Radar equipment, radar control methods, radar control programs

Abstract

To provide a radar device or the like capable of executing suppression processing of a side lobe signal component several times according to a situation.SOLUTION: A control unit in a radar device has an acquisition unit for acquiring mixed reception signals received at a particular receiving antenna. The control unit has a defining unit that defines a plurality of decoded signals in which the mixed received signals are decoded for each code corresponding to each transmitted signal. The control unit has a removal unit capable of repeatedly executing removal processing. In the removal processing, the removal unit estimates a sidelobe signal component detected in other decoded signals in correlation with a target signal component corresponding to the target transmitted signal in a specific decoded signal, and removes the sidelobe signal component from other decoded signals or related signals associated with the decoded signals. The removal unit executes the removal processing for the number of times at least correlated to a ratio of the intensity of the peak to the intensity of a thermal noise in the specific decoded signal.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This disclosure relates to technology for controlling radar equipment. [Background technology]

[0002] Patent Document 1 discloses a MIMO radar using a pseudo-random phase modulation scheme. Such a MIMO radar transmits a transmission signal modulated by a different CDM code from each transmitting antenna. The MIMO radar generates a decoded signal spectrum decoded according to each CDM code from the received signal and estimates the sidelobe signal components from each decoded signal spectrum. The MIMO radar can obtain a decoded signal spectrum with the sidelobe signal components suppressed by subtracting each estimated sidelobe signal component from the decoded signal spectrum corresponding to the target transmitting antenna. To increase the degree of suppression of the sidelobe signal components, the MIMO radar further estimates the sidelobe signal components from the decoded signal spectrum with the sidelobe signal components suppressed and subtracts them again from the decoded signal spectrum, thereby performing the sidelobe signal component suppression process multiple times. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] U.S. Patent No. 9952319 [Overview of the project] [Problems that the invention aims to solve]

[0004] Patent Document 1 does not describe how to determine the number of times the suppression process for sidelobe signal components is performed. Therefore, the technology described in Patent Document 1 does not allow for determining the number of times the suppression process is performed on a case-by-case basis.

[0005] The object of this disclosure is to provide a radar device capable of performing sidelobe signal component suppression processing a number of times depending on the situation. Another object of this disclosure is to provide a radar control method capable of performing sidelobe signal component suppression processing a number of times depending on the situation. Yet another object of this disclosure is to provide a radar control program capable of performing sidelobe signal component suppression processing a number of times depending on the situation. [Means for solving the problem]

[0006] The following describes the technical means of solving the problem described in this disclosure. Note that the claims and the reference numerals in parentheses in this section indicate the correspondence with the specific means described in the embodiments detailed later, and do not limit the technical scope of this disclosure.

[0007] A first aspect of this disclosure is a transmitting antenna (TX) comprising one or more transmitting antennas (TX), A transmission signal generation unit (2) generates multiple types of transmission signals modulated by different codes transmitted from a transmitting antenna, A receiving antenna (RX) receives a mixed received signal, which is a mixture of each transmitted signal reflected by a reflector. A control unit (100) that processes the mixed received signal, Equipped with, The control unit is An acquisition unit (110) that acquires a mixed reception signal received by a specific receiving antenna, A definition unit (120) defines multiple decoded signals, each of which is obtained by decoding a mixed received signal for each code corresponding to a transmitted signal. A removal unit (130) that estimates a sidelobe signal component, which is a received signal component detected in other decoded signals that correlates with a target signal component, which is a received signal component corresponding to a target transmitted signal in a specific decoded signal, and removes the sidelobe signal component from other decoded signals or related signals associated with the decoded signals, and can repeatedly perform a removal process by setting the correlation target of the sidelobe signal component to the target signal component of the specific decoded signal after the previous removal process, It has, The removed part is, Before executing the removal process, the number of times the removal process should be executed should be set. The number of times that the ratio of peak intensity to thermal noise intensity in a particular decoded signal is at least correlated. The number of times it was decided This is a radar device that performs removal processing for several minutes.

[0008] A second aspect of the present disclosure is a radar control method performed by a processor (102) for controlling a radar device (1) comprising one or more transmitting antennas (TX), a transmitting signal generation unit (2) that generates a plurality of types of transmitting signals modulated by different codes transmitted from the transmitting antennas, and a receiving antenna (RX) that receives a mixed receiving signal obtained by mixing each of the transmitting signals reflected by a reflector, To acquire a mixed reception signal received by a specific receiving antenna, This involves defining multiple decoded signals, each of which is obtained by decoding a mixed received signal for each code corresponding to a transmitted signal. This involves estimating the sidelobe signal component, which is a received signal component detected in other decoded signals that correlates with the target signal component, which is a received signal component corresponding to the target transmitted signal in a specific decoded signal, and performing a removal process to remove the sidelobe signal component from other decoded signals or related signals associated with the decoded signals. Includes, The removal process can be repeatedly performed by making the correlation target of the sidelobe signal component the target signal component of the specific decoded signal after the previous removal process. Performing the removal process means Before executing the removal process, the number of times the removal process should be executed should be set. The number of times that the ratio of peak intensity to thermal noise intensity in a particular decoded signal is at least correlated. The number of times it was decided This includes performing a removal process for several minutes.

[0009] A third aspect of the present disclosure is a radar control program stored in a storage medium (101) and containing instructions to be executed by a processor (102) for controlling a radar device (1) comprising one or more transmitting antennas (TX), a transmitting signal generation unit (2) that generates a plurality of types of transmitting signals modulated by different codes transmitted from the transmitting antennas, and a receiving antenna (RX) that receives a mixed receiving signal obtained by mixing each of the transmitting signals reflected by a reflector, The order is, To acquire a mixed reception signal received by a specific receiving antenna, This involves defining multiple decoded signals, each of which is obtained by decoding a mixed received signal for each code corresponding to a transmitted signal. This involves estimating the sidelobe signal component, which is a received signal component detected in other decoded signals that correlates with the target signal component, which is a received signal component corresponding to the target transmitted signal in a specific decoded signal, and then performing a removal process to remove the sidelobe signal component from other decoded signals or related signals associated with the decoded signals. Includes, The removal process can be repeatedly performed by making the correlation target of the sidelobe signal component the target signal component of the specific decoded signal after the previous removal process. Performing the removal process is, Before executing the removal process, the number of times the removal process should be executed should be set. The number of times that the ratio of peak intensity to thermal noise intensity in a particular decoded signal is at least correlated. The number of times it was decided This includes performing a removal process for several minutes.

[0010] According to these first to third embodiments, the removal process is performed at least a number of times correlated with the ratio of the peak intensity to the thermal noise intensity in a particular decoded signal. Since the ratio of the peak intensity to the thermal noise intensity correlates with the magnitude of the sidelobe signal component, the sidelobe signal component can be sufficiently suppressed by removing it a number of times corresponding to this ratio. Therefore, the suppression process of the sidelobe signal component can be performed a number of times depending on the situation. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram showing the overall configuration of the radar device according to the first embodiment. [Figure 2] This is a block diagram showing the functional configuration of the control unit according to the first embodiment. [Figure 3] This graph shows an example of a transmitted signal according to the first embodiment. [Figure 4] This is a flowchart showing the radar control method in the first embodiment. [Figure 5] This is a schematic diagram illustrating the signal processing steps for generating the frequency spectrum of a decoded signal from a distance bin signal. [Figure 6] This is an example of a frequency spectrum used to demonstrate the definition of the signal-to-noise ratio (SNR). [Figure 7] This graph shows an example of the number of iterations correlated with the signal-to-noise ratio (SNR). [Figure 8] This is a schematic diagram illustrating the overview of the iteration process. [Figure 9] This is a schematic diagram showing the difference between cases where sidelobe signal components are suppressed and cases where they are not. [Figure 10] This figure shows an example of the number of iterations correlated with the signal-to-noise ratio and the number of peaks in the second embodiment. [Figure 11] This graph illustrates the peak position correlated with the number of iterations in the third embodiment. [Figure 12] This is a flowchart showing the radar control method in the fourth embodiment. [Figure 13] This is a flowchart showing the radar control method in the fifth embodiment. [Figure 14] This graph shows an example of a buried peak determined in the radar control method of the fifth embodiment. [Modes for carrying out the invention]

[0012] Hereinafter, several embodiments of this disclosure will be described with reference to the drawings. In each embodiment, the same reference numerals will be used for corresponding components, and redundant explanations may be omitted. Furthermore, if only a part of the configuration is described in each embodiment, the configuration of other embodiments described earlier may be applied to the other parts of that configuration. Moreover, not only the combinations of configurations explicitly stated in the description of each embodiment, but also the configurations of multiple embodiments can be partially combined even if not explicitly stated, as long as there are no particular problems with the combination.

[0013] (First Embodiment) A first embodiment of this disclosure will be described with reference to Figures 1 to 9. The radar device 1 is mounted on a moving object such as a vehicle. The radar device 1 transmits a transmission signal to the outside world, receives the transmission signal reflected by an object as a received signal, and detects target information such as the distance to the target (which is the reflector that reflected the transmission signal), the relative speed to the target, and the orientation of the target.

[0014] Target information output from radar device 1 is input to the in-vehicle ECU (Electronic control unit) via an in-vehicle network such as CAN (Control Area Network®) and Ethernet®. Based on the target information of each acquired target, the in-vehicle ECU performs various processes for autonomous driving and advanced driver assistance of the vehicle.

[0015] Examples of processing based on target information include collision avoidance processing and warning processing. Collision avoidance processing is the process of controlling the vehicle to avoid collision with a target by controlling the braking system, steering system, etc., based on the target information of each target. Warning processing is the process of warning the driver of the possibility of collision with a target based on the target information of each target.

[0016] As shown in Figure 1, the radar device 1 of this embodiment includes a transmit signal generation unit 2, a plurality of transmit circuits 3, a plurality of transmit antennas TX, a plurality of receive antennas RX, a plurality of receive circuits 4, and a control unit 100. The radar device 1 is a so-called MIMO (Multiple-Input-Multiple-Output) radar that artificially increases the number of receive antennas RX beyond the actual number by transmitting transmit signals from a plurality of transmit antennas TX.

[0017] The transmission signal generation unit 2 acquires a control signal from the control unit 100 and generates a signal modulated according to the control signal. This generated signal is, for example, a so-called chirp signal whose frequency changes over time (see Figure 3). The generated signal is distributed and output to each channel of the transmission circuit 3 and the reception circuit 4. The transmission signal generation unit 2 outputs a generated signal with pseudo-random phase modulation using a different code for each transmission channel corresponding to each transmission antenna TX as the transmission signal. This modulation method is also called code division multiplexing (CDM). As shown in Figure 3, in this embodiment, the transmission signals transmitted from different transmission antennas TX are assumed to have substantially the same chirp transmission time, center frequency, and frequency bandwidth. In Figure 3, the transmission signals transmitted from different transmission antennas TX are represented by different line types, i.e., solid lines and dashed lines.

[0018] In other words, in this embodiment, transmission signals, each subjected to phase modulation with a different code, are transmitted to the outside world from each of the multiple transmitting antennas TX. The signal output to the receiving circuit 4 from the generated signals in relation to the transmission signal will be referred to as the local signal below.

[0019] The transmitting circuit 3 and the receiving circuit 4 are each mainly composed of semiconductor integrated circuit devices such as MMICs (Monolithic Microwave Integrated Circuits). The transmitting circuit 3 is connected to the transmitting antenna TX and outputs a transmission signal to the transmitting antenna TX. The transmitting circuit 3 is equipped with the same number of amplifiers 30 as the number of connected transmitting antennas TX. The amplifiers 30 amplify the transmission signal output from the transmitting signal generation unit 2 and output it to the corresponding transmitting antennas TX.

[0020] The transmitting antenna TX converts the electrical signal supplied as a transmission signal from the transmitting signal generation unit 2 into a radio wave signal and transmits it to the outside world. In this embodiment, it is assumed that there are 12 transmitting antennas TX. In the following, when each transmitting antenna TX is distinguished individually, it will be written as transmitting antenna TXn (where n is a natural number from 1 to 12). The transmitting antenna TX is composed of at least one antenna element. For example, the transmitting antenna TX is a patch antenna equipped with multiple flat-plate shaped antenna elements. The antenna elements are arranged on the side of the dielectric substrate opposite to the ground plate, where the ground plate is provided on one side, so as to face the ground plate. The multiple antenna elements are connected, for example, in series by a feed line that supplies an electrical signal.

[0021] The receiving antenna RX receives radio signals, including the transmitted signals reflected by the target, which acts as a reflector in the external environment. Each of the multiple receiving antennas RX receives a signal that is a mixture of the received signals corresponding to each transmitted signal from the multiple transmitting antennas TX. In the following, this mixed signal received by each receiving antenna RX will be referred to as the mixed received signal. The components of each received signal corresponding to each transmitted signal from the multiple transmitting antennas TX, which are mixed in the mixed received signal, will be referred to as the received signal components.

[0022] The receiving antenna RX converts the received signal, which is a radio wave signal, into an electrical signal and outputs it to the corresponding receiving circuit 4. The receiving antenna RX is a patch antenna, similar to the transmitting antenna TX, in which at least one antenna element is connected in series by a feed line.

[0023] The receiving circuit 4 is connected to the receiving antenna RX and acquires the received signal received by the receiving antenna RX for each receiving channel corresponding to each receiving antenna RX. The receiving circuit 4 is equipped with the same number of amplifiers 40 and signal mixers 41 as the number of connected receiving antennas RX.

[0024] The amplifier 40 amplifies the received signal received by the receiving antenna and outputs it to the signal mixing unit 41. The signal mixing unit 41 generates a beat signal by mixing the local signal from the transmission signal generation unit 2 and the received signal. The generated beat signal is an interference signal representing the frequency difference between the received signal and the local signal. The beat signal is output to the control unit 100 after high-frequency components that deviate from the frequency difference between the received signal and the local signal are filtered out by a low-pass filter (not shown).

[0025] The control unit 100 is connected to the signal generation unit and the receiving circuit via at least one of the following: a LAN (Local Area Network) line, a wire harness, an internal bus, and a wireless communication line. The control unit 100 is configured to include at least one dedicated computer.

[0026] The dedicated computer constituting the control unit 100 may be a radar ECU (Electronic Control Unit) specialized in controlling a specific radar device 1. The dedicated computer constituting the control unit 100 may be a radar integrated ECU that comprehensively controls multiple radar devices 1 mounted on a mobile body. The dedicated computer constituting the control unit 100 may be a sensor integrated ECU that comprehensively controls multiple sensors, including the radar device 1 and other sensors such as LiDAR (Light Detection and Ranging / Laser Imaging Detection and Ranging).

[0027] The dedicated computer constituting the control unit 100 has at least one memory 101 and one processor 102. The memory 101 is at least one type of non-transitory tangible storage medium, such as semiconductor memory, magnetic media, and optical media, which non-temporarily stores programs and data that can be read by the computer. Here, storage may be accumulation where data is retained even when the vehicle is turned off, or temporary storage where data is erased when the vehicle is turned off. The processor 102 includes at least one type as a core, such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), RISC (Reduced Instruction Set Computer)-CPU, DFP (Data Flow Processor), and GSP (Graph Streaming Processor).

[0028] In the control unit 100, the processor 102 executes multiple instructions included in the radar control program stored in the memory 101 for controlling the radar device 1. This allows the control unit 100 to construct multiple functional blocks for controlling the radar device 1. The multiple functional blocks constructed in the control unit 100 include, as shown in Figure 2, an acquisition block 110, a definition block 120, a removal block 130, and an output block 140. These functional blocks can also be referred to as the acquisition unit, definition unit, removal unit, and output unit, respectively.

[0029] Through the combined efforts of blocks 110, 120, 130, and 140, the radar control method by which the control unit 100 controls the radar device 1 is executed according to the radar control flow shown in Figure 4. This radar control flow is executed repeatedly during the startup of the radar device 1. This radar control flow is executed, for example, for each receiving channel, and one cycle is defined as the execution of the flow for all receiving channels. In this radar control flow, each "S" represents multiple steps executed by multiple instructions included in the radar control program.

[0030] First, in S10, the acquisition block 110 acquires the mixed received signal. The mixed received signal is a beat signal obtained by mixing the local signal from the signal generation unit and the received signal from the receiving antenna RX. The beat signal is an interference signal that represents the frequency difference between the received signal and the local signal. The mixed received signal is acquired as a digitized digital signal sampled at predetermined time intervals by the A / D converter.

[0031] In subsequent S20, the definition block 120 performs a Fast Fourier Transform (FFT) process on the mixed received signal. As a result, the definition block 120 obtains the distance spectrum of each chirp in the mixed received signal. The obtained distance spectrum is a frequency spectrum indicating a peak corresponding to the distance to the target, and is discrete distance data including signal intensity information for each bin (distance bin) corresponding to the distance as distance information. Thereafter, as shown in FIG. 5, Ns samples of each of the Nc chirps are converted into distance data by FFT processing, and data obtained by extracting Nc samples for a specific distance bin is denoted as the distance bin signal R. Here, the received signal component encoded by the code C txn derived from the transmission signal from the transmission antenna TXn is denoted as P n . The distance bin signal R before decoding can be defined by the following equation (1) as the sum of the received signal components C txn P n before decoding from each transmission antenna TX.

Equation

[0032] In S30, the definition block 120 defines a decoded signal according to the distance bin signal R. Specifically, the definition block 120 generates a decoded signal obtained by decoding the distance bin signal R with the code corresponding to each transmission antenna TX. The definition block 120 stores the decoded signal for each code in the memory 101, respectively.

[0033] For example, assume that the transmission antenna TX1 is the target transmission antenna. In this case, the definition block 120 in S30 performs decoding for codes that have not been decoded until the previous loop among the codes C tx2 ~C tx12 corresponding to the other transmission antennas TX2 to TX12. For example, when performing decoding for a specific code C txn , the decoded signal decodes the phase modulation by C txn using the code C txn *Using this, it can be expressed by the following equation (2). Here, the sign C txn * C txn This is a sign that, when multiplied by a number, results in all elements being 1.

number

[0034] In the subsequent S40, definition block 120 performs a Fast Fourier Transform (FFT) on the decoded signal. This allows definition block 120 to obtain the Doppler frequency spectrum of the mixed received signal. This frequency spectrum is a velocity spectrum showing peaks corresponding to the target velocity, and is discrete signal data containing signal intensity information for each velocity bin. This second FFT process allows definition block 120 to obtain two-dimensional distance and velocity map data, as shown in Figure 5. This two-dimensional map data can also be called an RV map. Note that in the Fast Fourier Transform process, definition block 120 multiplies the distance bin signal R by a window function. Examples of window functions other than the rectangular function include the Hanning function and the Gaussian function.

[0035] In the above equation (2), when k=n, P n The coefficient becomes 1. Therefore, as shown in Figure 6, the velocity spectrum is, Peak P n This is the sum of the spectrum of P and the diffused spectrum due to other terms. n The spectrum consisting of terms other than those listed corresponds to the sidelobe signal component.

[0036] In the subsequent S50, the removal block 130 detects peaks from the frequency spectrum. For peak detection, the removal block 130 can identify the frequency bin where the intensity is maximum as the peak location. The removal block 130 detects the peak by, for example, performing CFAR (Constant False Alarm Rate) processing. The removal block 130 acquires at least the identified peak location and its peak intensity as peak information related to the detected peak. The peak information may include the phase at the peak. Decoded signal RC txn * In this case, peak detection is performed using equation (2) P n This is equivalent to detecting [the target signal]. The peak in the frequency spectrum of the decoded signal is an example of a "target signal component," which is the received signal component corresponding to the transmitted signal targeted in the decoded signal.

[0037] Then, in S60, the removal block 130 determines the number of iterations. Here, iteration means estimating new sidelobe signal components in other decoded signals from the peak of the decoded signal that has undergone removal processing, and removing the new sidelobe signal components from the decoded signal. In other words, iteration corresponds to the process of estimating the sidelobe signal components correlated with a specific peak of the decoded signal after the previous removal processing by making that peak the correlation target of the sidelobe signal components, and then repeating the removal processing on those sidelobe signal components.

[0038] The removal block 130 is the signal-to-noise ratio (SNR) χ in the frequency spectrum of the decoded signal corresponding to the target transmitted signal. tgt The number of iterations N that correlates with at least one of the following: itr Determine the signal-to-noise ratio (SNR) χ. tgtThis is the ratio from the peak intensity in the decoded signal to the noise floor (magnitude) of the thermal noise, i.e., the ratio of the peak intensity to the noise floor of the thermal noise. The removal block 130 may acquire thermal noise as a theoretically estimable parameter correlated with, for example, the circuit configuration and ambient temperature in the radar device 1. Alternatively, the removal block 130 may acquire thermal noise as a parameter correlated with the received signal intensity in areas where no target exists in the RV map. When the removal block 130 acquires thermal noise as a parameter correlated with the received signal intensity, it is sufficient to acquire thermal noise corresponding to the average or median value of the received signal intensity in the aforementioned area. Alternatively, the removal block 130 may acquire thermal noise corresponding to the mode value of the received signal intensity in the aforementioned area.

[0039] If multiple peaks exist in the frequency spectrum, the removal block 130 determines the signal-to-noise ratio (SNR) χ for the peak with the highest intensity. tgt It may also be considered to be correlated with the number of iterations N for the removal block 130. itr The signal-to-noise ratio (SNR) of each peak is χ². tgt It may also be considered to be correlated with the sum of. Alternatively, the removal block 130 is the number of iterations N. itr The signal-to-noise ratio (SNR) of each peak is χ². tgt It may also be considered to correlate with the mean.

[0040] The removal block 130 has an S / N ratio χ, as shown in the graph in Figure 7, for example. tgt The larger the number of iterations, the larger the number of iterations N. itr Determine the signal-to-noise ratio (SNR) χ. tgt and the number of iterations N itr Relationship information regarding the relationship is stored in memory 101 in the form of a function or table. The removal block 130 is obtained from the stored relationship information and the signal-to-noise ratio χ. tgt Depending on the iteration, N itr To decide.

[0041] In the subsequent S70, the removal block 130 performs the removal process. In the sidelobe suppression process, the removal block 130 removes the decoded signal RC. txn The sidelobe signal component is removed. Furthermore, the removal block 130 determines the number of iterations N. itr This iterative process repeats the sidelobe suppression process for several minutes.

[0042] In the sidelobe suppression process, the removal block 130 estimates the sidelobe signal components contained in the decoded signal decoded with the code corresponding to another transmitted signal, which correlate with the peak of the decoded signal decoded with the code corresponding to a certain transmitted signal. Here, for simplicity, as shown in Figure 8, the code C is transmitted from two transmitting antennas TX1 and TX2. tx1 ,C tx2 The sidelobe suppression process will be explained using, as an example, the distance bin signal R based on the received signal reflected at the target from the modulated transmitted signal. In this case, the removal block 130 is the decoded signal RC tx1 * and decoded signal RC tx2 * For each of these, we estimate the sidelobe signal components in the other frequency spectrum that correlate with the target peaks P1 and P2 in the other frequency spectrum.

[0043] Specifically, the removal block 130 removes the decoded signal RC. tx1 * From the peak P1^ in the frequency spectrum, the decoded signal RC tx2 * Side lobe signal component C in the frequency spectrum tx2 * C tx1 P1^ is calculated. Similarly, the removal block 130 is the decoded signal RC. tx2 * From the peak P2^ in the frequency spectrum, the decoded signal RC tx1 * Side lobe signal component C in the frequency spectrum tx1 * C tx2 Calculate P2^.

[0044] Then, the removal block 130 contains the estimated sidelobe signal component C. tx1 * C tx2 P2^ is decoded into signal RC tx1 * From there, the sidelobe signal component C tx2 * C tx1 P1^ is decoded into signal RC tx2 * By subtracting from the original signal, each sidelobe signal component is removed. Hereafter, the decoded signal from which the sidelobe signal components have been removed will be referred to as the decoded signal with the sidelobe components removed.

[0045] Furthermore, the removal block 130 is determined by the number of iterations N. itr The system performs iteration processing accordingly. Iteration processing involves reestimating the sidelobe signal component in other decoded signals from the peak in the removed decoded signal, and then removing this estimated sidelobe signal component from the other decoded signal.

[0046] In the example shown in Figure 8, the removal block 130 is the decoded signal RC. tx1 * Peak P in the decoded signal after removal 1_1 From ^, decoded signal RC tx2 * New sidelobe signal component C in tx2 * C tx1 P 1_1 ^ is calculated. Then, the removal block 130 removes this new sidelobe signal component C tx2 * C tx1 P 1_1 ^ is the decoded signal RC tx2 * Subtract from it. As a result, the removal block 130 removes the sidelobe signal component C. tx2 * C tx1 P 1_1 ^ is suppressed and further removed decoded signal is obtained. Similarly, removal block 130 is peak P 2_1A new side lobe signal component C is obtained from ^ tx1 * C tx2 P 2_1 ^ is calculated, and this is subtracted from the decoded signal RC tx1 * to obtain a further processed decoded signal.

[0047] The removal block 130 repeats the iteration process for the determined number of iterations N itr times. In FIG. 8, for simplicity, an example of executing one iteration process is shown. However, the removal block 130 estimates side lobe signal components from each of the peaks P 2_2 ^, P 1_2 ^, subtracts them from the decoded signal RC tx1 * , RC tx2 * [[ID=二十六]]to execute the second iteration process. Similarly, by repeating the estimation and removal of side lobe signal components, the removal block 130 executes the iteration process for the determined number of iterations Nitr. Also, even when three or more types of codes are used in modulation, the removal block 130 executes the side lobe suppression process in the same manner. For example, even when the transmission signals of each of the 12 transmission antennas TX are modulated with different codes, the same applies. In this case, the removal block 130 estimates the side lobe signal components in other decoded signals from each peak of the 12 types of decoded signals decoded for each code, and removes each side lobe signal component from each decoded signal.

[0048] Thereafter, in S80, the output block 140 obtains target information from the frequency spectrum. The target information includes at least one of the distance, speed, and azimuth of the target. The output block 140 estimates the azimuth, for example, by the DoA (Direction of Arrival) method. In the subsequent S130, the output block 140 outputs the target information to the outside.

[0049] The difference in dynamic range PSR between cases where the above sidelobe suppression is performed and cases where it is not will be explained with reference to Figure 9. Assuming one target, the dynamic range PSR can be expressed as the ratio from the maximum value of the target's peak to the sidelobes. If the suppression process is not performed, this dynamic range PSR satisfies the relationship shown in the following equation (3), where Nc is the total number of chirps in the transmitted signal and Ntx is the number of transmitting antennas modulated with CDM code.

number

[0050] On the other hand, when the removal process shown in this embodiment is performed, the dynamic range PSR satisfies the relationship shown in the following formula (4).

number

[0051] In other words, radar device 1 that performs sidelobe suppression has a larger dynamic range (PSR) than radar device 1 that does not perform sidelobe suppression.

[0052] According to the first embodiment described above, the removal of the sidelobe signal is performed at least a number of times correlated with the ratio of the peak intensity in the received signal component corresponding to the target transmitted signal to the thermal noise. Since the ratio correlates with the magnitude of the sidelobe signal component, the sidelobe signal component can be sufficiently suppressed by removing it a number of times corresponding to the ratio. Therefore, the suppression process of the sidelobe signal component can be performed a number of times depending on the situation.

[0053] (Second embodiment) As shown in Figure 10, the second embodiment is a modification of the first embodiment.

[0054] In the second embodiment, the removal block 130 in S60 has an S / N ratio of χ tgt In addition, the number of peaks N tgtNumber of iterations N correlated with itr This is determined. Specifically, the removal block 130 has a peak number N, as shown in Figure 10, for example. tgt The more iterations N there are, the more iterations N itr This is determined by the signal-to-noise ratio (SN ratio) χ. tgt Even if the signals are equivalent, the number of peaks N tgt If the number is large, the number of iterations N for that signal. itr The number increases. SN ratio χ tgt and the number of peaks N tgt And, the number of iterations N itr The relationship information between and is stored in memory 101 in the form of a function or table. The removal block 130 uses the stored relationship information and the acquired signal-to-noise ratio χ tgt And, the number of peaks N tgt And, accordingly, the number of iterations N itr To decide.

[0055] (Third embodiment) As shown in Figure 11, the third embodiment is a modification of the first embodiment.

[0056] In the third embodiment, the removal block 130 in S60 reduces the signal-to-noise ratio (SNR) χ when there are multiple peaks in the frequency spectrum. tgt In addition, the number of iterations N correlates with the Doppler frequency difference between peaks. itr This is determined. The Doppler frequency difference between peaks is the difference in Doppler frequencies at each peak, as shown in Figure 11. When multiple peaks exist, the overlapping of the sidelobe signal components originating from each peak determines the overall spectral shape of the sidelobe signal components. Number of iterations N itr The optimal number of iterations N varies depending on the position of each peak in the overall spectral shape of the sidelobe signal components. itr The optimal number can be determined by the Doppler frequency difference between peaks, i.e., the relative positions of the peaks in the Doppler frequency domain, the code used, and the number of transmitting antennas TX.

[0057] Therefore, the removal block 130 has an iteration count N that correlates with the Doppler frequency difference, the code used, and the number of transmitting antennas TX. itr Determine the signal-to-noise ratio (SNR) χ. tgt , Doppler frequency difference, code, number of transmitting antennas TX, and number of iterations N itr The relationship information between and is stored in memory 101 in the form of a function or table. The removal block 130 uses the stored relationship information and the acquired signal-to-noise ratio χ tgt The number of iterations N depends on the Doppler frequency difference, the code, and the number of transmitting antennas TX. itr To decide.

[0058] (Fourth embodiment) As shown in Figure 12, the fourth embodiment is a modification of the first embodiment.

[0059] In the fourth embodiment, as shown in Figure 12, the flow moves from S50 to S51. In S51, the removal block 130 removes the sidelobe signal component from the decoded signal only a predetermined number of times (e.g., once). That is, at S51, no iteration process is performed to re-estimate and remove the sidelobe signal component from the decoded signal after the removal has been completed. After S51, the flow moves to S52.

[0060] In S52, the removal block 130 obtains the sidelobe level, which is the magnitude of the sidelobe signal component after sidelobe suppression in S51. The removal block 130 obtains the average or median value of the sidelobe signal component in at least a portion of the frequency spectrum as the sidelobe level. After S52, this flow proceeds to S53.

[0061] In S53, the removal block 130 determines whether or not to perform iteration processing according to the sidelobe level. For example, the removal block 130 determines that iteration processing is unnecessary if the sidelobe level falls within the upper limit of the allowable level range, and determines that iteration processing is necessary if it falls outside the upper limit of the allowable level difference range. Here, the allowable level range is, for example, the range in which the sidelobe level is below or less than a threshold, and the upper limit is that threshold. The threshold is, for example, a value that correlates with the magnitude of the noise floor of thermal noise. Note that determining that iteration processing is unnecessary in S53 is performed after N iterations. itr This can also be rephrased as deciding that it occurs zero times.

[0062] If it is determined in S53 that iteration processing is not required, this flow proceeds to S80. On the other hand, if it is determined in S53 that iteration processing is required, this flow proceeds to S60, and the number of iterations is N. itr The following is determined. Furthermore, even if it is determined that iteration processing is required based on the side lobe level, the signal-to-noise ratio χ tgt Depending on the size, the number of iterations in S60 is N itr In some cases, the number of occurrences may be determined to be zero.

[0063] After S60, this flow proceeds to S71. In S71, the removal block 130 executes the iteration process according to the determined number of iterations, Nitr. In S71, as in S70 of the first embodiment, it is possible that the iteration process is executed zero times, i.e., that the iteration process is not executed. After S71, this flow proceeds to S80.

[0064] (Fifth embodiment) As shown in Figures 13 and 14, the fifth embodiment is a modification of the first embodiment.

[0065] In the fifth embodiment, as shown in Figure 13, the flow transitions from S50 to S53. In S53, the removal block 130 determines whether or not there is a buried peak in the previous cycle. Here, a buried peak is a peak in the frequency spectrum of the decoded signal before suppression of the sidelobe signal component that is buried by the sidelobe signal component, as shown in Figure 14. In other words, a buried peak is a peak with a lower intensity than the sidelobe signal component.

[0066] If it is determined that there is a buried peak, the flow proceeds to S54. In S54, the removal block 130 determines whether the current receiving antenna RX is the first receiving antenna RX to undergo sidelobe suppression in the current cycle. If it is determined that it is the first receiving antenna RX to perform sidelobe suppression, the flow proceeds to S60. On the other hand, if it is determined that it is not the first receiving antenna RX, the flow proceeds to S55. In S55, the removal block 130 determines whether there is a buried peak in the first receiving antenna RX. If it is determined that there is a buried peak, the flow proceeds to S60.

[0067] On the other hand, if it is determined in S53 that there were no buried peaks in the previous cycle, i.e., that no buried peaks were detected, or if it is determined in S55 that there were no buried peaks at the first receiving antenna, this flow proceeds to S55. In other words, if it is determined that there are no buried peaks, the sidelobe suppression process is interrupted.

[0068] (Other embodiments) Although several embodiments have been described above, this disclosure is not limited to those embodiments and can be applied to various embodiments and combinations without departing from the spirit of this disclosure.

[0069] In a modified example, the removal block 130 may remove the sidelobe signal component from the distance bin signal instead of the decoded signal. In this case, the distance bin signal is an example of an "associated signal" related to the decoded signal.

[0070] In a modified example, the transmission signal generation unit 2 may apply modulation with a different code to each antenna set containing multiple transmission antennas TX. In this case, a different code is applied to the transmission signal for each of the multiple antenna sets containing a predetermined number of transmission antennas TX. In this case, the control unit 100 performs a removal process for each code of each antenna set. Furthermore, the transmission signal corresponding to each transmission antenna TX in the antenna set is subjected to phase shift modulation or amplitude modulation, making it possible to separate the corresponding received signal component for each transmission signal.

[0071] In the modified example, the output block 140 of S80 may output the frequency spectrum externally as target information. For example, the output block 140 outputs the frequency spectrum to an in-vehicle ECU outside the radar device 1. In this case, the in-vehicle ECU that receives the output obtains the target's position and other information from the target's peaks included in the frequency spectrum.

[0072] In a modified example, the radar device 1 may be equipped with only a single transmitting antenna TX. In this case, the transmitting signal generation unit 2 generates a transmitting signal for a single transmitting antenna that is a mixture of multiple transmitting signals modulated with different codes.

[0073] In the modified examples, the dedicated computer constituting the control unit 100 may be an integrated ECU that integrates the vehicle's driving control. The dedicated computer constituting the control unit 100 may be a decision ECU that determines the driving tasks in the vehicle's driving control. The dedicated computer constituting the control unit 100 may be a monitoring ECU that monitors the vehicle's driving control. The dedicated computer constituting the control unit 100 may be an evaluation ECU that evaluates the vehicle's driving control.

[0074] In the modified examples, the dedicated computer constituting the control unit 100 may be a navigation ECU that navigates the vehicle's travel route. The dedicated computer constituting the control unit 100 may be a locator ECU that estimates the vehicle's own state variables. The dedicated computer constituting the control unit 100 may be an actuator ECU that controls the vehicle's travel actuators. The dedicated computer constituting the control unit 100 may be an HCU (HMI (Human Machine Interface) Control Unit) that controls information presentation in the vehicle. The dedicated computer constituting the control unit 100 may be a computer other than the vehicle that constructs, for example, an external center or mobile terminal that can communicate with the vehicle.

[0075] In the modified example, the dedicated computer constituting the control unit 100 may have at least one of the digital circuit and the analog circuit as a processor. Here, the digital circuit is at least one of the following, for example, ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), SOC (System on a Chip), PGA (Programmable Gate Array), and CPLD (Complex Programmable Logic Device). Furthermore, such a digital circuit may have a memory that stores a program.

[0076] In the modified example, the mobile body to which the control unit 100 is applied may be, for example, an autonomous robot capable of transporting goods or collecting information by autonomous or remote driving. Furthermore, the autonomous robot may be an autonomous vehicle or the like, an autonomous driving robot.

[0077] In addition to the embodiments described so far, the above-described embodiments and modifications may be implemented as control devices configured to be mounted on a mobile body and having at least one processor 102 and one memory 101. Specifically, the above-described embodiments and modifications may be implemented in the form of a processing circuit (e.g., a processing ECU) or a semiconductor device (e.g., a semiconductor chip).

[0078] (Disclosure of technical ideas) This specification discloses several technical concepts, as listed in the following paragraphs. Some paragraphs are written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs are written in a multiple dependent form, referring to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical concepts.

[0079] (Technical thought 1) One or more transmitting antennas (TX), A transmission signal generation unit (2) generates multiple types of transmission signals modulated by different codes transmitted from the aforementioned transmitting antenna, A receiving antenna (RX) that receives a mixed received signal obtained by mixing each of the aforementioned transmitted signals reflected by a reflector, A control unit (100) that processes the mixed received signal, Equipped with, The control unit is An acquisition unit (110) that acquires the mixed reception signal received by a specific receiving antenna, A definition unit (120) defines a plurality of decoded signals obtained by decoding the mixed received signal for each of the codes corresponding to each of the transmitted signals, A removal unit (130) that estimates a sidelobe signal component, which is a received signal component detected in another decoded signal in correlation with a target signal component, which is a received signal component corresponding to the target transmitted signal in a specific decoded signal, and removes the sidelobe signal component from the other decoded signal or related signals associated with the decoded signal, and can repeatedly perform a removal process by setting the correlation target of the sidelobe signal component to the target signal component of the specific decoded signal after the previous removal process, It has, The removal section is, A radar device that performs the removal process a number of times that correlates at least with the ratio of peak intensity to thermal noise intensity in a specific decoded signal.

[0080] (Technical thought 2) The radar device according to technical concept 1, wherein the removal unit performs the removal process at least a number of times correlated with the ratio and the number of peaks.

[0081] (Technical Thought 3) The radar device according to Technical Concept 1 or Technical Concept 2, wherein the removal unit performs the removal process at least a number of times correlated with the ratio and the Doppler frequency difference between the plurality of peaks.

[0082] (Technical Thought 4) The radar apparatus according to any one of Technical Concepts 1 to 3, wherein the removal unit interrupts the removal process when the intensity of the sidelobe signal component in a specific decoded signal falls within the upper limit of the allowable intensity range.

[0083] (Technical Thought 5) The radar device according to technical concept 4, wherein the removal unit stops the removal process when the strength after performing the removal process a specified number of times falls within the upper limit of the allowable strength range.

[0084] (Technical Thought 6) The radar apparatus according to any one of Technical Concepts 1 to 5, wherein the removal unit cancels the removal process if the peak having a lower intensity than the sidelobe signal component was not detected in a specific decoded signal in the previous cycle.

[0085] (Technical Thought 7) The radar apparatus according to any one of Technical Concepts 1 to 6, wherein the removal unit cancels the removal process if the peak having a lower intensity than the sidelobe signal component is not detected in a specific decoded signal decoded from the mixed received signal received by another receiving antenna.

[0086] Furthermore, technical concepts 1 to 7 described above may be implemented in the form of radar control methods and radar control programs. [Explanation of Symbols]

[0087] 1: Radar device, 2: Transmit signal generation unit, 100: Control unit, 101: Memory (storage medium), 102: Processor, 110: Acquisition block (acquisition unit), 120: Definition block (definition unit), 130: Removal block (removal unit), TX: Transmit antenna, RX: Receiving antenna

Claims

1. One or more transmitting antennas (TX), A transmission signal generation unit (2) generates multiple types of transmission signals modulated by different codes transmitted from the aforementioned transmitting antenna, A receiving antenna (RX) that receives a mixed received signal obtained by mixing each of the aforementioned transmitted signals reflected by a reflector, A control unit (100) that processes the mixed received signal, Equipped with, The control unit is An acquisition unit (110) that acquires the mixed reception signal received by a specific receiving antenna, A definition unit (120) defines a plurality of decoded signals obtained by decoding the mixed received signal for each of the codes corresponding to each of the transmitted signals, A removal unit (130) that estimates a sidelobe signal component, which is a received signal component detected in another decoded signal in correlation with a target signal component, which is a received signal component corresponding to the target transmitted signal in a specific decoded signal, and removes the sidelobe signal component from other decoded signals or related signals associated with the decoded signals, and can repeatedly perform a removal process by setting the correlation target of the sidelobe signal component to the target signal component of the specific decoded signal after the previous removal process, It has, The removal section is, A radar device that, before performing the removal process, determines the number of times to perform the removal process to be at least correlated with the ratio of the peak intensity to the thermal noise intensity in a particular decoded signal, and performs the removal process for the determined number of times.

2. The radar device according to claim 1, wherein the removal unit determines the number of times to perform the removal process to be at least correlated with the ratio and the number of peaks before performing the removal process, and performs the removal process for the determined number of times.

3. The radar device according to claim 1, wherein the removal unit determines, before executing the removal process, the number of times to execute the removal process to be correlated with at least the ratio and the Doppler frequency difference between the plurality of peaks, and executes the removal process for the determined number of times.

4. The radar apparatus according to claim 1, wherein the removal unit interrupts the removal process when the intensity of the sidelobe signal component in a specific decoded signal falls within the upper limit of the allowable intensity range.

5. The radar device according to claim 4, wherein the removal unit discontinues the removal process when the strength after performing the removal process a specified number of times falls within the upper limit of the allowable strength range.

6. The radar apparatus according to claim 1, wherein the removal unit discontinues the removal process if the peak having a lower intensity than the sidelobe signal component was not detected in a specific decoded signal in the previous cycle.

7. The radar apparatus according to claim 1, wherein the removal unit discontinues the removal process if the peak having a lower intensity than the sidelobe signal component is not detected in a specific decoded signal decoded from the mixed received signal received by another receiving antenna.

8. A radar control method performed by a processor (102) to control a radar device (1) comprising one or more transmitting antennas (TX), a transmitting signal generation unit (2) that generates a plurality of types of transmitting signals modulated by different codes transmitted from the transmitting antennas, and a receiving antenna (RX) that receives a mixed receiving signal obtained by mixing each of the transmitting signals reflected by a reflector, To acquire the mixed reception signal received by a specific receiving antenna, Define a plurality of decoded signals obtained by decoding the mixed received signal for each of the codes corresponding to each of the transmitted signals, Estimate a sidelobe signal component, which is a received signal component detected in another decoded signal in correlation with a target signal component, which is a received signal component corresponding to the target transmitted signal in a specific decoded signal, and perform a removal process to remove the sidelobe signal component from the other decoded signal or related signals associated with the decoded signal. Includes, The removal process can be repeatedly performed by making the correlation target of the sidelobe signal component the target signal component of the specific decoded signal after the previous removal process, A radar control method that includes, before performing the removal process, determining the number of times to perform the removal process to be at least correlated with the ratio of peak intensity to thermal noise intensity in a particular decoded signal, and performing the removal process for the determined number of times.

9. A radar control program, which includes instructions to be executed by a processor (102) and stored in a storage medium (101) for controlling a radar device (1) comprising one or more transmitting antennas (TX), a transmitting signal generation unit (2) that generates a plurality of types of transmitting signals modulated by different codes transmitted from the transmitting antennas, and a receiving antenna (RX) that receives a mixed receiving signal obtained by mixing each of the transmitting signals reflected by a reflector, The aforementioned instruction is, To acquire the mixed reception signal received by a specific receiving antenna, Define a plurality of decoded signals obtained by decoding the mixed received signal for each of the codes corresponding to each of the transmitted signals, The process involves estimating a sidelobe signal component, which is a received signal component detected in another decoded signal in correlation with a target signal component, which is a received signal component corresponding to the target transmitted signal in a specific decoded signal, and performing a removal process to remove the sidelobe signal component from the other decoded signal or related signals associated with the decoded signal. Includes, The removal process can be repeatedly performed by making the correlation target of the sidelobe signal component the target signal component of the specific decoded signal after the previous removal process, A radar control program that, before executing the removal process, determines the number of times the removal process will be performed to a number that is at least correlated with the ratio of the peak intensity to the thermal noise intensity in a particular decoded signal, and then performs the removal process for the determined number of times.

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