.

[0044] As an example of the first subtraction signal Ss1 generated in step S135 Figure 5 The power spectrum of the first subtracted signal Ss1a with respect to the peak Ps1, which has the largest power value among the five peaks Ps, is shown. Furthermore, Figure 6 The power spectrum of the comparison signal Cs1, which is an example of the comparison signal Cs, is shown in relation to the peak value Ps1. Figure 7 The power spectrum of the comparison signal Cs2 is shown, which is associated with the peak Ps2 adjacent to peak Ps1 on the high-frequency side of peak Ps1.

[0045] like Figure 6 and Figure 7 As shown, the difference between the first frequency domain sample signal Fs1 and the comparison signal Cs1 is greater than the difference between the first frequency domain sample signal Fs1 and the comparison signal Cs2. The reason is described as follows: A portion of the signal within the peak range of peak Ps1 is the true portion of the signal. The first subtraction signal Ss1a is subtracted from the first frequency domain sample signal Fs1. The sidelobe convolved with the portion of the signal within the peak range of peak Ps1 is subtracted from the first frequency domain sample signal Fs1. This sidelobe is caused by the multiplication of the sample signal Ts and the subtraction signal Ti performed in step S110. On the other hand, the sidelobe is not convolved with the portion of the signal that is not the true portion of the signal, and the frequency component of the first subtraction signal Ss1 for such portion of the signal does not correspond to the frequency component of the first frequency domain sample signal Fs1. Therefore, as Figure 7 As shown, the difference between the first frequency domain sample signal Fs1 and the comparison signal Cs generated by subtracting the first subtraction signal Ss1, which is a partial signal that is not a real part of the signal, from the first frequency domain sample signal Fs1 becomes smaller.

[0046] In step S140, the calculation processing unit 243 of the evaluation value calculator 240 calculates the evaluation value Vs. In this embodiment, the evaluation value calculator 240 calculates the evaluation value Vs for each peak Ps extracted in step S125 based on the difference between the first frequency domain sample signal Fs1 and the comparison signal Cs calculated in step S135. More specifically, the evaluation value calculator 240 calculates the evaluation value Vs as the sum of the differences between the absolute value of the first frequency domain sample signal Fs1 and the absolute value of the comparison signal Cs. Therefore, the evaluation value Vs reflects the difference between the first frequency domain sample signal Fs1 and the comparison signal Cs, and the evaluation value Vs increases as the difference increases. Figure 8 Five evaluation values ​​Vs for the five peak values ​​Ps mentioned above are shown as examples of evaluation values ​​Vs. Figure 8 In the example, the peak Ps1 has the largest evaluation value Vs1 among the five evaluation values ​​Vs.

[0047] In step S145, selection unit 244 performs a selection process. The selection process involves selecting one or more partial signals as true partial signals based on the evaluation value Vs, and recording information about the frequency position of the selected partial signals. The partial signals selected in the selection process are called selected partial signals. The selected partial signals can also be described as partial signals determined to be true partial signals. The information about the frequency position of the selected partial signals recorded in the selection process is called frequency position information PP.

[0048] In this embodiment, in step S145, the selection unit 244 first extracts an evaluation value Vs that is equal to or greater than a predetermined reference value from the evaluation values ​​Vs calculated in step S140. Next, the selection unit 244 selects the largest evaluation value Vs from the extracted evaluation values ​​Vs, and selects a portion of the signal within the peak range of a peak value Ps having that evaluation value Vs as the true signal portion. Then, the selection unit 244 records the frequency position of the peak value Ps in the memory of the control device 200 as frequency position information PP. For example, in... Figure 8 In the example, a portion of the signal within the peak range of peak Ps1 of peak Ps is selected as the true partial signal, and the frequency position of peak Ps1 is recorded as frequency position information PP. Note that if there is no evaluation value Vs equal to or greater than the predetermined reference value in step S145, selection unit 244 advances the process to step S150 without selecting the true partial signal.

[0049] In step S150, the selection unit 244 determines whether the real part signal was selected in step S145, that is, whether there is a part signal selected in the previous selection process.

[0050] If it is determined in step S150 that a true portion of the signal has been selected, then in step S155, the update unit 275 updates the first frequency domain sample signal Fs1 to generate the updated signal Fs1R. More specifically, the update unit 275 first generates a second subtraction signal Ss2 in step S155. The second subtraction signal Ss2 is generated by correcting the frequency position and frequency components of the subtraction template signal VFi1 in a second range based on the frequency position and frequency components of the selected portion of the signal, respectively. In this embodiment, the second subtraction signal Ss2 has symmetry around the frequency position of the peak Ps corresponding to the selected portion of the signal. In this embodiment, the second range is the same as the first range, corresponding to the entire frequency range of the subtraction template signal VFi1. Next, the update unit 275 generates the updated signal Fs1R by subtracting the second subtraction signal Ss2 from the first frequency domain sample signal Fs1.

[0051] Figure 9 The upper part shows the power spectrum of the second subtraction signal Ss2a, which is a portion of the signal within the peak range of the peak value Ps1, as an example of the second subtraction signal Ss2 generated in step S155. Figure 9 The lower part shows the power spectrum of the updated signal Fs1Ra, as an example of the updated signal Fs1R generated in step S155. For example... Figure 5 and Figure 9As shown, in this embodiment, the first subtraction signal Ss1 and the second subtraction signal Ss2 regarding a certain peak value Ps are the same signal. In another embodiment, the first subtraction signal Ss1 and the second subtraction signal Ss2 can be different signals, for example, when the first range and the second range are different ranges.

[0052] Next, the interference signal processing unit 210 returns to step S125. In the re-executed step S125, the peak extraction unit 235 extracts at least one peak Ps included in the updated signal Fs1R. In the re-executed step S125, the peak extraction unit 235 excludes peak Ps corresponding to the frequency positions of the selected portion of the signal selected in the previous selection process, that is, peak Ps corresponding to the frequency positions included in the frequency position information PP from the peak extraction target. Therefore, in Figure 9 In the example shown, the peak Ps1 included in the updated signal Fs1Ra is excluded from the peak extraction target. Furthermore, when a new partial signal is selected as the true partial signal in the selection process of the re-executed step S145, information about the frequency position of the newly selected partial signal, along with information related to the previously recorded frequency position information, is accumulated and recorded as frequency position information PP.

[0053] like Figure 3 As shown, in this embodiment, steps S125 to S155 are repeated until it is determined in step S130 that no peak Ps has been extracted, or until it is determined in step S150 that no true signal has been selected, and the first frequency domain sample signal Fs1 is repeatedly updated. Thus, by repeatedly updating the first frequency domain sample signal Fs1, the signals derived from the sidelobes included in the first frequency domain sample signal Fs1 are subtracted. Therefore, it is possible to more accurately determine whether the portion of the signal included in the first frequency domain sample signal Fs1 is the true signal, and to detect the true signal more effectively.

[0054] If it is determined in step S130 that no peak Ps is extracted, or if it is determined in step S150 that no true partial signal is selected, then in step S160, the interpolation signal generator 265 generates an interpolation signal Ts3 based on the frequency positions of all selected partial signals selected in the previous selection process (i.e., based on all frequency positions included in the frequency position information PP). The interpolation signal Ts3 is a time-domain signal used to interpolate the range Ri1 corresponding to the interference range Ri in the modified sample signal Ts2. More specifically, in this embodiment, the interpolation signal generator 265 performs an inverse Fourier transform on all partial signals determined as true partial signals in step S160 and appropriately corrects the amplitude of each signal after the inverse Fourier transform. Then, the interpolation signal generator 265 generates the interpolation signal Ts3 by adding these signals. The frequency position and width of the range Ri1 are the same as the frequency position and width of the interference range Ri, respectively. In another embodiment, the interpolated signal Ts3 based on each real part signal can be generated individually by performing an inverse Fourier transform on each part signal that is determined to be a real part signal.

[0055] In step S165, interpolator 270 interpolates the modified sample signal Ts2 based on the interpolation signal Ts3 generated in step S160 to generate an interference-removed signal Ts4. More specifically, in this embodiment, interpolator 270 generates the interference-removed signal Ts4 in step S165 by adding the interpolation signal Ts3 to the modified sample signal Ts2 in range Ri1. As a result, the interference-removed signal Ts4 is generated such that the time-domain signal based on the portion of the signal determined to be the true partial signal is included in the corresponding range. More specifically, the interference-removed signal Ts4 is generated such that the time-domain signal generated based on the frequency position of the selected partial signal is included in the corresponding range. It should be noted that the corresponding range refers to the range of the interference-removed signal Ts4 corresponding to the interference range Ri. More specifically, the frequency position and width of the corresponding range are the same as the frequency position and width of the interference range Ri, respectively.

[0056] The measurement processing unit 290 measures the object OB based on the interference-removed signal Ts4 generated through interference signal processing. For example, the measurement processing unit 290 analyzes the interference-removed signal Ts4 while appropriately processing it using Fourier transform or the like, thereby measuring the distance, angle, and velocity of the object OB relative to the reflected electromagnetic wave Ew.

[0057] According to the radar device 100 of this embodiment, the evaluation value calculator 240 calculates an evaluation value Vs based on the first frequency domain sample signal Fs1 and the subtraction template signal VFi1 to determine whether a portion of the signal is a true portion of the signal. The interference signal processing unit 210 generates an interference-removed signal Ts4 such that the time-domain signal based on the portion of the signal determined to be a true portion of the signal is included in the corresponding range of the interference-removed signal Ts4. Therefore, it is possible to determine whether the portion of the signal is a true portion of the signal based on the evaluation value Vs (which is calculated based on the first frequency domain sample signal Fs1 and the subtraction template signal VFi1). Therefore, the possibility that the sidelobes included in the first frequency domain sample signal Fs1 are incorrectly identified as true portion of the signal can be reduced. As a result, even if the intensity of the peaks corresponding to these sidelobes appears to be greater than the intensity of the peaks associated with the true portion of the signal, for example, since the multiple sidelobes included in the first frequency domain sample signal Fs1 reinforce each other, the possibility that the sidelobes are incorrectly identified as true portion of the signal can be reduced. Additionally, for example, compared to detecting an object OB using a signal interpolated from a partial signal whose intensity is estimated to be the true part of the signal, the possibility of measuring the object OB with high accuracy by measuring the object OB based on the interference-removed signal Ts4 increases.

[0058] In this embodiment, the evaluation value calculator 240 generates a comparison signal Cs by subtracting a first subtraction signal Ss1 from a first frequency domain sample signal Fs1, and calculates an evaluation value Vs based on the difference between the first frequency domain sample signal Fs1 and the comparison signal Cs. Therefore, the evaluation value Vs can be calculated based on the difference between the first frequency domain sample signal Fs1 and the comparison signal Cs.

[0059] In this embodiment, the evaluation value calculator 240 calculates the evaluation value Vs as the sum of the differences between the absolute value of the first frequency domain sample signal Fs1 and the absolute value of the comparison signal Cs. As a result, the evaluation value Vs can be easily calculated as a value reflecting the amplitude and phase differences between the first frequency domain sample signal Fs1 and the comparison signal Cs. Therefore, it is possible to more accurately determine whether a partial signal is a true partial signal.

[0060] In this embodiment, the interference signal processing unit 210 has a peak extraction unit 235 that extracts at least one peak Ps included in the first frequency domain sample signal Fs1. An evaluation value calculator 240 calculates an evaluation value Vs to determine whether a portion of the signal within the peak range is the true portion of each extracted peak Ps. As a result, since the evaluation value Vs is calculated for each peak Ps, the evaluation value Vs can be calculated more efficiently, for example, compared to calculating the evaluation value Vs for the entire signal value of the first frequency domain sample signal Fs1.

[0061] In this embodiment, the interference signal processing unit 210 includes a selection unit 244, which is configured to select one or more partial signals as true partial signals based on an evaluation value Vs, and record the frequency position information PP of the selected partial signals. The interference signal processing unit 210 generates an interference-removed signal Ts4, such that the time-domain signal generated based on the frequency position of the selected partial signals is included in the corresponding range. Therefore, one or more partial signals can be selected as true partial signals based on the evaluation value Vs, and an interference-removed signal Ts4 can be generated, allowing interpolation of the corresponding range based on the frequency position of the selected partial signals. Furthermore, since the frequency position information PP of the selected partial signals is recorded, the interpolation of the modified sample signal Ts2 and the update of the first frequency domain sample signal Fs1 can be easily performed by referring to the recorded frequency position information PP.

[0062] In this embodiment, the interference signal processing unit 210 has an interpolation signal generator 265 that generates an interpolated signal Ts3 based on the frequency position of a selected portion of the signal. The interference signal processing unit 210 generates an interference-removed signal Ts4 by interpolating a modified sample signal Ts2 based on the interpolated signal Ts3. Therefore, for example, compared to directly generating the interference-removed signal Ts4 by transforming the last generated updated signal Fs1R into the time domain, the noise included in the corresponding range of the interference-removed signal Ts4 can be reduced because the modified sample signal Ts2 is interpolated based on the interpolated signal Ts3.

[0063] In this embodiment, the updating unit 275 updates the first frequency domain sample signal Fs1 by subtracting the second subtraction signal Ss2 from the first frequency domain sample signal Fs1. As a result, the updated signal Fs1R can be used as the new first frequency domain sample signal Fs1 to repeatedly perform the calculation of the evaluation value Vs and the determination of the partial signal based on the evaluation value Vs. Therefore, it is possible to more accurately determine whether the partial signal contained in the first frequency domain sample signal Fs1 is the true partial signal, and the possibility of accurately measuring the object OB is improved.

[0064] B. Second Embodiment

[0065] like Figure 10 As shown, unlike the first embodiment, the interference signal processing unit 210b in the second embodiment does not have an update unit 275. Furthermore, in this embodiment, the interference signal processing unit 210b repeatedly interpolates the modified sample signal Ts2 and generates an interference-removed signal Ts4 based on the interpolated modified sample signal Ts2. Regarding the configuration of the radar device 100b in the second embodiment, several points are the same as in the first embodiment unless specifically described.

[0066] In this embodiment, the interference signal processing unit 210b executes... Figure 11 The interference signal processing shown is used to generate the interference-removed signal Ts4. Figure 11 In, as described in the first embodiment Figure 3 Steps similar to those are assigned to Figure 3 The same reference numerals are used in the accompanying drawings.

[0067] In step S145b of this embodiment, the difference is different from that described in the first embodiment. Figure 3 In step S145, selection unit 244 selects all peak values ​​Ps whose evaluation value Vs is equal to or greater than a predetermined reference value, and selects a portion of the signal within each peak range of the selected peak values ​​Ps as a partial signal. Furthermore, selection unit 244 records the frequency position of each peak value Ps.

[0068] When it is determined in step S150 that the real portion of the signal has been selected, the interpolation signal generator 265 generates the interpolation signal Ts3b in step S151. The process performed in step S151 is similar to that in... Figure 3 The process performed in step S160 is the same.

[0069] In step S152, interpolator 270 interpolates the modified sample signal Ts2 based on the interpolation signal Ts3b generated in step S151 to generate an interpolated sample signal Ts2R, and uses the interpolated sample signal Ts2R to overwrite the modified sample signal Ts2. Furthermore, in step S152, interpolator 270 records the number of interpolation executions in memory. The number of interpolation executions refers to the cumulative number of times the modified sample signal Ts2 is interpolated based on the interpolation signal Ts3b. For example, in step S152, which is executed first in interference signal processing, "once" is recorded as the number of interpolation executions.

[0070] In step S153, the interpolator 270 determines whether the number of interpolation operations is equal to or less than a predetermined number.

[0071] When it is determined in step S153 that the number of interpolation operations is equal to or less than a predetermined number, the sample signal conversion unit 225 converts the modified sample signal Ts2, which is covered by the interpolated sample signal Ts2R, into a frequency domain signal by means of Fourier transform or the like, and then covers the first frequency domain sample signal Fs1 with the transformed signal in step S154. Then, in the steps following step S125, which is executed again, the covered first frequency domain sample signal Fs1 is processed back into the first frequency domain sample signal Fs1. The process performed in step S154 is essentially the same as the process performed in step S115, except that the interpolated sample signal Ts2R is converted.

[0072] like Figure 11As shown, in this embodiment, steps S125 to S154 are repeated until it is determined in step S130 that no peak Ps has been extracted, until it is determined in step S150 that no true part of the signal has been selected, or until it is determined in step S153 that the number of interpolation operations is not equal to or less than a predetermined number. As a result, the transformation from the modified sample signal Ts2 to the first frequency domain sample signal Fs1 and the transformation from the first frequency domain sample signal Fs1 to the modified sample signal Ts2 are repeatedly performed, and the interpolation of the modified sample signal Ts2 based on the interpolated signal Ts3b is repeatedly performed. The method of interpolating the signal by repeatedly performing the transformation from the time domain to the frequency domain and its inverse transformation in this way is also called the Iterative Method with Adaptive Thresholding (IMAT).

[0073] When no peak is extracted in step S130, when no true partial signal is determined in step S150, or when it is determined in step S153 that the number of interpolation executions is not equal to or less than a predetermined number, the interpolator 270 generates an interference-removed signal Ts4 in step S165b based on the modified sample signal Ts2 at this time (i.e., the last generated interpolated sample signal Ts2R). In this embodiment, the interpolator 270 uses the modified sample signal Ts2 at this time as the interference-removed signal Ts4. As a result, as in the first embodiment, the interference-removed signal Ts4 is generated such that the time-domain signal corresponding to the partial signal determined as the true partial signal is included in the corresponding range.

[0074] The second embodiment also reduces the likelihood that side lobes included in the first frequency domain sample signal Fs1 are incorrectly identified as the true portion of the signal. Furthermore, by measuring the object OB using the interference-removed signal Ts4, the possibility of measuring the object OB with higher accuracy is increased.

[0075] C. Third Embodiment

[0076] like Figure 12 As shown, unlike the first embodiment, the evaluation value calculator 240b of the interference signal processing unit 210c in the third embodiment does not have a first subtraction signal generator 241, a comparison signal generator 242, and a calculation processing unit 243. Furthermore, in this embodiment, the evaluation value calculator 240b calculates the evaluation value Vs based on the cross-correlation function between at least a portion of the first frequency domain sample signal Fs1 and at least a portion of the subtraction template signal VFi1. Regarding the configuration of the radar device 100c in the third embodiment, several points are the same as in the first embodiment unless specifically described.

[0077] In this embodiment, the interference signal processing unit 210b executes... Figure 13The interference signal processing shown is used to generate the interference-removed signal Ts4. Figure 13 In, as described in the first embodiment Figure 3 Steps similar to those are assigned to Figure 3 The same reference numerals are used in the accompanying drawings.

[0078] In this embodiment, when it is determined that a peak value has been extracted in step S130, the evaluation value calculator 240b calculates an evaluation value Vs in step S140b. In this embodiment, the evaluation value calculator 240b calculates the evaluation value Vs of a specific portion of the signal in step S140b as the value of the cross-correlation function between the first frequency domain sample signal Fs1 and the subtraction template signal VFi1. Each portion of the first frequency domain sample signal Fs1 is convolved with a sidelobe generated by multiplying the sample signal Ts by the subtraction signal Ti. Therefore, when the frequency position of the main lobe of the subtraction signal Ti overlaps with the frequency position of the true portion of the sample signal Ts, the value of the cross-correlation function is larger than when the frequency position of the main lobe of the subtraction signal Ti overlaps with the frequency position of the sidelobe of the sample signal Ts. Therefore, for example, the evaluation value Vs of the true portion of the signal is greater than the evaluation value Vs of the sidelobe. In this way, it is possible to determine whether a portion of the signal is a true portion of the signal based on the evaluation value Vs (which is calculated based on the cross-correlation function).

[0079] According to the third embodiment, the evaluation value calculator 240b calculates the evaluation value V based on the cross-correlation function between at least a portion of the first frequency domain sample signal Fs1 and at least a portion of the subtraction template signal VFi1. Therefore, the evaluation value Vs can be calculated more easily based on the cross-correlation function between at least a portion of the first frequency domain sample signal Fs1 and at least a portion of the subtraction template signal VFi1.

[0080] In another embodiment, the interference signal processing unit 210c calculates an evaluation value Vs based on, for example, a cross-correlation function, and then generates an interference-removed signal Ts4 using the IMAT method in the same manner as in the second embodiment. More specifically, in Figure 11 In the interference signal processing shown, step S135 can be omitted, and step S140b can be performed instead of step S140.

[0081] D. Other embodiments

[0082] (D-1) In this embodiment, the sample signal Ts is a digital signal in the time domain. Alternatively, the sample signal Ts can be a digital signal in the time-frequency domain. In this case, the sample signal generator 105 can convert the beat signal Bw into a digital signal in the time-frequency domain, for example, using a short-term Fourier transform (STFT). In this case, for example, in Figure 3In step S105, the interference range determination unit 215 determines the interference range Ri as the time range for each frequency bin. In this case, the interference range Ri can be determined as a different time range for each frequency bin, or it can be determined as the same time range. Furthermore, in step S110, for example, a modified sample signal Ts2 is generated for each frequency bin by multiplying each frequency bin of the sample signal Ts in the time-frequency domain by a reduction signal Ti. Similarly, after step S115, by processing the modified sample signal Ts2, etc., for each frequency bin, an interference-removed signal Ts4 can be generated as a signal in the time-frequency domain. The measurement processing unit 290 converts the interference-removed signal Ts4, which is generated as a signal in the time-frequency domain, into a signal in the time domain by inverse STFT, and appropriately processes and analyzes the signal in the time domain. Therefore, the distance, angle, and velocity relative to the object OB can be measured in the same manner as described in the first embodiment. Note that the sample signal generator 105 can use a transformation method other than STFT (e.g., wavelet transform) to generate the sample signal Ts as a digital signal in the time-frequency domain.

[0083] (D-2) In this embodiment, the evaluation value Vs is calculated as the sum of the absolute values ​​of the first frequency domain sample signal Fs1 and the comparison signal Cs. However, the evaluation value Vs may not be calculated as the sum of the differences between the absolute values ​​of the first frequency domain sample signal Fs1 and the comparison signal Cs. In this case, for example, the evaluation value Vs may be calculated as the sum of the differences between the square of the absolute value of the first frequency domain sample signal Fs1 and the square of the absolute value of the comparison signal Cs.

[0084] (D-3) In this embodiment, the peak extraction unit 235 extracts at least one peak Ps contained in the first frequency domain sample signal Fs1, and the evaluation value calculator 240 calculates an evaluation value Vs to determine whether a portion of the signal within the peak range is the true portion of each extracted peak Ps. However, it is not necessary to calculate the evaluation value Vs for each peak Ps. For example, the evaluation value Vs can be calculated for each frequency band of the first frequency domain sample signal Fs1. In this case, the interference signal processing unit 210 may not have the peak extraction unit 235.

[0085] (D-4) In this embodiment, the selection unit 244 records the frequency position information PP of the selected portion of the signal. However, the selection unit 244 may not record the frequency position information PP of the selected portion of the signal.

[0086] (D-5) In this embodiment, the interpolator 270 generates the interference-removed signal Ts4 by interpolating the modified sample signal Ts2 based on the interpolated signal Ts3. However, the interference-removed signal Ts4 can be generated without interpolating the modified sample signal Ts2 based on the interpolated signal Ts3. In this case, for example, the interference-removed signal Ts4 can be generated by performing an inverse Fourier transform on the last generated updated signal Fs1R among the updated signals Fs1R described in the first embodiment. In this case, the updated signal Fs1R can undergo an inverse Fourier transform after setting the signal strength to 0 in the frequency range of the last generated updated signal Fs1R, except for the frequency position corresponding to the real part of the signal.

[0087] (D-6) In this embodiment, the Fourier transform is used as the method for transforming each signal from the time domain to the frequency domain, but other methods such as wavelet transform can also be used. The same applies to methods for transforming from the frequency domain to the time domain.

[0088] E. Other:

[0089] This disclosure should not be limited to the above embodiments, and various other embodiments can be implemented without departing from the scope of this disclosure. For example, to solve some or all of the above problems, or to achieve some or all of the above effects, the technical features in the embodiments can be appropriately replaced or combined. In addition, some technical features may be appropriately omitted.

[0090] The control apparatus and methods described in this disclosure can be implemented by a dedicated computer configured with memory and a processor programmed to execute one or more specific functions embodied in a computer program stored in memory. Alternatively, the control apparatus and methods described in this disclosure can be implemented by a dedicated computer configured with a processor having one or more dedicated hardware logic circuits. Alternatively, the control apparatus and methods described in this disclosure can be implemented by one or more dedicated computers configured as: a combination of a processor and memory programmed to perform one or more functions; and a processor configured with one or more hardware logic circuits. The computer program can be stored in a computer-readable, non-transitory tangible storage medium as instructions executable by a computer.

[0091] According to a first aspect of this disclosure, a radar device includes:

[0092] A transmitter configured to transmit a signal as an electromagnetic wave;

[0093] A receiver configured to receive a reflected wave representing an electromagnetic wave reflected by an object as a received signal;

[0094] A beat signal generator configured to generate a beat signal based on the transmitted signal and the received signal;

[0095] A sample signal generator configured to generate a sample signal based on the clock signal, the sample signal being a digital signal in the time domain or time-frequency domain; and

[0096] An interference signal processing unit is configured to generate an interference-removed signal obtained by removing interference components from the sample signal, wherein...

[0097] The interference signal processing unit includes:

[0098] An interference range determination unit is configured to determine an interference range, which represents the range in which the sample signal contains the interference component.

[0099] The modified sample signal generator is configured to generate the modified sample signal by multiplying the sample signal by a reduction signal used to reduce the signal strength in the interference range.

[0100] A sample signal conversion unit is configured to convert the modified sample signal into a first frequency domain sample signal in the frequency domain.

[0101] A signal reduction conversion unit configured to convert the reduced signal into a subtraction template signal in the frequency domain; and

[0102] An evaluation value calculator, configured to calculate an evaluation value based on the first frequency domain sample signal and the subtraction template signal, to determine whether a portion of the signal representing at least a part of the first frequency domain sample signal is derived from the reflected wave, and

[0103] The interference signal processing unit generates the interference-removed signal such that the time-domain signal, which is determined to be a portion of the signal derived from the reflected wave based on the evaluation value, is included in the corresponding range that corresponds to the interference range of the interference-removed signal.

[0104] According to the second aspect, the evaluation value calculator in the first aspect is configured to: generate a first subtraction signal by correcting the frequency position, amplitude, and phase of the subtraction template signal based on the frequency position, amplitude, and phase of the target partial signal, respectively, within a frequency range that includes at least the frequency with the largest amplitude in the subtraction template signal, the target partial signal representing the partial signal to be determined based on the evaluation value; generate a comparison signal by subtracting the first subtraction signal from the first frequency domain sample signal; and calculate an evaluation value of the target partial signal based on the difference between the first frequency domain sample signal and the comparison signal.

[0105] According to the third aspect, the evaluation value calculator in the second aspect calculates the evaluation value of the target partial signal as the sum of the differences between the absolute value of the first frequency domain sample signal and the absolute value of the comparison signal.

[0106] According to the fourth aspect, the evaluation value calculator in the first aspect calculates the evaluation value based on the cross-correlation function between at least a portion of the first frequency domain sample signal and at least a portion of the subtraction template signal.

[0107] According to the fifth aspect, the interference signal processing unit in any one of the first to fourth aspects has a peak extraction unit, the peak extraction unit being configured to extract at least one peak contained in the first frequency domain sample signal, and the evaluation value calculator calculating the evaluation value for each peak based on the first frequency domain sample signal and the subtraction template signal to determine whether a portion of the signal in the frequency range including the frequency position of the peak is derived from the reflected wave.

[0108] According to the sixth aspect, the interference signal processing unit in any one of the first to fifth aspects has a selection unit configured to select one or more partial signals as partial signals derived from the reflected wave based on the evaluation value, and record information about the frequency position of the selected partial signals, the selected partial signals representing the partial signals selected by the selection unit; and the interference signal processing unit generates the interference-removed signal such that the time-domain signal generated based on the frequency position of the selected partial signals is included in the corresponding range.

[0109] According to the seventh aspect, the interference signal processing unit in the sixth aspect has an interpolation signal generator configured to generate a time-domain interpolation signal to interpolate a range corresponding to the interference range in a modified sample signal based on the frequency position of a selected portion of the signal, and the interference signal processing unit generates the interference-removed signal by interpolating the modified sample signal based on the interpolation signal.

[0110] Eighthly, the interference signal processing unit in the sixth or seventh aspect further comprises an update unit configured to update the first frequency domain sample signal, wherein the update unit generates a second subtraction signal by correcting the frequency position, amplitude, and phase of the subtraction template signal based on the frequency position, amplitude, and phase of a selected portion of the signal in a frequency range that includes at least the subtraction template signal having the maximum amplitude, and the update unit updates the first frequency domain sample signal by subtracting the second subtraction signal from the first frequency domain sample signal.

Claims

1. A radar device, comprising: A transmitter configured to transmit a signal (Tw) as an electromagnetic wave (Ew); A receiver configured to receive a reflected wave representing the electromagnetic wave reflected by the object (OB) as a received signal (Dw); A beat signal generator configured to generate a beat signal (Bw) based on the transmitted signal and the received signal; A sample signal generator is configured to generate a sample signal (Ts) based on the beat signal, wherein the sample signal (Ts) is a digital signal in the time domain or the time-frequency domain; as well as An interference signal processing unit is configured to generate an interference-removed signal (Ts4) obtained by removing the interference component (Ci) from the sample signal, wherein... The interference signal processing unit includes: An interference range determination unit is configured to determine an interference range (Ri), which represents the range in which the interference component is included in the sample signal; The generator of the modified sample signal is configured to generate the modified sample signal (Ts2) by multiplying the sample signal by a reduction signal (Ti), the reduction signal being used to reduce the signal strength in the interference range; A sample signal conversion unit is configured to convert the modified sample signal into a first frequency domain sample signal (Fs1) in the frequency domain; A signal reduction conversion unit is configured to convert the reduced signal into a subtraction template signal (VFi1) in the frequency domain; and An evaluation value calculator, configured to calculate an evaluation value (Vs) based on the first frequency domain sample signal and the subtraction template signal, in order to determine whether a portion of the signal representing at least a part of the first frequency domain sample signal is derived from the reflected wave, and The interference signal processing unit generates the interference-removed signal such that the time-domain signal based on the partial signal is included in a corresponding range corresponding to the interference range of the interference-removed signal, the partial signal being determined to be derived from the reflected wave based on the evaluation value.

2. The radar device according to claim 1, wherein, The evaluation value calculator is configured as follows: A first subtraction signal is generated by correcting the frequency position, amplitude, and phase of the subtraction template signal based on the frequency position, amplitude, and phase of the target partial signal, respectively, within a frequency range that includes at least the frequency with the largest amplitude in the subtraction template signal, wherein the target partial signal represents the partial signal to be determined based on the evaluation value; The comparison signal (Cs) is generated by subtracting the first subtraction signal from the first frequency domain sample signal; as well as The evaluation value of the target portion of the signal is calculated based on the difference between the first frequency domain sample signal and the comparison signal.

3. The radar device according to claim 2, wherein, The evaluation value calculator calculates the evaluation value of the target portion signal as the sum of the differences between the absolute value of the first frequency domain sample signal and the absolute value of the comparison signal.

4. The radar device according to claim 1, wherein, The evaluation calculator calculates the evaluation value based on the cross-correlation function between at least a portion of the first frequency domain sample signal and at least a portion of the subtraction template signal.

5. The radar device according to claim 1, wherein, The interference signal processing unit includes a peak extraction unit configured to extract at least one peak value (Ps) included in the first frequency domain sample signal. The evaluation value calculator calculates the evaluation value for each peak based on the first frequency domain sample signal and the subtraction template signal, in order to determine whether the portion of the signal in the frequency range including the frequency position of the peak is derived from the reflected wave.

6. The radar device according to any one of claims 1 to 5, wherein, The interference signal processing unit has a selection unit configured to: select one or more partial signals as the partial signals derived from the reflected wave based on the evaluation value, and record information about the frequency position of the selected partial signals, wherein the selected partial signals represent the partial signals selected by the selection unit; as well as The interference signal processing unit generates the interference-removed signal, such that the time-domain signal generated based on the frequency position of the selected portion of the signal is included in the corresponding range.

7. The radar device according to claim 6, wherein, The interference signal processing unit includes an interpolation signal generator configured to generate a time-domain interpolation signal (Ts3) to interpolate a range corresponding to the interference range into the modified sample signal based on the frequency position of a selected portion of the signal. The interference signal processing unit generates the interference-removed signal by interpolating the modified sample signal based on the interpolated signal.

8. The radar device according to claim 6, wherein, The interference signal processing unit further includes an update unit configured to update the first frequency domain sample signal. The updating unit generates the second subtraction signal by: correcting the frequency position, amplitude, and phase of the subtraction template signal based on the frequency position, amplitude, and phase of a selected portion of the signal, within a frequency range that includes at least the frequency with the maximum amplitude of the subtraction template signal; and The updating unit updates the first frequency domain sample signal by subtracting the second subtraction signal from the first frequency domain sample signal.

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