Radar equipment and signal processing program

Abstract

To more preferably reduce an effect of an interference wave in a received signal than before under an environment where radio wave interference occurs.SOLUTION: Parameters in a formula indicating a waveform of an interference wave by taking a frequency of an inference wave as one being linearly changed, and taking an interference start time Tb, a chirp inclination K, an amplitude A, and a phase θ as parameters are estimated. The parameter estimation includes processing of calculating a coefficient vector x in an operational expression indicating a received waveform vector y of N rows and one column corresponding to a waveform of a received wave by a product of a dictionary matrix D of N rows and M columns as an aggregate of base vectors corresponding to a combination of the interference start time Tb and the chirp inclination K, and a coefficient vector x of M rows and one column including an amplitude A and a phase θ so as to include only one non-zero component and the other zero components, by using an orthogonal tracking algorithm. The waveform of the interference wave is estimated by the one base vector.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a radar device and a signal processing program executed by the radar device. [Background technology]

[0002] For example, radar systems are known that are mounted on vehicles and detect targets such as other vehicles and stationary objects in the vicinity of the vehicle. Such radar systems may experience radio wave interference with radar systems mounted on other vehicles. In systems that extract various information using the Fourier analysis results of beat signals, such as FMCW radar, radio wave interference raises the noise floor of the frequency spectrum obtained by Fourier transforming the time waveform. As a result, peaks based on the waves reflected from the target are buried in the noise floor, making target detection difficult. Note that FMCW stands for Frequency Modulated Continuous Wave.

[0003] Various proposals have been made to realize stable radar device operation even when radio wave interference as described above occurs. For example, a radar device described in Patent Document 1 includes an object information calculation unit that calculates object information based on a received signal, an interference situation analysis unit that measures the surrounding radio wave interference situation between a predetermined minimum frequency and a maximum frequency during a search and modulation operation period that does not overlap with a modulation operation period, and a band selection unit that selects the frequency band of a transmission signal based on the radio wave interference situation measured by the interference situation analysis unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6744481 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, the radar device described in Patent Document 1 measures the radio wave interference situation around the vehicle, searches for a frequency band with less interference, and selects that frequency band as the frequency band for subsequent transmission signals. This allows the radar device to operate stably even when radio wave interference occurs. However, for example, when there are many other vehicles around the vehicle, it can be difficult to search for a frequency band with less interference.

[0006] On the other hand, it is also possible to achieve stable operation of a radar device by reducing the influence of interference waves on a received signal through signal processing of the received signal. Various techniques of this type have been proposed in the past. The present invention has been made in consideration of the circumstances exemplified above. That is, the present invention provides a technique that can more effectively reduce the influence of interference waves on a received signal than conventional techniques, for example, in an environment where radio wave interference occurs. [Means for solving the problem]

[0007] The radar device (1) according to claim 1 comprises: a transmission signal generating unit (51) that generates a transmission signal (TX) that is an electrical signal having a predetermined frequency change corresponding to the frequency modulation mode of the transmission wave, so that the transmission wave, which is a frequency-modulated radar wave, is transmitted from a transmission antenna (2); a signal processing unit (7) that performs interference suppression processing on a received signal (RX), which is an electrical signal corresponding to a received wave that is a radar wave received by a receiving antenna (3), based on a signal processing result including detection processing based on the transmitted signal, to suppress the influence of an interference wave included in the received wave; Equipped with The interference suppression process includes: a waveform estimation process for estimating a waveform of the interference wave; a subtraction process of subtracting the estimated waveform of the interference wave from the waveform of the received wave; Including, The waveform estimation process includes: a parameter estimation process for estimating parameters in a mathematical formula representing a waveform of the interference wave, the parameters being an interference start time Tb corresponding to the time when the frequency becomes a predetermined value, a chirp slope K which is the slope of the time change of the frequency, an amplitude A, and a phase θ, assuming that the frequency of the interference wave changes linearly with time; the parameter estimation process includes a process of calculating, using an orthogonal matching pursuit algorithm, a received waveform vector y of N rows and 1 column corresponding to the waveform of the received wave, expressed as the product of an N row and M column dictionary matrix D which is a set of basis vectors corresponding to a combination of the interference start time Tb and the chirp slope K, and an M row and 1 column coefficient vector x including the amplitude A and the phase θ, in an arithmetic expression y=Dx, such that the coefficient vector x includes only one non-zero component and the rest are zero components; The waveform of the interference wave is estimated using one of the basis vectors. The signal processing program according to claim 10 is a program executed by the signal processing unit, The interference suppression processing executed by the signal processing unit includes: a waveform estimation process for estimating a waveform of the interference wave; a subtraction process of subtracting the estimated waveform of the interference wave from the waveform of the received wave; Including, The waveform estimation process includes: a parameter estimation process for estimating parameters in a mathematical formula representing a waveform of the interference wave, the parameters being an interference start time Tb corresponding to the time when the frequency becomes a predetermined value, a chirp slope K which is the slope of the time change of the frequency, an amplitude A, and a phase θ, assuming that the frequency of the interference wave changes linearly with time; the parameter estimation process includes a process of calculating, using an orthogonal matching pursuit algorithm, a received waveform vector y of N rows and 1 column corresponding to the waveform of the received wave, expressed as the product of an N row and M column dictionary matrix D which is a set of basis vectors corresponding to a combination of the interference start time Tb and the chirp slope K, and an M row and 1 column coefficient vector x including the amplitude A and the phase θ, in an arithmetic expression y=Dx, such that the coefficient vector x includes only one non-zero component and the rest are zero components; The waveform of the interference wave is estimated using one of the basis vectors.

[0008] In addition, in each section of the application documents, each element may be given a reference symbol in parentheses. However, such reference symbol merely indicates an example of the correspondence between the element and the specific means described in the embodiment described below. Therefore, the present invention is not limited in any way by the above-mentioned reference symbols. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a schematic configuration of a radar device according to an embodiment of the present invention; [Figure 2] 10 is a distance map showing a comparison of the Fourier transform results of the received waveform when there is interference and when there is no interference. [Figure 3] 2 is a diagram showing an example of output signals in the in-phase signal AD converter and the quadrature phase signal AD converter shown in FIG. 1 in the form of time waveforms. [Figure 4] 10A and 10B are diagrams illustrating time variations in the frequencies of a local signal, a received signal (before frequency downmixing), and a received signal (after frequency downmixing). [Figure 5] FIG. 5 is a diagram showing a change over time in beat frequency of an interference wave having the frequency characteristics shown in FIG. [Figure 6] FIG. 10 is a conceptual diagram showing an outline of a waveform estimation process when an orthogonal matching pursuit algorithm is used as a commonly known method as a comparative example. [Figure 7] FIG. 1 is a conceptual diagram illustrating an example of a waveform estimation process using an orthogonal matching pursuit algorithm in one embodiment of the present invention. [Figure 8] FIG. 1 is a conceptual diagram illustrating an example of a waveform estimation process using an orthogonal matching pursuit algorithm in one embodiment of the present invention. [Figure 9] FIG. 1 is a conceptual diagram illustrating an example of a waveform estimation process using an orthogonal matching pursuit algorithm in one embodiment of the present invention. [Figure 10] FIG. 1 is a conceptual diagram illustrating an example of a waveform estimation process using an orthogonal matching pursuit algorithm in one embodiment of the present invention. [Figure 11] FIG. 1 is a conceptual diagram illustrating an example of a waveform estimation process using an orthogonal matching pursuit algorithm in one embodiment of the present invention. [Figure 12] FIG. 1 is a conceptual diagram illustrating an example of a waveform estimation process using an orthogonal matching pursuit algorithm in one embodiment of the present invention. [Figure 13] 10 is a table illustrating an example of how the value of chirp slope K converges through waveform estimation processing using an orthogonal matching pursuit algorithm in one embodiment of the present invention. [Figure 14] 10 is a table illustrating an example of how the value of interference start time Tb converges through waveform estimation processing using an orthogonal matching pursuit algorithm in one embodiment of the present invention. [Figure 15A] 10A and 10B are diagrams illustrating how interference waves are removed from received waves according to an embodiment of the present invention. [Figure 15B] 10A and 10B are diagrams illustrating how interference waves are removed from received waves according to an embodiment of the present invention. [Figure 16] FIG. 10 illustrates the reduction of the noise floor in the distance FFT spectrum according to an embodiment of the present invention. [Figure 17] FIG. 10 is a diagram showing how two interference waves are removed from a received wave according to an embodiment of the present invention. [Figure 18] 10 is a flowchart illustrating a specific example of an interference suppression process according to an embodiment of the present invention. [Figure 19] 10 is a flowchart illustrating another specific example of the interference suppression process according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Embodiment) Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that various modifications applicable to one embodiment may be hindered from being understood if they are introduced in the middle of a series of explanations relating to the embodiment. Therefore, the modifications will be described together after the explanation of the embodiment.

[0011] (composition) The radar device 1 shown in FIG. 1 is mounted on a vehicle and configured to detect targets such as other vehicles and stationary objects around the vehicle. Hereinafter, the vehicle equipped with the radar device 1 according to this embodiment shown in FIG. 1 will be referred to as the "host vehicle." The radar device 1 mounted on the host vehicle will be referred to as the "host device." The radar device 1 according to this embodiment includes a transmitting antenna 2, a receiving antenna 3, and a control unit 4. The transmitting antenna 2 is configured to transmit a transmitting wave, which is a radar wave in the microwave or millimeter wave band, toward a space outside the host vehicle. The receiving antenna 3 is configured to receive a receiving wave, which is a radar wave in a frequency band corresponding to the transmitting wave. That is, the radar device 1 transmits a transmitting wave within a predetermined frequency band toward a space outside the vehicle and receives a receiving wave within the frequency band from the space outside the vehicle. The control unit 4 is electrically connected to the transmitting antenna 2 and the receiving antenna 3. In this embodiment, the radar device 1 has a configuration as a so-called FMCW radar. That is, the radar device 1 is configured to transmit and receive frequency-modulated radar waves.

[0012] The control unit 4 includes a transmission circuit section 5, a reception circuit section 6, and a signal processing section 7. The transmission circuit section 5 is electrically connected to the transmission antenna 2 and configured to transmit a transmission wave from the transmission antenna 2. The reception circuit section 6 is electrically connected to the reception antenna 3 and configured to perform various signal processing such as amplification and detection processing on an RF signal generated by reception of a reception wave by the reception antenna 3. The signal processing section 7 is electrically connected to the transmission circuit section 5 and the reception circuit section 6 so as to be able to communicate signals. The signal processing section 7 controls the operation of the transmission circuit section 5 to control the frequency and transmission timing of the transmission wave, and is configured to perform various processing including interference suppression processing, which will be described later, based on the signal processing results by the reception circuit section 6.

[0013] The transmission circuit unit 5 includes a transmission signal generation unit 51, a distributor 52, and a transmission-side amplifier 53. The transmission signal generation unit 51 is configured to generate a transmission signal TX for transmitting a transmission wave, which is a frequency-modulated radar wave, from the transmission antenna 2, and output the transmission signal TX to the distributor 52. The transmission signal TX is an electrical signal having a predetermined frequency change corresponding to the frequency modulation mode of the transmission wave. Specifically, the transmission signal generation unit 51 includes a phase-locked control circuit (i.e., a PLL circuit), a voltage-controlled oscillator (i.e., a VCO), and the like. PLL stands for Phase Locked Loop. VCO stands for Voltage Control Oscillator. Note that configurations for generating a transmission signal TX using a phase-locked control circuit or a voltage-controlled oscillator were already publicly known or well-known at the time of filing of the present application (see, for example, Japanese Patent Application Laid-Open Nos. 2010-71899, 2011-12960, and 2016-219938). Therefore, further detailed description of the configuration of the transmission signal generation unit 51 will be omitted in this specification. The divider 52 is interposed in the signal transmission path between the transmission signal generation unit 51 and the transmission-side amplifier 53, and is configured to distribute power of the transmission signal TX output from the transmission signal generation unit 51 to the transmission-side amplifier 53 and the receiving circuit unit 6. A signal having the same frequency characteristics as the transmission signal TX and distributed to the receiving circuit unit 6 by the divider 52 will be referred to as the "local signal LO" hereinafter. The configuration for distributing the local signal LO from the transmission signal TX by the divider 52 was also already publicly known or well-known at the time of filing this application, so further detailed description will be omitted in this specification. The transmission-side amplifier 53 is interposed in the signal transmission path between the divider 52 and the transmitting antenna 2, and is configured to power-amplify the transmission signal TX and output it to the transmitting antenna 2.

[0014] The receiving circuit unit 6 includes a receiving amplifier 61, a phase shifter 62, an in-phase signal mixer 63, a quadrature-phase signal mixer 64, an in-phase signal filter 65, a quadrature-phase signal filter 66, an in-phase signal AD converter 67, and a quadrature-phase signal AD converter 68. The receiving amplifier 61 is electrically connected to the receiving antenna 3. The receiving amplifier 61 is configured to generate a receiving signal RX by amplifying an RF signal generated by the receiving antenna 3 receiving a receiving wave. In other words, the receiving signal RX is an electrical signal corresponding to the receiving wave, which is a radar wave received by the receiving antenna 3.

[0015] The phase shifter 62 is interposed in the signal transmission path between the divider 52 and the quadrature-phase signal mixer 64 and is configured to shift the phase of the local signal LO by -90 degrees. The in-phase signal mixer 63 and the quadrature-phase signal mixer 64 are arranged in parallel at the output destination of the received signal RX from the receiving amplifier 61. The in-phase signal mixer 63 and the quadrature-phase signal mixer 64 are configured to perform so-called quadrature detection processing on the received signal RX based on the transmission signal TX, i.e., the local signal LO. Specifically, the in-phase signal mixer 63 mixes the local signal LO and the received signal RX to generate an I component, which is the real part of an IF signal corresponding to the frequency difference between the two, and outputs the I component to the in-phase signal filter 65. The IF signal is an abbreviation for an intermediate frequency signal. The quadrature-phase signal mixer 64 mixes the local signal LO, whose phase has been shifted by the phase shifter 62, with the received signal RX to generate a Q component, which is the imaginary part of the IF signal, and outputs the Q component to the quadrature-phase signal filter 66. Note that the above-described configuration for generating the I and Q components of an IF signal using a local signal LO and a signal obtained by phase-shifting the local signal LO was already publicly known or well-known at the time of filing of the present application (see, for example, Japanese Patent Application Laid-Open Nos. 2021-47111, 2014-153216, and 2001-91639). Therefore, further detailed description of the phase shifter 62, in-phase signal mixer 63, and quadrature-phase signal mixer 64 will be omitted in this specification.

[0016] The in-phase signal filter 65 is a low-pass filter having a predetermined cutoff frequency and is provided to perform filtering on the output of the in-phase signal mixer 63. The quadrature-phase signal filter 66 is a low-pass filter having the same cutoff frequency as the in-phase signal filter 65 and is provided to perform filtering on the output of the quadrature-phase signal mixer 64. The in-phase signal AD converter 67 is provided to analog-to-digital convert the output signal of the in-phase signal filter 65 and output the converted signal to the signal processing unit 7. The quadrature-phase signal AD converter 68 is provided to analog-to-digital convert the output signal of the quadrature-phase signal filter 66 and output the converted signal to the signal processing unit 7.

[0017] The signal processing unit 7 is configured to perform various operations, including target detection, based on the signal processing results, including detection processing, of the received signal RX by the receiving circuit unit 6. In this embodiment, the signal processing unit 7 is configured as a digital signal processing unit that processes the digital signals, i.e., beat signals, output from the in-phase signal AD converter 67 and the quadrature-phase signal AD converter 68 to perform interference suppression processing for suppressing the influence of interference waves contained in the received waves. Specifically, the signal processing unit 7 is an on-board microcomputer including a processor 71 and a memory 72, and is configured so that the processor 71 reads and executes programs from the memory 72 (e.g., a flash memory), which is a non-transient tangible storage medium, to perform various types of digital signal processing, including interference suppression processing.

[0018] (Operation overview) Below, with reference to the drawings, we will explain the outline of the operation of the radar device 1 according to this embodiment and the outline of the execution of the signal processing program executed by the signal processing unit 7 provided in the radar device 1, along with the effects achieved by these. In the following explanation, the radar device 1 according to this embodiment and the signal processing method and signal processing program executed by the signal processing unit 7 may be collectively referred to simply as "this embodiment."

[0019] The transmission signal generation unit 51 generates a transmission signal TX having a predetermined frequency change corresponding to the frequency modulation mode of the transmission wave, and outputs it to the transmission-side amplifier 53. The transmission signal TX output from the transmission signal generation unit 51 is distributed by the distributor 52 into a transmission signal TX that is output to the transmission-side amplifier 53 and a local signal LO that is output to the receiving circuit unit 6. The transmission signal TX input to the transmission-side amplifier 53 is power-amplified by the transmission-side amplifier 53 and output to the transmission antenna 2. As a result, a transmission wave having a predetermined frequency modulation is transmitted from the transmission antenna 2 toward the space outside the vehicle.

[0020] When the receiving antenna 3 receives a radar wave (e.g., a desired wave) in a frequency band corresponding to the transmitted wave, the receiving antenna 3 outputs an RF signal. The "desired wave" is a wave reflected from a target of the transmitted wave transmitted from the device itself. The receiving amplifier 61 amplifies the RF signal to generate a received signal RX. The received signal RX is output to an in-phase signal mixer 63 and a quadrature-phase signal mixer 64, which are arranged in parallel with each other.

[0021] The received signal RX input to the in-phase signal mixer 63 is mixed with the local signal LO in the in-phase signal mixer 63. This generates an I component, which is the real part of the IF signal. This I component is filtered by the in-phase signal filter 65 and analog-to-digital converted by the in-phase signal AD converter 67, and then output to the signal processing unit 7. The received signal RX input to the quadrature-phase signal mixer 64 is mixed with the local signal LO, which has been phase-shifted by the phase shifter 62, in the quadrature-phase signal mixer 64. This generates a Q component, which is the imaginary part of the IF signal. This Q component is filtered by the quadrature-phase signal filter 66 and analog-to-digital converted by the quadrature-phase signal AD converter 68, and then output to the signal processing unit 7. In other words, a beat signal, which is a signal obtained by converting an IF signal, which is an analog signal having an I component and a Q component and whose band has been limited by a low-pass filter, into a digital signal, is output to the signal processing unit 7.

[0022] When the beat signal is input, the signal processing unit 7 performs various digital signal processing such as FFT on the beat signal. FFT is an abbreviation for fast Fourier transform. This allows the distance to the target and the relative velocity to be calculated. The FFT performed by the signal processing unit 7 includes a so-called distance FFT. The distance FFT is an FFT in the time series direction of the beat signal. The time series direction corresponds to the distance direction, which is the distance to the target. The result of the distance FFT processing is the frequency spectrum of the beat signal, and the power (i.e., electric power) level for each frequency of the beat signal.

[0023] However, as devices similar to the radar device 1 according to this embodiment that detect targets by transmitting and receiving radar waves become widespread, concerns arise about radio wave interference due to interference waves from other vehicles. Such radio wave interference raises the noise floor in the distance FFT spectrum, i.e., the distance map, as shown in FIG. 2 . This causes peaks based on the desired wave to be buried in the noise floor, making target detection difficult. In particular, as shown in FIG. 3 , interference waves tend to have a larger voltage amplitude than the desired wave. This is because the voltage amplitude of interference waves propagating directly from other devices to the radar device is inversely proportional to the square of the distance, while the voltage amplitude of the desired wave reflected from the radar device and received by the radar device is inversely proportional to the fourth power of the distance. Therefore, in this embodiment, the signal processing unit 7 performs interference suppression processing to estimate the waveform of the interference wave and subtract, or remove, the waveform of the interference wave from the waveform of the received wave to suppress the influence of the interference wave contained in the received wave. The following describes in detail the waveform estimation process for estimating the waveform of an interference wave and the subtraction process for subtracting the waveform of an interference wave from the waveform of a received wave, both of which are included in the interference suppression process.

[0024] FIG. 4 shows the frequency characteristics of the RF and IF signals of the desired and interference waves. LPFis the cutoff frequency of the in-phase signal filter 65 and the quadrature-phase signal filter 66, which are low-pass filters. As shown in FIG. 4, the frequency of the interference wave changes linearly over time, with a different slope from that of the desired wave. Specifically, for example, FIG. 4 shows an example in which the RF signal in the interference wave has a steeper slope than the RF signal in the desired wave. In this case, the IF signal in the desired wave is represented by a horizontal line with a constant frequency. In contrast, the IF signal in the interference wave is represented by a straight line sloping downward to the right, with the frequency decreasing over time. That is, as shown in FIG. 5, the beat frequency of the interference wave is +F LPF Starts with -F LPF This means that the IF signal in the interference wave is +F LPF Starts with -F LPF Since the frequency spectrum has frequency components ending in , the entire floor will rise, as shown in Figure 2.

[0025] 5, the chirp gradient K indicates the rate of change over time, i.e., the gradient, of the frequency of the IF signal in the interference wave, i.e., the beat frequency. Here, the interference start time Tb is the time when the beat frequency of the interference wave is a predetermined value + F LPF On the other hand, the interference end time Te corresponds to the time when the beat frequency of the interference wave reaches a predetermined value -F LPF Then, the beat frequency of the interference wave is expressed by the following formulas (1) and (2). In formula (1), F(t) represents the beat frequency of the interference wave, and t represents the time, i.e., the duration.

number

number

[0026] Phase is the time integral of frequency. More precisely, phase is the time integral of the angular frequency obtained by multiplying frequency by 2π. Therefore, phase can be expressed as in the following equation (3), where θ is an integral constant.

number

[0027] Therefore, the interference wave can be expressed by the following equation (4): Generally, in a radar transmission wave, the amplitude A does not change over time, so the amplitude A is taken to be a constant.

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[0028] Furthermore, in this embodiment, the receiving circuit unit 6 has the configuration of a so-called IQ receiver. Therefore, the interference wave has a complex waveform, and a real waveform obtained by taking its real part is observed at the RX_I terminal (i.e., the output terminal of the in-phase signal AD converter 67). Furthermore, a real waveform obtained by taking its imaginary part is observed at the RX_Q terminal (i.e., the output terminal of the quadrature phase signal AD converter 68). The waveform of the real part can be expressed as in the following equation (5). The waveform of the imaginary part can be expressed as in the following equation (6).

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[0029] Here, the above formula (4) is transformed into the following formula (7), and θ in the formula is newly defined as a phase.

number

[0030] Here, the interference end time Te can be calculated from the interference start time Tb and the chirp slope K. Therefore, the following four unknown parameters are included in equation (7) which shows the waveform of the interference wave. By estimating these parameters, it is possible to estimate the waveform of the interference wave. In other words, the waveform estimation process includes a parameter estimation process for estimating these parameters. This embodiment uses sparse modeling for the parameter estimation process. Specifically, this embodiment uses the orthogonal matching pursuit algorithm, which is one of various sparse modeling techniques. Hereinafter, orthogonal matching pursuit will be abbreviated as OMP. OMP stands for Orthogonal Matching Pursuit. Interference start time Tb Chirp slope K of interference wave Interference wave amplitude A Interference wave phase θ

[0031] Next, an outline of the OMP algorithm used in this embodiment will be described. First, the received waveform vector y corresponding to the waveform of the received wave including the desired wave and the interference wave is expressed by the formula y=Dx. The received waveform vector y is a vector with N rows and 1 column. The dictionary matrix D is a matrix of basis vectors Φ corresponding to the combination of the interference start time Tb and the chirp slope K. k is a matrix with N rows and M columns, where M>N and k=1,2,…,M. The basis vector Φ k is an N-by-1 vector with a norm of 1. Also, the basis vector Φ k The phase of is set to 0. The dictionary matrix D is a basis vector Φ k That is, it is a set of chirplets. The coefficient vector x is an M-row, 1-column vector containing an amplitude A and a phase θ. Then, the coefficient vector x in the following simultaneous equations is found as a solution. y=Dx D=[Φ1Φ2…Φ M ]

[0032] When M=N, there is only one solution. On the other hand, when M>N, there are an infinite number of solutions. Generally, in the OMP algorithm, to find the coefficient vector x, which is the solution to the above simultaneous equations, the component x of the coefficient vector x is k are calculated one by one, starting from the one with the largest amplitude. Specifically, first, the received waveform vector y and each basis vector Φ k Calculate the complex inner product with the received waveform vector y and find the basis vector Φ that maximizes the complex inner product with k , that is, the basis vector Φ that has the highest correlation with the received waveform vector y k Then, find the basis vector Φ k x[1] is calculated from the component x k Only the non-zero component is x j (j≠k) are all vectors with zero components. That is, x[1] is a vector with only one non-zero component and the rest are zero components. Next, x[1] and the found basis vector Φ k Similarly, x[2] can be calculated from the residual between the product of x and the received waveform vector y, and then x[3], x[4], ... can be calculated. x[p] is a vector that contains only p non-zero components and the rest are zero components. Hereinafter, the calculation of x[1] will be referred to as the "first step". Therefore, x[p] indicates the coefficient vector x obtained in the pth step of the OMP algorithm. In this way, by repeating the "step" in the OMP algorithm M times, all components x1, x2, ... x in the M-row, 1-column coefficient vector x can be calculated. M That is, the coefficient vector x can be found as one of an infinite number of solutions.

[0033] However, the amplitude of x is large. kSince the calculation is performed from

[0046] , it is possible to obtain a good approximate solution even if the calculation is completed in fewer than M steps. In this regard, when estimating the waveform of an interference wave, as in this embodiment, expressing the interference wave as a linear combination of multiple chirplets has little physical meaning. This is because an actual interference wave is composed of a single chirplet, not multiple chirplets. Furthermore, during the interference period of the received waveform, the interference wave and the desired wave overlap. Therefore, if the interference wave is expressed as a linear combination of multiple chirplets, the overlapping waveform of the interference wave and the desired wave will be modeled. Therefore, during the final subtraction, while the interference wave is removed to some extent, the desired wave may also be subtracted.

[0034] Therefore, in this embodiment, the OMP algorithm is first performed as the first step, that is, the first complex inner product calculation and the resulting maximum basis vector Φ k In other words, in the parameter estimation process, the signal processing unit 7 calculates the coefficient vector x in the arithmetic expression y=Dx, which represents the received waveform vector y as the product of the dictionary matrix D and the coefficient vector x, using the OMP algorithm so that the coefficient vector x contains only one non-zero component and the rest are zero components. Then, the waveform estimation process is performed by selecting the coefficient vector x containing only one non-zero component and one basis vector Φ k The waveform of the interference wave is estimated by

[0035] Specifically, in the parameter estimation process, the signal processing unit 7 selects a basis vector Φ from the dictionary matrix D that maximizes the inner product with the received waveform vector y. k If you select only one, the selected basis vector Φ k and the received waveform vector y, the coefficient vector x, i.e., x[1], is calculated. k The coefficient vector x includes the estimation results of the above four parameters. The signal processing unit 7 estimates the waveform of the interference wave based on the estimation results of the four parameters, and subtracts the estimated waveform of the interference wave from the waveform of the received wave.

[0036] More specifically, in the parameter estimation process, the signal processing unit 7 selects a basis vector Φ from the dictionary matrix D that maximizes the inner product with the received waveform vector y. k The process of selecting only one basis vector Φ k The process of updating the dictionary matrix D based on the basis vector Φ corresponding to the combination of the interference start time Tb and the chirp gradient K is repeated a predetermined number of times. k The dictionary matrix D is updated so that the range of the chirp slope K is smaller after the update than before the update. Specifically, the range of the chirp slope K is narrowed by the selected basis vector Φ k Then, the signal processing unit 7 updates the dictionary matrix D after a predetermined number of updates to a value around the value corresponding to the basis vector Φ k If you select only one, the selected basis vector Φ k and the received waveform vector y, a coefficient vector x is calculated.

[0037] As described above, in this embodiment, after executing the OMP algorithm for the first time, the signal processing unit 7 updates the dictionary matrix D for the first time and executes the OMP algorithm for the second time using the updated dictionary matrix D. Furthermore, after executing the OMP algorithm for the second time, the signal processing unit 7 updates the dictionary matrix D for the second time and executes the OMP algorithm for the third time using the updated dictionary matrix D. Then, after executing the OMP algorithm for the Pth time, the signal processing unit 7 obtains the coefficient vector x=x[1] and uses this to estimate the waveform of the interference wave. Note that, as is clear from the above, the number of "steps" in each OMP algorithm is one.

[0038] Here, the number of times the dictionary matrix D is updated, i.e., the number of times the OMP algorithm is executed, is set in advance according to the expected conditions of use of the radar device 1. If the number of times the OMP algorithm is executed is P, this value P is the number of times the dictionary matrix D is updated plus "1". Specifically, for example, the number of times P at which the noise floor level does not improve even after the (P+1)th execution can be determined in advance by experiment or computer simulation. This is because, just as the number of frequency bins in a distance FFT is limited and it is not possible to match the frequency of a desired wave, it is theoretically impossible to match the frequency of an interference wave and perform complete interference removal. Therefore, there is no point in limiting the number of times the OMP algorithm is executed.

[0039] FIG. 6 shows, as a comparative example, an example in which the coefficient vector x=x

[15] is obtained by performing the OMP algorithm multiple times, specifically 15 times. In the comparative example shown in FIG. 6, 20 discrete chirp slopes K are prepared. Also, a total of 300 interference start times Tb, ranging from 1 to 300, are prepared. In contrast, FIGS. 7 to 12 show an embodiment in which the above-mentioned value P, which is the number of times the OMP algorithm is executed, is 5. That is, in this embodiment, after the OMP algorithm is once completed in the first step, the basis vector Φ is selected by repeating four times the updating of the dictionary matrix D and the first step of the OMP algorithm using the updated dictionary matrix D. k In this example, the coefficient vector x=x[1] is calculated using the above formula. In this example, 17 discrete chirp slopes K are provided. Also, a total of 512 interference start times Tb are provided, ranging from 1 to 512.

[0040] FIG. 13 shows how the value of chirp slope K converges according to an embodiment. That is, FIG. 13 shows how the value of chirp slope K converges in FIGS. 7 to 11 or 12. In the figure, the current value, i.e., the value selected by the current OMP algorithm, is surrounded by a solid-line square, and the previous value is surrounded by a dashed-line square. In FIG. 13, multiple discrete chirp slope K values ​​are set geometrically. Specifically, for example, the chirp slope K in the first OMP is set so that adjacent values ​​are 1.3200 times larger when arranged in ascending order. Similarly, the chirp slope K in the second OMP is set so that adjacent values ​​are 1.0533 times larger. The chirp slope K in the third OMP is set so that adjacent values ​​are 1.0089 times larger. The chirp slope K in the fourth OMP is set so that adjacent values ​​are 1.0015 times larger. The chirp slope K for the fifth OMP is set so that adjacent values ​​are 1.0002 times larger. Figure 14 shows how the interference start time Tb values ​​converge in this example. In Figure 14, the current value, i.e., the value selected by the current OMP algorithm, is enclosed in a solid-line box.

[0041] 6 to 12, the matrix expressions and waveforms are shown in a schematic and simplified form for the sake of illustration, in order to facilitate understanding of the effects of this embodiment. That is, for example, the received waveform vector y is actually a complex waveform, but for the sake of simplicity, it is shown in a schematic manner as if it were a real waveform. The sampling points shown in the schematic waveform of the received waveform vector y are also originally many (for example, a power of 2, such as 512), but to avoid complicating the illustration, most of them are omitted and only a portion is shown in a schematic manner. Also, in FIG. 6, "K=54.293e12" represents K=54.293×10 12 The same applies to "K=84e12" and the like. The same applies to Figs. 7 to 12. In Fig. 13, "×10 12" is omitted. Also, for the sake of simplicity, "K=84e12" in FIG. 7 should actually be written as "K=84.8e12" according to the table in FIG. 13, but considering that this is a stage before the values ​​converge, the part after the decimal point has been omitted. The same applies to FIGS. 8 and 9.

[0042] In the comparative example shown in Fig. 6, a single dictionary matrix D is used without being updated, and the OMP algorithm is executed for multiple steps to calculate a coefficient vector x containing multiple non-zero components. However, in the comparative example, the noise floor is not sufficiently lowered, and the SNR, which is one of the indicators of interference cancellation, remains low (for example, about 10 dB). This is because, as mentioned above, the interference wave, which should actually be a single chirplet, is represented by the linear sum of multiple chirplets, and the interference wave is not represented correctly physically or mathematically, resulting in inability to completely cancel the interference.

[0043] In contrast to this, in the embodiment, first, the basis vector Φ k Then, (K, Tb) = (48.7 × 10 12 ,124) is selected. Then, the basis vector Φ selected by the first OMP algorithm is k The chirp slope K value at 48.7×10 12 As shown in Figure 8, the dictionary matrix D is updated using the above. In the dictionary matrix D used in the first OMP algorithm, the range of values ​​of the chirp slope K is set wide. On the other hand, in the updated dictionary matrix D, the range of values ​​of the chirp slope K is set wide depending on the selected basis vector Φ k The value at 48.7×10 12 is set as the central value and is set narrower than the previous time.

[0044] Next, the second OMP algorithm is used to calculate the basis vector Φ as shown in Figs. 8 and 13-14. k Then, (K, Tb) = (54.0 × 10 12,123) is selected. Then, the basis vector Φ selected by the second OMP algorithm is k The chirp slope K value at 54.0×10 12 9, the dictionary matrix D is updated using the selected basis vector Φ k The value at 54.0×10 12 is set as the central value and is set narrower than the previous time.

[0045] Next, the third OMP algorithm is used to calculate the basis vector Φ k Then, (K, Tb) = (54.48 × 10 12 ,123) is selected. Then, the basis vector Φ selected by the third OMP algorithm is k The chirp slope K value at 54.48×10 12 , the dictionary matrix D is updated as shown in FIG. 10. In the updated dictionary matrix D, the range of values ​​of the chirp slope K is determined by the selected basis vector Φ k The value at 54.48×10 12 is set as the central value and is set narrower than the previous time.

[0046] Similarly, the fourth OMP algorithm generates the basis vector Φ as shown in Figs. 10 and 13-14. k Then, (K, Tb) = (54.32 × 10 12 ,122) is selected. Then, the basis vector Φ selected by the fourth OMP algorithm is k The chirp slope K value at 54.32×10 12 , the dictionary matrix D is updated as shown in FIG. 11. In the updated dictionary matrix D, the range of values ​​of the chirp slope K is determined by the selected basis vector Φ k The value at 54.32×10 12 is set as the central value and is set narrower than the previous time.

[0047] Then, by the fifth OMP algorithm, the basis vector Φ k Then, (K, Tb) = (54.293 × 10 12 , 122) is selected. Then, such a basis vector Φ k The waveform of the interference wave is estimated based on the coefficient vector x calculated using the current dictionary matrix D. k Then, (K, Tb) = (54.293 × 10 12 ,122) is selected. The selected basis vector Φ k The waveform of the interference wave differs only in amplitude A and phase θ.

[0048] 15A and 15B show how the influence of interference waves is reduced from the waveform of a received wave according to this embodiment. In the figures, (0) indicates the waveform before interference suppression processing, (1) indicates the effect of reducing the influence of interference waves by the first OMP, (2) indicates the effect of reducing the influence of interference waves by the second OMP, (3) indicates the effect of reducing the influence of interference waves by the third OMP, (4) indicates the effect of reducing the influence of interference waves by the fourth OMP, and (5) indicates the effect of reducing the influence of interference waves by the fifth OMP. In FIGS. 15A and 15B, the vertical axis represents voltage, and the horizontal axis represents sampling points corresponding to time. The influence of the interference waves is almost completely eliminated by the fourth OMP, and almost completely eliminated by the fifth OMP. For ease of understanding, FIGS. 15A and 15B show the reduction effect of interference waves subtracted from each of the first to fifth OMPs. In an actual embodiment, interference waves are subtracted only after the fifth OMP. Figure 16 compares the distance map before and after interference removal, i.e., after the effects of the interference wave have been almost completely removed by the fifth OMP. In Figure 16, the horizontal axis indicates frequency bins corresponding to distance, and the vertical axis is in dB. The single sharp peak on the left is the peak of the desired wave. As shown in Figure 16(A), before interference removal, the noise floor is raised by the interference wave, resulting in a low SNR. In contrast, as shown in Figure 16(B), after interference removal, the SNR improves to about 40 dB.

[0049] In this way, in this embodiment, a coefficient vector x containing only one non-zero component is calculated by a one-step OMP algorithm, and the coefficient vector x and one basis vector Φ k The waveform of the interference wave is estimated by the above. Specifically, in this embodiment, one step of the OMP algorithm is repeated a small number of times while updating the dictionary matrix D. This makes it possible to improve the estimation accuracy of the waveform of the interference wave while reducing the calculation load. Therefore, according to this embodiment, in an environment where radio wave interference occurs, it is possible to reduce the influence of the interference wave on the received signal RX more effectively than ever before.

[0050] In this embodiment, the values of a plurality of chirp slopes K in the dictionary matrix D are set discretely and geometrically. The ratio is decreased for each number of OMP iterations, that is, for each update of the dictionary matrix D. Also, the dictionary matrix D is composed of combinations of M1 chirp slope K values set discretely and M2 (where M1 < M2 and M1 × M2 = M) interference start time Tb values, and a plurality of basis vectors Φ k are generated by setting each of them. That is, in the dictionary matrix D, the interference start time Tb of the basis vector Φ k is set using all possible sampling times. This is to ensure the estimation of the interference wave waveform.

[0051] Note that there may be two or more interference waves. In this case, by repeating the interference suppression process as described above a plurality of times, it is possible to sequentially remove a plurality of interference waves. Specifically, when the noise floor in the FFT result of the waveform of the received wave after the subtraction process is below the threshold value, the signal processing unit 7 ends the interference suppression process, while when it exceeds the threshold value, the dictionary matrix D is initialized and the interference suppression process is executed again. In other words, after the signal processing unit 7 performs the interference suppression process for one interference wave by repeating one-step OMP and the update of the dictionary matrix D, it checks the level of the noise floor. When the noise floor exceeds the threshold value, the signal processing unit 7 initializes the dictionary matrix D so that the range of the value of the chirp slope K is set wider, and repeats one-step OMP and the update of the dictionary matrix D to execute the interference suppression process for one interference wave again. Then, the signal processing unit 7 repeats this until the noise floor becomes below the threshold value. The threshold value corresponds to the noise floor level for determining whether to move to the next OMP. Such a threshold value is preset according to the usage conditions of the radar device 1.

[0052] FIG. 17 shows how the influence of the interference waveform is reduced from the received waveform by repeating the interference suppression process twice when two interference waves are present. The vertical axis in FIG. 17 represents voltage, where (0) represents the state before the interference suppression process, (1) represents the effect of reducing the influence of the interference wave by the first cycle of the interference suppression process, and (2) represents the effect of reducing the influence of the interference wave by the second cycle of the interference suppression process. In each cycle of the interference suppression process, the dictionary matrix D is updated four times, i.e., the OMP algorithm is executed five times. As is clear from a comparison between (0) and (1) in FIG. 17, the first cycle of the interference suppression process first removes the one with the larger amplitude, i.e., power, of the two interference waves. At this time, the one with the smaller amplitude, i.e., power, of the two interference waves is not removed. Then, as is clear from a comparison between (1) and (2) in FIG. 17, the second cycle of the interference suppression process removes the one with the smaller power, of the two interference waves.

[0053] 18 is a flowchart showing the flow of a series of processes corresponding to this specific example. This series of processes is realized by processor 71 reading necessary data such as a program and initial values ​​from memory 72 and executing the program.

[0054] First, in S1801, the processor 71 estimates the range of the interference start time Tb from the received waveform, and sets the interference start time Tb to be used in the dictionary matrix D. Next, in S1802, the processor 71 calculates the basis vector Φ k That is, the processor 71 sets the chirp slope K used in the dictionary matrix D in a wide range. As a result, an initialized dictionary matrix D is generated. Subsequently, in S1803, the processor 71 initializes the received waveform vector y and each basis vector Φ k Then, in S1804, the processor 71 calculates the basis vector Φ k Then, in S1805, the processor 71 selects the basis vector Φ k It is determined whether the selection is the Pth time.

[0055] If it is less than the Pth time (i.e., S1805=NO), the processor 71 executes the process of S1806 and then returns the process to S1803. In S1806, the processor 71 calculates the basis vector Φ k That is, the processor 71 updates the value of the dictionary matrix D. On the other hand, if it is the Pth time (that is, S1805=YES), the processor 71 advances the process to S1807 and subsequent steps.

[0056] At S1807, the processor 71 obtains the coefficient vector x, i.e., x[1]. At S1808, the processor 71 obtains the waveform of the interference wave. At S1809, the processor 71 subtracts the waveform of the interference wave obtained at S1808 from the waveform of the received wave. At S1810, the processor 71 performs distance FFT on the waveform after subtraction. At S1811, the processor 71 determines whether the noise floor in the distance FFT waveform is equal to or less than a threshold. If the noise floor exceeds the threshold (i.e., S1811=NO), the processor 71 returns the process to S1801. At this time, the processor 71 obtains the basis vector Φ k The processor 71 initializes a counter for determining whether the selection is Pth time or not. On the other hand, if the noise floor is equal to or lower than the threshold (that is, S1811=YES), the processor 71 ends the interference suppression process.

[0057] (Variation) The present invention is not limited to the above-described embodiment. Therefore, the above-described embodiment can be modified as appropriate. Representative modifications will be described below. In the following description of the modifications, differences from the above-described embodiment will be mainly described. Furthermore, the same reference numerals are used for parts that are identical or equivalent to each other in the above-described embodiment and the modifications. Therefore, in the following description of the modifications, the description of the above-described embodiment can be used as appropriate for components that have the same reference numerals as the above-described embodiment, unless there is a technical contradiction or special additional explanation.

[0058] The present invention is not limited to the specific device configurations shown in the above embodiments. For example, all or part of the control unit 4 may be configured to include a digital circuit, such as an ASIC or FPGA, configured to enable the above-described operations. ASIC stands for Application Specific Integrated Circuit. FPGA stands for Field Programmable Gate Array. In other words, the control unit 4 may include both an on-board microcomputer and a digital circuit.

[0059] There are no particular limitations on the specific circuit configurations of the transmission circuit unit 5 and the reception circuit unit 6. That is, for example, the in-phase signal filter 65 and the quadrature phase signal filter 66 are not limited to low-pass filters and may be band-pass filters.

[0060] The signal processing unit 7 may include an arithmetic processing device such as a DSP for performing signal processing such as FFT on the digital signals input from the in-phase signal AD converter 67 and the quadrature phase signal AD converter 68. DSP is an abbreviation for Digital Signal Processor.

[0061] The program according to the present invention, which enables the execution of the various operations, procedures, or processes described in the above embodiments, can be downloaded or upgraded via V2X communication. V2X stands for Vehicle to X. Alternatively, the program can be downloaded or upgraded via a terminal device installed in a vehicle manufacturing plant, a repair shop, a dealer, or the like. The program can be stored on a memory card, an optical disk, a magnetic disk, or the like.

[0062] As described above, each of the above functional configurations and processes may be implemented by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, each of the above functional configurations and processes may be implemented by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, each of the above functional configurations and processes may be implemented by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured by one or more hardware logic circuits. Further, the computer program may be stored in a computer-readable non-transitory tangible storage medium as instructions to be executed by a computer. That is, each of the above functional configurations and processes can also be represented as a computer program including procedures for realizing the same, or as a non-transitory tangible storage medium storing the program.

[0063] The present invention is not limited to the specific operation modes shown in the above embodiments. That is, for example, the present invention is not limited to the case of M > N as described above, and can be similarly applied to the case of M ≤ N. In particular, as will be described later, when the interference start time Tb is estimated and the size of the dictionary matrix D is reduced, M < N may occur. Also, in the examples of FIGS. 7 to 12, for simplicity of explanation, the setting range of the interference start time Tb was set to 1, but the present invention is not limited to such a mode. That is, actually, there may be a case where the interference start time Tb ≤ 0 is satisfied. By including the basis vector Φ k for the interference start time Tb ≤ 0 in the dictionary matrix D as well, it becomes possible to handle an interference wave in which the interference wave hits the chirp end and part of it is interrupted. Also, the above number P may be variably set according to the noise level. That is, the signal processing unit 7 may be configured to set the above number P according to the difference between the noise level and the reference level.

[0064] The signal processing unit 7 may set the value of the interference start time Tb in the dictionary matrix D based on the detection result of the interference wave. FIG. 19 is a flowchart corresponding to such an example. In this example, first, in S1900, the processor 71 detects the interference wave and estimates the timing at which the interference wave entered. Next, in S1901, the processor 71 estimates the range of the interference start time Tb based on the estimation result of the timing at which the interference wave entered, and sets the interference start time Tb to be used in the dictionary matrix D. S1902 and subsequent steps are the same as S1802 and subsequent steps shown in FIG. 18. In this way, by detecting the interference wave and estimating the timing at which the interference wave entered, and limiting the range of the interference start time Tb to the vicinity of the estimated value, the size of the dictionary matrix D can be narrowed. This reduces the amount of memory used and improves the calculation speed. Note that interference wave detection can be performed using various methods. For example, interference wave detection can be performed by an interference detection program (not shown) provided inside the signal processing unit 7.

[0065] It goes without saying that the elements constituting the above-described embodiments are not necessarily essential unless expressly stated as essential or clearly considered essential in principle. Furthermore, when numerical values ​​such as the number, amount, range, etc. of components are mentioned, the present invention is not limited to those specific numerical values ​​unless expressly stated as essential or clearly limited to specific numerical values ​​in principle. Similarly, when the shape, direction, positional relationship, etc. of components are mentioned, the present invention is not limited to those shapes, directions, positional relationship, etc. unless expressly stated as essential or clearly limited to specific shapes, directions, positional relationship, etc. in principle.

[0066] The modified examples are not limited to the above examples. Furthermore, multiple modified examples may be combined with each other. Furthermore, all or part of the above embodiment and all or part of the modified examples may be combined with each other.

[0067] (Perspectives included in the disclosure) As is clear from the above description of the configurations and operations according to the embodiments and modifications, the present disclosure includes at least the following aspects. [Point 1] A radar device (1), a transmission signal generating unit (51) that generates a transmission signal (TX) that is an electrical signal having a predetermined frequency change corresponding to the frequency modulation mode of the transmission wave, so that the transmission wave, which is a frequency-modulated radar wave, is transmitted from a transmission antenna (2); a signal processing unit (7) that performs interference suppression processing on a received signal (RX), which is an electrical signal corresponding to a received wave that is a radar wave received by a receiving antenna (3), based on a signal processing result including detection processing based on the transmitted signal, to suppress the influence of an interference wave included in the received wave; Equipped with The interference suppression process includes: a waveform estimation process for estimating a waveform of the interference wave; a subtraction process of subtracting the estimated waveform of the interference wave from the waveform of the received wave; Including, The waveform estimation process includes: a parameter estimation process for estimating parameters in a mathematical formula representing a waveform of the interference wave, the parameters being an interference start time Tb corresponding to the time when the frequency becomes a predetermined value, a chirp slope K which is the slope of the time change of the frequency, an amplitude A, and a phase θ, assuming that the frequency of the interference wave changes linearly with time; the parameter estimation process includes a process of calculating, using an orthogonal matching pursuit algorithm, a received waveform vector y of N rows and 1 column corresponding to the waveform of the received wave, expressed as the product of an N row and M column dictionary matrix D which is a set of basis vectors corresponding to a combination of the interference start time Tb and the chirp slope K, and an M row and 1 column coefficient vector x including the amplitude A and the phase θ, in an arithmetic expression y=Dx, such that the coefficient vector x includes only one non-zero component and the rest are zero components; A waveform of the interference wave is estimated using one of the basis vectors. Radar equipment. [Point 2] In the parameter estimation process, the signal processing unit selects only one of the basis vectors from the dictionary matrix D, which has a maximum inner product with the received waveform vector y. The radar device according to aspect 1. [Point 3] The signal processing unit, in the parameter estimation process, A process of selecting only one basis vector from the dictionary matrix D, which maximizes the inner product with the received waveform vector y; updating the dictionary matrix D based on the selected basis vector so as to narrow the range of the chirp slope K, with the chirp slope K corresponding to the selected basis vector as a center value; Repeat the above a predetermined number of times. selecting only one basis vector from the dictionary matrix D updated the predetermined number of times, which has a maximum inner product with the received waveform vector y, and then calculating the coefficient vector x based on the selected basis vector and the received waveform vector y; The radar device according to aspect 2. [Point 4] The predetermined number of times is set in advance depending on the conditions of use of the radar device. A radar device according to aspect 3. [Point 5] the signal processing unit terminates the interference suppression process when the noise floor in the fast Fourier transform result of the waveform of the received wave after the subtraction process is equal to or less than a threshold, and initializes the dictionary matrix D and executes the interference suppression process again when the noise floor exceeds the threshold. The radar device according to any one of the first to fourth aspects. [Point 6] The threshold value is set in advance depending on the conditions of use of the radar device. A radar device according to aspect 5. [Point 7] The signal processing unit generates the dictionary matrix D by setting each of the plurality of basis vectors according to a combination of M1 discretely set values of the chirp slope K and M2 values of the interference start time Tb (where M1 < M2 and M1 × M2 = M). The radar device according to any one of Aspects 1 to 6. [Aspect 8] The signal processing unit sets the values of the plurality of chirp slopes K in the dictionary matrix D in a geometric progression. The radar device according to Aspect 7. [Aspect 9] Based on the detection result of the interference wave, the signal processing unit estimates the interference start time Tb and sets the range of the value of the interference start time Tb in the dictionary matrix D by limiting it. The radar device according to Aspect 7 or 8. [Aspect 10] A transmission signal generation unit (51) that generates a transmission signal (TX), which is an electrical signal having a predetermined frequency change corresponding to the frequency modulation mode in the transmission wave, so that a transmission wave that is a frequency-modulated radar wave is transmitted from the transmission antenna (2); A signal processing unit (7) that executes an interference suppression process for suppressing the influence of an interference wave included in the received wave based on a signal processing result including a detection process based on the transmission signal on a received signal (RX), which is an electrical signal corresponding to the received wave that is a radar wave received by the reception antenna (3); A signal processing program executed by the signal processing unit in the radar device (1) including: The interference suppression process executed by the signal processing unit is: <000044^A waveform estimation process for estimating the waveform of the interference wave; A subtraction process for subtracting the estimated waveform of the interference wave from the waveform of the received wave; And includes The waveform estimation process is: a parameter estimation process for estimating parameters in a mathematical formula representing a waveform of the interference wave, the parameters being an interference start time Tb corresponding to the time when the frequency becomes a predetermined value, a chirp slope K which is the slope of the time change of the frequency, an amplitude A, and a phase θ, assuming that the frequency of the interference wave changes linearly with time; the parameter estimation process includes a process of calculating, using an orthogonal matching pursuit algorithm, a received waveform vector y of N rows and 1 column corresponding to the waveform of the received wave, expressed as the product of an N row and M column dictionary matrix D which is a set of basis vectors corresponding to a combination of the interference start time Tb and the chirp slope K, and an M row and 1 column coefficient vector x including the amplitude A and the phase θ, in an arithmetic expression y=Dx, such that the coefficient vector x includes only one non-zero component and the rest are zero components; A waveform of the interference wave is estimated using one of the basis vectors. Signal processing program. [Point 11] In the parameter estimation process, only one basis vector is selected from the dictionary matrix D, which has a maximum inner product with the received waveform vector y. A signal processing program according to aspect 10. [Point 12] In the parameter estimation process, A process of selecting only one basis vector from the dictionary matrix D, which maximizes the inner product with the received waveform vector y; updating the dictionary matrix D based on the selected basis vector so as to narrow the range of the chirp slope K, with the chirp slope K corresponding to the selected basis vector as a center value; Repeat the above a predetermined number of times. selecting only one basis vector from the dictionary matrix D updated the predetermined number of times, which has a maximum inner product with the received waveform vector y, and then calculating the coefficient vector x based on the selected basis vector and the received waveform vector y; A signal processing program according to aspect 11. [Point 13] The predetermined number of times is preset according to the usage conditions of the radar device. The signal processing program according to Aspect 12. [Aspect 14] When the noise floor in the fast Fourier transform result of the waveform of the received wave after the subtraction process is below the threshold value, the interference suppression process is terminated. On the other hand, when it exceeds the threshold value, the dictionary matrix D is initialized and the interference suppression process is executed again. The signal processing program according to any one of Aspects 10 to 13. [Aspect 15] The threshold value is preset according to the usage conditions of the radar device. The signal processing program according to Aspect 14. [Aspect 16] The dictionary matrix D is generated by setting each of the plurality of basis vectors by combining the values of M1 chirp slopes K set discretely and the values of M2 interference start times Tb (where M1 < M2 and M1 × M2 = M). The signal processing program according to any one of Aspects 10 to 15. [Aspect 17] The values of the plurality of chirp slopes K in the dictionary matrix D are set geometrically. The signal processing program according to Aspect 16. [Aspect 18] Based on the detection result of the interference wave, the interference start time Tb is estimated, and the range of the value of the interference start time Tb in the dictionary matrix D is limited and set. The signal processing program according to Aspect 16 or 17.

Explanation of Symbols

[0068] 1 Radar device 2 Transmitting antenna 3 Receiving antenna 4 Control unit 5 Transmitting circuit section 51 Transmitting signal generation section 6 Receiving circuit section 7 Signal processing section 71 Processor 72 memory

Claims

1. A radar device (1), a transmission signal generating unit (51) that generates a transmission signal (TX) that is an electrical signal having a predetermined frequency change corresponding to the frequency modulation mode of the transmission wave, so that the transmission wave, which is a frequency-modulated radar wave, is transmitted from a transmission antenna (2); a signal processing unit (7) that performs interference suppression processing on a received signal (RX), which is an electrical signal corresponding to a received wave that is a radar wave received by a receiving antenna (3), based on a signal processing result including detection processing based on the transmitted signal, to suppress the influence of an interference wave included in the received wave; Equipped with The interference suppression process includes: a waveform estimation process for estimating a waveform of the interference wave; a subtraction process of subtracting the estimated waveform of the interference wave from the waveform of the received wave; Including, The waveform estimation process includes: a parameter estimation process for estimating parameters in a mathematical formula representing a waveform of the interference wave, the parameters being an interference start time Tb corresponding to the time when the frequency reaches a predetermined value, a chirp slope K which is the slope of the time change of the frequency, an amplitude A, and a phase θ, assuming that the frequency of the interference wave changes linearly with time; the parameter estimation process includes a process of calculating, using an orthogonal matching pursuit algorithm, a received waveform vector y of N rows and 1 column corresponding to the waveform of the received wave, expressed as the product of an N row and M column dictionary matrix D which is a set of basis vectors corresponding to a combination of the interference start time Tb and the chirp slope K, and an M row and 1 column coefficient vector x including the amplitude A and the phase θ, in an arithmetic expression y=Dx, the coefficient vector x including only one non-zero component and the rest being zero components; A waveform of the interference wave is estimated using one of the basis vectors. Radar equipment.

2. In the parameter estimation process, the signal processing unit selects only one basis vector from the dictionary matrix D, which has a maximum inner product with the received waveform vector y. The radar device according to claim 1 .

3. The signal processing unit, in the parameter estimation process, a process of selecting only one basis vector from the dictionary matrix D, which maximizes the inner product with the received waveform vector y; updating the dictionary matrix D based on the selected basis vector so as to narrow the range of the chirp slope K, with the chirp slope K corresponding to the selected basis vector as a center value; Repeat the above a predetermined number of times. selecting only one basis vector from the dictionary matrix D updated the predetermined number of times, which has a maximum inner product with the received waveform vector y, and then calculating the coefficient vector x based on the selected basis vector and the received waveform vector y; The radar device according to claim 2 .

4. The predetermined number of times is set in advance depending on the conditions of use of the radar device. The radar device according to claim 3 .

5. the signal processing unit terminates the interference suppression process when a noise floor in a fast Fourier transform result of the waveform of the received wave after the subtraction process is equal to or less than a threshold, whereas when the noise floor exceeds the threshold, it initializes the dictionary matrix D and executes the interference suppression process again. The radar device according to any one of claims 1 to 4.

6. The threshold value is set in advance depending on the conditions of use of the radar device. The radar device according to claim 5 .

7. The signal processing unit generates the dictionary matrix D by setting each of the plurality of basis vectors by combining M1 discretely set values ​​of the chirp slope K and M2 (where M1<M2 and M1×M2=M) values ​​of the interference start time Tb. The radar device according to claim 1 .

8. the signal processing unit geometrically sets a plurality of values ​​of the chirp slope K in the dictionary matrix D. The radar device according to claim 7.

9. the signal processing unit estimates the interference start time Tb based on the detection result of the interference wave, and limits and sets a range of values ​​of the interference start time Tb in the dictionary matrix D; The radar device according to claim 7.

10. a transmission signal generating unit (51) that generates a transmission signal (TX) that is an electrical signal having a predetermined frequency change corresponding to the frequency modulation mode of the transmission wave, so that the transmission wave, which is a frequency-modulated radar wave, is transmitted from a transmission antenna (2); a signal processing unit (7) that performs interference suppression processing on a received signal (RX), which is an electrical signal corresponding to a received wave that is a radar wave received by a receiving antenna (3), based on a signal processing result including detection processing based on the transmitted signal, to suppress the influence of an interference wave included in the received wave; A signal processing program executed by the signal processing unit in a radar device (1) comprising: The interference suppression processing executed by the signal processing unit includes: a waveform estimation process for estimating a waveform of the interference wave; a subtraction process of subtracting the estimated waveform of the interference wave from the waveform of the received wave; Including, The waveform estimation process includes: a parameter estimation process for estimating parameters in a mathematical formula representing a waveform of the interference wave, the parameters being an interference start time Tb corresponding to the time when the frequency reaches a predetermined value, a chirp slope K which is the slope of the time change of the frequency, an amplitude A, and a phase θ, assuming that the frequency of the interference wave changes linearly with time; the parameter estimation process includes a process of calculating, using an orthogonal matching pursuit algorithm, a received waveform vector y of N rows and 1 column corresponding to the waveform of the received wave, expressed as the product of an N row and M column dictionary matrix D which is a set of basis vectors corresponding to a combination of the interference start time Tb and the chirp slope K, and an M row and 1 column coefficient vector x including the amplitude A and the phase θ, in an arithmetic expression y=Dx, the coefficient vector x including only one non-zero component and the rest being zero components; A waveform of the interference wave is estimated using one of the basis vectors. Signal processing program.

11. In the parameter estimation process, only one basis vector is selected from the dictionary matrix D, which has a maximum inner product with the received waveform vector y. The signal processing program according to claim 10.

12. In the parameter estimation process, a process of selecting only one basis vector from the dictionary matrix D, which maximizes the inner product with the received waveform vector y; updating the dictionary matrix D based on the selected basis vector so as to narrow the range of the chirp slope K, with the chirp slope K corresponding to the selected basis vector as a center value; Repeat the above a predetermined number of times. selecting only one basis vector from the dictionary matrix D updated the predetermined number of times, which has a maximum inner product with the received waveform vector y, and then calculating the coefficient vector x based on the selected basis vector and the received waveform vector y; The signal processing program according to claim 11.

13. The predetermined number of times is set in advance depending on the conditions of use of the radar device. The signal processing program according to claim 12.

14. If the noise floor in the fast Fourier transform result of the waveform of the received wave after the subtraction process is equal to or less than a threshold, the interference suppression process is terminated, whereas if the noise floor exceeds the threshold, the dictionary matrix D is initialized and the interference suppression process is executed again. The signal processing program according to any one of claims 10 to 13.

15. The threshold value is set in advance depending on the conditions of use of the radar device. The signal processing program according to claim 14.

16. The dictionary matrix D is generated by setting each of the plurality of basis vectors by combining M1 discretely set values ​​of the chirp slope K and M2 (where M1<M2 and M1×M2=M) values ​​of the interference start time Tb. The signal processing program according to claim 10.

17. The values ​​of the chirp slopes K in the dictionary matrix D are set geometrically. The signal processing program according to claim 16.

18. estimating the interference start time Tb based on the detection result of the interference wave, and setting a limited range of values ​​of the interference start time Tb in the dictionary matrix D; The signal processing program according to claim 16.

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