WO2023170766A1 - Radar cross section calculation device, radar cross section calculation method, and radar device - Google Patents

Abstract

In this radar device, a reception signal acquisition unit (11) acquires each of a plurality of first reception signals and a second reception signal from a reception antenna (3) that receives first reflected waves over a plurality of times from a calibration target and outputs the plurality of first reception signals, which are the reception signals of the first reflected waves, and that receives a second reflected wave not from the calibration target but from an object being observed and present in the same location, and outputs the second reception signal, which is a reception signal of the second reflected wave. A reception signal selection unit (12) calculates a similarity between a time waveform of the power of the second reception signal and a time waveform of the power of each of the plurality of first reception signals, and selects one of the plurality of first reception signals on the basis of the similarity calculation result. A radar cross section calculation unit (15) uses the power of the first reception signal selected by the reception signal selection unit (12) and the power of the second reception signal acquired by the reception signal acquisition unit (11) to calculate the radar cross section of the object being observed.

Description

Radar cross section calculation device, radar cross section calculation method, and radar device

The present disclosure relates to a radar cross-sectional area calculation device, a radar cross-sectional area calculation method, and a radar device.

There is a radar cross-sectional area calculation device that calculates the radar cross-sectional area of an observed object existing in a measurement space (for example, see Patent Document 1).
The radar cross section calculation device includes a transceiver and a calculator. The transmitter/receiver has a transmitting antenna that transmits radio waves toward a reference target (hereinafter referred to as "calibration target") installed in the measurement space, and receives reflected waves that are radio waves after being reflected by the calibration target. and a receiving antenna that outputs a received signal (hereinafter referred to as "first received signal") to the computer. Furthermore, after the calibration target is removed from the measurement space, the transmitting antenna transmits radio waves toward the observed object existing in the measurement space. The receiving antenna receives a reflected wave that is a radio wave after being reflected by the object to be observed, and outputs a received signal of the reflected wave (hereinafter referred to as "second received signal") to the computer. The installation position of the calibration target in the measurement space and the position of the object to be observed in the measurement space are the same position.
The computer calculates the radar cross section of the observed object using the first received signal and the second received signal.

Japanese Patent Application Publication No. 2012-163399

The transceiver may be mounted on a mobile object. Examples of the moving object include a drone or a helicopter. When a transmitter/receiver transmits and receives radio waves, even if a moving object performs hovering or other operations to stay in the same position, the position of the receiving antenna of the transmitter/receiver may change slightly over time. be.
In the radar cross-sectional area calculation device disclosed in Patent Document 1, when the transmitter/receiver is mounted on a moving object, the position of the receiving antenna when receiving the reflected wave from the calibration target and the object to be observed are A deviation (hereinafter referred to as "first positional deviation") may occur between the position of the receiving antenna and the position of the receiving antenna when receiving the reflected wave from the antenna. In addition, in this radar cross section calculation device, even if the position of the receiving antenna is fixed, there is a deviation (hereinafter referred to as "second This may result in "misalignment"). There has been a problem in that under a situation where either the first positional deviation or the second positional deviation has occurred, the calculation accuracy of the radar cross section by the computer may deteriorate.

The present disclosure has been made to solve the above-mentioned problems, and the accuracy of calculating the radar cross section can be improved in a situation where either the first positional deviation or the second positional deviation occurs. It is an object of the present invention to obtain a radar cross-sectional area calculation device and a radar cross-sectional area calculation method that can suppress deterioration.

A radar cross-sectional area calculation device according to the present disclosure receives a first reflected wave, which is a radio wave reflected by a calibration target installed in a measurement space, multiple times, and receives a received signal of each first reflected wave. A first received signal is output, and a second reflected wave, which is a radio wave reflected by an observed object existing in place of the calibration target, is received at the position where the calibration target was installed. The apparatus includes a received signal acquisition section that acquires each of the first received signal and the second received signal from a receiving antenna that outputs a second received signal that is a received signal of the second reflected wave. Further, the radar cross section calculation device calculates the degree of similarity between the power time waveform of each first received signal acquired by the received signal acquisition unit and the power time waveform of the second received signal, and The apparatus includes a received signal selection section that selects one of the first received signals from among the plurality of first received signals acquired by the acquisition section based on the calculation result of the degree of similarity. Further, the radar cross section calculation device calculates the radar cross section of the observed object using the power of the first received signal selected by the received signal selection section and the power of the second received signal acquired by the received signal acquisition section. It is equipped with a radar cross-sectional area calculation unit that calculates the area.

According to the present disclosure, deterioration in the calculation accuracy of the radar cross-sectional area can be suppressed in a situation where either the first positional deviation or the second positional deviation occurs.

1 is a configuration diagram showing a radar device including a radar cross-sectional area calculating device 4 according to a first embodiment. 1 is a configuration diagram showing a radar cross-sectional area calculation device 4 according to Embodiment 1. FIG. FIG. 2 is a hardware configuration diagram showing the hardware of a radar cross-sectional area calculation device 4 according to the first embodiment. FIG. 4 is a hardware configuration diagram of a computer when a radar cross-sectional area calculating device 4 is realized by software, firmware, or the like. 3 is a flowchart showing a radar cross-sectional area calculation method, which is a processing procedure of the radar cross-sectional area calculating device 4. FIG. FIG. 2 is an explanatory diagram showing a background power measurement environment. It is an explanatory view showing a measurement environment of a calibration target Tp. FIG. 2 is an explanatory diagram showing a measurement environment of an observed object. FIG. 9A is an explanatory diagram showing the received power g _n (t) of the first reflected wave by the calibration target Tp, and FIG. 9B is an explanatory diagram showing the received power f(t) of the second reflected wave by the observed object. 9C are explanatory diagrams showing the received power h _m (t) of the third reflected wave from the walls of the measurement space, etc. FIG. 2 is a configuration diagram showing a radar cross-sectional area calculation device 4 according to a second embodiment. FIG. 2 is an explanatory diagram showing a background power measurement environment. It is an explanatory view showing a measurement environment of a calibration target Tp. FIG. 2 is an explanatory diagram showing a measurement environment of an observed object. FIG. 14A is an explanatory diagram showing the received power g _n (t) of the first reflected wave by the position reference target Tr and the calibration target Tp, and FIG. FIG. 14C is an explanatory diagram showing the received power f(t) of the reflected wave. FIG. 14C is an explanatory diagram showing the received power h _m (t) of the third reflected wave by the position reference target Tr. FIG. 2 is an explanatory diagram showing a background power measurement environment. It is an explanatory view showing a measurement environment of a calibration target Tp. FIG. 2 is an explanatory diagram showing a measurement environment of an observed object. FIG. 3 is a configuration diagram showing a radar device including a radar cross-sectional area calculating device 4 according to a fourth embodiment.

Hereinafter, in order to explain the present disclosure in more detail, embodiments for carrying out the present disclosure will be described with reference to the accompanying drawings.

Embodiment 1.
FIG. 1 is a configuration diagram showing a radar device including a radar cross-sectional area calculation device 4 according to the first embodiment.
FIG. 2 is a configuration diagram showing the radar cross-sectional area calculating device 4 according to the first embodiment.
FIG. 3 is a hardware configuration diagram showing the hardware of the radar cross section calculation device 4 according to the first embodiment.
The radar device shown in FIG. 1 includes a transceiver 1, a transmitting antenna 2, a receiving antenna 3, and a radar cross-sectional area calculation device 4.
A calibration target Tp is installed in the measurement space of the radar device shown in FIG. Thereafter, after the calibration target Tp is removed from the measurement space, the object to be observed appears at the position where the calibration target Tp was installed. The calibration target Tp is a scatterer with a known shape. The scatterer is realized, for example, by metal.
When the transceiver 1 is mounted on a moving object, the position of the receiving antenna 3 when receiving the reflected wave from the calibration target Tp and the receiving antenna 3 when receiving the reflected wave from the observed object (hereinafter referred to as "first positional deviation") may occur. Furthermore, even if the position of the receiving antenna 3 is fixed, there is a deviation (hereinafter referred to as "second positional deviation") between the installation position of the calibration target Tp in the measurement space and the existing position of the observed object in the measurement space. may occur.

Transceiver 1 outputs a transmission signal to transmission antenna 2 .
Further, the transceiver 1 performs reception processing on each of the first reception signal, second reception signal, and third reception signal output from the reception antenna 3. The reception process is a detection process of the received signal. The reception process may include a process of converting the received signal from an analog signal to a digital signal. Further, the reception process may include a process of measuring the power of the received signal.
Here, for convenience of explanation, the transceiver 1 detects each of the first received signal, the second received signal, and the third received signal, and detects the first received signal, the second received signal, and the third received signal. It is assumed that each of the received signals is output to the radar cross section calculation device 4.

The transmitting antenna 2 transmits radio waves related to the transmitting signal output from the transceiver 1 in a situation where neither the calibration target Tp nor the observed object exists in the measurement space (hereinafter referred to as "background power measurement environment"). is transmitted toward the measurement space.
In addition, the transmitting antenna 2 is connected to the transmitter/receiver in a situation where the object to be observed does not exist in the measurement space and the calibration target Tp exists in the measurement space (hereinafter referred to as "measurement environment of the calibration target"). A radio wave related to a transmission signal outputted from 1 is transmitted toward the measurement space.
In addition, the transmitting antenna 2 is configured to operate the transmitter/receiver in a situation where the calibration target Tp does not exist in the measurement space and the object to be observed exists in the measurement space (hereinafter referred to as "measurement environment of the object to be observed"). A radio wave related to a transmission signal outputted from 1 is transmitted toward the measurement space.
In the radar device shown in FIG. 1, the radio waves transmitted from the transmitting antenna 2 are, for example, terahertz band radio waves. However, this is just an example, and the radio waves transmitted from the transmitting antenna 2 may be radio waves in a low frequency band, for example.

The receiving antenna 3 receives the third reflected wave, which is a radio wave after being reflected by the wall or ceiling of the measurement space, multiple times in the background power measurement environment, and calculates the value of each third reflected wave. A third received signal, which is a received signal, is output to the transceiver 1.
The receiving antenna 3 receives the first reflected wave, which is the radio wave after being reflected by the calibration target Tp, multiple times in the measurement environment of the calibration target, and receives the first reflected wave, which is the received signal of each first reflected wave, a plurality of times. 1 received signal is output to the transceiver 1.
The receiving antenna 3 receives a second reflected wave, which is a radio wave reflected by the observed object, under the measurement environment of the observed object, and outputs a second received signal, which is a received signal of the second reflected wave. Output to transceiver 1.

The radar cross section calculation device 4 includes a received signal acquisition section 11, a received signal selection section 12, and a radar cross section calculation section 15.
The received signal acquisition unit 11 is realized, for example, by the received signal acquisition circuit 21 shown in FIG. 3.
The received signal acquisition unit 11 acquires each of the first received signal, the second received signal, and the third received signal from the transceiver 1 .
The received signal acquisition unit 11 outputs each of the first received signal, second received signal, and third received signal to the received signal selection unit 12.

The received signal selection section 12 is realized, for example, by a received signal selection circuit 22 shown in FIG. 3.
The received signal selection section 12 includes a correlation coefficient calculation section 13 and a received signal selection processing section 14.
The received signal selection unit 12 calculates the degree of similarity between the power time waveform of each first received signal acquired by the received signal acquisition unit 11 and the power time waveform of the second received signal.
The received signal selection unit 12 selects any first received signal from among the plurality of first received signals acquired by the received signal acquisition unit 11 based on the calculation result of the degree of similarity.
The received signal selection unit 12 calculates the degree of similarity between the power time waveform of each third received signal acquired by the received signal acquisition unit 11 and the power time waveform of the second received signal.
The received signal selection unit 12 selects any third received signal from among the plurality of third received signals acquired by the received signal acquisition unit 11 based on the calculation result of the degree of similarity.

The correlation coefficient calculation unit 13 calculates the degree of similarity between the time waveform of the power of each first received signal and the time waveform of the power of the second received signal acquired by the received signal acquisition unit 11. A correlation coefficient between the time waveform of the power of the second received signal and the time waveform of the power of the second received signal is calculated.
The received signal selection processing section 14 selects one of the plurality of first reception signals acquired by the reception signal acquisition section 11 based on the plurality of correlation coefficients calculated by the correlation coefficient calculation section 13. Selecting a first received signal.

Further, the correlation coefficient calculation unit 13 calculates the degree of similarity between the time waveform of the power of each third received signal acquired by the received signal acquisition unit 11 and the time waveform of the power of the second received signal. A correlation coefficient between the power time waveform of the third received signal and the power time waveform of the second received signal is calculated.
Further, the received signal selection processing section 14 selects which of the third received signals acquired by the received signal acquisition section 11 is based on the plurality of correlation coefficients calculated by the correlation coefficient calculation section 13. The third received signal is selected.

The radar cross section calculation section 15 is realized, for example, by a radar cross section calculation circuit 23 shown in FIG.
The radar cross section calculation section 15 calculates the power of the first received signal selected by the received signal selection section 12, the power of the second received signal acquired by the received signal acquisition section 11, and the power of the first received signal selected by the received signal selection section 12. The radar cross section (RCS) of the object to be observed is calculated using the power of the third received signal.
In the radar device shown in FIG. 1, the radar cross section calculation unit 15 calculates the radar cross section of the object using the power of the first received signal, the power of the second received signal, and the power of the third received signal. is being calculated. However, the power of the third received signal is close to 0, or the power of the third received signal is small compared to the power of the first received signal and the power of the second received signal, and the power of the third received signal is If there is no practical problem even if the power of the received signal is ignored, the radar cross section calculation unit 15 calculates the power of the first received signal and the power of the second received signal without using the power of the third received signal. The radar cross section of the object to be observed may be calculated using the power.
Further, even if the position of the receiving antenna 3 changes slightly over time, if the power of the third received signal hardly changes, the received signal acquisition unit 11 acquires one third received signal. Alternatively, the radar cross section calculation unit 15 may calculate the radar cross section using the power of the third received signal. Furthermore, if the power of the third received signal is known, the radar cross section calculation unit 15 may calculate the radar cross section using the known third received signal.

In FIG. 1, each of the received signal acquisition section 11, the received signal selection section 12, and the radar cross section calculation section 15, which are components of the radar cross section calculation device 4, is realized by dedicated hardware as shown in FIG. It is assumed that That is, it is assumed that the radar cross section calculation device 4 is realized by the received signal acquisition circuit 21, the received signal selection circuit 22, and the radar cross section calculation circuit 23.
Each of the received signal acquisition circuit 21, the received signal selection circuit 22, and the radar cross-sectional area calculation circuit 23 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), This applies to FPGA (Field-Programmable Gate Array) or a combination thereof.

The components of the radar cross section calculation device 4 are not limited to those realized by dedicated hardware, but the radar cross section calculation device 4 is realized by software, firmware, or a combination of software and firmware. It may be something.
Software or firmware is stored in a computer's memory as a program. A computer means hardware that executes a program, and includes, for example, a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor). do.

FIG. 4 is a hardware configuration diagram of a computer when the radar cross-sectional area calculating device 4 is realized by software, firmware, or the like.
When the radar cross section calculation device 4 is realized by software, firmware, etc., a program for causing a computer to execute the respective processing procedures in the received signal acquisition section 11, the received signal selection section 12, and the radar cross section calculation section 15 is implemented. It is stored in the memory 31. Then, the processor 32 of the computer executes the program stored in the memory 31.

Further, FIG. 3 shows an example in which each of the components of the radar cross section calculation device 4 is realized by dedicated hardware, and FIG. 4 shows an example in which the radar cross section calculation device 4 is realized by software, firmware, etc. It shows. However, this is just an example, and some of the components in the radar cross section calculation device 4 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, or the like.

Next, the operation of the radar device shown in FIG. 1 will be explained.
FIG. 5 is a flowchart showing a radar cross-sectional area calculation method, which is a processing procedure of the radar cross-sectional area calculation device 4.
First, in a background power measurement environment as shown in FIG. 6, the transmitting antenna 2 transmits radio waves related to the transmit signal output from the transceiver 1 toward the measurement space M times. M is an integer of 2 or more.
FIG. 6 is an explanatory diagram showing the background power measurement environment.
In the measurement environment shown in FIG. 6, a transmitting antenna 2 and a receiving antenna 3 are installed in the measurement space.

The receiving antenna 3 receives the third reflected wave, which is a radio wave after being reflected by the wall or ceiling of the measurement space, M times in the background power measurement environment, for example.
The receiving antenna 3 is mounted on, for example, a drone or a helicopter. When the receiving antenna 3 receives the third reflected wave M times, even if the drone performs hovering etc. to stay in the same position, the position of the receiving antenna 3 may change over time. may change.
The receiving antenna 3 outputs a third received signal R _3,m (t) (m=1, . . . , M), which is a received signal of each third reflected wave, to the transceiver 1.
The transceiver 1 performs reception processing on the third received signal R _3,m (t) output from the receiving antenna 3, and transmits the third received signal R _3,m (t) to the radar cross section calculation device 4. Output to.
The received signal acquisition unit 11 of the radar cross section calculation device 4 acquires the third received signal R 3,m (t) from the transceiver 1 (step ST1 in FIG. 5), and receives the third received signal R _3,m (t) from the transceiver 1 (step ST1 in FIG. 5) _. Store _m (t) in internal memory.

Next, in the measurement environment of the calibration target as shown in FIG. 7, the transmitting antenna 2 transmits radio waves related to the transmit signal output from the transceiver 1 toward the measurement space N times. N is an integer of 2 or more.
FIG. 7 is an explanatory diagram showing the measurement environment of the calibration target Tp.
In the measurement environment shown in FIG. 7, a calibration target Tp, a transmitting antenna 2, and a receiving antenna 3 are installed in the measurement space.

The receiving antenna 3 receives the first reflected wave, which is the radio wave after being reflected by the calibration target Tp, N times under the measurement environment of the calibration target Tp.
When the receiving antenna 3 receives the first reflected wave N times, even if the drone performs hovering etc. to stay in the same position, the position of the receiving antenna 3 may change over time. may change.
The receiving antenna 3 outputs a first received signal R _1,n (t) (n=1, . . . , N), which is a received signal of each first reflected wave, to the transceiver 1.
The transceiver 1 performs reception processing on the first received signal R _1,n (t) output from the receiving antenna 3, and transmits the first received signal R _1,n (t) to the radar cross section calculation device 4. Output to.
The received signal acquisition unit 11 of the radar cross section calculation device 4 acquires the first received signal R 1,n (t) from the transceiver 1 (step ST1 in FIG. 5), and obtains the first received signal R _1,n (t) from the transceiver 1 (step ST1 in FIG. 5) _. Store _n (t) in internal memory.

Next, in the measurement environment of the observed object as shown in FIG. 8, the transmission antenna 2 transmits radio waves related to the transmission signal output from the transceiver 1 toward the measurement space.
FIG. 8 is an explanatory diagram showing the measurement environment of the observed object.
In the measurement environment shown in FIG. 8, the transmitting antenna 2 and the receiving antenna 3 are installed in the measurement space, and the object to be observed exists in the measurement space.

The receiving antenna 3 receives a second reflected wave, which is a radio wave reflected by the observed object, under the measurement environment of the observed object, and generates a second received signal R, which is a received signal of the second reflected wave. ₂ (t) is output to the transceiver 1.
The transceiver 1 performs reception processing on the second received signal R ₂ (t) output from the receiving antenna 3 and outputs the second received signal R ₂ (t) to the radar cross section calculation device 4 .
The received signal acquisition unit 11 of the radar cross section calculation device 4 acquires the second received signal R ₂ (t) from the transceiver 1 (step ST1 in FIG. 5), and obtains the second received signal R ₂ (t). is stored in internal memory.

In the radar device shown in FIG. 1, the receiving antenna 3 receives the third received signal R _3,m (t), the first received signal R _1,n (t), and the second received signal R ₂ (t). They are received in order. However, this is just an example, and the signals may be received in any order. Therefore, the receiving antenna 3 receives, for example, the first received signal R _1,n (t), the third received signal R _3,m (t), and the second received signal R ₂ (t) in this order. Alternatively, the first received signal R _1,n (t), the second received signal R ₂ (t), and the third received signal R _3,m (t) may be received in this order.

The correlation coefficient calculation unit 13 of the received signal selection unit 12 calculates the N first received signals R _1,1 (t) to R _1,N (t) and the second received signal from the internal memory of the received signal acquisition unit 11. The received signal R ₂ (t) and M third received signals R _3,1 (t) to R _3,M (t) are obtained.
The correlation coefficient calculation unit 13 calculates the power g _n (t) at time t in the first received signal R _1,n (t) (n=1, . . . , N). The power g _n (t) at time t is the received power of the first reflected wave by the calibration target Tp. The power g _n (t) also includes the received power of the first reflected wave from the walls of the measurement space. The power calculation process itself is a well-known technique, so a detailed explanation will be omitted.
Furthermore, the correlation coefficient calculation unit 13 calculates the power f(t) at time t in the second received signal R ₂ (t). The power f(t) at time t is the received power of the second reflected wave by the observed object. The power f(t) also includes the received power of the second reflected wave from the walls of the measurement space.
Furthermore, the correlation coefficient calculation unit 13 calculates the power _{h m} (t) at time t in the third received signal R _3,m (t) (m=1, . . . , M). The power h _m (t) at time t is the received power of the third reflected wave from a wall or the like in the measurement space.
FIG. 9A is an explanatory diagram showing the received power g _n (t) of the first reflected wave by the calibration target Tp.
FIG. 9B is an explanatory diagram showing the received power f(t) of the second reflected wave by the observed object.
FIG. 9C is an explanatory diagram showing the received power h _m (t) of the third reflected wave due to the wall of the measurement space or the like.

The correlation coefficient calculation unit 13 calculates the power g _n of the first received signal R _1,n (t) (n=1, . . . , N) as shown in the following equations (1) to (4). The correlation coefficient S _1-2,n between the time waveform of (t) and the time waveform of the power f(t) of the second received signal R ₂ (t) is calculated (step ST2 in FIG. 5).

The correlation coefficient calculation unit 13 calculates the power h _m of the third received signal R _3,m (t) (m=1,...,M) as shown in the following equations (5) to (8). The correlation coefficient S _3-2,m between the time waveform of (t) and the time waveform of the power f(t) of the second received signal R ₂ (t) is calculated (step ST3 in FIG. 5).

The received signal selection processing unit 14 selects the correlation coefficient calculation unit 13 from among the N first received signals R _1,1 (t) to R _1,N (t) acquired by the received signal acquisition unit 11. One of the first received signals R _1,n (t) is selected based on the N correlation coefficients S _1-2,1 to S _1-2,N calculated by (step in FIG. ST4).
That is, the received signal selection processing unit 14 identifies the largest correlation coefficient S 1-2 _,MAX among the N correlation coefficients S _1-2,1 to S _1-2,N . Then, the received signal selection processing unit 14 selects a signal corresponding to the largest correlation coefficient S _1-2,MAX from among the N first received signals R _1,1 (t) to R _1,N (t). Select the first received signal R _1,n (t).
When the transceiver 1 is mounted on a moving object, even if the position of the receiving antenna 3 of the transceiver 1 changes slightly over time, the signal selected by the received signal selection processing section 14 The first received signal R _1,n (t) and the second received signal R ₂ (t) are signals received when the receiving antenna 3 is at the same position.
In addition, even when the position of the receiving antenna 3 is fixed, the received signal selection processing unit The installation position of the calibration target Tp when the first received signal R _1,n (t) selected by 14 is received, and the observed position when the second received signal R ₂ (t) is received. The existing position of the body is the same position.
The same position here is a concept that includes not only cases in which the positions are completely coincident, but also cases in which the positions are shifted within a range that causes no practical problem.

Further, the received signal selection processing unit 14 calculates a correlation coefficient from among the M third received signals R _3,1 (t) to R _3,M (t) acquired by the received signal acquisition unit 11. One of the third received signals R _3,m (t) is selected based on the M correlation coefficients S _3-2,1 to S _3-2,M calculated by the section 13 (FIG. 5). step ST5).
That is, the received signal selection processing unit 14 specifies the largest correlation coefficient S 3-2, _MAX among the M correlation coefficients S _3-2,1 to S _3-2,M . Then, the received signal selection processing unit 14 selects a signal related to the largest correlation coefficient S _3-2,MAX from among the M third received signals R _3,1 (t) to R _3,M (t). Select the third received signal R _3,m (t).
When the transceiver 1 is mounted on a moving object, even if the position of the receiving antenna 3 of the transceiver 1 changes slightly over time, the signal selected by the received signal selection processing section 14 The received signal R _3,m (t) of No. 3 and the second received signal R ₂ (t) are signals received when the receiving antenna 3 is at the same position.

The received signal selection processing unit 14 calculates the power g n (t) at time t of the selected first received signal R _1,n (t) and the power g _n (t) of the selected third received signal R _3,m (t). The power h _m (t) at time t is output to the radar cross-sectional area calculation unit 15 .
Further, the received signal selection processing section 14 outputs the power f(t) at time t in the second received signal R ₂ (t) to the radar cross section calculation section 15 .

The radar cross section calculation unit 15 acquires the power g _n (t), the power h _m (t), and the power f(t) from the received signal selection unit 12 .
The radar cross section calculation unit 15 calculates the radar cross section RCS of the observed object using the power g _n (t), the power h _m (t), and the power f(t), as shown in the following equation (9). is calculated (step ST6 in FIG. 5).

In the radar device shown in FIG. 1, the radar cross section calculating device 4 calculates the radar cross section of the object to be observed, assuming that the calibration target Tp and the object to be observed are each present at a certain position in the measurement space. Calculating area. However, this is just an example, and while changing the positions of the calibration target Tp and the observed object, the radar cross-sectional area calculation device 4 can set the calibration target Tp and the observed object at the respective positions. The radar cross section of the object to be observed may be calculated when the object exists.

In the first embodiment described above, the first reflected wave, which is a radio wave after being reflected by the calibration target Tp installed in the measurement space, is received multiple times, and the received signal of each first reflected wave is A first received signal is output, and a second reflected wave, which is a radio wave reflected by an observed object existing in place of the calibration target Tp, is received at the position where the calibration target Tp was installed. and a received signal acquisition unit 11 that acquires each of the first received signal and the second received signal from the receiving antenna 3 that outputs the second received signal that is the received signal of the second reflected wave. A radar cross-sectional area calculating device 4 was constructed. In addition, the radar cross section calculation device 4 calculates the degree of similarity between the power time waveform of each first received signal acquired by the received signal acquisition unit 11 and the power time waveform of the second received signal, A received signal selection unit 12 is provided that selects one of the first received signals from among the plurality of first received signals acquired by the received signal acquisition unit 11 based on the calculation result of the degree of similarity. Further, the radar cross section calculation device 4 uses the power of the first received signal selected by the received signal selection unit 12 and the power of the second received signal acquired by the received signal acquisition unit 11 to The radar cross section calculation section 15 is provided to calculate the radar cross section of the radar cross section. Therefore, the radar cross-sectional area calculating device 4 can suppress deterioration in the calculation accuracy of the radar cross-sectional area in a situation where either the first positional deviation or the second positional deviation occurs.

Embodiment 2.
In the second embodiment, a radar cross section calculation device 4 in which the received signal selection section 12 includes a correlation coefficient acquisition section 16 will be described.

The configuration of the radar device according to Embodiment 2 is similar to the configuration of the radar device according to Embodiment 1, and the configuration diagram showing the radar device according to Embodiment 2 is FIG. 1.
FIG. 10 is a configuration diagram showing a radar cross-sectional area calculation device 4 according to the second embodiment. In FIG. 10, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts, so the explanation will be omitted.
The received signal selection section 12 includes a correlation coefficient acquisition section 16 and a received signal selection processing section 14.

The correlation coefficient acquisition unit 16 has a built-in learning model 17.
The correlation coefficient acquisition unit 16 acquires the time waveform of the power _g n (t) of the first received signal R _1,n (t) (n=1,...,N) acquired by the reception signal acquisition unit 11. and the time waveform of the power f(t) of the second received signal R ₂ (t) are given to the learning model 17.
The correlation coefficient acquisition unit 16 extracts from the learning model 17 the time waveform of the power g _n (t) of the first received signal R _1,n (t) (n=1,...,N) and the second A correlation coefficient S _1-2,n between the power f(t) of the received signal R ₂ (t) and the time waveform is obtained.
Further, the correlation coefficient acquisition unit 16 calculates the power _h m (t) of the third reception signal R _3,m (t) (m=1,...,M) acquired by the reception signal acquisition unit 11. The time waveform and the time waveform of the power f(t) of the second received signal R ₂ (t) are provided to the learning model 17 .
The correlation coefficient acquisition unit 16 extracts from the learning model 17 the temporal waveform of the power h _m (t) of the third received signal R _3,m (t) (m=1,...,M) and the second A correlation coefficient S _3-2,m between the power f(t) of the received signal R ₂ (t) and the time waveform is obtained.

In the radar cross-sectional area calculation device 4 shown in FIG. 10, the correlation coefficient acquisition unit 16 includes a learning model 17. However, this is just an example, and the learning model 17 may be provided outside the correlation coefficient acquisition unit 16.

The learning model 17 includes, for example, a first learning model for obtaining the correlation coefficient S _1-2,n and a second learning model for obtaining the correlation coefficient S _3-2,m. are doing.
During learning, the first learning model uses as input data the time waveform of the power g _n (t) of the first received signal R _1,n (t) (n=1,...,N) and the If the time waveform of the power f(t) of the received signal R ₂ (t) of 2 is given, and the correlation coefficient S _1-2,n is given as teacher data, then the correlation coefficient S _1-2,n Learn.
During learning, the second learning model uses as input data the time waveform of the power h _m (t) of the third received signal R _3,m (t) (m=1,...,M) and the If the time waveform of the power f(t) of the received signal R ₂ (t) of 2 is given, and the correlation coefficient S _3-2,m is given as teacher data, the correlation coefficient S _3-2,m Learn.

The first learning model uses, as input data, the time waveform of the power g _n (t) of the first received signal R _1,n (t) (n=1,...,N) and the first learning model at the time of inference. When the time waveform of the power f(t) of the received signal R ₂ (t) of 2 is given, the correlation coefficient S _1-2,n is output.
The second learning model uses, as input data, the time waveform of the power h _m (t) of the third received signal R _3,m (t) (m=1,...,M) and the When the time waveform of the power f(t) of the received signal R ₂ (t) of 2 is given, the correlation coefficient S _3-2,m is output.

Next, the operation of the radar cross-sectional area calculation device 4 shown in FIG. 10 will be explained. Since the components other than the correlation coefficient acquisition section 16 are the same as the radar cross section calculation device 4 shown in FIG. 2, only the operation of the correlation coefficient acquisition section 16 will be described here.

The correlation coefficient acquisition unit 16 retrieves the N first received signals R _1,1 (t) to R _1,N (t) and the second received signal R ₂ ( t) and M third received signals R _3,1 (t) to R _3,M (t).
The correlation coefficient acquisition unit 16 calculates the power g _n (t) at time t in the first received signal R _1,n (t) (n=1, . . . , N). The power g _n (t) at time t is the received power g _n (t) of the first reflected wave by the calibration target Tp.
Furthermore, the correlation coefficient acquisition unit 16 calculates the power f(t) of the second received signal R ₂ (t) at time t. The power f(t) at time t is the received power f(t) of the second reflected wave by the observed object.
Furthermore, the correlation coefficient acquisition unit 16 calculates the power h _m (t) at time t in the third received signal R _3,m (t) (m=1, . . . , M). The power h _m (t) at time t is the received power h _m (t) of the third reflected wave from a wall or the like in the measurement space.

The correlation coefficient acquisition unit 16 calculates the temporal waveform of the power g _{n (t) of the first received signal R 1,n (} t) (n=1,...,N) and the second received signal R ₂ ( t) and the time waveform of power f(t) are given to the learning model 17.
The correlation coefficient acquisition unit 16 extracts from the learning model 17 the time waveform of the power g _n (t) of the first received signal R _1,n (t) (n=1,...,N) and the second A correlation coefficient S _1-2,n between the power f(t) of the received signal R ₂ (t) and the time waveform is obtained.
The correlation coefficient acquisition unit 16 outputs the correlation coefficient S _1-2,n to the received signal selection processing unit 14.

The correlation coefficient acquisition unit 16 calculates the temporal waveform of the power h _{m (t) of the third received signal R 3,m} (t) ( _m =1,...,M) and the second received signal R ₂ ( t) and the time waveform of power f(t) are given to the learning model 17.
The correlation coefficient acquisition unit 16 extracts from the learning model 17 the temporal waveform of the power h _m (t) of the third received signal R _3,m (t) (m=1,...,M) and the second A correlation coefficient S _3-2,m between the power f(t) of the received signal R ₂ (t) and the time waveform is obtained.
The correlation coefficient acquisition unit 16 outputs the correlation coefficient S _3-2,m to the received signal selection processing unit 14.

In the second embodiment described above, the received signal selection unit 12 learns the power time waveform of each first received signal and the power time waveform of the second received signal acquired by the received signal acquisition unit 11. From the learning model 17, the power of each first received signal is calculated as the similarity between the time waveform of the power of each first received signal and the time waveform of the power of the second received signal. The radar cross section calculation device 4 shown in FIG. 10 was configured to include a correlation coefficient acquisition unit 16 that acquires a correlation coefficient between the time waveform and the time waveform of the power of the second received signal. Therefore, similarly to the radar cross-sectional area calculation device 4 shown in FIG. 2, the radar cross-sectional area calculation device 4 shown in FIG. In this case, it is possible to suppress deterioration in the calculation accuracy of the radar cross section.

Embodiment 3.
In Embodiment 3, a description will be given of a radar cross-sectional area calculation device 4 that calculates the radar cross-sectional area of an observed object existing in a measurement space in which a position reference target Tr is installed.

The configuration of the radar device according to Embodiment 3 is similar to the configuration of the radar device according to Embodiments 1 and 2, and a configuration diagram showing the radar device according to Embodiment 3 is FIG. 1.
The configuration of the radar cross section calculation device 4 according to the third embodiment is similar to the configuration of the radar cross section calculation device 4 according to the first and second embodiments. The configuration diagram shown is FIG. 2 or FIG. 10.

First, in a background power measurement environment as shown in FIG. 11, the transmitting antenna 2 transmits radio waves related to the transmit signal output from the transceiver 1 toward the measurement space M times. M is an integer of 2 or more.
FIG. 11 is an explanatory diagram showing the background power measurement environment.
In the measurement environment shown in FIG. 11, a position reference target Tr, a transmitting antenna 2, and a receiving antenna 3 are installed in the measurement space. The position reference target Tr is a scatterer with a known shape.

The receiving antenna 3 receives the third reflected wave, which is the radio wave after being reflected by the position reference target Tr, M times in a background power measurement environment.
The receiving antenna 3 is mounted on, for example, a drone or a helicopter. When the receiving antenna 3 receives the third reflected wave M times, even if the drone performs hovering etc. to stay in the same position, the position of the receiving antenna 3 may change over time. may change.
The receiving antenna 3 outputs a third received signal R _3,m (t) (m=1, . . . , M), which is a received signal of each third reflected wave, to the transceiver 1.
The transceiver 1 performs reception processing on the third received signal R _3,m (t) output from the receiving antenna 3, and transmits the third received signal R _3,m (t) to the radar cross section calculation device 4. Output to.
The received signal acquisition unit 11 of the radar cross section calculation device 4 acquires the third received signal R _3,m (t) from the transceiver 1 and stores the third received signal R _3,m (t) in the internal memory. Store in.

Next, in the measurement environment of the calibration target as shown in FIG. 12, the transmitting antenna 2 transmits radio waves related to the transmit signal output from the transceiver 1 toward the measurement space N times. N is an integer of 2 or more.
FIG. 12 is an explanatory diagram showing the measurement environment of the calibration target Tp.
In the measurement environment shown in FIG. 12, a calibration target Tp, a transmitting antenna 2, and a receiving antenna 3 are installed in the measurement space.
In addition, in the measurement environment shown in FIG. 12, when the reception antenna 3 receives the reflected wave from the calibration target Tp, the position reference target Tr is installed in the measurement space at a position that does not interfere with the reception of the reflected wave. has been done. Here, the position reference target Tr is installed at a position where the distance R _c between the position reference target Tr and the reception antenna 3 is shorter than the distance R _t between the calibration target Tp and the reception antenna 3 .

The receiving antenna 3 receives the first reflected wave, which is the radio wave after being reflected by the calibration target Tp, N times under the measurement environment of the calibration target Tp.
When the receiving antenna 3 receives the first reflected wave N times, even if the drone performs hovering etc. to stay in the same position, the position of the receiving antenna 3 may change over time. may change.
The receiving antenna 3 outputs a first received signal R _1,n (t) (n=1, . . . , N), which is a received signal of each first reflected wave, to the transceiver 1.
The transceiver 1 performs reception processing on the first received signal R _1,n (t) output from the receiving antenna 3, and transmits the first received signal R _1,n (t) to the radar cross section calculation device 4. Output to.
The received signal acquisition unit 11 of the radar cross section calculation device 4 acquires the first received signal R _1,n (t) from the transceiver 1 and stores the first received signal R _1,n (t) in the internal memory. Store in.

Next, in the measurement environment of the observed object as shown in FIG. 13, the transmission antenna 2 transmits radio waves related to the transmission signal output from the transceiver 1 toward the measurement space.
FIG. 13 is an explanatory diagram showing the measurement environment of the observed object.
In the measurement environment shown in FIG. 13, the position reference target Tr, the transmitting antenna 2, and the receiving antenna 3 are installed in the measurement space, and the object to be observed exists in the measurement space.

The receiving antenna 3 receives a second reflected wave, which is a radio wave reflected by the observed object, under the measurement environment of the observed object, and generates a second received signal R, which is a received signal of the second reflected wave. ₂ (t) is output to the transceiver 1.
The transceiver 1 performs reception processing on the second received signal R ₂ (t) output from the receiving antenna 3 and outputs the second received signal R ₂ (t) to the radar cross section calculation device 4 .
The received signal acquisition unit 11 of the radar cross section _{calculation device 4 acquires the second received signal R 2 (t) from the transceiver 1 and stores the second received signal R 2 (} t) in the internal memory.

Although the received signal selection section 12 will be described below as including the correlation coefficient calculation section 13, the reception signal selection section 12 may include the correlation coefficient acquisition section 16.
The correlation coefficient calculation unit 13 of the received signal selection unit 12 calculates the N first received signals R _1,1 (t) to R _1,N (t) and the second received signal from the internal memory of the received signal acquisition unit 11. The received signal R ₂ (t) and M third received signals R _3,1 (t) to R _3,M (t) are obtained.
The correlation coefficient calculation unit 13 calculates the power g _n (t) at time t in the first received signal R _1,n (t) (n=1, . . . , N). The power g _n (t) at time t is the received power of the first reflected wave from each of the position reference target Tr and the calibration target Tp. The power g _n (t) also includes the received power of the first reflected wave from the walls of the measurement space.
Furthermore, the correlation coefficient calculation unit 13 calculates the power f(t) at time t in the second received signal R ₂ (t). The power f(t) at time t is the received power of the second reflected wave from each of the position reference target Tr and the observed object. The power f(t) also includes the received power of the second reflected wave from the walls of the measurement space.
Furthermore, the correlation coefficient calculation unit 13 calculates the power h _m (t) at time t in the third received signal R _3,m (t) (m=1, . . . , M). The power h _m (t) at time t is the received power h _m (t) of the third reflected wave by the position reference target Tr. The power h _m (t) also includes the received power of the third reflected wave from the walls of the measurement space.

FIG. 14A is an explanatory diagram showing the received power g _n (t) of the first reflected wave by the position reference target Tr and the calibration target Tp.
In the example of FIG. 14A, the received power g _n (t) of the first reflected wave by the calibration target Tp appears between times T1 and T2, and the position reference target Tr appears between times T3 and T4. The received power g _n (t) of the first reflected wave appears. Since the distance R _c is shorter than the distance R _t , the received power g _n (t) of the first reflected wave by the position reference target Tr is the received power g _n (t) of the first reflected wave by the calibration target Tp. ) appears earlier than.
FIG. 14B is an explanatory diagram showing the received power f(t) of the second reflected wave from the position reference target Tr and the observed object.
In the example of FIG. 14B, the received power f(t) of the second reflected wave from the observed object appears between times T1 and T2, and the received power f(t) of the second reflected wave from the position reference target Tr appears between times T3 and T4. The received power f(t) of the reflected wave of No. 2 appears. Since the distance R _c is shorter than the distance R _t , the received power f(t) of the second reflected wave from the position reference target Tr is lower than the received power f(t) of the second reflected wave from the observed object. It appears early.
FIG. 14C is an explanatory diagram showing the received power h _m (t) of the third reflected wave by the position reference target Tr.
In the example of FIG. 14C, the received power h _m (t) of the third reflected wave by the position reference target Tr appears between times T3 and T4.

The correlation coefficient calculation unit 13 calculates the power g _n ( _t ) and the time waveform of the power f(t) of the second received signal R ₂ ( _t ).
The correlation coefficient calculation unit ₁₃ calculates the power h _m (t ) and the time waveform of the power f(t) of the second received signal R ₂ ( _t ).

The received signal selection processing unit 14 selects the correlation coefficient calculation unit 13 from among the N first received signals R _1,1 (t) to R _1,N (t) acquired by the received signal acquisition unit 11. One of the first received signals R _1,n (t) is selected based on the N correlation coefficients S _1-2,1 to S _1-2,N calculated as follows.
That is, the received signal selection processing unit 14 identifies the largest correlation coefficient S _1-2,MAX among the N correlation coefficients S _1-2,1 to S _1-2,N . Then, the received signal selection processing unit 14 selects a signal corresponding to the largest correlation coefficient S _1-2,MAX from among the N first received signals R _1,1 (t) to R _1,N (t). Select the first received signal R _1,n (t).

Further, the received signal selection processing unit 14 calculates a correlation coefficient from among the M third received signals R _3,1 (t) to R _3,M (t) acquired by the received signal acquisition unit 11. Based on the M correlation coefficients S _3-2,1 to S _3-2,M calculated by the section 13, one of the third received signals R _3,m (t) is selected.
That is, the received signal selection processing unit 14 specifies the largest correlation coefficient S 3-2, _MAX among the M correlation coefficients S _3-2,1 to S _3-2,M . Then, the received signal selection processing unit 14 selects a signal related to the largest correlation coefficient S _3-2,MAX from among the M third received signals R _3,1 (t) to R _3,M (t). Select the third received signal R _3,m (t).

The received signal selection processing unit 14 calculates the power g n (t) at time t of the selected first received signal R _1,n (t) and the power g _n (t) of the selected third received signal R _3,m (t). The power h _m (t) at time t is output to the radar cross-sectional area calculation unit 15 .
Further, the received signal selection processing section 14 outputs the power f(t) at time t in the second received signal R ₂ (t) to the radar cross section calculation section 15 .

The radar cross section calculation unit 15 acquires the power g _n (t), the power h _m (t), and the power f(t) from the received signal selection unit 12 .
The radar cross section calculation unit 15 calculates the radar cross section RCS of the observed object using the power g _n (t), the power h _m (t), and the power f(t), as shown in equation (9). do.

In the radar device according to the third embodiment, a position reference target is installed in the measurement space. When the position reference target is installed in the measurement space, the difference in the time waveforms of the M powers h _m (t) becomes clearer than when the position reference target is not installed in the measurement space. Therefore, when the position reference target is installed in the measurement space, the third reception signal R _3,m ( t) selection accuracy is improved. As a result, the radar cross-sectional area calculating device 4 according to the third embodiment can further suppress deterioration in the calculation accuracy of the radar cross-sectional area than the radar cross-sectional area calculating device 4 according to the first and second embodiments.

Embodiment 4.
In Embodiment 4, a radar device including a position estimating section 5 that estimates the position of the receiving antenna 3 will be described.
In the fourth embodiment, three or more position reference targets Tr are installed in the measurement space.

FIG. 15 is an explanatory diagram showing the background power measurement environment.
FIG. 16 is an explanatory diagram showing the measurement environment of the calibration target Tp.
FIG. 17 is an explanatory diagram showing the measurement environment of the observed object.
In the examples shown in FIGS. 15 to 17, three position reference targets Tr are installed in the measurement space.
The installation positions of the three position reference targets Tr are different from each other. In addition, the three position reference targets Tr and the receiving antenna 3 are placed at positions where the distances R _c1 , R _c2 , R _c3 are each shorter than the distance R _t between the calibration target Tp and the receiving antenna 3. A position reference target Tr is installed.
Three position reference targets Tr are installed at positions that do not interfere with the reception of the reflected waves when the receiving antenna 3 receives the reflected waves from the calibration target Tp. The installation positions of the three position reference targets Tr are known.

FIG. 18 is a configuration diagram showing a radar device including a radar cross-sectional area calculation device 4 according to the fourth embodiment. In FIG. 18, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts, so the explanation will be omitted.
The position estimating unit 5 estimates the position of the receiving antenna 3 based on the reception time of the third reflected wave from each position reference target by the receiving antenna 3.
In the radar device shown in FIG. 18, the position estimation unit 5 is provided outside the radar cross-sectional area calculation device 4. However, this is only an example, and the position estimation unit 5 may be provided inside the radar cross-sectional area calculation device 4.

Next, the operation of the radar device shown in FIG. 18 will be explained. Since everything other than the position estimating section 5 is the same as the radar device shown in FIG. 1, only the operation of the position estimating section 5 will be described here.
The position estimation unit 5 acquires the third received signal R _3,m (t) (m=1, . . . , M) from the transceiver 1.
The position estimation unit 5 calculates the power h _m (t) at time t in the third received signal R _3,m (t).
Since each of the distances R _c1 , R _c2 , and R _c3 between the three position reference targets Tr and the receiving antenna 3 is shorter than the distance R _t between the calibration target Tp and the receiving antenna 3, the power h _m (t) Among the plurality of peak values, the first three peak values in the order of reception time are the peak values related to the respective position reference targets Tr.

The position estimation unit 5 specifies the reception times t ₁ , t ₂ , and t ₃ of the first three peak values, and determines when the radio waves are transmitted from the transmitting antenna 2 as shown in equations (10) to (12) below. The time differences Δt ₁ , Δt ₂ , and Δt ₃ from the received time t ₀ to the reception times t ₁ , t ₂ , and t ₃ are calculated.
Δt ₁ =t ₁ -t ₀ (10)
Δt ₂ = t ₂ −t ₀ (11)
Δt ₃ =t ₃ -t ₀ (12)
Here, for convenience of explanation, it is assumed that Δt ₁ <Δt ₂ <Δt ₃ .

As shown in equation (13) below, the position estimation unit 5 selects a position reference target installed at a position closest to the reception antenna 3 among the three position reference targets Tr based on the time difference Δt ₁ . The distance R _c1 to the target Tr is calculated.
R _c1 = (c×Δt ₁ )/2 (13)
In equation (13), c is the speed of radio waves.
The position estimating unit 5 is installed at the second closest position to the receiving antenna ₃ among the three position reference targets Tr based on the time difference Δt2, as shown in equation (14) below. A distance R _c2 to the position reference target Tr is calculated.
R _c2 = (c×Δt ₂ )/2 (14)
As shown in equation (15) below, the position estimation unit 5 selects the position reference target installed at the farthest position from the reception antenna ₃ among the three position reference targets Tr based on the time difference Δt3. The distance R _c3 to the target Tr is calculated.
R _c3 = (c×Δt ₃ )/2 (15)

Finally, the position estimation unit 5 calculates the position of the receiving antenna 3 based on the known installation positions of the three position reference targets Tr and the distances R _c1 , R _c2 , and R _c3 . The position calculation process itself is a well-known technique, so a detailed explanation will be omitted.

In the fourth embodiment described above, the radar is equipped with a position estimating unit 5 that estimates the position of the receiving antenna 3 based on the reception time of the third reflected wave from each position reference target by the receiving antenna 3. Configured the device. Therefore, the radar device can specify the position of the receiving antenna 3.

Note that in the present disclosure, it is possible to freely combine the embodiments, to modify any component of each embodiment, or to omit any component in each embodiment.

The present disclosure is suitable for a radar cross-sectional area calculation device, a radar cross-sectional area calculation method, and a radar device.

1 Transmitter/receiver, 2 Transmitting antenna, 3 Receiving antenna, 4 Radar cross section calculation device, 11 Received signal acquisition section, 12 Received signal selection section, 13 Correlation coefficient calculation section, 14 Received signal selection processing section, 15 Radar cross section calculation section, 16 correlation coefficient acquisition section, 17 learning model, 21 received signal acquisition circuit, 22 received signal selection circuit, 23 radar cross section calculation circuit, 31 memory, 32 processor.

Claims (11)

1. receiving a first reflected wave that is a radio wave after being reflected by a calibration target installed in a measurement space a plurality of times, and outputting a first received signal that is a received signal of each first reflected wave; A second reflected wave, which is a radio wave after being reflected by an observed object existing in place of the calibration target, is received at the position where the calibration target was installed, and the second reflected wave is a received signal acquisition unit that acquires each of the first received signal and the second received signal from a receiving antenna that outputs a second received signal that is a received signal;
   The degree of similarity between the time waveform of the power of each of the first received signals acquired by the received signal acquisition unit and the time waveform of the power of the second received signal is calculated, a received signal selection unit that selects one of the first received signals from among the plurality of first received signals based on the calculation result of the degree of similarity;
   a radar cross section that calculates a radar cross section of the observed object using the power of the first received signal selected by the received signal selection section and the power of the second received signal acquired by the received signal acquisition section; A radar cross section calculation device comprising an area calculation section and.
2. The received signal selection section includes:
   As the degree of similarity between the time waveform of the power of each first received signal acquired by the received signal acquisition unit and the time waveform of the power of the second received signal, the time waveform of the power of each first received signal is calculated. a correlation coefficient calculation unit that calculates a correlation coefficient between the waveform and the time waveform of the power of the second received signal;
   Selecting one of the first received signals from among the plurality of first received signals acquired by the received signal acquisition section based on the plurality of correlation coefficients calculated by the correlation coefficient calculation section. 2. The radar cross-sectional area calculation device according to claim 1, further comprising a received signal selection processing section.
3. The received signal selection section includes:
   The time waveform of the power of each first received signal and the time waveform of the power of the second received signal acquired by the received signal acquisition unit are given to a learning model, and from the learning model, each first As the similarity between the time waveform of the power of the received signal and the time waveform of the power of the second received signal, the time waveform of the power of the first received signal and the time waveform of the power of the second received signal, respectively. a correlation coefficient acquisition unit that acquires a correlation coefficient with
   Selecting one of the first received signals from among the plurality of first received signals acquired by the received signal acquisition section based on the plurality of correlation coefficients acquired by the correlation coefficient acquisition section. 2. The radar cross-sectional area calculation device according to claim 1, further comprising a received signal selection processing section.
4. A position reference target is installed in the measurement space at a position different from the position where the calibration target is installed,
   The receiving antenna is
   Among the position reference target, the calibration target, and the observed object, the radio wave is a radio wave after being reflected by the position reference target in a situation where only the position reference target exists in the measurement space. The third reflected wave is received a plurality of times, and a third received signal that is a received signal of each third reflected wave is output, and each of the position reference target and the calibration target is placed in the measurement space. In such a situation, radio waves reflected by each of the position reference target and the calibration target are received multiple times as the first reflected waves, and a received signal of each first reflected wave is generated. outputs a first received signal that is receiving the radio waves reflected by each of the observed objects and outputting a second received signal that is a received signal of the second reflected wave;
   The received signal acquisition unit includes:
   obtaining respective first received signals, said second received signals, and respective third received signals;
   The received signal selection section includes:
   The degree of similarity between the time waveform of the power of each of the first received signals acquired by the received signal acquisition unit and the time waveform of the power of the second received signal is calculated, Selecting one of the first received signals from among the plurality of first received signals based on the calculation result of the similarity,
   Calculate the degree of similarity between the power time waveform of each third received signal acquired by the received signal acquisition unit and the power time waveform of the second received signal, and Selecting any third received signal from among the plurality of third received signals based on the calculation result of the similarity,
   The radar cross-sectional area calculation unit includes:
   of the observed object using the power of each of the first received signal and third received signal selected by the received signal selection section and the power of the second received signal acquired by the received signal acquisition section. 2. The radar cross-sectional area calculating device according to claim 1, wherein the radar cross-sectional area calculation device calculates a radar cross-sectional area.
5. The received signal selection section includes:
   As the degree of similarity between the time waveform of the power of each third received signal acquired by the received signal acquisition unit and the time waveform of the power of the second received signal, the time waveform of the power of each third received signal is calculated. a correlation coefficient calculation unit that calculates a correlation coefficient between the waveform and the time waveform of the power of the second received signal;
   Selecting one of the third reception signals from among the plurality of third reception signals acquired by the reception signal acquisition section based on the plurality of correlation coefficients calculated by the correlation coefficient calculation section. 5. The radar cross-sectional area calculation device according to claim 4, further comprising a received signal selection processing section.
6. The received signal selection section includes:
   The time waveform of the power of each of the third received signals acquired by the received signal acquisition unit and the time waveform of the power of the second received signal are given to a learning model, and each of the third received signals is acquired from the learning model. As the similarity between the time waveform of the power of the received signal and the time waveform of the power of the second received signal, the time waveform of the power of the respective third received signal and the time waveform of the power of the second received signal are calculated. a correlation coefficient acquisition unit that acquires a correlation coefficient with
   Selecting one of the third reception signals from among the plurality of third reception signals acquired by the reception signal acquisition unit based on the plurality of correlation coefficients acquired by the correlation coefficient acquisition unit. 5. The radar cross-sectional area calculation device according to claim 4, further comprising a received signal selection processing section.
7. receiving a first reflected wave that is a radio wave after being reflected by a calibration target installed in a measurement space a plurality of times, and outputting a first received signal that is a received signal of each first reflected wave; A second reflected wave, which is a radio wave after being reflected by an observed object existing in place of the calibration target, is received at the position where the calibration target was installed, and the second reflected wave is From a receiving antenna that outputs a second received signal, which is a received signal,
   a received signal acquisition unit acquires each of the first received signal and the second received signal,
   A received signal selection unit calculates the degree of similarity between the power time waveform of each first received signal acquired by the received signal acquisition unit and the power time waveform of the second received signal, and selects the received signal. Selecting one of the first received signals from among the plurality of first received signals acquired by the acquisition unit based on the calculation result of the degree of similarity,
   A radar cross section calculation unit calculates the radar cross section of the observed object using the power of the first reception signal selected by the reception signal selection unit and the power of the second reception signal acquired by the reception signal acquisition unit. Calculate the cross-sectional area How to calculate the radar cross-sectional area.
8. A calibration target installed in the measurement space,
   A first reflected wave that is a radio wave after being reflected by the calibration target is received a plurality of times, a first received signal that is a received signal of each first reflected wave is outputted, and the calibration target is installed. A second reflected wave, which is a radio wave after being reflected by an observed object existing in place of the calibration target, is received at the position where the calibration target was located, and a second reflected wave, which is a received signal of the second reflected wave, is received. a receiving antenna that outputs a received signal;
   a received signal acquisition unit that acquires each of the first received signal and the second received signal from the receiving antenna;
   The degree of similarity between the time waveform of the power of each of the first received signals acquired by the received signal acquisition unit and the time waveform of the power of the second received signal is calculated, a received signal selection unit that selects one of the first received signals from among the plurality of first received signals based on the calculation result of the degree of similarity;
   a radar cross section that calculates a radar cross section of the observed object using the power of the first received signal selected by the received signal selection section and the power of the second received signal acquired by the received signal acquisition section; A radar device equipped with an area calculation section and.
9. A position reference target installed in the measurement space at a position different from the position where the calibration target is installed,
   The receiving antenna is
   Among the position reference target, the calibration target, and the observed object, the radio wave is a radio wave after being reflected by the position reference target in a situation where only the position reference target exists in the measurement space. The third reflected wave is received a plurality of times, and a third received signal that is a received signal of each third reflected wave is output, and each of the position reference target and the calibration target is placed in the measurement space. In such a situation, radio waves reflected by each of the position reference target and the calibration target are received multiple times as the first reflected waves, and a received signal of each first reflected wave is generated. outputs a first received signal that is receiving the radio waves reflected by each of the observed objects and outputting a second received signal that is a received signal of the second reflected wave;
   The received signal acquisition unit includes:
   obtaining respective first received signals, said second received signals, and respective third received signals;
   The received signal selection section includes:
   The degree of similarity between the time waveform of the power of each of the first received signals acquired by the received signal acquisition unit and the time waveform of the power of the second received signal is calculated, Selecting one of the first received signals from among the plurality of first received signals based on the calculation result of the similarity,
   Calculate the degree of similarity between the power time waveform of each third received signal acquired by the received signal acquisition unit and the power time waveform of the second received signal, and Selecting any third received signal from among the plurality of third received signals based on the calculation result of the similarity,
   The radar cross-sectional area calculation unit includes:
   of the observed object using the power of each of the first received signal and third received signal selected by the received signal selection section and the power of the second received signal acquired by the received signal acquisition section. 9. The radar device according to claim 8, further comprising calculating a radar cross-sectional area.
10. The radar device according to claim 9, wherein the installation position of the position reference target is closer to the receiving antenna than the installation position of the calibration target.
11. As the position reference targets, three or more position reference targets are installed in the measurement space,
    The radar device according to claim 10, further comprising a position estimating unit that estimates the position of the receiving antenna based on the reception time of the third reflected wave by each position reference target by the receiving antenna. .

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