Automotive radar equipment

Abstract

To provide a technique that can effectively remove interference signals from a signal without using extreme values of the time derivative of the signal.SOLUTION: A vehicle-mounted radar system 100 includes a first receiving antenna 131 that receives a reflected wave from an object OB based on a transmitted signal Tw as a first received signal Dw1, a first receiving circuit 141 that is connected to the first receiving antenna and generates a first signal Sg1 by mixing the transmitted signal with the first received signal, and a processing unit 200. The processing unit performs processes of (a) phase-connecting a phase of the first signal in at least a part of an interference section Sci including a first interference signal Sgi1 representing an interference signal included in the first signal, (b) calculating a function corresponding to time variation of the phase of the first interference signal by approximating the phase that is phase-connected in the process (a) by a curve, and (c) calculating, using the first signal and the function, a first desired signal Sd1 representing the first signal from which an estimated value of the first interference signal is subtracted.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an on-vehicle radar device. [Background technology]

[0002] In an on-board radar device that measures a target based on a received signal derived from a wave reflected by the target, an interference signal may occur in the received signal due to interference from a transmitted signal from another radar device. Regarding a technology for removing such an interference signal, Patent Document 1 discloses a method for estimating a line representing a parameter of the time differential of the phase response of the interference signal from the extreme value of the time differential of the received signal, and removing the interference signal from the received signal based on the estimated line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 10,564,255 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology of Patent Document 1, if the extreme value of the time derivative of the received signal cannot be accurately identified, the line representing the parameter of the time derivative of the phase response of the interference signal cannot be accurately estimated, and therefore, there is a possibility that the interference signal cannot be effectively removed from the received signal. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] According to a first aspect of the present disclosure, there is provided an on-vehicle radar device (100). The on-vehicle radar device includes a first receiving antenna (131) that receives, as a first received signal (Dw1), a reflected wave from a target (OB) that reflects a transmission wave based on a transmission signal (Tw), a first receiving circuit (141) connected to the first receiving antenna that generates a first signal (Sg1) by mixing the transmission signal and the first received signal, and a processing unit (200). The processing unit executes the following processes: (a) unwrapping the phase of the first signal in at least a part of an interference interval (Sci) including a first interference signal (Sgi1) that represents an interference signal included in the first signal; (b) calculating a function corresponding to a time change in the phase of the first interference signal by approximating the phase unwrapped in the process (a) with a curve; and (c) calculating, using the first signal and the function, a first desired signal (Sd1) that represents the first signal from which an estimated value of the first interference signal has been subtracted.

[0007] According to this embodiment, a function corresponding to the phase change of the first interfering signal can be estimated by approximating the unwrapped phase with a curve without using the extreme value of the time derivative of the first signal, and the first desired signal can be calculated using this function, thereby increasing the possibility of effectively removing the first interfering signal from the first signal. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing a schematic configuration of an on-vehicle radar device according to a first embodiment. [Figure 2] FIG. 4 is an explanatory diagram showing an example of a first signal. [Figure 3] 4 is a flowchart of interference signal processing in the first embodiment. [Figure 4] FIG. 10 is a diagram showing an example of a phase-unwrapped phase. [Figure 5] 10 is a flowchart of a first calculation process in the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating a first subtraction process. [Figure 7] 10 is a flowchart of a second calculation process in the first embodiment. [Figure 8] FIG. 10 is an explanatory diagram showing a schematic configuration of an on-vehicle radar device according to a second embodiment. [Figure 9] 10 is a flowchart of interference signal processing in the second embodiment. [Figure 10] 10 is a flowchart of a first calculation process in the second embodiment. [Figure 11] 10 is a flowchart of a second calculation process in the second embodiment. [Figure 12] FIG. 10 is an explanatory diagram showing a schematic configuration of an on-vehicle radar device according to a third embodiment. [Figure 13] FIG. 4 is a diagram illustrating filtering of a first signal by a filter. [Figure 14] 10 is a flowchart of interference signal processing in the third embodiment. [Figure 15] FIG. 10 is an explanatory diagram showing a schematic configuration of an on-vehicle radar device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. First embodiment: The on-board radar device 100 shown in FIG. 1 is mounted on a vehicle such as an automobile or a motorcycle, and measures an object OB. The object OB refers to, for example, a pedestrian, another vehicle, or an obstacle on the road. "Measuring the object OB" refers to, for example, measuring the distance and angle between the vehicle on which the on-board radar device 100 is mounted and the object OB, and the relative speed of the object OB with respect to the vehicle. The on-board radar device 100 in this embodiment is configured as a millimeter-wave radar that measures the object OB using an FCM (Fast-Chirp Modulation) method.

[0010] As shown in FIG. 1, the automotive radar device 100 includes a transmission signal generating unit 110, a transmitting unit 120, a receiving antenna 130, a receiving circuit 140, and a processing unit 200.

[0011] The transmission signal generation unit 110 is configured, for example, by a PLL (Phase Locked Loop) circuit, and generates a transmission signal Tw. In this embodiment, the transmission signal generation unit 110 continuously generates chirp signals whose frequency is linear with respect to time as the transmission signal Tw. Hereinafter, a bundle of a series of multiple transmission signals Tw generated as one set by the transmission signal generation unit 110 is also referred to as a chirp signal group. A chirp signal group is usually configured by a number of chirp signals that is a power of 2, for example, 512 chirp signals.

[0012] The transmitter 120 is configured with a transmitting antenna that radiates the transmission signal Tw into space as electromagnetic waves Ew, and radiates the transmission signal Tw amplified by the power amplifier PA as the electromagnetic waves Ew. In this embodiment, the transmitter 120 is configured with one transmitting antenna. In other embodiments, the transmitter 120 may have two or more transmitting antennas. Hereinafter, the electromagnetic waves Ew transmitted as the transmission signal Tw are also referred to as transmission waves.

[0013] The receiving antenna 130 receives the electromagnetic wave Ew reflected by the target object OB as a received signal. Hereinafter, the electromagnetic wave Ew reflected by the target object OB will also be referred to as a reflected wave. As shown in FIG. 1 , in this embodiment, the in-vehicle radar device 100 includes, as the receiving antenna 130, a first receiving antenna 131 that receives the reflected wave as a first received signal Dw1 and another receiving antenna that receives the reflected wave as another received signal different from the first received signal Dw1. More specifically, the in-vehicle radar device 100 includes, as the other receiving antennas, a second receiving antenna 132 that receives the reflected wave as a second received signal Dw2 and a third receiving antenna 133 that receives the reflected wave as a third received signal Dw3.

[0014] The receiving circuit 140 is connected to the receiving antenna 130. The receiving circuit 140 mixes the receiving signal received by the receiving antenna 130 with the transmitting signal Tw to generate an intermediate frequency signal based on the receiving signal and the transmitting signal Tw, and outputs the intermediate frequency signal to the processing unit 200. As shown in FIG. 1 , in this embodiment, the automotive radar device 100 includes, as the receiving circuit 140, a first receiving circuit 141 connected to the first receiving antenna 131 and another receiving circuit different from the first receiving circuit 141. More specifically, the automotive radar device 100 includes, as the other receiving circuits, a second receiving circuit 142 connected to the second receiving antenna 132 and a third receiving circuit 143 connected to the third receiving antenna 133. The first receiving circuit 141 mixes the transmitting signal Tw with the first receiving signal Dw1 to generate a first signal Sg1 as an intermediate frequency signal between the transmitting signal Tw and the first receiving signal Dw1. Similarly, the second receiving circuit 142 generates a second signal Sg2 as an intermediate frequency signal between the transmission signal Tw and the second receiving signal Dw2. The third receiving circuit 143 generates a third signal Sg3 as an intermediate frequency signal between the transmission signal Tw and the third receiving signal Dw3. It can also be said that the second receiving circuit 142 and the third receiving circuit 143 generate the second signal Sg2 and the third signal Sg3 as signals different from the first signal Sg1, more specifically, as other intermediate frequency signals.

[0015] In other embodiments, the automotive radar device 100 may have only the second receiving antenna 132 as the other receiving antenna. In this case, the automotive radar device 100 may have only the second receiving circuit 142 as the other receiving circuit. Furthermore, the automotive radar device 100 may have three or more receiving antennas 130 as the other receiving antennas, and in this case, may have three or more receiving circuits 140 as the other receiving circuits corresponding to the respective other receiving antennas.

[0016] In this embodiment, each receiving circuit 140 is configured as a quadrature detection circuit, and has a quadrature mixer 145, a low-pass filter 146, and an analog-to-digital converter 147 configured by an analog-to-digital converter (ADC). The receiving circuits 140 in this embodiment have approximately the same configuration.

[0017] In this embodiment, the first receiving circuit 141 generates the first signal Sg1 as a complex signal. More specifically, the quadrature mixer 145 of the first receiving circuit 141 generates the signal ISg1 and the signal QSg1. The signal ISg1 is a signal obtained by mixing a local oscillation signal LO, which is in phase with the transmission signal Tw, with the first reception signal Dw1 amplified by the low-noise amplifier LNA. The signal Qsg1 is a signal obtained by mixing a local oscillation signal LO, which is delayed in phase by 90° with respect to the transmission signal Tw, with the first reception signal Dw1 amplified in the same manner. The low-pass filter 146 of the first receiving circuit 141 attenuates high-frequency components from the output signal of the quadrature mixer 145 and suppresses aliasing in the analog-to-digital converter 147. The analog-to-digital converter 147 converts the signal processed by the low-pass filter 146 into a time-domain digital signal and outputs it. In this way, the signal ISg1 output by the first receiving circuit 141 corresponds to the real part of the first signal Sg1, and the signal QSg2 corresponds to the imaginary part of the first signal Sg1. Similarly, the second receiving circuit 142 generates the second signal Sg2 as a complex signal, and the third receiving circuit 143 generates the third signal Sg3 as a complex signal.

[0018] FIG. 2 is a schematic graph with the horizontal axis representing time and the vertical axis representing frequency. FIG. 2 shows an example of the first signal Sg1. In FIG. 2, the first signal Sg1 is schematically represented by target signals SgO1 and SgO2, which respectively originate from two targets OB at different distances from the first receiving antenna 131, and a first interference signal Sgi1. The target signal SgO1 has a higher frequency than the target signal SgO2. Therefore, the target signal SgO1 originates from a target OB that is farther away than the target signal SgO2. The first interference signal Sgi1 represents an interference signal included in the first signal Sg1. The interference signal refers to a signal derived from a contaminating signal included in an intermediate frequency signal. The contaminating signal is generated when electromagnetic waves transmitted from a radar system or the like installed in another vehicle enter the received signal. More specifically, the first interference signal Sgi1 shown in FIG. 2 is derived from a chirp signal transmitted from another radar system or the like.

[0019] Similarly, hereinafter, the interference signal included in the second signal Sg2 and the interference signal included in the third signal Sg3 are also referred to as the second interference signal and the third interference signal, respectively. Although not shown, as described above, if the first signal Sg1 includes two target signals and one first interference signal Sgi1, the second signal Sg2 also includes two target signals and one second interference signal. In this case, the third signal Sg3 also includes two target signals and one third interference signal.

[0020] The processing unit 200 is configured as a computer including a CPU, a storage unit, and an input / output interface for inputting and outputting signals from and to the outside. The processing unit 200 includes a signal processing unit 210 and a measurement unit 250. In this embodiment, the signal processing unit 210 and the measurement unit 250 are functional units realized by the CPU executing a program stored in the storage unit of the processing unit 200. The processing unit 200 is also referred to as a signal processing device. In other embodiments, some or all of the functions of the processing unit 200 may be realized by a hardware circuit. Furthermore, for example, the measurement unit 250 may be configured separately from the processing unit 200.

[0021] The processing unit 200 generates a desired signal by performing the interference signal processing shown in FIG. 3. The desired signal refers to an intermediate frequency signal from which an estimated value of an interference signal included in the intermediate frequency signal has been subtracted. In this embodiment, the signal processing unit 210 of the processing unit 200 generates a first desired signal Sd1 to a third desired signal Sd3 by performing interference signal processing. The first desired signal Sd1 refers to the first signal Sg1 from which an estimated value of the first interference signal Sgi1 has been subtracted. Similarly, the second desired signal Sd2 refers to the second signal Sg2 from which an estimated value of the second interference signal has been subtracted. The third desired signal Sd3 refers to the third signal Sg3 from which an estimated value of the third interference signal has been subtracted. The measurement unit 250 measures the target OB based on each generated desired signal, as will be described later.

[0022] In this embodiment, the interference signal processing shown in Fig. 3 is performed for each chirp signal group. More specifically, the signal processing unit 210 starts the interference signal processing when the first signal Sg1 based on the first transmission signal Tw constituting a certain chirp signal group is input to the processing unit 200.

[0023] In step S110, the signal processing unit 210 detects the interference interval Sci of the first signal Sg1 shown in FIG. 2. The interference interval Sci refers to a time interval of the first signal Sg1 that includes the first interference signal Sgi1. As described above, the interference signal originates from a chirp-like mixed signal, so a chirp-like signal occurs in the interference interval Sci of the first signal Sg1, and a sinusoidal signal occurs in other ranges. Furthermore, the signal strength in the interference interval Sci is usually stronger than the signal strength in other ranges. Therefore, the signal processing unit 210 detects the interference interval Sci based on, for example, such differences in waveform or signal strength. In the example of FIG. 2, the interference interval Sci corresponds to the entire time range of the first signal Sg1.

[0024] In step S120, the signal processing unit 210 executes a phase unwrapping process to unwrap the phase of at least a portion of the interference interval Sci of the first signal Sg1 shown in FIG. 2. Phase unwrapping refers to extending the phase, defined in the range of -π to π, to a range outside of -π to π, taking into account the continuity of the phase. More specifically, in phase unwrapping, 2πn (n is an integer other than 0) is added or subtracted from the phase as appropriate to eliminate jumps in the phase value that occur at boundaries of 2π periods, etc. Jumps in the phase value are also called phase jumps. Phase unwrapping is also called phase unwrapping or phase unwrapping. In this embodiment, in step S120, the signal processing unit 210 unwraps the phase over the entire interval of the interference interval Sci.

[0025] FIG. 4 is a graph with time on the horizontal axis and phase on the vertical axis. FIG. 4 shows an example of the unwrapped phase Up obtained by the phase unwrapping process. The unwrapped phase Up mainly reflects the phase of the first interference signal Sgi1 in the interference interval Sci. This is because, in the interference interval Sci, the intensity of the first interference signal Sgi1 is usually greater than the intensity of the target signal included in the first signal Sg1. Furthermore, because the frequency of the first interference signal Sgi1 derived from the chirp signal varies linearly, the temporal change in the phase of the first interference signal Sgi1 is expressed by a quadratic function. As a result, the unwrapped phase Up has a waveform that is a curve expressed by a quadratic function, to which variation derived from the target signal is added. In particular, the greater the intensity of the first interference signal Sgi1 relative to the target signal in the interference interval Sci, the more strongly the phase of the first interference signal Sgi1 is reflected in the unwrapped phase Up.

[0026] In step S130, the signal processing unit 210 performs approximation processing to calculate a phase function φ corresponding to the phase change over time of the first interference signal Sgi1 by approximating the phase unwrapped in step S120 with a curve. In this embodiment, the signal processing unit 210 approximates the phase unwrapped by a quadratic function in the approximation processing. The signal processing unit 210 also uses the least squares method in the approximation processing. More specifically, in step S130, the signal processing unit 210 curve fits the phase unwrapped in step S120 with a quadratic function using the least squares method. The signal processing unit 210 then calculates the phase function φ as a quadratic function with respect to time t having the same quadratic coefficient c1 and linear coefficient c2 as the quadratic function that approximated the phase unwrapped. Therefore, the phase function φ is expressed by the following equation (1). φ(t)=c1t 2 +c2t …(1) The coefficient c1 corresponds to an approximation value of a second-order parameter representing the phase change of the first interference signal Sgi1. The coefficient c2 corresponds to an approximation value of a first-order parameter representing the phase change of the first interference signal Sgi1. In other words, the approximation process in this embodiment determines the coefficients c1 and c2 of the phase function φ.

[0027] In step S140, signal processing unit 210 executes a first calculation process to calculate first desired signal Sd1 using first signal Sg1 and phase function φ.

[0028] 5, in this embodiment, in the first calculation process, the signal processing unit 210 executes a first estimation process of steps S141 to S143 and a first subtraction process of step S144. The first estimation process refers to a process of estimating the first interference signal Sgi1 using the first signal Sg1 and the phase function φ. The first subtraction process refers to a process of calculating the first desired signal Sd1 by subtracting the first interference signal Sgi1 estimated by the first estimation process from the first signal Sg1.

[0029] In step S141, the signal processing unit 210 calculates a waveform v whose phase changes according to the phase function φ. The waveform v is a waveform with an amplitude of 1 whose phase changes according to the phase function φ, and is calculated as a vector expressed by the following equation (2).

[0030]

number

[0031] In the above formula (2), the subscript N represents the time sample number, and the subscript T represents the transpose of the matrix.

[0032] In step S142, the signal processing unit 210 calculates a projection matrix M from the waveform v calculated in step S141. The projection matrix M is a matrix that orthogonally projects an arbitrary vector into a subspace with the waveform v as a base vector, and is expressed by the following formula (3). M=(v v H ) / (v H ·v)…(3) In the above formula (3), the subscript H represents the Hermitian transpose, which is also called the conjugate transpose.

[0033] In step S143, the signal processing unit 210 multiplies the first signal Sg1 by the projection matrix M. This operation corresponds to extracting, from the first signal Sg1, a signal corresponding to the phase change of the first interference signal Sgi1. The signal processing unit 210 estimates this signal corresponding to the phase change of the first interference signal Sgi1 as the first interference signal Sgi1. In other words, step S143 calculates an estimated value of the first interference signal Sgi1. The waveform S1 of the first interference signal Sgi1 estimated in step S143 is expressed by the following equation (4). S1=A·exp(j·(a1t 2 +a2t+φ0))…(4) In the above equation (4), A represents the amplitude of the first interference signal Sgi1. φ0 represents the initial phase of the first interference signal Sgi1. The coefficient a1 in equation (4) corresponds to an estimate of a second-order parameter representing a phase change of the first interference signal Sgi1, and is mutually approximate to the coefficient c1 described above. Similarly, the coefficient a2 corresponds to an estimate of a first-order parameter representing a phase change of the first interference signal Sgi1, and is mutually approximate to the coefficient c2.

[0034] In a first subtraction process in step S144, the signal processing unit 210 subtracts the estimated value of the first interference signal Sgi1 calculated in step S143 from the first signal Sg1, thereby calculating the first desired signal Sd1 as shown in FIG.

[0035] In step S150, signal processing unit 210 executes a second calculation process to calculate second desired signal Sd2 using second signal Sg2 and the phase function φ calculated in step S120.

[0036] 7, in this embodiment, in the second calculation process, the signal processing unit 210 executes a second estimation process in step S151 and a second subtraction process in step S152. The second estimation process refers to a process of estimating a second interference signal using the second signal Sg2 and the phase function φ calculated for the first signal Sg1 described above. The second subtraction process refers to a process of calculating a second desired signal Sd2 by subtracting the second interference signal estimated by the second estimation process from the second signal Sg2.

[0037] In step S151 of FIG. 7, the signal processing unit 210 multiplies the second signal Sg2 by a projection matrix M based on the phase function φ described above, and estimates the signal calculated by multiplying the second signal Sg2 by the projection matrix M as the second interference signal. The second interference signal estimated in this manner is an interference signal derived from the same contaminating signal as the first interference signal Sgi1 used to calculate the phase function φ. Hereinafter, interference signals derived from the same contaminating signal are also referred to as "corresponding interference signals." More specifically, the second interference signal has the same coefficients a1 and a2 as the corresponding first interference signal Sgi1, but typically has a different amplitude and initial phase from the corresponding first interference signal Sgi1. In step S152, the signal processing unit 210 calculates the second desired signal Sd2 by subtracting the estimated value of the second interference signal estimated by the second estimation process from the second signal Sg2.

[0038] 3, signal processing unit 210 executes a third calculation process to calculate third desired signal Sd3 using third signal Sg3 and the phase function φ calculated in step S120. Step S160 is substantially the same as step S150 described above, and therefore a description thereof will be omitted.

[0039] The measurement unit 250 measures the target OB based on each desired signal generated by the above-described interference signal processing. In this case, the measurement unit 250 may measure the target OB by, for example, individually analyzing these signals, or may measure the target OB based on the results of further Fourier transforming these signals.

[0040] According to the automotive radar device 100 of the present embodiment described above, the processing unit 200 executes (a) a phase unwrapping process for unwrapping the phase of the first signal Sg1 in the interference interval Sci, (b) an approximation process for calculating a phase function φ corresponding to a time change in the phase of the first interference signal Sgi1 by approximating the unwrapped phase with a curve, and (c) a first calculation process for calculating a first desired signal Sd1 representing the first signal Sg1 from which an estimated value of the first interference signal Sgi1 has been subtracted, using the first signal Sg1 and the phase function φ. This allows the phase function φ corresponding to the phase change of the first interference signal Sgi1 to be estimated by approximating the unwrapped phase with a curve without using the extreme value of the time derivative of the first signal Sg1, and allows the first desired signal Sd1 to be calculated using this phase function φ. This increases the likelihood of effectively removing the first interference signal Sgi1 from the first signal Sg1.

[0041] Furthermore, in this embodiment, in the first calculation process, the processing unit 200 executes (c1) a first estimation process that estimates the first interference signal Sgi1 using the first signal Sg1 and the phase function φ, and (c2) a first subtraction process that calculates the first desired signal Sd1 by subtracting the first interference signal Sgi1 estimated in the first estimation process from the first signal Sg1. This allows the first interference signal Sgi1 included in the first signal Sg1 to be estimated with high accuracy using the phase function φ without using the extreme value of the time derivative of the first signal Sg1. Then, by subtracting the first interference signal Sgi1 estimated in this manner from the first signal Sg1, the possibility of effectively removing the first interference signal Sgi1 from the first signal Sg1 increases.

[0042] Furthermore, in this embodiment, the first receiving circuit 141 is configured as a quadrature detection circuit and generates the first signal Sg1 as a complex signal. In the first estimation process, the processing unit 200 calculates a projection matrix M from a waveform v whose phase changes over time according to a phase function φ, and estimates the first interference signal Sgi1 by multiplying the first signal Sg1 by the projection matrix M. This allows accurate estimation of parameters of the first interference signal Sgi1, including the amplitude A and initial phase φ0, without using extreme values ​​of the first signal Sg1 or the extreme values ​​of the time derivative of the first signal Sg1. Therefore, the first interference signal Sgi1 can be accurately estimated. Furthermore, since the first desired signal Sd1 can be generated as a complex signal by subtracting the first interference signal Sgi1 from the first signal Sg1, more advanced signal processing can be performed using the first desired signal Sd1 compared to when the first desired signal Sd1 is generated as a real signal.

[0043] Furthermore, in this embodiment, the processing unit 200 approximates the unwrapped phase using a quadratic function in the approximation process. Since the interference signal included in the intermediate frequency signal is usually derived from a chirp wave transmitted by another radar device or the like, its frequency changes linearly, and the time change of the unwrapped phase is represented by a quadratic function. Therefore, by approximating the unwrapped phase using a quadratic function in the approximation process, the phase function φ can be calculated more quickly than when using a function of a higher order than a quadratic function.

[0044] In this embodiment, the processing unit 200 calculates the phase function φ using the least squares method in the approximation process, which makes it possible to more easily calculate the phase function φ.

[0045] Furthermore, in this embodiment, the processing unit 200 executes (e) a second calculation process in which the second desired signal Sd2 is calculated by subtracting an estimated value of the second interference signal from the second signal Sg2 using the second received signal Dw2 and the phase function φ. This allows the second desired signal Sd2 to be calculated using the phase function φ calculated for the first signal Sg1, without having to calculate a function for the second interference signal that corresponds to the change in the phase of the second interference signal over time. This allows the second desired signal Sd2 to be calculated more quickly.

[0046] Furthermore, in this embodiment, in the second calculation process, the processing unit 200 executes (e1) a second estimation process of estimating the second interference signal using the second signal Sg2 and the phase function φ, and (e2) a process of calculating the second desired signal Sd2 by subtracting the second interference signal estimated in the second estimation process from the second signal Sg2. This makes it possible to estimate the second interference signal without calculating a function corresponding to the time change in the phase of the second interference signal, and to calculate the second desired signal Sd2 by subtracting the estimated second interference signal from the second signal Sg2.

[0047] B. Second embodiment: 8, unlike the first embodiment, the processing unit 200b in the second embodiment includes a complex signal conversion unit 205 having a Hilbert transformer 206. Furthermore, the receiving circuit 140b in this embodiment generates an intermediate frequency signal as a real signal rather than a complex signal. The configuration of the automotive radar device 100b in the second embodiment is the same as that of the first embodiment except for the points not specifically described.

[0048] Each receiver circuit 140b in this embodiment is not configured as a quadrature detection circuit, but is configured as a circuit that receives a received signal from each receive antenna 130 and generates each intermediate frequency signal as a real signal. For example, the first receiver circuit 141b generates a first signal Sg1 as a real signal by mixing the transmit signal Tw and the first receive signal Dw1 using the mixer 144. Similarly, the second receiver circuit 142b and the third receiver circuit 143b generate a second signal Sg2 and a third signal Sg3 as real signals, respectively.

[0049] As will be described later, the complex signal conversion unit 205 executes conversion processing, which will be described later, using a Hilbert transformer 206. The Hilbert transformer 206 is configured, for example, with an FIR (Finite Impulse Response) filter or the like, and performs a Hilbert transform on the signal input to the Hilbert transformer 206. The original signal input to the Hilbert transformer 206 is converted by the Hilbert transform into a signal equivalent to a signal whose phase is delayed by π / 2.

[0050] The processing unit 200b in this embodiment executes the interference signal processing shown in FIG.

[0051] Step S210 is the same as step S110 in FIG. 3. In step S215, the complex signal converter 205 of the processing unit 200b executes a conversion process. The conversion process refers to a process of converting at least a portion of the interference interval Sci of the first signal Sg1 into a complex signal using a Hilbert transform. In this embodiment, the complex signal converter 205 converts the first signal Sg1 into a first signal Sg1b, in which the imaginary part of the interference interval Sci of the first signal Sg1 has a signal that has been Hilbert transformed by the Hilbert transformer 206, and the real part of the interference interval Sci of the first signal Sg1 has a signal that has not been Hilbert transformed. A signal converted into a complex signal using a Hilbert transform in this way is also called an analytic signal. In step S205, it can be said that the first signal Sg1 is converted into an analytic signal in at least a portion of the interference interval Sci.

[0052] Next, in step S220, the signal processing unit 210 unwraps the phase of the first signal Sg1b converted into a complex signal in the interference interval Sci, in the same manner as in step S120 of Fig. 3. Thereafter, in step S230, the signal processing unit 210 executes approximation processing. In the approximation processing of this embodiment, the signal processing unit 210 calculates the phase function φ by approximating the phase unwrapped in step S220 with a curve, in the same manner as in step S130 of Fig. 3.

[0053] In step S240, signal processing unit 210 executes a first calculation process. In the first calculation process in this embodiment, signal processing unit 210 calculates a first desired signal Sd1 using a first signal Sg1 as a real signal and a phase function φ. As shown in Fig. 10, in the first calculation process in this embodiment, steps S241 to S243 correspond to a first estimation process, and step S244 corresponds to a first subtraction process.

[0054] 10, the signal processing unit 210 calculates a first waveform v1 and a second waveform v2. The first waveform v1 is a waveform with an amplitude of 1 whose phase changes according to a phase function φ, and is calculated as a vector similar to the waveform v described in the first embodiment. The second waveform v2 is a waveform that is a complex conjugate of the first waveform v1.

[0055] In step S242, the signal processing unit 210 calculates a first projection matrix M1 from the first waveform v1 and calculates a second projection matrix M2 from the second waveform v2. The first projection matrix M1 and the second projection matrix M2 are calculated in the same manner as the projection matrix M described in the first embodiment.

[0056] In step S243, the signal processing unit 210 estimates the first partial signal and the second partial signal. More specifically, the signal processing unit 210 multiplies the first signal Sg1 as a real signal by a first projection matrix M1 and estimates the signal calculated thereby as the first partial signal. Similarly, the signal processing unit 210 multiplies the first signal Sg1 as a real signal by a second projection matrix M2 and estimates the signal calculated thereby as the second partial signal. The first partial signal and the second partial signal estimated in this manner are different signals that both represent parts of the first interference signal Sgi1. More specifically, one of the first partial signal and the second partial signal corresponds to the positive frequency component of the first interference signal Sgi1, and the other corresponds to the negative frequency component of the first interference signal Sgi1.

[0057] In step S244, signal processing unit 210 subtracts the first partial signal and the second partial signal from first signal Sg1, which is the real signal, to thereby calculate first desired signal Sd1.

[0058] In the second calculation process of step S250, the signal processing unit 210 calculates the second desired signal Sd2 using the second signal Sg2 as a real signal and the phase function φ. As shown in Fig. 11, in the second calculation process in this embodiment, step S251 corresponds to the second estimation process, and step S252 corresponds to the second subtraction process.

[0059] In step S251 of FIG. 11, the signal processing unit 210 estimates the third partial signal and the fourth partial signal. More specifically, the signal processing unit 210 multiplies the second signal Sg2 as a real signal by the first projection matrix M1 and estimates the signal calculated thereby as the third partial signal. Similarly, the signal processing unit 210 multiplies the second signal Sg2 as a real signal by the second projection matrix M2 and estimates the signal calculated thereby as the fourth partial signal. One of the third partial signal and the fourth partial signal estimated in this way corresponds to the positive frequency component of the second interference signal, and the other corresponds to the negative frequency component of the second interference signal. In step S252, the signal processing unit 210 subtracts the third partial signal and the fourth partial signal from the second signal Sg2 as a real signal. This calculates the second desired signal Sd2. Step S260 is similar to step S160 of FIG. 3.

[0060] According to the second embodiment described above, the processing unit 200b performs a conversion process to convert the first signal Sg1b, which is a real signal, into a complex signal using a Hilbert transform at least in the interference interval Sci prior to the phase unwrapping process. In the phase unwrapping process, the processing unit 200b unwraps the phase of the first signal Sg1b, which has been converted into a complex signal, in the interference interval Sci. Next, in a first estimation process, the processing unit 200b multiplies the first signal Sg1b, which is a real signal, by a first projection matrix M1 calculated from the first waveform v1 to estimate a first partial signal representing a portion of the first interference signal Sgi1. Then, the processing unit 200b multiplies the first signal Sg1b, which is a real signal, by a second projection matrix M2 calculated from the second waveform v2, which is a complex conjugate of the first waveform v1, to estimate a second partial signal representing a portion of the first interference signal Sgi1. Then, in a first subtraction process, the processing unit 200b subtracts the first partial signal and the second partial signal from the first signal Sg1, which is a real signal, to calculate a first desired signal Sd1. Therefore, even if the first receiving circuit 141b is not configured as a quadrature detection circuit, each parameter including the amplitude A and initial phase φ0 of the first interference signal Sgi1 can be accurately estimated without using the extreme values ​​of the first signal Sg1 or the extreme values ​​of the time derivative of the first signal Sg1.

[0061] Furthermore, in the second embodiment, as described above, it is sufficient to convert at least a portion of the interference interval Sci into a complex signal, and it is not necessary to convert the entire time interval of the first signal Sg1 as a real signal into a complex signal. Therefore, by converting a portion of the interference interval Sci into a complex signal, the first desired signal Sd1 can be calculated more quickly compared to converting the entire interference interval Sci or the entire time interval of the first signal Sg1 as a real signal into a complex signal.

[0062] In another embodiment, when the entire time interval of the first signal Sg1 as a real signal is converted into a complex signal, for example, in the first calculation process, the first desired signal Sd1 may be calculated using the first signal Sg1b as a complex signal and the phase function φ. In this case, the processing unit 200b may calculate the first desired signal Sd1 by performing the first calculation process in the same manner as described in the first embodiment. Similarly, in this case, the processing unit 200b may calculate the second desired signal Sd2 using the second signal as a complex signal and the phase function φ in the second calculation process.

[0063] C. Third embodiment: 12, the automotive radar device 100c according to the third embodiment is different from the first embodiment in that it includes a filter 207. The configuration of the automotive radar device 100c according to the third embodiment is the same as that of the first embodiment except for the points not specifically described.

[0064] In this embodiment, the filter 207 is provided in the processing unit 200c. The filter 207 amplifies the first interference signal of the first signal Sg1 relative to the signal based on the target OB in at least a part of the interference interval. In this embodiment, the filter 207 is configured as a high-pass filter that passes frequencies higher than a predetermined cutoff frequency fc and cuts off frequencies equal to or lower than the cutoff frequency fc. Note that "high frequency" means "the absolute value of the frequency is large." A high-pass filter is also called a low-cut filter.

[0065] 13, the upper part of FIG. 13 shows the first signal Sg1 represented by the target signals SgO1 and SgO2 and one first interference signal Sgi1a, as in FIG. 2. The upper part of FIG. 13 also shows an interference interval Sci1a including the first interference signal Sgi1a. As shown in FIG. 13, the first signal Sg1 passes through the filter 207 and is filtered, thereby generating a filtered signal Sg1f representing the first signal Sg1 that has passed through the filter 207. The intervals Sc1 and Sc2 of the filtered signal Sg1f are separate from each other and correspond to intervals where the frequency of the first interference signal Sgi1a is greater than the cutoff frequency fc. The interval Sc3 of the filtered signal Sg1f corresponds to the interval where the frequency of the interference interval Sci1a is equal to or less than the cutoff frequency fc. Hereinafter, unless otherwise specified, the term "first signal Sg1" simply refers to the first signal Sg1 that has not passed through the filter 207.

[0066] In the example of FIG. 13 , the filtered signal Sg1f is generated by cutting the entire target signal SgO2 and a portion of the first interference signal Sgi1a in a frequency range below the cutoff frequency fc. As a result, the filtered signal Sg1f does not include a signal corresponding to the target signal SgO2. Because the target signal SgO2 originates from a target OB at a closer distance, the intensity of the target signal SgO2 is usually greater than the intensity of the target signal SgO1. Therefore, since the filtered signal Sg1f does not include a signal corresponding to the target signal SgO2, the first interference signal Sgi1a that passed through the filter 207 is amplified relative to the target signal that passed through the filter 207 in sections Sc1 and Sc2 of the filtered signal Sg1f. Furthermore, sections Sc1 and Sc2 each include the first interference signal Sgi1a that passed through the filter 207 and correspond to interference sections Scif of the filtered signal Sg1f. Therefore, the two interference intervals Scif in the filtered signal Sg1f are separate from each other, but both result from the same first interference signal Sgi1a.

[0067] The signal processing unit 210 can determine that each interference interval Scif is caused by the same first interference signal Sgi1a, for example, by utilizing the fact that the intensity of the filtered signal Sg1f in the two separated interference intervals Scif is equivalent. This also allows the signal processing unit 210 to estimate the interference interval Sci1a in the first signal Sg1 from the filtered signal Sg1f. More specifically, the signal processing unit 210 can estimate, as the interference interval Sci1a, a section corresponding to a continuous section formed by, for example, two interference intervals Scif caused by the same first interference signal Sgi1a and the section Sc3 sandwiched between these two interference intervals Scif. Hereinafter, the interference signal included in the filtered signal Sg1f, i.e., the first interference signal that has passed through the filter 207, is also referred to as the filtered interference signal. Similarly to the interference interval Scif, the interference interval of the filtered signal Sg1f, i.e., the interference interval including the filtered interference signal, is also referred to as the filtered interference interval.

[0068] In the example of FIG. 13 , section Sc3 does not include a filtered interference signal derived from the first interference signal Sgi1a, but includes only a signal corresponding to the target signal SgO1 that has passed through the filter 207. Here, for example, as indicated by the dashed line at the top of FIG. 13 , if the first signal Sg1 includes a first interference signal Sgi1b, which has a larger absolute value of the slope of the change in frequency over time than the first interference signal Sgi1a, at the same time as the first interference signal Sgi1a, then in the filtered signal Sg1f, an interference section including the filtered interference signal derived from the first interference signal Sgi1b is included in section Sc3, not in section Sc1 or section Sc2. As such, in this embodiment, multiple filtered interference sections are easily detected individually in the filtered signal Sg1f. Furthermore, the signal processing unit 210 can estimate the interference section Sci1b including the first interference signal Sgi1b in the first signal Sg1 from the filtered signal Sg1f, just as it estimates the interference section Sci1a from the filtered signal Sg1f. Furthermore, by estimating each interference interval in the first signal Sg1 from the filtered signal Sg1f in this manner, the number of interference signals included in the first signal Sg1 can be estimated. For example, if the first signal Sg1 includes the first interference signal Sgi1a and the first interference signal Sgi1b, the filtered signal Sg1f will include two filtered interference intervals caused by the same first interference signal Sgi1a and two filtered interference intervals caused by the same first interference signal Sgi1b, for a total of four filtered interference intervals, but the number of first interference signals or interference intervals included in the first signal Sg1 is estimated to be two.

[0069] The processing unit 200c in this embodiment executes the interference signal processing shown in Fig. 14. In Fig. 14, the same steps as in Fig. 3 are denoted by the same reference numerals as in Fig. 3. In this embodiment, in the interference signal processing, the processing unit 200c executes phase unwrapping processing and approximation processing on the filtered signal Sg1f, and executes first calculation processing on the first signal Sg1 that has not passed through the filter 207.

[0070] In step S105 of FIG. 14, the processing unit 200c filters the first signal Sg1 using the filter 207 as described above.

[0071] In step S110b of FIG. 14, the signal processing unit 210 of the processing unit 200c detects a post-filter interference interval included in the filtered signal Sg1f. In step S115, the signal processing unit 210 estimates the number of first interference signals included in the first signal Sg1. In step S115, for example, as described above, the signal processing unit 210 uses the intensity of the filtered signal Sg1f in the interference interval Scif to identify post-filter signals derived from the same first interference signal and estimate the number of first interference signals included in the first signal Sg1. In the phase unwrapping process of step S120b, the signal processing unit 210 unwraps the phase in at least a portion of the post-filter interference interval. For example, when performing the phase unwrapping process on the first interference signal Sgi1a described in FIG. 13 in step S120b, the signal processing unit 210 unwraps the phase in at least a portion of either the interval Sc1 or the interval Sc2. In the approximation process of step S130b, signal processing unit 210 calculates phase function φ by approximating the phase unwrapped in step S120b with a curve. Then, in the first calculation process of step S140, signal processing unit 210 calculates first desired signal Sd1 using first signal Sg1 that has not passed through filter 207 and the phase function φ calculated in step S130.

[0072] In step S145, signal processing unit 210 determines whether or not another first interference signal is included in first desired signal Sd1. If signal processing unit 210 determines that another first interference signal is included in first desired signal Sd1, it returns to step S120b. The "another first interference signal" in step S145 refers to a first interference signal that has not been processed at the time step S145 is executed. "A certain interference signal is processed" refers to the phase unwrapping process and approximation process being executed on that interference signal, thereby calculating a phase function φ for that interference signal. For example, if the number of first interference signals estimated in step S115 is two or more, signal processing unit 210 determines that another first interference interval is included in first desired signal Sd1 in step S145, which is executed initially.

[0073] In steps S120b to S140 that are executed again, the signal processing unit 210 performs the phase unwrapping process, the approximation process, and the first calculation process for each of the other detected first interference signals. Therefore, in this embodiment, when the first signal Sg1 includes a plurality of first interference signals, it can be said that the signal processing unit 210 performs the phase unwrapping process, the approximation process, and the first calculation process for each of the first interference signals.

[0074] 13, if the first signal Sg1 includes the first interference signal Sgi1b in addition to the first interference signal Sgi1a, and the first calculation process is performed on the first interference signal Sgi1a in the first executed step S140, the signal processing unit 210 performs the phase unwrapping process, the approximation process, and the first calculation process on the first interference signal Sgi1b in the re-executed steps S120b to S140. More specifically, in this case, in the re-executed step S120b, the signal processing unit 210 unwraps the phase of at least a part of the post-filter interference section of the filtered signal Sg1f that is derived from the first interference signal Sgi1b. In this case, regardless of whether the section Sc1 or the section Sc2 was the target of phase unwrapping in the previously executed step S120b, both the section Sc1 and the section Sc2 are excluded from the target of phase unwrapping in the re-executed step S120b. In step S130b, which is executed again, signal processing unit 210 calculates phase function φ using the phase connected in step S120b, which is executed again. In step S140, which is executed again, signal processing unit 210 calculates a new first desired signal Sd1 using first desired signal Sd1 calculated immediately before as first signal Sg1 and phase function φ for first interference signal Sgi1b calculated in step S130b, which is executed again. In other words, step S140b, which is executed again, can be said to be processing for updating first desired signal Sd1 using first desired signal Sd1 and phase function φ calculated immediately before. Note that, when the number of estimated interference signals is three or more, signal processing unit 210 repeats steps S120b, S130b, and S140 a number of times corresponding to the number of estimated interference signals, as described above.

[0075] After performing the second calculation process in step S150, signal processing unit 210 determines in step S155 whether processing of all second interference signals included in second signal Sg2 has been completed. If signal processing unit 210 determines that processing of all second interference signals has not been completed, signal processing unit 210 returns to step S150. More specifically, since the number of second interference signals included in second signal Sg2 is the same as the number of first interference signals included in first signal Sg1, signal processing unit 210 executes step S150 the same number of times as the number of times step S140 was executed. When step S150 is executed again, the second desired signal Sd2 calculated immediately before is used as second signal Sg2. Furthermore, the phase function φ used in the re-executed step S150 and the phase function φ used in the previously executed step S150 are derived from different first interference signals. Steps S160 and S165 are substantially the same as steps S150 and S155, respectively, and therefore will not be described here.

[0076] According to the third embodiment described above, the filter 207 amplifies the first interference signal of the first signal Sg1 relative to the target signal in at least a portion of the interference interval. The processing unit 200c performs (a) phase unwrapping and (b) approximation on the filtered signal Sg1f, and (c) first calculation on the first signal Sg1 that has not passed through the filter 207. This allows the filter 207 to increase the strength of the first interference signal relative to the strength of the target signal, thereby enabling more accurate approximation of the unwrapped phase Up in the approximation process. Therefore, the first desired signal Sd1 can be calculated more accurately in the first calculation process. Note that the configuration including the filter 207 in this embodiment may also be applied to a configuration including the receiver circuit 140b that generates the first signal Sg1 as a real signal and the Hilbert transformer 206, as in the automotive radar device 100b described in the second embodiment.

[0077] Furthermore, in this embodiment, the filter 207 is configured as a high-pass filter. This allows the filter 207 to be easily configured as a filter that amplifies the first interference signal relative to the target signal by cutting off signals derived from closer targets OB in at least a portion of the interference interval. Furthermore, since each post-filter interference interval of the filtered signal Sg1f can be shortened, it becomes easier to individually detect multiple post-filter interference intervals in the filtered signal Sg1f, and thus easier to individually detect multiple interference intervals included in the first signal Sg1. Note that in other embodiments, the filter 207 may be configured as, for example, a band-pass filter. Even in this case, substantially the same effect as described above can be obtained by appropriately setting the passband of the filter 207.

[0078] In this embodiment, when the first signal Sg1 includes multiple first interference signals, the processing unit 200c performs the phase unwrapping process, the approximation process, and the first calculation process for each first interference signal. Therefore, even when the first signal Sg1 includes multiple first interference signals, each first interference signal can be effectively removed from the first signal Sg1.

[0079] Even in a configuration in which the filter 207 is not provided, as in the first and second embodiments, when the first signal Sg1 includes multiple first interference signals, the processing unit 200 may perform the phase unwrapping process, the approximation process, and the first calculation process for each first interference signal.

[0080] D. Fourth embodiment As shown in Fig. 15, the automotive radar device 100d in the fourth embodiment includes a filter 207b. Unlike the filter 207 described in the third embodiment, the filter 207b is not configured as a high-pass filter. The filter 207b is configured as a filter that amplifies the first interference signal Sgi1 of the first signal Sg1 relative to the target signal in at least a part of the interference interval Sci by using an intermediate frequency signal different from the first signal Sg1. The configuration of the automotive radar device 100d in the fourth embodiment, except for the points not specifically described, is the same as that of the first embodiment.

[0081] In this embodiment, the filter 207b is provided in the processing unit 200d. The filter 207b uses the second signal Sg2 to amplify the first interference signal Sgi1 relative to the target signal included in the first signal Sg1. For example, the filter 207b is configured as a filter that adjusts the phase of the second signal Sg2 so that the phase of the second interference signal included in the second signal Sg2 matches the phase of the first interference signal Sgi1 corresponding to that second interference signal, and adds the phase-adjusted second signal Sg2 to the first signal Sg1. Since the phase difference between the target signal and the first interference signal Sgi1 in the first signal Sg1 is usually different from the phase difference between the target signal and the second interference signal in the second signal Sg2, the filter 207b configured in this manner amplifies the first interference signal Sgi1 of the first signal Sg1 relative to the target signal. This generates the filtered signal Sg1fb.

[0082] The phases of the first interference signal Sgi1 and the second interference signal described above may be detected, for example, by performing a process similar to a phase unwrapping process or an approximation process on the second interference signal and the first interference signal Sgi1. Furthermore, for example, if the azimuth from which the mixed signal is emitted can be roughly predicted, the phase difference between the corresponding first interference signal Sgi1 and the second interference signal can be roughly predicted. In this case, the phase of the second signal Sg2 added to the first signal Sg1 may be adjusted based on this phase difference. In these cases, the phase and phase difference described above only need to be detected with enough accuracy to amplify the first interference signal Sgi1 by adding the second signal Sg2 to the first signal Sg1.

[0083] In this embodiment, the processing unit 200d generates the first to third desired signals Sd1 to Sd3 by performing the same processing as the interference signal processing in Fig. 3 after performing the above filtering, for example. More specifically, in the interference signal processing, the processing unit 200d performs phase unwrapping processing and approximation processing on the filtered signal Sg1fb, as in the third embodiment, and performs first calculation processing on the first signal Sg1 that has not passed through the filter 207b. In other embodiments, the processing unit 200d may perform processing similar to the interference signal processing in Fig. 9 or 14.

[0084] According to the fourth embodiment described above, the filter 207b amplifies the first interference signal relative to the target signal in at least a part of the interference interval Sci by using an intermediate frequency signal different from the first signal Sg1. Even in this configuration, the filter 207b can increase the intensity of the first interference signal Sgi1 of the first signal Sg1 relative to the intensity of the target signal, thereby enabling more accurate approximation of the unwrapped phase Up in the approximation process.

[0085] In other embodiments, the filter 207b may be configured as a filter that adjusts the phase of the second signal Sg2 so that the phase of a target signal included in the second signal Sg2 matches the phase of a target signal included in the first signal Sg1 that corresponds to the second signal Sg2, and subtracts the second signal Sg2 whose phase has been adjusted in this manner from the first signal Sg1. Even in this case, as in the fourth embodiment, the filter 207b may be configured as a filter that amplifies the first interference signal Sgi1 relatively to the target signal included in the first signal Sg1 by using a signal different from the first signal Sg1.

[0086] In another embodiment, the filter 207b may be configured as a filter that uses the third signal Sg3 to amplify the first interference signal Sgi1 relative to the target signal included in the first signal Sg1. In this case, for example, the third desired signal Sd3 may not be calculated based on the third signal Sg3, and the third signal Sg3 may be used only for filtering by the filter 207b.

[0087] E. Other Embodiments: (E-1) In the above embodiment, the processing unit 200 executes the first estimation process and the first subtraction process in the first calculation process. In contrast, the processing unit 200 does not have to execute the first estimation process and the first subtraction process in the first calculation process. For example, the processing unit 200 may add a matrix M b The first desired signal Sd1 may be calculated by multiplying the matrix M b is expressed by the following equation (5) using the above-mentioned projection matrix M. M b =IM …(5) In the above equation (5), I represents a unit matrix. bThe first desired signal Sd1 calculated by multiplying by is mathematically equivalent to the first desired signal Sd1 calculated by performing the first estimation process and the first subtraction process. Therefore, even in this case, it is more likely that the first interference signal Sgi1 can be effectively removed from the first signal Sg1. Similarly, the processing unit 200 does not need to perform the second estimation process and the second subtraction process in the second calculation process.

[0088] (E-2) In the above embodiment, the processing unit 200 calculates the projection matrix M in the first estimation process, but it is not necessary to calculate the projection matrix M. In this case, the processing unit 200 calculates, for example, a phase function φ expressed by the following equation (6) in the approximation process. b is calculated, and the phase function φ b The first interference signal Sgi1 may be estimated based on the following: φ b =c1t 2 +c2t+c3…(6) That is, in this case, in the approximation process, the processing unit 200 determines a coefficient c3 in addition to the coefficients c1 and c2 by approximating the unwrapped phase Up with a curve. The coefficient c3 corresponds to an approximation value of the initial phase of the first interference signal Sgi1. Then, in the first estimation process, the processing unit 200 estimates the amplitude A of the first interference signal Sgi1, thereby estimating the waveform S2 of the first interference signal Sgi1 expressed by the following equation (7). S2=A·exp(j·(c1t 2 +c2t+c3))…(7) In this case, the amplitude A is calculated based on the amplitude of the first signal Sg1, for example. In addition, in this case, the processing unit 200 performs the same process as the phase unwrapping process and the same process as the above-mentioned approximation process on the second signal Sg2 to obtain the phase function φ expressed by the above-mentioned equation (6). b Then, in the second estimation process, the processing unit 200 can estimate the second interference signal based on this function.

[0089] (E-3) In the above embodiment, the processing unit 200 approximates the unwrapped phase Up by a quadratic function in the approximation process, but it is not necessary to approximate it by a quadratic function. Also, in the above embodiment, the processing unit 200 approximates the unwrapped phase Up by a quadratic function using the least squares method in the approximation process. b However, the phase function φ is calculated using a method other than the least squares method. b may be calculated.

[0090] (E-4) In the above embodiment, the processing unit 200 calculates the second desired signal Sd2 using the phase function φ of the first interference signal Sgi1 in the second calculation process. However, for example, prior to the second calculation process, it may calculate a function corresponding to the change in the phase of the second interference signal over time by performing processing similar to the phase unwrapping processing and approximation processing on the second signal Sg2, and then use the calculated function to calculate the second desired signal Sd2.

[0091] (E-5) In the above embodiment, the automotive radar device 100 is provided with another receiving antenna 130 different from the first receiving antenna 131 and another receiving circuit 140 different from the first receiving circuit 141, but it is not necessary for the automotive radar device 100 to be provided with another receiving antenna 130 or another receiving circuit 140.

[0092] F. Other Forms: The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments can be appropriately replaced or combined to solve some or all of the above-described problems or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0093] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0094] <Feature 1> An automotive radar device (100) includes a first receiving antenna (131) that receives, as a first received signal (Dw1), a reflected wave from a target (OB) that reflects a transmission wave based on a transmission signal (Tw), a first receiving circuit (141) connected to the first receiving antenna that generates a first signal (Sg1) by mixing the transmission signal and the first received signal, and a processing unit (200). The processing unit executes the following processes: (a) unwrapping the phase of the first signal in at least a part of an interference interval (Sci) that includes a first interference signal (Sgi1) that represents an interference signal included in the first signal; (b) calculating a function corresponding to a time change in the phase of the first interference signal by approximating the phase unwrapped in the process (a) with a curve; and (c) calculating, using the first signal and the function, a first desired signal (Sd1) that represents the first signal from which an estimated value of the first interference signal has been subtracted.

[0095] <Mode 2> In the signal processing device of Mode 1, in the process (c), the processing unit may execute the following processes: (c1) a process of estimating the first interference signal using the first signal and the function; and (c2) a process of calculating the first desired signal by subtracting the first interference signal estimated in the process (c1) from the first signal.

[0096] <Mode 3> In the signal processing device of Mode 2, the first receiving circuit may be configured as a quadrature detection circuit and generate the first signal as a complex signal, and the processing unit may, in the process (c1), calculate a projection matrix (M) from a waveform (v) whose phase changes over time according to the function, and estimate the first interference signal by multiplying the first signal by the projection matrix.

[0097] <Mode 4> In the signal processing device of mode 2, the first receiving circuit generates the first signal as a real signal, and the processing unit, prior to the process (a), performs a conversion process of converting the first signal as a real signal into a complex signal using a Hilbert transform in at least a part of the interference interval, and in the process (a), phase-unwraps the phase of the first signal converted into a complex signal in an interval including the first interference signal, and in the process (c1), calculates a first projection matrix (M1) from a first waveform (v1) whose phase changes according to the function, and converts the first signal as a real signal into a complex signal using a Hilbert transform. a first partial signal representing a part of the first interference signal is estimated by multiplying the first signal by the first projection matrix, a second projection matrix (M2) is calculated from a second waveform (v2) that is a complex conjugate of the first waveform, a second partial signal representing a part of the first interference signal and different from the first partial signal is estimated by multiplying the first signal as a real signal by the second projection matrix, and in the process (c2), the first desired signal is calculated by subtracting the first partial signal and the second partial signal from the first signal as a real signal.

[0098] <Mode 5> In the automotive radar device of any one of Modes 1 to 4, in the process (b), the processing unit may approximate the phase unwrapped in the process (a) by a quadratic function.

[0099] <Mode 6> In the on-vehicle radar device of any one of Modes 1 to 5, the processing unit may calculate the function in the process (b) using a least squares method.

[0100] <Mode 7> In the automotive radar device of any one of Modes 1 to 6, when the first signal includes a plurality of the first interfering signals, the processing unit may perform the processes (a) to (c) for each of the first interfering signals.

[0101] <Form 8> In the automotive radar device of any one of Forms 1 to 7, a filter (207) may be provided that amplifies the first interference signal of the first signal relatively to a target signal representing a signal based on the target in at least a part of the interference section, and the processing unit may perform the processes (a) and (b) on the first signal that has passed through the filter, and may perform the process (c) on the first signal that has not passed through the filter.

[0102] <Mode 9> In the vehicle-mounted radar device of Mode 8, the filter may be configured as a high-pass filter.

[0103] <Form 10> The automotive radar device of Form 8 may further include an other receiving antenna different from the first receiving signal, which receives the reflected wave as another receiving signal different from the first receiving signal, and an other receiving circuit different from the first receiving circuit, which is connected to the other receiving antenna and generates another signal different from the first signal by mixing the transmission signal and the other receiving signal, and the filter may use the other signal to amplify the first interference signal of the first signal relative to the target signal in at least a part of the interference interval.

[0104] <Form 11> In the automotive radar device of any one of Forms 1 to 10, there is provided a second receiving antenna (132) that receives the reflected wave as a second receiving signal (Dw2), and a second receiving circuit (142) that is connected to the second receiving antenna and generates a second signal (Sg2) by mixing the transmission signal and the second receiving signal (Dw2), and the processing unit may (e) perform a process of calculating, using the second receiving signal and the function, a second desired signal (Sd2) that represents the second signal from which an estimated value of a second interfering signal that represents an interfering signal included in the second signal has been subtracted.

[0105] <Form 12> In the automotive radar device of Form 11, in the process (e), the processing unit may execute the following processes: (e1) a process of estimating the second interference signal using the second signal and the function; and (e2) a process of calculating the second desired signal by subtracting the second interference signal estimated in the process (e1) from the second signal. [Explanation of symbols]

[0106] Dw1...first received signal, OB...target, Sci...interference section, Sd1...first desired signal, Sg1...first signal, Sgi1...first interference signal, Tw...transmitted signal, 100...vehicle-mounted radar device, 130...receiving antenna, 131...first receiving antenna, 140...receiving circuit, 141...first receiving circuit

Claims

1. a first receiving antenna (131) that receives a reflected wave from a target (OB) that reflects a transmission wave based on a transmission signal (Tw) as a first received signal (Dw1); a first receiving circuit (141) connected to the first receiving antenna and configured to generate a first signal (Sg1) by mixing the transmission signal and the first receiving signal; a processing unit (200), The processing unit (a) a process of unwrapping the phase of the first signal in at least a part of an interference section (Sci) including a first interference signal (Sgi1) representing an interference signal included in the first signal; (b) calculating a function corresponding to a time change in the phase of the first interference signal by approximating the phase unwrapped in the process (a) with a curve; (c) calculating a first desired signal (Sd1) representing the first signal from which the estimated value of the first interference signal has been subtracted, using the first signal and the function; An on-vehicle radar device (100).

2. 2. The on-vehicle radar device according to claim 1, The processing unit, in the process (c), (c1) estimating the first interfering signal using the first signal and the function; (c2) calculating the first desired signal by subtracting the first interference signal estimated in the process (c1) from the first signal; Automotive radar equipment.

3. 3. The on-vehicle radar device according to claim 2, the first receiving circuit is configured as a quadrature detection circuit and generates the first signal as a complex signal; In the process (c1), the processing unit calculates a projection matrix (M) from a waveform (v) whose phase changes over time according to the function, and estimates the first interference signal by multiplying the first signal by the projection matrix.

4. 3. The on-vehicle radar device according to claim 2, the first receiving circuit generates the first signal as a real signal; The processing unit Prior to the process (a), a conversion process is performed in which the first signal as a real signal is converted into a complex signal using a Hilbert transform in at least a part of the interference interval; In the process (a), a phase of the first signal converted into a complex signal is unwrapped in a section including the first interference signal; In the process (c1), A first projection matrix (M １ ) and multiplying the first signal as a real signal by the first projection matrix to estimate a first partial signal representing a part of the first interference signal; A second waveform (v2) that is a complex conjugate of the first waveform is used to obtain a second projection matrix (M ２ ) and multiplying the first signal as a real signal by the second projection matrix to estimate a second partial signal that represents a part of the first interference signal and is different from the first partial signal; In the process (c2), the first desired signal is calculated by subtracting the first partial signal and the second partial signal from the first signal as an actual signal.

5. 2. The on-vehicle radar device according to claim 1, In the process (b), the processing unit approximates the phase unwrapped in the process (a) by a quadratic function.

6. 2. The on-vehicle radar device according to claim 1, In the process (b), the processing unit calculates the function using a least squares method.

7. 2. The on-vehicle radar device according to claim 1, When the first signal includes a plurality of the first interference signals, the processing unit performs the processes (a) to (c) on each of the first interference signals.

8. 2. The on-vehicle radar device according to claim 1, a filter (207) that amplifies the first interference signal of the first signal relative to a target signal representing a signal based on the target in at least a portion of the interference section; The processing unit performs the processing (a) and the processing (b) on the first signal that has passed through the filter, and performs the processing (c) on the first signal that has not passed through the filter.

9. 9. The on-vehicle radar device according to claim 8, The filter is configured as a high-pass filter.

10. 9. The on-vehicle radar device according to claim 8, another receiving antenna for receiving the reflected wave as another receiving signal different from the first receiving signal; another receiving circuit different from the first receiving circuit, the another receiving circuit being connected to the another receiving antenna and mixing the transmission signal with the another receiving signal to generate another signal different from the first signal; The filter amplifies the first interference signal of the first signal relative to the target signal in at least a part of the interference interval by using the other signal.

11. The on-vehicle radar device according to any one of claims 1 to 10, a second receiving antenna (132) that receives the reflected wave as a second receiving signal (Dw2); a second receiving circuit (142) connected to the second receiving antenna and configured to generate a second signal (Sg2) by mixing the transmission signal and the second receiving signal (Dw2); The processing unit (e) performing a process of calculating a second desired signal (Sd2) representing the second signal from which an estimated value of a second interference signal representing an interference signal included in the second signal has been subtracted, using the second received signal and the function; Automotive radar equipment.

12. The on-vehicle radar device according to claim 11, The processing unit, in the process (e), (e1) estimating the second interference signal using the second signal and the function; (e2) calculating the second desired signal by subtracting the second interference signal estimated in the process (e1) from the second signal; Automotive radar equipment.

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