DETECTION SYSTEM, TRANSMITTER, RECEIVER, CONTROL CIRCUIT, STORAGE MEDIUM, DETECTION METHOD, TRANSMISSION METHOD AND RECEPTION METHOD

Abstract

A detection system (30) comprises: a transmitter (10) comprising transmission antenna elements (18), controlling times of generation of a radar signal, generation of a code, and generation of a carrier signal for dividing an available frequency band into sub-bands, and periodically alternating the sub-bands, multiplying the radar signal and the code for each transmission antenna element (18), generating a radio frequency signal with a bandwidth of the sub-band using the radar signal multiplied by the code and the carrier signal, and transmitting the radio frequency signal from each transmission antenna element (18);and a receiver (20) comprising receiving antenna elements (22) receiving the high-frequency signals transmitted from the transmitter (10) and reflected or scattered by a measurement target, generating channel information between the transmitter (10) and the receiver (20) using the carrier signal, the radar signal and the code, specifying a position of the measurement target using the channel information, and generating an image of the measurement target by performing focus correction.;

Description

Area

[0001] The present disclosure relates to a detection system, a transmitter, a receiver, a control circuit, a storage medium, a detection method, a transmission method, and a reception method, wherein the detection system measures a measurement target using electromagnetic waves. background

[0002] In recent years, tackling challenges such as the advancement of automated control of systems known as digital twins or cyber-physical systems, and the realization of a safe and secure society with a declining workforce, has created an increasing need for sensing technology to detect the near environment. An in-vehicle radar for forward and sideways monitoring, essential for automated driving, is one example of such sensing technology. Furthermore, new applications based on sensing technology have emerged, such as non-stop security gates for quality control and safety assurance on production lines.

[0003] As a means of obtaining information about the surrounding environment from a remote location, a radar device that utilizes electromagnetic waves is commonly used. For example, Patent Literature 1 discloses a multiple-input, multiple-output (MIMO) radar device with improved moving object detection performance. The radar device described in Patent Literature 1 acquires information through MIMO channels formed between a plurality of transmitting elements and a plurality of receiving elements and measures a reflection point. Reference listPatent literature

[0004] Patent Literature 1: Japanese Patent Application, Publication No. 2021-81282 SummaryTechnical problem

[0005] Conventional radar technology was primarily developed for the purpose of detecting aircraft, vehicles, and the like, and therefore mainly focuses on detecting the position and relative movement speed of the reflection point located at a certain distance. New applications, such as security gates that require detecting a metal object in the possession of a pedestrian and determining its shape, that is, determining the type and hazard of the metal object, and non-destructive testing that detects a crack, void, or the like in a synthetic resin, require high resolution at a position near a sensor and multi-layer spatial analysis performance in the depth direction.

[0006] To increase the resolution of a radar device, it is effective to use a shorter wavelength, i.e., a higher frequency, and to increase the aperture diameter of an antenna. However, when considering a short-range detection application, downsizing the device is an important factor, and increasing the size of the antenna is difficult. Since the aperture diameter of the antenna can be reduced relative to the wavelength, using a high-frequency band is a necessary and effective solution.

[0007] An application such as non-destructive testing requires resolution in the depth direction, that is, in a distance direction. So-called distance resolution depends on a frequency bandwidth that can be used as a radar signal. However, a low-frequency band is already being used by another system, so the use of the high-frequency band is necessary to ensure a wide band. In close-range detection, where the aperture diameter cannot be ignored with respect to the measurement distance (that is, the aperture diameter cannot be considered as a single point), a function equivalent to focus adjustment based on the measurement distance is required. Furthermore, for tomographic imaging, such as computed tomography (CT) scanning, which is realized by X-rays on a measurement target, it is important to perform focus adjustment based on the position of each layer.

[0008] Therefore, to achieve a three-dimensional, high-resolution detection system, it is important to use a broadband signal for which the use of the high-frequency band is effective. However, the design and manufacture of a high-frequency circuit that processes a broadband signal of more than 10 GHz in the high-frequency band is very difficult and leads to increased costs.

[0009] The present disclosure has been realized in view of the above aspects, and an object of the present disclosure is to provide a detection system capable of improving resolution at a low cost while utilizing a high frequency signal when measuring a measurement target located nearby. Solution to the problem

[0010] To overcome the problems described above and achieve the object, a detection system according to the present disclosure comprises: a transmitter including a plurality of transmission antenna elements for: controlling timings of generation of a radar signal, generating a code for a receiver to separate high-frequency signals transmitted from the plurality of transmission antenna elements into the high-frequency signals transmitted from individual ones of the transmission antenna elements, and generating a carrier signal to divide an available frequency band into a plurality of sub-bands and periodically switch the sub-bands used for the high-frequency signals transmitted from the plurality of transmission antenna elements so that an entire range of the frequency band is utilized; multiplying the radar signal and the code for each of the plurality of transmission antenna elements;generate the high-frequency signal having a bandwidth of the subband using the code-multiplied radar signal and the carrier signal; and transmit the high-frequency signal from each of the plurality of transmitting antenna elements; and a receiver comprising a plurality of receiving antenna elements for: receiving the high-frequency signals transmitted from the transmitter and reflected or scattered by a measurement target; generating channel information indicating a state of a channel between the transmitter and the receiver using the carrier signal, the radar signal, and the code; specifying a position of the measurement target using the channel information; and generating an image of the measurement target by performing focus correction on the measurement target. Advantageous effects of the invention

[0011] The detection system according to the present disclosure can improve the resolution at a low cost while utilizing the high frequency signal when measuring the measurement target that is nearby. Brief description of the drawings Fig. 1 is a diagram illustrating a general concept of measurement intended to be performed by a detection system according to a first embodiment. Fig. 2 is a diagram illustrating an exemplary configuration for the detection system according to the first embodiment. Fig. 3 is a diagram illustrating an example of high-frequency signals transmitted by a transmitter according to the first embodiment. Fig. 4 is a flowchart illustrating an operation of the detection system according to the first embodiment. Fig. 5 is a flowchart illustrating an operation of the transformer according to the first embodiment. Fig. 6 is a flowchart illustrating an operation of a receiver according to the first embodiment. Fig. 7 is a diagram showing an exemplary configuration of a processing circuit in a case where the processing circuit implementing the transmitter according to the first embodiment is implemented by a processor and a memory. Fig. 8 is a diagram showing an example of a processing circuit in a case where the processing circuit implementing the transmitter according to the first embodiment includes the dedicated hardware. Fig. 9 is a diagram illustrating a general concept of measurement intended to be performed by a detection system according to a second embodiment. Fig. 10 is a diagram illustrating an exemplary configuration for the detection system according to the second embodiment. Fig. 11 is a diagram illustrating an example of high-frequency signals transmitted by transmitters according to a third embodiment. Fig. 12 is a diagram illustrating a general concept of measurement intended to be performed by a detection system according to a fourth embodiment. Fig. 13 is a diagram illustrating an example of high-frequency signals transmitted by a transmitter according to the fourth embodiment. Fig. 14 is a diagram illustrating a concept of an operation of a layer clipping unit of a receiver according to a fifth embodiment. Fig. 15 is a diagram illustrating a concept of an operation of a focus correction unit of the receiver according to the fifth embodiment. Description of embodiments

[0012] Hereinafter, a detection system, a transmitter, a receiver, a control circuit, a storage medium, a detection method, a transmission method, and a reception method according to embodiments of the present disclosure will be described in detail with reference to the drawings. First embodiment.

[0013] Fig. 1 is a diagram illustrating a general concept of measurement intended to be performed by a detection system 30 according to a first embodiment. The detection system 30 is a system that includes a transmitter 10 and a receiver 20 and measures a measurement target 40. In the detection system 30, the transmitter 10 transmits radio waves from a transmission assembly 17 having a plurality of transmission antenna elements 18 to the measurement target 40, and the receiver 20 receives reflected waves, scattered waves, and the like from the measurement target 40 through a reception assembly 21 having a plurality of reception antenna elements 22, thereby measuring the measurement target 40. In the first embodiment, the transmitter 10 transmits high-frequency signals as the transmission of the radio waves. In the transmitter 10, the transmission assembly 17 includes N TPieces of the transmission antenna elements 18 as the plurality of transmission antenna elements 18. In the receiver 20, the receiver arrangement 21 comprises N R Pieces of the receiving antenna elements 22 as the plurality of receiving antenna elements 22. As will be described later, the detection system 30 extracts information about the measurement target 40 from N T ×N R or more pieces of channel information that are transmitted between the N R Pieces of the transmission antenna elements 18 and the N R pieces of the receiving antenna elements 22.

[0014] Fig. Fig. 2 is a diagram illustrating an exemplary configuration for the detection system 30 according to the first embodiment. As explained above, the detection system 30 comprises the transmitter 10 and the receiver 20. The transmitter 10 comprises a synchronization unit 11, a radar signal generation unit 12, a code generation unit 13, a carrier signal generation unit 14, a coding unit 15, a high-frequency signal generation unit 16, and the transmission arrangement 17. As explained above, the transmission arrangement 17 comprises the N T Pieces of the transmission antenna elements 18.

[0015] The synchronization unit 11 adjusts the timing of operation of each unit in the transmitter 10 and the receiver 20. The synchronization unit 11 controls the timing of radar signal generation by the radar signal generation unit 12, code generation by the code generation unit 13, and carrier signal generation by the carrier signal generation unit 14 in the transmitter 10. The radar signal generation unit 12 generates the radar signal at a baseband or intermediate frequency. The radar signal is a periodic broadband signal, as described later. The code generation unit 13 generates the codes for the receiver 20 to separate the high-frequency signals transmitted from the transmission assembly 17 including the plurality of transmission antenna elements 18 into the high-frequency signals transmitted from the transmission antenna elements 18.The carrier signal generation unit 14 generates a reference carrier for generating a final high-frequency signal. As described later, the carrier signal generation unit 14 generates carrier signals to divide a frequency band available to the transmitter 10 into a plurality of subbands and periodically alternate the subbands used for the high-frequency signals transmitted by the plurality of transmitting antenna elements 18, so that the entire frequency band is utilized.

[0016] The coding unit 15 performs code multiplication for each of the plurality of transmission antenna elements 18, in which the radar signal generated by the radar signal generation unit 12 is multiplied by the code generated by the code generation unit 13. For each of the transmission antenna elements 18, the high-frequency signal generation unit 16 generates the high-frequency signal to be transmitted by the transmission antenna element 18 using the signal obtained by multiplying the radar signal by the code in the coding unit 15 and the reference carrier generated in the carrier signal generation unit 14.The high-frequency signal generating unit 16 is, for example, an upconverter or a multiplier, and generates the high-frequency signal with a bandwidth of the subband using the radar signal multiplied by the code and the carrier signal to cause the high-frequency signal to be transmitted by each of the plurality of transmission antenna elements 18. In the transmission arrangement 17, the transmission antenna elements 18 transmit the high-frequency signals generated by the high-frequency signal generating unit 16.

[0017] The receiver 20 comprises the receiving arrangement 21, a signal conversion unit 23, a detection unit 24, a correlation processing unit 25, a MIMO channel reproduction unit 26, a layer clipping unit 27 and a focus correction unit 28. As explained above, the receiving arrangement 21 comprises the N R Pieces of the receiving antenna elements 22.

[0018] In the receiving arrangement 21, the receiving antenna elements 22 receive the high-frequency signals transmitted from the transmitter 10, where the high-frequency signals are the waves reflected by the measurement target 40 or the waves scattered by the measurement target 40. That is, the receiving antenna elements 22 receive the reflected waves or the scattered waves of the high-frequency signals transmitted from the transmitter 10. Note that the receiving antenna elements 22 may also directly receive the high-frequency signals transmitted from the transmitter 10, depending on the positional relationship, the orientation relationship, and the like between the transmitting antenna elements 18 of the transmitter 10 and the receiving antenna elements 22 of the receiver 20.For each of the receiving antenna elements 22, the signal conversion unit 23 converts the radio-frequency signals received by the receiving antenna element 22 into baseband or intermediate frequency signals, i.e., it downconverts the radio-frequency signals. The signal conversion unit 23 is, for example, a downconverter and converts the radio-frequency signals received by the plurality of receiving antenna elements 22 into received signals in the frequency band of the radar signals used to generate the radio-frequency signals by the transmitter 10, using the carrier signals used to generate the radio-frequency signals.

[0019] The detection unit 24 is arranged for each of the receiving antenna elements 22 and detects the baseband or intermediate frequency received signals obtained after conversion by the signal conversion unit 23 using the radar signals generated by the radar signal generation unit 12 of the transmitter 10, thereby obtaining the received information. The received information is the reflected waves or the scattered waves of the high-frequency signals received by the receiving antenna elements 22 and includes the high-frequency signals transmitted by the plurality of transmitting antenna elements 18. Note that the receiver 20 can obtain the received information by mixing the baseband or intermediate frequency received signals obtained after conversion by the signal conversion unit 23 with a mixer. A case where the detection unit 24 performs the detection will be described below.The correlation processing unit 25 is arranged for each of the receiving antenna elements 22 and performs correlation processing of the received information detected by the detection unit 24 using the codes generated by the code generation unit 13 of the transmitter 10, thereby separating the received information into the signals from the transmitting antenna elements 18 of the transmitter 10, that is, the received signals received by the plurality of receiving antenna elements 22 are separated into the individual signals of the transmitting antenna elements 18 transmitted from the transmitter 10 for each of the receiving antenna elements 22.

[0020] The MIMO channel reproduction unit 26 reproduces a state of the channels between the transmitter 10 and the receiver 20 by using the signals separated for each transmission antenna element 18 for each reception antenna element 22 by the correlation processing unit 25, and generates MIMO channel information indicating the state of the channels. The MIMO channel reproduction unit 26 generates the MIMO channel information for each frequency bin, which will be described later. In the following description, the MIMO channel reproduction unit may be simply referred to as a channel reproduction unit, and the MIMO channel information may be simply referred to as channel information. The layer clipping unit 27 determines the position of the measurement target 40 based on the MIMO channel information.The layer clipping unit 27 clips the measurement target 40 around a specific curved surface from the MIMO channel information reproduced by the MIMO channel reproduction unit 26. Specifically, the layer clipping unit 27 specifies the position of the measurement target 40 by extracting reflection point information of a layer corresponding to a distance in a depth direction of the measurement target 40 as viewed from the plurality of receiving antenna elements 22 from the MIMO channel information. The focus correction unit 28 performs focus correction on the measurement target 40 whose position has been specified, and generates and outputs an image that is the image information of the measurement target 40. As the focus correction on the measurement target 40, the focus correction unit 28 performs focus correction according to the position of the layer on the extracted reflection point information.

[0021] The operation of the detection system 30 is described below. In the transmitter 10, the synchronization unit 11 controls, based on a frame configuration described later, a timing of radar signal generation by the radar signal generation unit 12, a timing of code generation by the code generation unit 13, and a timing of carrier frequency change by the carrier signal generation unit 14.

[0022] Fig. 3 is a diagram illustrating an example of high-frequency signals transmitted by the transmitter 10 according to the first embodiment. Fig. 3 illustrates the example in which an up-chirp is used as the radar signal generated by the radar signal generation unit 12, but the radar signal is not limited to the up-chirp and only needs to be a signal whose spectrum extends over an entire specific frequency band, wherein the signal includes an up-down chirp, a Zadoff-Chu (ZC) sequence, a pseudo-noise signal (hereinafter referred to as a PN signal), an OFDM (Orthogonal Frequency Division Multiplexing) signal, a frequency hopping signal, which is a signal whose frequency changes stepwise in a time direction, a general spread signal, and the like. The frequency band available to the detection system 30 is divided into N B Subbands with a bandwidth f B divided into Fig. 3 are the bands with subband 1 to subband N B These bands, that is, subband 1 to subband N B, may partially overlap.

[0023] The radar signal generation unit 12 generates a periodic broadband signal as the radar signal, which is represented by a chirp signal in each subband. At this time, the synchronization unit 11 instructs the radar signal generation unit 12 about the time of the start of each period. The period of the broadband signal is set to 1 / A of a chip period T C where “A” is an integer. That is, the code generation unit 13 generates the code such that the chip period T C of the code is an integer multiple of the period of the radar signal. Fig. 3 shows an example when A=1. The code generation unit 13 generates the code with a code length of M chips to be used by each of the transmission antenna elements 18. As shown in Fig. 3, the code period T SC =M×T CAt this time, the synchronization unit 11 instructs the code generation unit 13 of the start time of the code period. The coding unit 15 performs code multiplication, in which the radar signal generated by the radar signal generation unit 12 is multiplied by the code generated by the code generation unit 13. The code is generally expressed as ±1. The coding unit 15 performs the multiplication processing as phase modulation, amplitude modulation, frequency modulation, or a combination thereof.

[0024] The transmitter 10 transmits the radar signal in each subband at least for the code period T SC , but can transmit the radar signal by repeated use of the code for a duration equal to or longer than the code period T SC is, such as for a Fig. 3 shown time period “T B “. The Fig. 3 shown time period “T B“ is a subband change period.

[0025] After completion of the transmission of the radar signal for the subband change period T B In a subband, the transmitter 10 changes the frequency, i.e., it changes the subband. The carrier signal generation unit 14 generates the carrier signal for converting the radar signal coded by the coding unit 15 into the radio-frequency signal in each subband. The carrier signal generation unit 14 receives an instruction from the synchronization unit 11 and generates a suitable carrier signal to change the subband in each subband change period T BThe high-frequency signal generation unit 16 converts the radar signal encoded by the encoding unit 15 into the high-frequency signal in each subband using the carrier signal generated by the carrier signal generation unit 14, and transmits the high-frequency signal from the transmission antenna element 18 of the transmission arrangement 17. A period in which the transmitter 10 converts the radar signal from subband 1 to subband N B transmits, that is, over the entire frequency band of the N B subbands, is called frame period T f =N B ×T B Assuming that the high frequency signals in subband 1 to subband N B , which in Fig. 3 correspond to a single frame, the transmitter 10 completes a single measurement by transmitting a single frame, that is, in a single frame period T f .

[0026] The codes generated by the code generation unit 13 are used to identify the signals between the transmission antenna elements 18. Therefore, the code generation unit 13 generates so-called orthogonal codes or quasi-orthogonal codes with a low cross-correlation between the transmission antenna elements 18. Note that, as the code generated by the code generation unit 13 and used for identification between the transmission antenna elements 18, an M sequence, a Gold code, a Walsh-Hadamard code, a PN sequence, and the like are known, but the code is not limited to these as long as the code has high orthogonality.

[0027] In the acquisition system 30, the transmitter 10 and the receiver 20 are synchronized in time and frequency and operate according to the same instructions of the synchronization unit 11. It should be noted that the acquisition system 30 may have a bistatic configuration in which the transmitter 10 and the receiver 20 are arranged at physically separate locations. In this case, the transmitter 10 and the receiver 20 can be synchronized not only via a wired connection, but also via a global positioning system (GPS), various wireless connections, and the like. For example, the acquisition system 30 may be in a mode in which the carrier signal generation unit 14 is arranged independently of the transmitter 10 and the receiver 20, and a base signal and a reference signal for frequency tuning are shared by the transmitter 10 and the receiver 20. Here, as in Fig. 2, the configuration in which the functional units of the transmitter 10 and the receiver 20 are connected by wire is used as an example to describe the operations of the transmitter 10 and the receiver 20.

[0028] In the receiver 20, the radio-frequency signals transmitted from the transmitter 10 to the measurement target 40 and reflected or scattered by the measurement target 40 are received by the receiving antenna elements 22 of the receiving array 21. The signal conversion unit 23 uses the carrier signal corresponding to each subband generated by the carrier signal generation unit 14 to convert the radio-frequency signals received by the receiving antenna elements 22 of the receiving array 21 into baseband or intermediate frequency signals, i.e., to downconvert the radio-frequency signals. The detection unit 24 is arranged for each of the receiving antenna elements 22 and detects the baseband or intermediate frequency signals obtained after conversion by the signal conversion unit 23 using the radar signals generated by the radar signal generation unit 12 of the transmitter 10, thereby obtaining the reception information. The reception information includes the information received from all N TPieces of the transmitting antenna elements 18 transmitted signals so that the signals are received by a specific one of the receiving antenna elements 22.

[0029] The correlation processing unit 25 uses the codes generated by the code generation unit 13 of the transmitter 10 to perform correlation processing on the reception information obtained by the detection unit 24 through detection, thereby separating the reception information into the signals from the transmission antenna elements 18 of the transmitter 10. In the receiver 20, the processing of the correlation processing unit 25 is performed for each of the reception antenna elements 22, so that N T ×N RPieces of channel information of each subband are obtained. Note that the detection processing in the detection unit 24 varies depending on the type of signal used as the radar signal, so a detailed description is omitted here. In the first embodiment, the detection processing in the detection unit 24 can be a versatile processing method.

[0030] How wide the range f B of the subband depends on the frequency band used by the detection system 30, its various architectures, and the like. Particularly, in a case where the detection system 30 uses an ultra-high frequency band such as a terahertz band, there is a high probability that a large fluctuation in the frequency characteristics will occur in the subband. Therefore, the detection system 30 can adjust the bandwidth f Bof the subband into a plurality of frequency bins and calculate the channel information. Generally, the frequency bin is set to a bandwidth in which a frequency fluctuation within the band is considered constant. In the receiver 20, the MIMO channel reproduction unit 26 divides each subband into N F Frequency bins and calculates the channel information formed between the transmission arrangement 17 of the transmitter 10 and the reception arrangement 21 of the receiver 20 with the measurement target 40 in between, as shown in Fig. 1. As a result, the MIMO channel reproduction unit 26 can integrate the information of all subbands to generate the MIMO channel information with N T ×N R ×N F ×N B elements. In the following description, the frequency bin may be referred to as a frequency bin.

[0031] As described above, the transmitter 10 transmits the high-frequency signals by dividing the available frequency band into the plurality of subbands, and periodically switching the subbands used for the high-frequency signals transmitted by the plurality of transmission antenna elements 18 so that the entire frequency band is utilized. At this time, the MIMO channel reproducing unit 26 generates, as MIMO channel information, the MIMO channel information whose number is equal to a number obtained by multiplying the number of the plurality of transmission antenna elements 18 included in the transmitter 10, the number of the plurality of reception antenna elements 22 included in the receiver 20, the number of subbands, and the number of frequency bins obtained when the bandwidth of the subband is divided into the plurality of frequency bins.

[0032] For the spatial generation of N T ×NR Pieces of the MIMO channel information, the technique of using N T ×N R pieces of the real antenna elements. On the other hand, with the help of an approximation technique, i.e., interpolation, extrapolation or the like, N T ×N R Pieces of the MIMO channel information are generated while reducing the number of real antenna elements. Such processing is a well-known technique, so a detailed description is omitted here.

[0033] As with detection processing, different techniques are used to generate MIMO channel information depending on the type of radar signal, the detection method, and the like, so the technique for generating MIMO channel information is not limited here. For example, in a case where the Fig. When the chirp signal shown in Figure 3 is used as the radar signal, the receiver 20 receives the carrier signal with a frequency difference δf corresponding to a distance to the reflection point after detection. In a case where there are a plurality of reflection points, the carrier signals are superimposed at a plurality of frequencies. From this information, the receiver 20 calculates a phase, amplitude characteristics, and the like for each frequency bin.

[0034] The obtained MIMO channel information includes all reflection point information of the measurement target 40. The layer clipping unit 27 clips only the reflection point information on a specific curved surface determined from the placement of the transmitting antenna elements 18 and the receiving antenna elements 22. Note that the specific curved surface may be a specific flat surface. The focus correction unit 28 may obtain a tomographic image of a specific portion of the measurement target 40 by focusing on the curved surface. Note that the processing of the layer clipping unit 27 and the processing of the focus correction unit 28 are performed in no particular order.Furthermore, in a case where the measurement target 40 is made of a non-transparent material so that the main reflection point is located only on one surface of the target, the layer clipping processing of the layer clipping unit 27 may also be omitted.

[0035] Fig. 4 is a flowchart illustrating the operation of the detection system 30 according to the first embodiment. In the detection system 30, the transmitter 10 generates the high-frequency signals (step S11) and transmits the high-frequency signals from the transmission device 17 to the measurement target 40 (step S12). The receiver 20 receives the high-frequency signals transmitted by the transmitter 10 and reflected or scattered by the measurement target 40 (step S13), generates the MIMO channel information indicating the state of the channels between the transmitter 10 and the receiver 20 based on the carrier signals, the radar signals, and the codes (step S14), and specifies the position of the measurement target 40 using the MIMO channel information to generate the image of the measurement target 40 by performing focus correction on the measurement target 40 (step S15).

[0036] Fig. Fig. 5 is a flowchart illustrating the operation of the transformer 10 according to the first embodiment. Fig. The flow chart shown in Figure 5 illustrates details of the work steps in step S11 and step S12 of the Fig. 4. In the transmitter 10, the synchronization unit 11 controls the timing of radar signal generation in the radar signal generation unit 12, code generation in the code generation unit 13, and carrier signal generation in the carrier signal generation unit 14, that is, it controls the timing of each operation (step S21). The radar signal generation unit 12 generates the radar signals as the broadband signals under the control of the synchronization unit 11 (step S22). The code generation unit 13 generates the codes for the receiver 20 to separate the high-frequency signals transmitted from the plurality of transmission antenna elements 18 into the high-frequency signals transmitted from the individual transmission antenna elements 18 under the control of the synchronization unit 11 (step S23).The coding unit 15 multiplies the radar signal by the code for each of the plurality of transmission antenna elements 18 (step S24). The carrier signal generation unit 14, under the control of the synchronization unit 11, generates the carrier signals to divide the frequency band available to the transmitter 10 into the plurality of subbands and periodically alternate the subbands used for the high-frequency signals transmitted by the plurality of transmission antenna elements 18 so that the entire frequency band is utilized (step S25). The high-frequency signal generation unit 16 generates the high-frequency signal with the bandwidth of the subband using the code-multiplied radar signal and the carrier signal (step S26). The plurality of transmission antenna elements 18 transmit the high-frequency signals (step S27).

[0037] Fig. Fig. 6 is a flowchart illustrating the operation of the receiver 20 according to the first embodiment. Fig. The flow chart shown in Figure 6 illustrates details of the work steps in step S13 to step S15 of the Fig. 4. In the receiver 20, the plurality of receiving antenna elements 22 receive the reflected waves or the scattered waves of the high-frequency signals transmitted from the transmitter 10 including the plurality of transmitting antenna elements 18 and reflected or scattered by the measurement target 40 (step S31). The signal conversion unit 23 converts the reflected waves or the scattered waves of the high-frequency signals received by the plurality of receiving antenna elements 22 into the received signals in the frequency band of the radar signals used for generating the high-frequency signals by the transmitter 10, by using the carrier signals used for generating the high-frequency signals by the transmitter 10 (step S32).The detection unit 24 detects the received signals using the radar signals generated by the transmitter 10 and obtains the reception information, which is the reflected waves or scattered waves of the high-frequency signals received by the receiving antenna elements 22 and includes the high-frequency signals transmitted by the plurality of transmitting antenna elements 18 (step S33). The correlation processing unit 25 performs correlation processing on the reception information using the codes used in encoding the radar signals by the transmitter 10, and separates the received signals into the individual signals of the transmitting antenna elements 18 transmitted by the transmitter 10 for each of the receiving antenna elements 22 (step S34).The MIMO channel reproduction unit 26 uses the separated signals to generate MIMO channel information indicating the state of the channels between the transmitter 10 and the receiver 20 (step S35). The layer clipping unit 27 specifies the position of the measurement target 40 based on the MIMO channel information (step S36). The focus correction unit 28 performs focus correction on the measurement target 40 whose position has been specified and generates the image of the measurement target 40 (step S37).

[0038] Next, a hardware configuration of each device in the detection system 30 will be explained. In the transmitter 10, the transmission array 17 includes the plurality of transmission antenna elements 18. The synchronization unit 11, the radar signal generation unit 12, the code generation unit 13, the carrier signal generation unit 14, the coding unit 15, and the high-frequency signal generation unit 16 are implemented by a processing circuit. The processing circuit may include a RAM and a processor that executes a program stored in the RAM, or may include dedicated hardware. The processing circuit is also referred to as a control circuit.

[0039] Fig. Fig. 7 is a diagram showing an exemplary configuration of the processing circuit 90 in a case where the processing circuit implementing the transmitter 10 according to the first embodiment is implemented by a processor 91 and a memory 92. The Fig. The processing circuit 90 shown in Figure 7 is the control circuit and includes the processor 91 and the memory 92. In a case where the processing circuit 90 includes the processor 91 and the memory 92, the functions of the processing circuit 90 are implemented by software, firmware, or a combination of software and firmware. The software or firmware is described as the program and stored in the memory 92. The processing circuit 90 implements the functions by the processor 91 reading and executing the programs stored in the memory 92. That is, the processing circuit 90 includes the memory 92 for storing the program, the execution of which results in the execution of the processing of the transmitter 10.It can also be noted that this program is a program that causes the transmitter 10 to execute the functions implemented by the processing circuit 90. This program may be provided by a storage medium in which the program is stored or may be provided by other means, such as a communication medium.

[0040] The above-mentioned program may also be referred to as a program that causes the transmitter 10 to execute: a radar signal generation step in which the radar signal generation unit 12 generates the radar signals as the wideband signals; a code generation step in which the code generation unit 13 generates codes for the receiver 20 to separate the high-frequency signals transmitted from the plurality of transmission antenna elements 18 into the individual high-frequency signals transmitted from the transmission antenna elements 18; an encoding step in which the encoding unit 15 multiplies the radar signal by the code for each of the plurality of transmission antenna elements 18;a carrier signal generation step in which the carrier signal generation unit 14 generates carrier signals to divide the frequency band available for use by the transmitter 10 into the plurality of subbands, and periodically switches the subbands used for the high-frequency signals transmitted by the plurality of transmission antenna elements 18 so that the entire frequency band is used; a high-frequency signal generation step in which the high-frequency signal generation unit 16 generates the high-frequency signal with the bandwidth of the subband using the code-multiplied radar signal and the carrier signal, and causes the high-frequency signal to be transmitted from each of the plurality of transmission antenna elements 18; and a synchronization step in which the synchronization unit 11 controls the timing of radar signal generation, code generation, and carrier signal generation.

[0041] Here, the processor 91 is, for example, a central processing unit (CPU), a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a digital signal processor (DSP), or the like. The working memory 92 corresponds, for example, to a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable ROM (EPROM), and an electrically erasable programmable ROM (EEPROM (registered trademark)), a magnetic disk, a flexible disk, an optical disk, a compact disc, a minidisk, a digital versatile disc (DVD), or the like.

[0042] Fig. Fig. 8 is a diagram showing an example of a processing circuit 93 in a case where the processing circuit implementing the transmitter 10 according to the first embodiment includes the dedicated hardware. Fig. The processing circuit 93 illustrated in Figure 8 corresponds, for example, to a single circuit, a complex circuit, a programmed processor, a parallel programmed processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof. The processing circuit may be implemented partially by dedicated hardware and partially by software or firmware. In this way, the processing circuit may implement the functions described above through dedicated hardware, software, firmware, or a combination thereof.

[0043] While the hardware configuration of transmitter 10 has been described, receiver 20 has a similar hardware configuration. In receiver 20, receiving array 21 includes the plurality of receiving antenna elements 22. Signal conversion unit 23, detection unit 24, correlation processing unit 25, MIMO channel reproduction unit 26, layer clipping unit 27, and focus correction unit 28 are implemented by a processing circuit. The processing circuit may include a memory and a processor that executes a program stored in the memory, or may include dedicated hardware. The processing circuit is also referred to as a control circuit.

[0044] As described above, according to the present embodiment, in the detection system 30, the transmitter 10 controls the timing of radar signal generation, code generation, and carrier signal generation, generates high-frequency signals with the sub-band bandwidth, and transmits the high-frequency signals from the plurality of transmission antenna elements 18. The receiver 20 receives the high-frequency signals transmitted from the transmitter 10 and reflected or scattered from the measurement target 40, generates MIMO channel information based on the carrier signals, the radar signals, and the codes generated by the transmitter 10, and specifies the position of the measurement target 40. Thereby, the detection system 30 can improve resolution at low cost while utilizing the high-frequency signals when measuring the nearby measurement target 40.The acquisition system 30 can acquire reflection and scattering information in a wide frequency band required for high-resolution imaging and perform imaging or tomographic display at a desired distance. Second embodiment.

[0045] A second embodiment describes a case where a detection system includes a plurality of transmitters and a plurality of receivers.

[0046] Fig. Figure 9 is a diagram illustrating a general concept of measurement intended to be performed by a detection system 30a according to the second embodiment. The detection system 30a is a system that includes a plurality of transmitters 10 and a plurality of receivers 20 and measures the measurement target 40. That is, in the second embodiment, the plurality of transmitters 10 and the plurality of receivers 20 constitute the detection system 30a. Fig. In FIG. 9, the plurality of transmitters 10 are illustrated as transmitters 10-1 and 10-2, and the plurality of receivers 20 are illustrated as receivers 20-1 and 20-2, but the number of the plurality of transmitters 10 and the plurality of receivers 20 may be three or more. The detection system 30a is a system in which a plurality of groups of the transmitters 10 and the receivers 20 are arranged in close proximity, and the plurality of transmitters 10 perform detection by transmitting radio waves simultaneously. In the second embodiment, the transmission devices 17 of the plurality of transmitters 10 operate in close proximity, so a mechanism for suppressing interference between the transmission devices 17 is required.

[0047] Fig. 10 is a diagram illustrating an exemplary configuration for the detection system 30a according to the second embodiment. In the example of Fig. 10, the detection system 30a comprises the transmitter 10-1 to a transmitter 10-N as N pieces of the transmitters 10, and the receiver 20-1 to a receiver 20-N as N pieces of the receivers 20. The configurations of the transmitter 10-1 and the receiver 20-1 shown in Fig. 10 are similar to the configurations of the transmitter 10 and the receiver 20 shown in Fig. 2. However, the synchronization unit 11 of the transmitter 10-1 also instructs the other transmitters 10-2 to 10-N and receivers 20-2 to 20-N, which operate simultaneously, about the timing of each component's operation. In the following description, the transmitters 10-1 to 10-N may be referred to as transmitter 10 if they are not distinguished from each other, and the receivers 20-1 to 20-N may be referred to as receiver 20 if they are not distinguished from each other.

[0048] The transformers 10-2 to 10-N may each have a configuration similar to the configuration of the transformer 10-1, or a configuration achieved by removing the synchronization unit 11 from the transformer 10-1. For example, in the case where the transformers 10-2 to 10-N each have a configuration similar to the configuration of the transformers 10-1, the synchronization unit 11 of the transformer 10-1 serves as a master, and the synchronization unit 11 of each of the transformers 10-2 to 10-N serves as a slave, so that the synchronization unit 11 of the transformer 10-1 instructs the synchronization unit 11 of each of the transformers 10-2 to 10-N about the timing of operation of each component. As a result, the synchronization unit 11 of each of the transmitters 10-2 to 10-N can instruct each component therein of the timing of operation based on the instruction from the synchronization unit 11 of the transmitter 10-1.In the case where the transmitters 10-2 to 10-N each have the configuration achieved by removing the synchronization unit 11 from the transmitter 10-1, the synchronization unit 11 of the transmitter 10-1 directly instructs each component in the transmitters 10-2 to 10-N about the timing of operation. The following description will be made using a case example where the transmitters 10-2 to 10-N each have the configuration achieved by removing the synchronization unit 11 from the transmitter 10-1, that is, a case where the transmitters 10-2 to 10-N each do not include the synchronization unit 11. Note that the receivers 20-2 to 20-N each have a configuration similar to that of the receiver 20-1.

[0049] The operation of the detection system 30a will be explained. The operation of the transmitter 10-1 and the operation of the receiver 20-1 are similar to the operation of the transmitter 10 and the operation of the receiver 20 in the first embodiment, respectively. The transmitter 10-K receives the instruction from the synchronization unit 11 of the transmitter 10-1 and actuates the radar signal generation unit 12 and the code generation unit 13 of the transmitter 10-K at the same time as the transmitter 10-1 actuates the radar signal generation unit 12 and the code generation unit 13 of the transmitter 10-1. Note that "K" is an integer satisfying 2≤K≤N. At this time, the code generation unit 13 of the transmitter 10-K generates a code having a low correlation between the transmitters 10-1 to 10-N.Examples of the code generated by the code generation unit 13 of the transmitter 10-K include an M sequence, a Gold code, a Walsh-Hadamard code, a PN sequence, and the like, but the code is not limited to these as long as the code has high orthogonality. In the detection system 30a, the carrier signal generation units 14 and the high-frequency signal generation units 16 in the transmitters 10-1 to 10-N perform the same operation in all the transmitters 10-1 to 10-N and change the carrier frequency at the same time.

[0050] As described above, the radar signal generation units 12, the code generation units 13, and the carrier signal generation units 14 in the plurality of transmitters 10-1 to 10-N operate synchronously. Furthermore, the code generation units 13 in the plurality of transmitters 10-1 to 10-N generate the codes with a low correlation between the plurality of transmitters 10-1 to 10-N. The code generation units 13 in the plurality of transmitters 10-1 to 10-N generate orthogonal codes or quasi-orthogonal codes as the codes with a low correlation between the plurality of transmitters 10-1 to 10-N. That is, the plurality of transmitters 10-1 to 10-N operate synchronously with each other with respect to the generation of the radar signals, the generation of the codes and the generation of the carrier signals and generate the codes with a low correlation between the plurality of transmitters 10-1 to 10-N.

[0051] The operation of each of the receivers 20-2 to 20-N is also similar to the operation of the receiver 20-1, that is, the receiver 20 of the first embodiment. The correlation processing unit 25 of the receiver 20-K performs correlation processing using the code used in the transmitter 10-K to extract only the signal from the transmitter 10-K while suppressing the signals from the other transmitters 10, thereby enabling it to generate the MIMO channel information. Thus, the correlation processing unit 25 of each of the plurality of receivers 20-1 to 20-N performs correlation processing using the code used in the corresponding transmitter 10.

[0052] Note that in the description of the second embodiment, it was assumed that the number of transmitters 10 and the number of receivers 20 are the same, but in the detection system 30a, the number of transmitters 10 and the number of receivers 20 are not necessarily the same. For example, in a case where the transmitters 10-1 and 10-2 operate as two transmitters 10 and a receiver 20A operates as a single receiver 20, the receiver 20A can generate the MIMO channel information corresponding to two directions by the correlation processing unit 25 by jointly using the codes used in the transmitters 10-1 and 10-2, and generate and output an image corresponding to the two directions.In addition, in a case where a transmitter 10A is operated as a single transmitter 10 and the receivers 20-1 and 20-2 are operated as two receivers 20, the receivers 20-1 and 20-2 both use the code used in the transmitter 10A to be able to obtain images according to their respective positional relationships.

[0053] As described above, according to the present embodiment, in the detection system 30a, the plurality of transmitters 10-1 to 10-N simultaneously transmit the high-frequency signals, and the plurality of receivers 20-1 to 20-N perform measurement and imaging in parallel. This allows the detection system 30a to implement imaging from a variety of directions more quickly. Third embodiment.

[0054] In a third embodiment, the high-frequency signals transmitted by the plurality of transmitters 10 described in the second embodiment will be specifically described. Note that the detection system 30a, the transmitters 10-1 to 10-N, and the receivers 20-1 to 20-N of the third embodiment have similar configurations to the configurations of the detection system 30a, the transmitters 10-1 to 10-N, and the receivers 20-1 to 20-N of the second embodiment.

[0055] The operation of the detection system 30a of the third embodiment will be explained. Fig. 11 is a diagram illustrating an example of high-frequency signals transmitted by transmitters 10-1 and 10-2 according to the third embodiment. In the third embodiment, the operations of transmitter 10-1 and receiver 20-1 are similar to the operations of transmitter 10-1 and receiver 20-1 of the second embodiment, that is, the operations of transmitter 10 and receiver 20 of the first embodiment. However, code generation unit 13 can generate the same code in the plurality of transmitters 10. The transmitter 10-2 receives an instruction from the synchronization unit 11 of the transmitter 10-1 and actuates the radar signal generation unit 12, the code generation unit 13, and the carrier signal generation unit 14 of the transmitter 10-2 at the same time as the radar signal generation unit 12, the code generation unit 13, and the carrier signal generation unit 14 of the transmitter 10-1.At this time, the transmitters 10-1 and 10-2 must avoid mutual interference. Therefore, the carrier signal generation unit 14 of the transmitter 10-2 uses a frequency hopping pattern that is different from that of the carrier signal generation unit 14 of the transmitter 10-1. Fig. Figure 11 shows the example where the transformers 10-1 and 10-2 transmit the high-frequency signals simultaneously. As indicated by solid lines, the transformer 10-1 transmits the high-frequency signals while the subband is switched at each subband switching period T B in the order of subband 1, subband 2, subband 3, and so on. In the meantime, the transformer 10-2 transmits the high-frequency signals, as indicated by the dashed lines, while the subbands are switched at each subband switching period T B in the order of Part N B -1, Subband N B-2, subband 1 and so on in a subband selection pattern, that is, in a frequency hopping pattern different from that of the transformer 10-1.

[0056] As described above, the carrier signal generation units 14 of the plurality of transmitters 10-1 to 10-N generate the carrier signals in the different subbands simultaneously among the plurality of transmitters 10-1 to 10-N. Alternatively, the carrier signal generation units 14 of the plurality of transmitters 10-1 to 10-N generate the carrier signals in the frequency hopping patterns that differ among the plurality of transmitters 10-1 to 10-N.

[0057] Receivers 20-1 and 20-2 receive the high-frequency signals using the frequency hopping patterns of the transmitters 10-1 and 10-2 with which they are paired, and can thus acquire the reflected waves or the scattered waves of the desired transmitters 10. Generally, frequency hopping patterns that do not completely overlap between all transmitters 10-1 to 10-N are used, but in a case where the number of transmitters 10 is large or the like, frequency hopping patterns that simultaneously use the same subband in a certain period may also be used. Furthermore, transmitters 10 and receivers 20 do not necessarily have to correspond in a one-to-one relationship, and one of the receivers 20 may correspond to a plurality of transmitters 10.In this case, the receiver 20 may receive the signals using the frequency hopping patterns of the plurality of transmitters 10 simultaneously, or may receive the signals using the different frequency hopping patterns in a time-division multiplexed manner, for example, using the frequency hopping pattern of the transmitter 10-1 in a certain time period and using the frequency hopping pattern of the transmitter 10-2 in another time period.

[0058] As described above, according to the present embodiment, in the detection system 30a, the plurality of transmitters 10-1 to 10-N that simultaneously transmit the high-frequency signals generate the carrier signals in the different subbands or in the different frequency hopping patterns at the same time among the plurality of transmitters 10-1 to 10-N. Thereby, the detection system 30a can achieve a similar effect to that of the second embodiment. Fourth embodiment.

[0059] A fourth embodiment describes a case where the principle of synthetic aperture radar (hereinafter referred to as SAR) is applied to reduce the number of antenna elements of an array antenna, that is, the transmitting array 17 and the receiving array 21. Note that the detection system 30, the transmitter 10, and the receiver 20 of the fourth embodiment have similar configurations to the configurations of the detection system 30, the transmitter 10, and the receiver 20 of the first embodiment.

[0060] Fig. Fig. 12 is a diagram illustrating a general concept of measurement intended to be performed by a detection system 30 according to the fourth embodiment. Also in the Fig. 12, the MIMO channel reproduction unit 26 of the receiver 20 finally generates the channel information of N T ×NR ×N F ×N B elements. However, in the fourth embodiment, the number N T of the transmission antenna elements 18 of the transmission arrangement 17 and the number N R the receiving antenna elements 22 of the receiving arrangement 21 numbers including virtual antenna elements, and the number of real antenna elements, that is, the number of antenna elements that simultaneously transmit or receive radar signals, is less than N T and N R . Fig. Figure 12 shows the example in which, in the transmitting arrangement 17 and the receiving arrangement 21, two columns with filled antenna elements are the real antenna elements, and the other outlined antenna elements are the virtual antenna elements. In the fourth embodiment, it is assumed that the measurement target 40 is moving under a condition where the speed and direction are known. For example, the condition is that the measurement target 40 is located on a conveyor belt 50 or is traveling along a predetermined path.

[0061] The operation of the detection system 30 will be described below. The operation of the transmitter 10 is similar to the operation of the transmitter 10 in the first embodiment. The transmitter 10 performs the generation and coding of radar signals, the generation of high-frequency signals, and the like through the synchronization unit 11, which controls the transmission timing, and transmits the high-frequency signals from the transmission antenna elements 18, which are the real elements in the transmission array 17. In the receiver 20, the signal conversion unit 23, the detection unit 24, the correlation processing unit 25, and the like perform processing similar to that in the first embodiment, and the MIMO channel information corresponding to the positions of the real elements in the transmission array 17 and the reception array 21 can be obtained.

[0062] Fig. Figure 13 is a diagram illustrating an example of high-frequency signals transmitted by the transmitter 10 according to the fourth embodiment. The SAR can form a virtual wide-area array antenna by moving the measurement target 40. As shown in Fig. 13, the transmitter 10 first uses the transmit antenna elements 18 as the real elements in the transmit array 17 to transmit the high-frequency signals of all subbands in the period of frame 1. The receiver 20 uses the receive antenna elements 22 as the real elements in the receive array 21 to obtain the MIMO channel information based on the positions of the real elements in the transmit array 17 and the receive array 21. Next, the transmitter 10 uses the transmit antenna elements 18 as the real elements in the transmit array 17 to transmit the high-frequency signals of all subbands in the period of frame 2. The receiver 20 uses the receive antenna elements 22 as the real elements in the receive array 21 to obtain the MIMO channel information based on the positions of the real elements in the transmit array 17 and the receive array 21.At this time, the measurement target 40 is moving, so that the acquisition system 30 can virtually obtain the MIMO channel information corresponding to the measured information while shifting the positions of the transmitting antenna elements 18 and the positions of the receiving antenna elements 22.

[0063] How the positions of the transmitting antenna elements 18 and the positions of the receiving antenna elements 22 are shifted depends on the positional relationship between the transmitting arrangement 17, the receiving arrangement 21, the measurement target 40, and the like. Therefore, the detection system 30 transmits and receives the radio-frequency signals in frame 2 to obtain the MIMO channel information for the positions of the virtual elements that are shifted from the real elements. The detection system 30 can obtain the MIMO channel information for the positions of the virtual elements in frame 3 and frame 4 as time passes, that is, when the measurement target 40 moves, and can finally obtain the MIMO channel information of N T ×N R ×N F ×N BElements by the MIMO channel reproduction unit 26. It should be noted that in the receiver 20, the functions of the layer clipping unit 27 and the focus correction unit 28 after the MIMO channel reproduction unit 26 are similar to the functions of the layer clipping unit 27 and the focus correction unit 28 of the first embodiment. Thus, the receiver 20 can also be used in the case where the number of real elements of the transmission antenna elements 18 in the transmission array 17 of the transmitter 10 is less than N T and the number of real elements of the receiving antenna elements 22 in the receiving arrangement 21 of the receiver 20 is less than N R is to create an image based on the MIMO channel information of N T ×N R ×N F ×N B elements as in the first embodiment.

[0064] Note that the case where the measurement target 40 moves relative to the transmission antenna elements 18 of the transmission array 17 of the transmitter 10 and the reception antenna elements 22 of the reception array 21 of the receiver 20 has been described, but the present disclosure is not limited to this. For example, the measurement target 40 may be stationary, and the transmitter 10 and the receiver 20 may move. Regarding the transmitter 10 and the receiver 20, it is not necessary for the entire transmitter 10 and the entire receiver 20 to move; it is sufficient that the transmission array 17 of the transmitter 10 moves relative to the measurement target 40, and the reception array 21 of the receiver 20 moves relative to the measurement target 40.As described above, in the detection system 30, when the plurality of transmitting antenna elements 18 of the transmitter 10 and the plurality of receiving antenna elements 22 of the receiver 20 move, or the measurement target 40 moves, the positions of the plurality of transmitting antenna elements 18 of the transmitter 10 and the plurality of receiving antenna elements 22 of the receiver 20 relative to the measurement target 40 are changed. The transmitter 10 repeatedly transmits the high-frequency signals using the entire available frequency band. The MIMO channel reproduction unit 26 of the receiver 20 generates the channel information based on a larger number of transmitting antenna elements 18 than actually included in the transmitter 10 and a larger number of receiving antenna elements 22 than actually included in the receiver 20.

[0065] As described above, the detection system 30 according to the present embodiment utilizes the movement of the measurement target 40 or the movements of the plurality of transmitting antenna elements 18 of the transmitter 10 and the plurality of receiving antenna elements 22 of the receiver 20, thereby being capable of performing high-resolution measurement with a smaller number of antenna elements and performing high-resolution imaging. Fifth embodiment.

[0066] A fifth embodiment explains concrete functions of the layer clipping unit 27 and the focus correction unit 28 of the receiver 20.

[0067] Fig. 14 is a diagram illustrating a concept of an operation of the layer clipping unit 27 of the receiver 20 according to the fifth embodiment. When the space of the measurement target 40 is observed by dividing the space into small regions, these small regions are referred to as voxels. For example, in a case where the transmitting array 17 of the transmitter 10 and the receiving array 21 of the receiver 20 are aligned in the same direction, a curved surface is formed when the voxels are collected as measurement points located at an equal distance from the array surface of the transmitting array 17 or the receiving array 21. When this curved surface is regarded as a layer, the path from the transmitting antenna element 18 → reflection point → receiving antenna element 22 is shorter the closer the layer is to the front surface, thereby reducing a propagation delay.The layer clipping unit 27 can utilize this property to perform layer clipping by extracting only a signal within a specific delay time range from the measured received signals. Fig. 14 shows an example in which the layer clipping unit 27 cuts out the layers divided into the four layers L1, L2, L3, and L4 from the front side.

[0068] Fig. 15 is a diagram illustrating a concept of an operation of the focus correction unit 28 of the receiver 20 according to the fifth embodiment. Fig.Figure 15 focuses on a specific voxel and shows how the radar signal reflected from a specific voxel is received by the receiving antenna elements 22 of the receiving array 21. In a case where the receiving antenna elements 22 are arranged at element intervals “p”, with the receiving antenna element 22 facing the front of the voxel, which is the zeroth receiving antenna element 22, the k-th receiving antenna element 22 requires a phase shift ξ k , which is expressed by the following expression to focus on this voxel. ξk=−2π×(√(d2+(kp)2)) / λ

[0069] In expression (1), “d” is the distance between the array surface and the layer, and “λ” is the wavelength of the radar signal. Furthermore, “√(d 2 +(kp) 2 )” is a square root of “(d 2 +(kp) 2)". In a case where the receiving array 21 is a two-dimensional array antenna, the receiving antenna elements 22 are arranged in a plane, so the focus correction unit 28 calculates the amount of phase rotation taking two dimensions into account. Since the amount of phase rotation depends on the distance "d", that is, varies depending on the layer, the focus correction unit 28 performs focus correction processing for each layer and outputs an image. Note that either the layer clipping processing of the layer clipping unit 27 or the focus correction processing of the focus correction unit 28 may be applied first, and the processing is performed in no particular order.

[0070] Note that layer clipping processing by the layer clipping unit 27 is necessary when signals transmitted in the same direction or signals arriving from the same direction contain reflection point information over a wide range of distances. Thus, in a case where the measurement target 40 does not transmit electromagnetic waves, so the reflection point is only on the surface of the object, the reflected wave from a specific direction is limited to a single point, thereby eliminating the need for layer clipping processing by the layer clipping unit 27.

[0071] The configurations shown in the above embodiments merely illustrate an example, so that other known technology may be combined, the embodiments may be combined with each other, or the configurations may be partially omitted and / or modified without departing from the scope of the present disclosure. List of reference symbols

[0072] 10, 10-1 to 10-N transmitter; 11 synchronization unit; 12 radar signal generation unit; 13 code generation unit; 14 carrier signal generation unit; 15 coding unit; 16 high-frequency signal generation unit; 17 transmission assembly; 18 transmission antenna element; 20, 20-1 to 20-N receiver; 21 reception assembly; 22 reception antenna element; 23 signal conversion unit; 24 detection unit; 25 correlation processing unit; 26 MIMO channel reproduction unit; 27 layer clipping; 28 focus correction unit; 30, 30a acquisition system; 40 measurement target; 50 conveyor belt; 90, 93 processing circuit; 91 processor; 92 memory. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2021-81282

[0004]

Claims

[1] Recording system comprising: a transmitter comprising a plurality of transmitting antenna elements for: controlling timing of generating a radar signal, generating a code for a receiver to separate radio-frequency signals transmitted by the plurality of transmitting antenna elements into the radio-frequency signals transmitted by individual ones of the transmitting antenna elements, and generating a carrier signal to divide an available frequency band into a plurality of sub-bands and periodically switching the sub-bands used for the radio-frequency signals transmitted by the plurality of transmitting antenna elements so that an entire range of the frequency band is utilized; multiplying the radar signal and the code for each of the plurality of transmitting antenna elements; generating the radio-frequency signal having a bandwidth of the sub-band using the code-multiplied radar signal and the carrier signal;and transmit the radio frequency signal from each of the plurality of transmit antenna elements; and; a receiver including a plurality of receiving antenna elements for: receiving the high-frequency signals transmitted from the transmitter and reflected or scattered by a measurement target; generating channel information indicative of a state of a channel between the transmitter and the receiver using the carrier signal, the radar signal, and the code; specifying a position of the measurement target using the channel information; and generating an image of the measurement target by performing focus correction on the measurement target. [2] Detection system according to claim 1, wherein: the receiver generates the channel information whose number is equal to a number obtained by multiplying the number of the plurality of transmitting antenna elements included in the transmitter, the number of the plurality of receiving antenna elements included in the receiver, the number of subbands, and the number of frequency bins obtained when the bandwidth of the subband is divided into a plurality of frequency bins. [3] Detection system according to claim 1 or 2, wherein: the transmitter generates the code in such a way that one chip period of the code is an integer multiple of one period of the radar signal. [4] The detection system according to any one of claims 1 to 3, wherein the receiver specifies the position of the measurement target by extracting, from the channel information, reflection point information of a layer corresponding to a distance in a depth direction of the measurement target viewed from the plurality of receiving antenna elements, and performs, as the focus correction on the measurement target, a focus correction corresponding to a position of the layers on the extracted reflection point information. [5] Detection system according to one of claims 1 to 4, comprising: a plurality of transmitters and a plurality of receivers, whereby the plurality of transmitters operate synchronously with each other in generating the radar signal, generating the code and generating the carrier signal, and generates the code with a low correlation among the plurality of transmitters, and the plurality of receivers each perform correlation processing by using the code used in a corresponding one of the transmitters. [6] Detection system according to claim 5, wherein: the plurality of transformers generate an orthogonal code or a quasi-orthogonal code as the code with the low correlation among the plurality of transformers. [7] A detection system according to claim 5 or 6, wherein the plurality of transmitters generate the carrier signal in the mutually different sub-bands at the same time among the plurality of transmitters. [8] A detection system according to claim 5 or 6, wherein the plurality of transmitters generate the carrier signal in mutually different frequency hopping patterns among the plurality of transmitters. [9] Detection system according to one of claims 1 to 8, wherein, while positions of the plurality of transmitting antenna elements and the plurality of receiving antenna elements with respect to the measurement target are changed by movements of the plurality of transmitting antenna elements and the plurality of receiving antenna elements or a movement of the measurement target, the transmitter repeatedly transmits the high-frequency signals over the entire available range of the frequency band, and the receiver generates the channel information based on a larger number of transmitting antenna elements than those actually contained in the transmitter and a larger number of receiving antenna elements than those actually contained in the receiver. [10] A transmitter comprising a plurality of transmitting antenna elements, the transmitter comprising: a radar signal generating unit for generating a radar signal that is a broadband signal; a code generation unit for generating a code for a receiver to separate high-frequency signals transmitted from the plurality of transmission antenna elements into the high-frequency signals transmitted from individual ones of the transmission antenna elements; an encoding unit for multiplying the radar signal by the code for each of the plurality of transmitting antenna elements; a carrier signal generating unit for generating a carrier signal to divide a frequency band available for use by the transmitter into a plurality of sub-bands, and periodically switching the sub-bands used for the high-frequency signals transmitted by the plurality of transmission antenna elements so that an entire range of the frequency band is utilized; a high-frequency signal generating unit for generating the high-frequency signal having a bandwidth of the sub-band using the code-multiplied radar signal and the carrier signal, and causing the high-frequency signal to be transmitted from each of the plurality of transmission antenna elements; and a synchronization unit to control the timing of radar signal generation, code generation, and carrier signal generation. [11] A transmitter according to claim 10, wherein the code generation unit generates the code such that a chip period of the code is an integer multiple of a period of the radar signal. [12] Transformer according to claim 10 or 11, wherein a large number of transmitters and a large number of receivers form a detection system, the radar signal generating unit, the code generating unit and the carrier signal generating unit of the plurality of transmitters operate synchronously with each other, and the code generating unit of the plurality of transmitters generates the code with a low correlation among the plurality of transmitters. [13] The transmitter according to claim 12, wherein the code generation unit of the plurality of transmitters generates an orthogonal code or a quasi-orthogonal code as the code having the low correlation among the plurality of transmitters. [14] A transmitter according to claim 12 or 13, wherein the carrier signal generating unit of the plurality of transmitters generates the carrier signal in the mutually different sub-bands at the same time among the plurality of transmitters. [15] A transmitter according to claim 12 or 13, wherein the carrier signal generating unit of the plurality of transmitters generates the carrier signal in mutually different frequency hopping patterns among the plurality of transmitters. [16] A transmitter according to any one of claims 10 to 15, wherein the transmitter repeatedly transmits the high-frequency signals using the entire range of the frequency band while changing positions of the plurality of transmission antenna elements with respect to the measurement target by movements of the plurality of transmission antenna elements or a movement of the measurement target. [17] A receiver comprising a plurality of receiving antenna elements and receiving reflected waves or scattered waves of high-frequency signals transmitted from a transmitter comprising one of transmitting antenna elements and reflected or scattered from a measurement target, the receiver comprising: a signal conversion unit for converting the reflected waves or the scattered waves of the high-frequency signals received by the plurality of receiving antenna elements into received signals in a frequency band of a radar signal used for generating the high-frequency signal by the transmitter, using a carrier signal used for generating the high-frequency signal by the transmitter; a detection unit for detecting the received signals using the radar signal, and obtaining received information which is the reflected waves or the scattered waves of the high-frequency signals received by the receiving antenna elements and includes the high-frequency signals transmitted by the plurality of transmitting antenna elements; a correlation processing unit for performing correlation processing on the received information using a code used when the radar signal is encoded by the transmitter, and dividing the received signals into the individual signals of the transmitting antenna elements transmitted from the transmitter for each of the receiving antenna elements; a channel reproducing unit for generating channel information indicating a state of a channel between the transmitter and the receiver using the divided signals; a layer clipping unit for specifying a position of the measurement target using the channel information; and a focus correction unit for generating an image of the measurement target by performing focus correction on the measurement target after the position of the measurement target is specified. [18] Receiver according to claim 17, wherein the transmitter transmits the radio-frequency signals by dividing an available frequency band into a plurality of sub-bands, and periodically changing the sub-bands used for the radio-frequency signals transmitted by the plurality of transmitting antenna elements so that an entire range of the frequency band is used, and the channel reproduction unit generates the channel information whose number is equal to a number obtained by multiplying the number of the plurality of transmission antenna elements included in the transmitter, the number of the plurality of reception antenna elements included in the receiver, the number of subbands, and the number of frequency bins obtained when a bandwidth of the subband is divided into a plurality of frequency bins. [19] Receiver according to claim 17 or 18, wherein the layer clipping unit specifies the position of the measurement target by extracting from the channel information reflection point information of a layer corresponding to a distance in a depth direction of the measurement target viewed from the plurality of receiving antenna elements, and the focus correction unit performs a focus correction according to a position of the layer on the extracted reflection point information as the focus correction on the measurement target. [20] Receiver according to one of claims 17 to 19, wherein a plurality of transmitters and a plurality of receivers form a detection system, wherein the plurality of transmitters generate the code with a low correlation among the plurality of transmitters, and the correlation processing unit of the plurality of receivers performs correlation processing by using the code used in a corresponding one of the transmitters. [21] Receiver according to one of claims 17 to 20, wherein the high-frequency signals are transmitted using an entire range of a frequency band available for use by the transmitter, while positions of the plurality of transmitting antenna elements and the plurality of receiving antenna elements with respect to the measurement target are changed by movements of the plurality of transmitting antenna elements and the plurality of receiving antenna elements or a movement of the measurement target, and the channel reproduction unit generates the channel information based on a larger number of transmitting antenna elements than those actually included in the transmitter and a larger number of receiving antenna elements than those actually included in the receiver. [22] A control circuit for controlling a sensor system comprising a transmitter comprising a plurality of transmitting antenna elements and a receiver comprising a plurality of receiving antenna elements, the control circuit causing the sensor system to perform: Controlling timing of generation of a radar signal, generating a code for the receiver to separate radio-frequency signals transmitted by the plurality of transmission antenna elements into the radio-frequency signals transmitted by individual ones of the transmission antenna elements, and generating a carrier signal to divide an available frequency band into a plurality of sub-bands and periodically change the sub-bands used for the radio-frequency signals transmitted by the plurality of transmission antenna elements so that an entire range of the frequency band is used; Multiplying the radar signal and the code for each of the plurality of transmission antenna elements; Generating the radio-frequency signal with a bandwidth of the sub-band using the code-multiplied radar signal and the carrier signal;Transmitting the radio frequency signal from each of the plurality of transmitting antenna elements; Receiving the radio-frequency signals transmitted by the transmitter and reflected or scattered by a measurement target with the plurality of included receiving antenna elements; generating channel information indicating a state of a channel between the transmitter and the receiver using the carrier signal, the radar signal, and the code; specifying a position of the measurement target using the channel information; and generating an image of the measurement target by performing focus correction on the measurement target. [23] A control circuit for controlling a transmitter comprising a plurality of transmitting antenna elements, the control circuit causing the transmitter to perform: Generating a radar signal that is a broadband signal; Generating a code for a receiver to separate radio frequency signals transmitted by the plurality of transmitting antenna elements into the radio frequency signals transmitted by individual ones of the transmitting antenna elements; Multiplying the radar signal by the code for each of the plurality of transmit antenna elements; and generating a carrier signal to divide a frequency band available for use by the transmitter into a plurality of sub-bands, and periodically alternating the sub-bands for which radio frequency signals transmitted by the plurality of transmitting antenna elements are used so that an entire range of the frequency band is utilized; Generating the radio frequency signal having a bandwidth of the subband using the code-multiplied radar signal and the carrier signal, and transmitting the radio frequency signal from each of the plurality of transmitting antenna elements; and Controlling the timing of radar signal generation, code generation and carrier signal generation. [24] A control circuit for controlling a receiver comprising a plurality of receiving antenna elements and receiving reflected waves or scattered waves of high-frequency signals transmitted from a transmitter comprising a plurality of transmitting antenna elements reflected and scattered by a measurement target, the control circuit causing the receiver to perform: Converting the reflected waves or the scattered waves of the high-frequency signals received by the plurality of receiving antenna elements into received signals in a frequency band of a radar signal used for generating the high-frequency signal by the transmitter, using a carrier signal used for generating the high-frequency signal by the transmitter; Detecting the received signals using the radar signal, and obtaining received information which is the reflected waves or the scattered waves of the high-frequency signals received by the receiving antenna elements and includes the high-frequency signals transmitted by the plurality of transmitting antenna elements; Correlation processing on the received information using a code used when the radar signal is encoded by the transmitter, and separating the received signals into the individual signals of the transmitting antenna elements transmitted by the transmitter for each of the receiving antenna elements; generating channel information indicating a state of a channel between the transmitter and the receiver using the separated signals; Specifying a position of the measurement target using the channel information; and Creating an image of the measurement target by performing focus correction on the measurement target after the position of the measurement target is specified. [25] A storage medium storing a program for controlling a sensor system comprising a transmitter comprising a plurality of transmitting antenna elements and a receiver comprising a plurality of receiving antenna elements, the program causing the sensor system to execute: Controlling timing of generation of a radar signal, generating a code for the receiver to separate radio-frequency signals transmitted by the plurality of transmission antenna elements into the radio-frequency signals transmitted by individual ones of the transmission antenna elements, and generating a carrier signal to divide an available frequency band into a plurality of sub-bands and periodically change the sub-bands used for the radio-frequency signals transmitted by the plurality of transmission antenna elements so that an entire range of the frequency band is used; Multiplying the radar signal and the code for each of the plurality of transmission antenna elements; Generating the radio-frequency signal with a bandwidth of the sub-band using the code-multiplied radar signal and the carrier signal;Transmitting the radio frequency signal from each of the plurality of transmitting antenna elements; Receiving the radio-frequency signals transmitted by the transmitter and reflected or scattered by a measurement target with the plurality of included receiving antenna elements; generating channel information indicating a state of a channel between the transmitter and the receiver using the carrier signal, the radar signal, and the code; specifying a position of the measurement target using the channel information; and generating an image of the measurement target by performing focus correction on the measurement target. [26] A storage medium storing a program for controlling a transmitter comprising a plurality of transmission antenna elements; the program causing the transmitter to execute: Generating a radar signal that is a broadband signal; Generating a code for a receiver to separate radio frequency signals transmitted by the plurality of transmitting antenna elements into the radio frequency signals transmitted by individual ones of the transmitting antenna elements; Multiplying the radar signal by the code for each of the plurality of transmit antenna elements; generating a carrier signal to divide a frequency band available for use by the transmitter into a plurality of sub-bands, and periodically alternating the sub-bands for which radio frequency signals transmitted by the plurality of transmitting antenna elements are used so that an entire range of the frequency band is used; Generating the radio frequency signal having a bandwidth of the subband using the code-multiplied radar signal and the carrier signal, and transmitting the radio frequency signal from each of the plurality of transmitting antenna elements; and Controlling the timing of radar signal generation, code generation and carrier signal generation. [27] A storage medium storing a program for controlling a receiver comprising a plurality of receiving antenna elements and receiving reflected waves or scattered waves of high-frequency signals transmitted from a transmitter comprising a plurality of transmitting antenna elements reflected or scattered from a measurement target, the program causing the receiver to execute: Converting the reflected waves or the scattered waves of the high-frequency signals received by the plurality of receiving antenna elements into received signals in a frequency band of a radar signal used for generating the high-frequency signal by the transmitter, using a carrier signal used for generating the high-frequency signal by the transmitter; Detecting the received signals using the radar signal, and obtaining received information which is the reflected waves or the scattered waves of the high-frequency signals received by the receiving antenna elements and includes the high-frequency signals transmitted by the plurality of transmitting antenna elements; Correlation processing on the received information using a code used when the radar signal is encoded by the transmitter, and separating the received signals into the individual signals of the transmitting antenna elements transmitted by the transmitter for each of the receiving antenna elements; generating channel information indicating a state of a channel between the transmitter and the receiver using the separated signals; Specifying a position of the measurement target using the channel information; and Creating an image of the measurement target by performing focus correction on the measurement target after the position of the measurement target is specified. [28] Collection procedures, including: a transmission step of a transmitter comprising a plurality of transmission antenna elements, performing: controlling timings of generation of a radar signal, generating a code for a receiver to separate high-frequency signals transmitted by the plurality of transmission antenna elements into the high-frequency signals transmitted by individual ones of the transmission antenna elements, and generating a carrier signal to divide an available frequency band into a plurality of sub-bands and periodically switch the sub-bands used for the high-frequency signals transmitted by the plurality of transmission antenna elements so that an entire range of the frequency band is utilized; multiplying the radar signal and the code for each of the plurality of transmission antenna elements;Generating the radio frequency signal having a bandwidth of the subband using the code-multiplied radar signal and the carrier signal; and transmitting the radio frequency signal from each of the plurality of transmitting antenna elements; and ; a receiving step of the receiver, which includes a plurality of receiving antenna elements, performing: receiving the high-frequency signals transmitted from the transmitter and reflected or scattered by a measurement target; generating channel information indicating a state of a channel between the transmitter and the receiver using the carrier signal, the radar signal, and the code; specifying a position of the measurement target using the channel information; and generating an image of the measurement target by performing focus correction on the measurement target. [29] A transmission method by a transmitter comprising a plurality of transmission antenna elements, the transmission method comprising: a radar signal generating step of a radar signal generating unit generating a radar signal that is a wideband signal; a code generation step of a code generation unit generating a code for a receiver to separate high-frequency signals transmitted from the plurality of transmission antenna elements into the high-frequency signals transmitted from individual ones of the transmission antenna elements; a coding step of a coding unit multiplying the radar signal by the code for each of the plurality of transmission antenna elements; a carrier signal generating step of a carrier signal generating unit generating a carrier signal to divide a frequency band available for use by the transmitter into a plurality of sub-bands, and periodically switching the sub-bands used for the high-frequency signals transmitted by the plurality of transmission antenna elements so as to utilize an entire range of the frequency band; a high-frequency signal generating step of a high-frequency signal generating unit generating the high-frequency signal having a bandwidth of the sub-band using the code-multiplied radar signal and the carrier signal, and causing the high-frequency signal to be transmitted from each of the plurality of transmission antenna elements; and a synchronization step of a synchronization unit, controlling times of generation of the radar signal, generation of the code and generation of the carrier signal. [30] A receiving method by a receiver comprising a plurality of receiving antenna elements and receiving reflected waves or scattered waves of high-frequency signals reflected or scattered by a transmitter comprising a plurality of transmitting antenna elements and by a measurement target, the receiving method comprising: a signal conversion step of a signal conversion unit that converts the reflected waves or the scattered waves of the high-frequency signals received by the plurality of receiving antenna elements into received signals in a frequency band of a radar signal used for generating the high-frequency signal by the transmitter, using a carrier signal used for generating the high-frequency signal by the transmitter; a detection step of a detection unit detecting the received signals using the radar signal, and obtaining received information which is the reflected waves or the scattered waves of the high-frequency signals received by the receiving antenna elements and the high-frequency signals transmitted from the plurality of transmitting antenna elements; a correlation processing step of a correlation processing unit performing correlation processing on the received information using a code used when the radar signal is encoded by the transmitter, and separating the received signals into the individual signals of the transmitting antenna elements transmitted from the transmitter for each of the receiving antenna elements; a channel reproducing step of a channel reproducing unit generating channel information indicating a state of a channel between the transmitter and the receiver using the separated carrier signals; a layer clipping step of a layer clipping unit specifying a position of the measurement target using the channel information; and a focus correction step of a focus correction unit generating an image of the measurement target by performing focus correction on the measurement target after the position of the measurement target is specified.

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