WO2020003459A1 - Target detection device, angle measurement device, and radar device - Google Patents

Abstract

This angle measurement device (10) comprises a direction determination unit (14) for using the relative distances between a plurality of targets and the relative Doppler frequencies between the plurality of targets to determine an execution direction for constant false alarm rate processing of a range-Doppler map created by a map creation unit (22), and is configured such that clutter included in the range-Doppler map is suppressed as a result of a target detection unit (23) executing constant false alarm rate processing on the range-Doppler map in the direction determined by the direction determination unit (14).

Description

Target detecting device, angle measuring device and radar device

The present invention relates to a target detecting device and a radar device for detecting a target, and an angle measuring device for measuring an angle of the target.

Patent Document 1 below discloses an FMCW radar device that detects a distance to a target and a speed of the target.
In the FMCW radar device disclosed in Patent Literature 1, a received signal is multiplied by a window function in order to reduce side lobes contained in the received signal reflected on the target.
The window function by which the received signal is multiplied is a first window function for improving the resolution when the peak frequencies of a plurality of targets are close to each other. It is a 2nd window function to reduce.

JP-A-11-271432

2. Description of the Related Art Conventional radar apparatuses sometimes perform a constant false alarm rate (CFAR) process in order to suppress clutter components included in a received signal and improve target detection performance. In the FMCW radar device disclosed in Patent Literature 1, even though the process of multiplying the received signal by the window function is performed, the CFAR process is not performed.
However, when the CFAR processing is performed in the Doppler frequency direction when the relative distance between a plurality of targets is small, the power of an adjacent target leaks into a sample cell in the Doppler frequency direction at a certain target, and the CFAR threshold is reduced. It may not be possible to calculate correctly.
Further, when the relative Doppler frequency between a plurality of targets is small, if the CFAR processing is performed in the range direction, the power of an adjacent target leaks into a sample cell in the range direction of a certain target, and the CFAR threshold is correctly set. The calculation may not be possible. If the CFAR threshold cannot be calculated correctly, the possibility of erroneous detection of the target increases.
Therefore, in the conventional radar apparatus, since the CFAR threshold cannot be calculated correctly, there is a problem that even if the CFAR processing is performed, a target may be erroneously detected.

The present invention has been made to solve the above problems, and has as its object to obtain a target detection device and a radar device that can prevent erroneous detection of a target.

A target detection device according to the present invention, a received signal of electromagnetic waves reflected by a plurality of targets, a map creation unit that creates a range Doppler map indicating the distance to the plurality of targets and the Doppler frequency of the plurality of targets, A direction determining unit that determines a direction in which a constant false alarm rate process is performed on the range Doppler map based on a relative distance between the targets and a relative Doppler frequency between the plurality of targets; and a range created by the map creating unit. By performing the constant false alarm rate process on the Doppler map in the direction determined by the direction determination unit, clutter included in the range Doppler map is suppressed, and multiple targets are detected from the range Doppler map after clutter suppression. And a target detection unit that performs the processing.

According to the present invention, based on a relative distance between a plurality of targets and a relative Doppler frequency between a plurality of targets, a direction determining unit that determines a direction in which a constant false alarm rate process is performed on a range Doppler map is provided. The target detection unit performs a constant false alarm rate process on the range Doppler map created by the map creation unit in the direction determined by the direction determination unit, so as to suppress clutter included in the range Doppler map. And a target detecting device. Therefore, the target detection device according to the present invention can prevent erroneous detection of a target.

1 is a configuration diagram illustrating a radar device including a target detection device 10 according to a first embodiment. FIG. 2 is a configuration diagram illustrating a transmission / reception unit 1 of the radar device according to the first embodiment. FIG. 3 is a hardware configuration diagram illustrating hardware of the target detection device 10 according to the first embodiment. FIG. 2 is a configuration diagram illustrating a target detection unit 23 of the target detection device 10 according to the first embodiment. FIG. 2 is a hardware configuration diagram of a computer when the target detection device 10 is realized by software or firmware. 9 is a flowchart illustrating a processing procedure when the target detection device 10 is realized by software or firmware. FIG. 9 is an explanatory diagram illustrating a relationship between a relative distance Δr between a plurality of targets and a relative Doppler frequency Δf _dop . 8A is range resolution of the received data _{s r0 (τ,} h) before the pulse compression section 21 for multiplying the range window function _{w r} in the received data _{s r0 (τ,} h), shows a main lobe and side lobes Description Figure, FIG. 8B, pulse compression unit 21 is received data _{s r0 (τ,} h) the range window function _{w r} received data after it has been multiplied by the _{s r (τ,} h) range resolution, the main lobe and side lobes FIG. Figure 9A is a pulse compression unit 21 is received data _{s r0} (τ, h) diagram showing a main lobe and side lobes of the received data _{s r0} before multiplying the range window function _{w r} in (tau, h), Fig. 9B and 9C are explanatory views showing a main lobe and side lobes of the pulse compressor 21 receives data _{s r0 (τ,} h) receiving after multiplying the range window function _{w r} to the data _{s r (τ,} h) It is. Figure 10A is a pulse compressor 21 receives data _{s r0} (τ, h) diagram showing a main lobe and side lobes of the received data _{s r0} before multiplying the range window function _{w r} in (tau, h), Fig. 10B and 10C are explanatory views showing a main lobe and side lobes of the pulse compressor 21 receives data _{s r0 (τ,} h) receiving after multiplying the range window function _{w r} to the data _{s r (τ,} h) It is. FIG. 9 is an explanatory diagram showing an example in which the interference between the main lobes is small even when the range resolution Δr _{reso, w} is larger than the relative distance Δr. FIG. 4 is an explanatory diagram illustrating an outline of a CFAR process. FIG. 9 is an explanatory diagram illustrating an outline of a CFAR process when a plurality of targets (1) and (2) exist. FIG. 14A is an explanatory diagram illustrating a direction in which the CFAR process is performed when the relative Doppler frequency Δf _dop is smaller than the relative distance Δr. FIG. 14B is a diagram illustrating the execution of the CFAR process when the relative distance Δr is smaller than the relative Doppler frequency Δf _dop. It is explanatory drawing which shows a direction. FIG. 9 is a configuration diagram illustrating a radar device including an angle measurement device 60 according to a second embodiment. FIG. 9 is a configuration diagram illustrating a transmission / reception unit 50 of the radar device according to the second embodiment. FIG. 9 is a hardware configuration diagram illustrating hardware of an angle measurement device 60 according to a second embodiment.

Hereafter, in order to explain this invention in greater detail, the preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram illustrating a radar device including a target detection device 10 according to the first embodiment.
FIG. 2 is a configuration diagram illustrating the transmission / reception unit 1 of the radar device according to the first embodiment.
1 and 2, the transmission / reception unit 1 includes a transmission unit 2, a transmission / reception switch 3, a transmission / reception antenna 4, and a reception unit 5.
The transmission / reception unit 1 generates a transmission RF (Radio Frequency) signal, radiates the transmission RF signal into space as an electromagnetic wave, and then receives the transmission RF signal reflected on the target as a reception RF signal.

The transmission unit 2 includes an oscillator 2a, a pulse modulator 2b, and a transmitter 2c.
The oscillator 2a oscillates a transmission RF signal and outputs the transmission RF signal to the pulse modulator 2b.
The pulse modulator 2b performs pulse modulation on the transmission RF signal output from the oscillator 2a, and outputs the transmission RF signal after pulse modulation to the transmitter 2c.
Further, the pulse modulator 2b outputs a signal for down-conversion of the received RF signal to the receiver 5a.
The pulse modulator 2b outputs a reference signal to an analog-to-digital converter (hereinafter, referred to as an "A / D converter") 5b as a signal used for pulse compression.
The transmitter 2c performs amplification processing of the pulse-modulated transmission RF signal output from the pulse modulator 2b, and outputs the pulse-modulated transmission RF signal to the transmission / reception switch 3.

The transmission / reception switch 3 outputs the transmission RF signal output from the transmitter 2c to the transmission / reception antenna 4, and outputs the reception RF signal received by the transmission / reception antenna 4 to the receiver 5a.
The transmission / reception antenna 4 radiates the transmission RF signal output from the transmission / reception switch 3 to space as an electromagnetic wave, receives the transmission RF signal reflected on the target as a reception RF signal, and transmits the reception RF signal to the transmission / reception switch 3. Output.

The receiving unit 5 includes a receiver 5a and an A / D converter 5b.
The receiver 5a performs a reception process such as an amplification process on the reception RF signal output from the transmission / reception switch 3.
The receiver 5a down-converts the frequency of the received RF signal using the down-converting signal output from the pulse modulator 2b.
The receiver 5a outputs the received signal whose frequency has been down-converted to the A / D converter 5b.
The A / D converter 5b converts the received signal output from the receiver 5a from an analog signal to a digital signal, and outputs the digital signal to the data storage unit 6 as received data.
The A / D converter 5b converts the reference signal output from the pulse modulator 2b from an analog signal to a digital signal, and outputs the digital signal to the data storage unit 6 as reference data.
The data storage unit 6 is a storage medium that stores the received data and the reference data output from the A / D converter 5b.

The target detection device 10 includes a signal processing condition determination unit 11 and a signal processing unit 20.
The target detection device 10 is a device that detects a plurality of targets continuously ejected from the ejection device 100 for each elapsed time using each of the reception data and the reference data stored by the data storage unit 6. .
The injection apparatus 100 is an apparatus that continuously injects a plurality of targets into a space.
The injection device 100 outputs, to the target detection device 10, information indicating the injection speed, the injection angle, the injection time interval, and the like of the multiple targets as the injection conditions of the multiple targets.

FIG. 3 is a hardware configuration diagram illustrating hardware of the target detection device 10 according to the first embodiment.
The signal processing condition determination unit 11 includes a relative value calculation unit 12, a window function selection unit 13, and a direction determination unit 14.
The relative value calculation unit 12 is realized by, for example, a relative value calculation circuit 31 illustrated in FIG.
The relative value calculation unit 12 acquires a plurality of target injection conditions from the injection device 100.
The relative value calculation unit 12 predicts the trajectories of the plurality of targets from the injection conditions of the plurality of targets, and calculates the relative distance between the plurality of targets from the trajectory prediction result.
Further, the relative value calculation unit 12 calculates a relative Doppler frequency between a plurality of targets from the injection conditions of the plurality of targets.

The window function selection unit 13 includes a range window function selection unit 13a and a Doppler window function selection unit 13b, and is realized by, for example, a window function selection circuit 32 illustrated in FIG.
The range window function selector 13a selects a range window function corresponding to the relative distance calculated by the relative value calculator 12 from the plurality of range window functions, and outputs the selected range window function to the pulse compressor 21. I do.
The Doppler window function selection unit 13b selects a Doppler window function corresponding to the relative Doppler frequency calculated by the relative value calculation unit 12 from the plurality of Doppler window functions, and sends the selected Doppler window function to the map creation unit 22. Output.

The direction determining unit 14 is realized by, for example, a direction determining circuit 33 illustrated in FIG.
The direction determining unit 14 determines an execution direction of a constant false alarm rate (CFAR) process for the range Doppler map based on the relative distance and the relative Doppler frequency calculated by the relative value calculating unit 12.
The direction determination unit 14 outputs the determined execution direction to the target detection unit 23.

The signal processing unit 20 includes a pulse compression unit 21, a map creation unit 22, and a target detection unit 23.
The pulse compression unit 21 is realized by, for example, a pulse compression circuit 34 illustrated in FIG.
The pulse compression unit 21 multiplies the received data stored by the data storage unit 6 by the range window function output from the range window function selection unit 13a.
The pulse compression unit 21 performs pulse compression of the received data after multiplication by the range window function using the reference data stored by the data storage unit 6 and outputs the received data after the pulse compression to the map creation unit 22. .

The map creation unit 22 is realized by, for example, a map creation circuit 35 illustrated in FIG.
The map creator 22 multiplies the pulse-compressed reception data output from the pulse compressor 21 by the Doppler window function output from the Doppler window function selector 13b.
The map creation unit 22 creates a range Doppler map by converting the received data after the Doppler window function multiplication into a frequency domain in the hit direction, and outputs the range Doppler map to the target detection unit 23.
The range Doppler map is two-dimensional data indicating distances to a plurality of targets and Doppler frequencies of the plurality of targets.

As shown in FIG. 4, the target detection unit 23 includes a clutter suppression processing unit 23a and a peak detection processing unit 23b.
The target detection unit 23 is realized by, for example, a target detection circuit 36 illustrated in FIG.
The target detection unit 23 detects a plurality of targets from the range Doppler map output from the map creation unit 22.

FIG. 4 is a configuration diagram illustrating the target detection unit 23 of the target detection device 10 according to the first embodiment.
In FIG. 4, the clutter suppression processing unit 23 a suppresses clutter by performing CFAR processing on the range Doppler map created by the map creation unit 22 in the direction determined by the direction determination unit 14.
The clutter suppression processing unit 23a outputs the range Doppler map after the clutter suppression to the peak detection processing unit 23b.
The peak detection processing unit 23b detects a plurality of targets by detecting a peak value included in the range Doppler map output from the clutter suppression processing unit 23a.

In FIG. 1, each of the relative value calculation unit 12, window function selection unit 13, direction determination unit 14, pulse compression unit 21, map creation unit 22, and target detection unit 23, which are the components of the target detection device 10, is shown in FIG. It is assumed that it is realized by dedicated hardware as shown in (1). That is, it is assumed that the target detection device 10 is realized by a relative value calculation circuit 31, a window function selection circuit 32, a direction determination circuit 33, a pulse compression circuit 34, a map creation circuit 35, and a target detection circuit 36.
Here, the relative value calculation circuit 31, the window function selection circuit 32, the direction determination circuit 33, the pulse compression circuit 34, the map creation circuit 35, and the target detection circuit 36 are, for example, a single circuit, a composite circuit, a programmed processor, A processor programmed in parallel, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof is applicable.

The constituent elements of the target detection device 10 are not limited to those realized by dedicated hardware, and even if the target detection device 10 is realized by software, firmware, or a combination of software and firmware. Good.
Software or firmware is stored as a program in the memory of the computer. The computer means hardware for executing a program, 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). I do.
FIG. 5 is a hardware configuration diagram of a computer when the target detection device 10 is realized by software or firmware.
When the target detection device 10 is realized by software or firmware, the processing procedure of the relative value calculation unit 12, the window function selection unit 13, the direction determination unit 14, the pulse compression unit 21, the map creation unit 22, and the target detection unit 23 A program to be executed by a computer is stored in the memory 41. Then, the processor 42 of the computer executes the program stored in the memory 41.
FIG. 6 is a flowchart illustrating a processing procedure when the target detection device 10 is realized by software or firmware.

FIG. 3 shows an example in which each of the components of the target detection device 10 is realized by dedicated hardware, and FIG. 5 shows an example in which the target detection device 10 is realized by software or firmware. . However, this is only an example, and some components of the target detection device 10 may be realized by dedicated hardware, and the remaining components may be realized by software or firmware.

Next, the operation of the radar device shown in FIG. 1 will be described.
The oscillator 2a oscillates the transmission RF signal s _osc (τ) and outputs the transmission RF signal s _osc (τ) to the pulse modulator 2b.
In the radar device shown in FIG. 1, it is assumed that the oscillator 2a oscillates a chirp signal whose frequency changes with time as the transmission RF signal s _os (τ).
The transmission RF signal s _os (τ) whose frequency changes with the passage of time is represented by the following equation (1).

In the formula (1), Amp is the amplitude of the transmitted RF signal _{s osc (τ), τ} is the time in the range direction, _{K r} is the chirp rate.

Upon receiving the transmission RF signal s _os (τ) from the oscillator 2a, the pulse modulator 2b pulse-modulates the transmission RF signal s _os (τ) and transmits the pulse-modulated transmission RF signal s _t (τ) to the transmitter 2c. Output to
The transmission RF signal _st (τ) after the pulse modulation is represented by the following equation (2).

In the equation (2), _fc is the center frequency of the transmission RF signal _st (τ).
The chirp rate _Kr is represented by the following equation (3).

In the formula (3), B is the frequency bandwidth of the transmission RF signal _{s t (τ), T p} is the pulse width of the pulse signal constituting the transmission RF signal _{s t (τ).}

Further, the pulse modulator 2b outputs a signal s _down (τ) for down-conversion of the received RF signal s _r to the receiver 5a.
The signal s _down (τ) is represented by the following equation (4).

Further, the pulse modulator 2b outputs the reference signal s _ref (τ) to the A / D converter 5b as a signal used by the pulse compression unit 21 for pulse compression.
The reference signal s _ref (τ) is a signal obtained by taking the complex conjugate of the phase of the chirp component in the transmission RF signal _st (τ) after pulse modulation, as shown in the following equation (5).

Transmitter 2c receives the transmission from the pulse modulator 2b after the pulse-modulated RF signal _{s t} (tau), and out an amplification processing and the like of the transmission RF signal _{s t} (tau), transmission RF signal _{s t} (tau ) Is output to the transmission / reception switch 3.
The transmission / reception switch 3 outputs the transmission RF signal _st (τ) output from the transmitter 2c to the transmission / reception antenna 4, so that the transmission RF signal _st (τ) is emitted from the transmission / reception antenna 4 to space as an electromagnetic wave. .
The transmission RF signal _st (τ) radiated from the transmitting / receiving antenna 4 is reflected by the target and returns to the transmitting / receiving antenna 4.
The transmission / reception antenna 4 receives the transmission RF signal _st (τ) reflected on the target as the reception RF signal s _r (τ), and outputs the reception RF signal s _r (τ) to the transmission / reception switch 3.

The transmission / reception switch 3 outputs the reception RF signal s _r (τ) output from the transmission / reception antenna 4 to the receiver 5a.
The received RF signal s _r (τ) reflected on a certain target is represented by the following equation (6).

In Equation (6), Amp ′ is the amplitude of the received RF signal s _r (τ), and Amp> Amp ′.
τ _d is a round-trip reflection time from when the transmission RF signal _st (τ) is radiated from the transmission / reception antenna 4 to when it is reflected to the target and the reception RF signal s _r (τ) returns to the transmission / reception antenna 4. And is expressed as in the following equation (7).

In the equation (7), c is the propagation speed of the electromagnetic wave, and R (τ) is the distance from the transmitting / receiving antenna 4 to one target.

Upon receiving the received RF signal s _r (τ) from the transmission / reception switch 3, the receiver 5a performs a receiving process such as an amplification process on the received RF signal s _r .
Further, the receiver 5a down-converts the frequency of the received RF signal after the reception processing using the down-conversion signal s _down (τ) output from the pulse modulator 2b.
The receiver 5a outputs the received signal whose frequency has been down-converted to the A / D converter 5b.

When receiving the received signal from the pulse modulator 2b, the A / D converter 5b converts the received signal from an analog signal to a digital signal, and converts the digital signal into the data storage unit 6 as received data _sr0 (n, h). Output.
The received data s _r0 (n, h) is represented by the following equation (8).

In the equation (8), Amp ′ _h is the amplitude of each hit of the received data s _r0 (n, h), T _pri is the pulse repetition period (PRI), n is the sampling number in the PRI, and Δt is the PRI Within the sampling interval.
h is the hit number and H is the number of hits, which is represented by the following equation (9).

In Expression (9), floor is a function for rounding down the decimal point of the value represented by (T _p / T _pri ).
The received data s _r0 (τ, h) shown in Expression (8) is stored in the data storage unit 6 as two-dimensional data represented by the time τ in the range direction and the hit number h.

A / D converter 5b receives a reference signal _{s ref} (tau) from the pulse modulator 2b, the reference signal _{s ref} a (tau) from an analog signal to a digital signal, referring to the digital signal data _{s ref} ( n, h) to the data storage unit 6.
The reference data s _ref (n, h) is represented by the following equation (10).

The injection device 100 continuously injects a plurality of targets into space according to injection conditions such as a plurality of target injection speeds, a plurality of target injection angles, and a plurality of target injection time intervals.
The injection device 100 outputs information indicating the injection condition to the relative value calculation unit 12.
Here, FIG. 7 is an explanatory diagram showing a relationship between a relative distance Δr between a plurality of targets and a relative Doppler frequency Δf _dop .
FIG. 7 shows the relationship between the relative distance Δr and the relative Doppler frequency Δf _dop when a plurality of targets exist at positions that are close to the radar device. FIG. 7 shows the relationship between the relative distance Δr and the relative Doppler frequency Δf _dop when a plurality of targets exist at positions far from the radar device.

A plurality of targets located at a short distance from the radar device have less attenuation of the injection speed than a plurality of targets located at a long distance. Therefore, the relative distance Δr between a plurality of targets located at a short distance position is larger than the relative distance Δr between a plurality of targets located at a long distance position. Also, the relative Doppler frequency Δf _dop between a plurality of targets located at a short distance is larger than the relative Doppler frequency Δf _dop between a plurality of targets located at a long distance.
In addition, regardless of whether a plurality of targets are present at a position at a short distance from the radar device or at a position at a long distance, the injection speed and the injection angle when the target is emitted from the injection device 100 are different. Accordingly, the relative distance Δr and the relative Doppler frequency Δf _dop change together.

The relative value calculation unit 12 acquires a plurality of target injection conditions from the injection device 100.
The relative value calculation unit 12 predicts the trajectories of a plurality of targets from the injection speeds and the injection angles of the targets included in the injection conditions of the targets. The process of predicting the target trajectory itself is a well-known technique, and a detailed description thereof will be omitted.
The relative value calculation unit 12 calculates a relative distance Δr between a plurality of targets from the trajectory prediction result.
Since the injection conditions include the injection time intervals of a plurality of targets that are continuously injected from the injection device 100, the relative distance Δr can be easily calculated if the target trajectory is known.
Further, the relative value calculation unit 12 calculates a relative Doppler frequency Δf _dop between a plurality of targets as shown in the following equation (11).

In the formula (11), lambda is the wavelength of the transmitted RF signal _{s t (τ), v 1} -v 2 is injection speed of relative between adjacent target.
The relative value calculation unit 12 outputs the relative distance Δr to each of the range window function selection unit 13a and the direction determination unit 14.
Further, the relative value calculation unit 12 outputs the relative Doppler frequency Δf _dop to each of the Doppler window function selection unit 13b and the direction determination unit 14.

Range window function selection unit 13a receives the relative distance [Delta] r from the relative value calculating section 12, from among a plurality of ranges the window function, to select the range window function w _r corresponding to the relative distance [Delta] r, the selected range window function and outputs the w _r the pulse compressor 21 (step ST1 in FIG. 6).
Hereinafter, a specific example of the selection process of the range window function w _r by range window function selecting section 13a.

Here, FIG. 8 is an explanatory diagram showing the range resolution, main lobe, and side lobe of received data before and after multiplication of the range window function.
8A is range resolution of the received data _s r0 (n, h) of the front pulse compressor 21 for multiplying the range window function _{w r} in the received data _s r0 (n, h), shows the main lobe and side lobes I have. 8B is range resolution pulse compressor 21 receives data _s r0 (n, h) the range window function _{w r} received data after it has been multiplied by the _s r (n, h), shows the main lobe and side lobes I have.
The side lobe level shown in FIG. 8B is lower than the side lobe level shown in FIG. 8A. Therefore, the pulse compression unit 21 multiplies the reception data s _r0 (n, h) by the range window function _wr, thereby suppressing the side lobe of the reception data s _r0 (n, h).
The main lobe shown in FIG. 8B is wider than the main lobe shown in FIG. 8A. Accordingly, by pulse compression unit 21 multiplies the range window function _{w r} in the received data _s r0 (n, h), range resolution is changed from [Delta] r _reso [Delta] r _reso, to _w. Δr _reso <Δr _{reso, w} .

Range resolution [Delta] r _reso before pulse compression unit 21 multiplies the range window function _{w r} is expressed by the following equation (12).

Range resolution after pulse compression unit 21 is multiplied by the range window function _{w r Δr reso, w} is expressed by the following equation (13).

In the formula _(13), α _{r, w} is range resolution when multiplied by the range window function _{w r} [Delta] r _reso, a correction coefficient _w.

FIG. 9 is an explanatory diagram showing main lobes and side lobes of received data when two targets (1) and (2) are located at short distances from the radar device.
Figure 9A shows a main lobe and side lobes of the received data _s r0 (n, h) of the front pulse compressor 21 for multiplying the range window function _{w r} in the received data _s r0 (n, h).
9B and 9C shows the main lobe and side lobes of the received data _s r (n, h) after the pulse compressor 21 is obtained by multiplying the range window function _{w r} in the received data _s r0 (n, h) I have.
Shape of the range window function _{w r} that is multiplied to the received data _s r shown in FIG. 9C (n, h) the received data _s r (n, h) range window is multiplied by a function _{w r} shown in FIG. 9B The amplitude attenuation is steeper than that of the shape.

That is, the range window function w _r that is multiplied to the received data s _r shown in FIG. 9B _(n, h), the amplitude attenuation from the center to both ends of the applied section is a window function of a gentle shape. As a window function having a shape with a gentle amplitude attenuation, a window function with a small spread of a main lobe, such as a Hanning window, is applicable. However, a window function having a shape with gentle amplitude attenuation has a smaller sidelobe suppression effect than a window function with a shape with sharp amplitude attenuation.
Range window function w _r that is multiplied to the received data s _{r (n,} h) shown in FIG. 9C, the amplitude attenuation from the center to both ends of the applied section is a window function of steep shape. A window function having a sharp amplitude attenuation, such as a Blackman-Harris window, is a window function that has a large main lobe but can be expected to significantly suppress side lobes.
Range resolution [Delta] r _reso received data _s r (n, _{h), w} is the target (1) and the range window function _{w r} that is greater than the relative distance [Delta] r between the main lobe of the target (2) is selected In this case, since the main lobes interfere with each other, a phase shift occurs and the target detection accuracy decreases.
However, when the target (1) and the target (2) are located at a short distance from the radar device, the relative distance Δr between the target (1) and the target (2) is relatively large. Therefore, when the target (1) and the target (2) is present at a short distance from the position from the radar apparatus, the range window function selecting portion 13a, by selecting the range window function w _r of the amplitude attenuation steep shape However, it is unlikely that the main lobes interfere with each other.

FIG. 10 is an explanatory diagram showing main lobes and side lobes of received data when two targets (1) and (2) are present at positions far from the radar apparatus.
Figure 10A shows a main lobe and side lobes of the received data _s r0 (n, h) of the front pulse compressor 21 for multiplying the range window function _{w r} in the received data _s r0 (n, h).
10B and FIG. 10C shows the main lobe and side lobes of the received data _s r (n, h) after the pulse compressor 21 is obtained by multiplying the range window function _{w r} in the received data _s r0 (n, h) I have.
Shape of the range window function _{w r} that is multiplied to the received data _s r shown in FIG. 10C (n, h) the received data _s r (n, h) range window is multiplied by a function _{w r} shown in FIG. 10B The amplitude attenuation is steeper than that of the shape.

That is, the range window function w _r that is multiplied to the received data s _r shown in FIG. 10B _(n, h), the amplitude attenuation from the center to both ends of the applied section is a window function of a gentle shape.
Range window function w _r that is multiplied to the received data s _{r0 (n,} h) shown in FIG. 10C, amplitude attenuation from the center to both ends of the applied section is a window function of steep shape.
Range resolution [Delta] r _reso received data _s r (n, _{h), w} is the target (1) and the range window function _{w r} that is greater than the relative distance [Delta] r between the main lobe of the target (2) is selected In this case, since the main lobes interfere with each other, a phase shift occurs, and the target detection accuracy is reduced.
When the target (1) and the target (2) are located far from the radar device, the relative distance Δr between the target (1) and the target (2) is relatively small. Therefore, when the target (1) and the target (2) is present in the far position from the radar apparatus, the range window function selecting portion 13a, the amplitude attenuation selects range window function w _r a steep shape, There is a high possibility that the main lobes will interfere with each other.
In the example of FIG. 10C, are selected range window function w _r of the amplitude attenuation steep shape, but the side lobes are significantly reduced, mutual main lobe is interfering.
To the extent that another of the main lobe does not interfere, to reduce as much as possible the side lobes, [Delta] r _{reso, w <in} range window function w _r that satisfies [Delta] r, range resolution [Delta] r _{reso, w} and most larger range window function it is desirable to select a w _r.
When a window function that can change the parameters that characterize the shape of the window function, such as a Kaiser window, is used, the shape of the window function must be changed so as to satisfy Δr _{reso, w} <Δr by changing the parameters. Is possible.

Range window function selection unit 13a, when selecting a range window function w _r, in a plurality of ranges window functions are prepared in advance, as shown in the following equation (14), range resolution [Delta] r _{reso, w} Is determined whether or not there is a range window function smaller than the relative distance Δr.

Range window function selection unit 13a, range resolution [Delta] r _{reso, if w} is not present is small range window function than relative distance [Delta] r, since the mutual main lobe will interfere, not multiplied by a range window function w _r This is notified to the pulse compression unit 21.
Alternatively, as shown in FIG. 11, the range window function selection unit 13a determines that each Null point after the range window function multiplication in the two targets (1) and (2) is the main point of the next target (2) (1). A range window function _wr is selected so as to be the peak position of the lobe. When the range window function _wr is selected, interference between the main lobes is reduced.
FIG. 11 is an explanatory diagram showing an example in which the interference between the main lobes is small even when the range resolution Δr _{reso, w} is larger than the relative distance Δr.

Range window function selection unit 13a, range resolution [Delta] r _{reso, if w} is present a small range window function than relative distance [Delta] r, as a range window function _{w r,} range resolution [Delta] r _reso, than _w relative distance [Delta] r Choose a small range window function.
Range window function w _r that is selected by the range window function selecting section 13a is expressed by the following equation (15).

In equation (15), calc is a function for calculating a window function that satisfies the conditions in parentheses. beta _r is range resolution [Delta] r _reso, so _w is smaller than the relative distance [Delta] r, range resolution [Delta] r _reso, a factor for adjusting the _{w.
Preferably} , the coefficient β _r is a coefficient that _maximizes the range resolution Δr _{reso, w} after multiplication of the range window function within a range satisfying Δr _{reso, w} <Δr.

Upon receiving the relative Doppler frequency Δf _dop from the relative value calculation unit 12, the Doppler window function selecting unit 13b selects a Doppler window function w _dop corresponding to the relative Doppler frequency Δf _dop from among a plurality of Doppler window functions (FIG. Step ST2).
The Doppler window function selection unit 13b outputs the selected Doppler window function w _dop to the map creation unit 22.
Hereinafter, a specific example of the selection processing of the Doppler window function w _dop by the Doppler window function selection unit 13b will be described.

The resolution Δf _{dop, reso} of the Doppler frequency before the map creator 22 multiplies the Doppler window function w _dop is represented by the following equation (16).

In equation (16), N _hit is the number of hits.
The Doppler frequency resolution Δf _{dop, reso, w} after the map creator 22 multiplies the Doppler window function w _dop is represented by the following equation (17).

In Expression (17), α _{dop, w} is a correction coefficient of the resolution Δf _{dop, reso, w} of the Doppler frequency when multiplied by the Doppler window function w _dop .

Even if you select the Doppler window function _{w dop,} as in the case of selecting a range window function _{w r,} the Doppler frequency resolution Delta] f _{dop, reso, w} is greater than the relative Doppler frequency Delta] f _dop, in a plurality of target The main lobes interfere with each other.
Therefore, as shown in the following equation (18), the Doppler window function selection unit 13b sets the resolution Δf _{dop, reso, w} to the relative Doppler frequency Δf _dop among a plurality of Doppler window functions prepared in advance. It is determined whether a small Doppler window function exists.

If there is no Doppler window function whose resolution Δf _{dop, reso, w} is smaller than the relative Doppler frequency Δf _dop , the Doppler window function selection unit 13b interferes with each other's main lobes, so that the Doppler window function w _dop Is notified to the map creation unit 22.
Alternatively, the Doppler window function selection unit 13b selects a Doppler window function w _dop such that each Null point after multiplication of the range window function in a plurality of targets is a peak position of a main lobe of an adjacent target. When the Doppler window function w _dop is selected, interference between the main lobes is reduced.

When a Doppler window function having a resolution Δf _{dop, reso, w} smaller than the relative Doppler frequency Δf _{dop exists, the} Doppler window function selection unit 13b determines the Doppler window function w _dop as a Doppler window that satisfies Expression (18). Select a function.
The range resolution Δr _{reso, w} selected by the Doppler window function selection unit 13b is represented by the following equation (19).

In the formula (20), beta _dop is the Doppler frequency resolution Delta] f _{dop, reso,} so _w is smaller than the relative Doppler frequency Delta] f _dop, a factor for adjusting resolution Delta] f _{dop, reso,} the _w.
The coefficient β _dop is desirably a coefficient that _maximizes the resolution Δf _{dop, reso, w} after Doppler window function multiplication within a range satisfying Δf _{dop, reso, w} <Δf _dop .
calc is a function for calculating a window function under the conditions in parentheses.

FIG. 12 is an explanatory diagram showing an outline of the CFAR processing.
In the CFAR process, as shown in FIG. 12, the sample cell average power and the CFAR coefficient, which are the average values of the powers of a plurality of sample cells existing before and after the test cell that is the target cell for determining the presence or absence of the target, are calculated. The CFAR threshold is calculated by multiplication.
Next, in the CFAR processing, the power of the test cell is compared with the CFAR threshold, and if the power of the test cell is equal to or greater than the CFAR threshold, it is determined that the target is present in the test cell, and the power of the test cell is determined by the CFAR threshold. If less than the threshold, it is determined that the target does not exist in the test cell.
In the CFAR process, as shown in FIG. 12, by providing a guard cell, it is possible to prevent leakage of power of side lobes when calculating a CFAR threshold.

FIG. 13 is an explanatory diagram illustrating an outline of the CFAR processing when a plurality of targets (1) and (2) exist.
The target (1) and the target (2) may have a small relative distance Δr from each other. The target (1) and the target (2) may have a small relative Doppler frequency Δf _{dop in} each case.
When the CFAR processing is performed in the Doppler frequency direction when the relative distance Δr is small, as shown in FIG. 13, the power of the adjacent target (2) leaks into the sample cell of the target (1), and the CFAR threshold is correctly calculated. May not be possible.
If the CFAR processing is performed in the range direction when the relative Doppler frequency Δf _dop is small, the CFAR threshold may not be calculated correctly similarly.

Therefore, when the relative Doppler frequency Δf _dop is smaller than the relative distance Δr, as shown in FIG. 14A, performing the CFAR processing in the Doppler frequency direction can calculate the CFAR threshold more correctly than performing the CFAR processing in the range direction. The likelihood increases.
When the relative distance Δr is smaller than the relative Doppler frequency Δf _dop , there is a possibility that the CFAR processing can be correctly calculated by performing the CFAR processing in the range direction rather than in the Doppler frequency direction as shown in FIG. 14B. Will be higher.
FIG. 14 is an explanatory diagram showing the relationship between the relative distance Δr and the relative Doppler frequency Δf _dop and the direction in which the CFAR process is performed.
14A is a relative Doppler frequency Delta] f _dop represents the implementation direction of CFAR processing is smaller than the relative distance [Delta] r, FIG. 14B, the relative distance [Delta] r is the implementation direction of CFAR processing is smaller than the relative Doppler frequency Delta] f _dop Is shown.

Upon receiving the relative distance Δr and the relative Doppler frequency Δf _dop from the relative value calculation unit 12, the direction determining unit 14 normalizes the relative distance Δr with the range resolution Δr _{reso, w} as shown in the following equation (20). .

In equation (20), Δr _bin is the normalized relative distance.
The direction determination unit 14 _{normalizes the} relative Doppler frequency Δf _dop with the Doppler frequency resolution Δf _{dop, reso, w} as shown in the following equation (21).

In equation (21), Δf _{dop, bin} is the normalized relative Doppler frequency.

The direction determining unit 14 compares the normalized relative distance Δr _bin with the normalized relative Doppler frequency Δf _{dop, bin} (step ST3 in FIG. 6).
If the relative distance Δr _bin after the standardization is larger than the relative Doppler frequency Δf _{dop, bin} after the standardization (step ST3 in FIG. 6: Yes), the direction determination unit 14 determines the direction of the CFAR processing as the Doppler frequency. The direction is determined (step ST4 in FIG. 6).
If the normalized relative distance Δr _bin is equal to or _smaller than the normalized relative Doppler frequency Δf _{dop, bin} (step ST3 of FIG. 6: No), the direction determining unit 14 sets the direction of execution of the CFAR processing to the range direction. (Step ST5 in FIG. 6).
The direction determination unit 14 outputs the determined execution direction to the target detection unit 23.

The pulse compression unit 21 acquires the reception data s _r0 (n, h) and the reference data s _ref (n, h) from the data storage unit 6.
Pulse compressor 21 receives the range window function _{w r} from range window function selecting section 13a, as shown in the following equation (22), the received data _s r0 (n, h) to multiply the range window function _{w r} (Step ST6 in FIG. 6).

Pulse compressor 21, when receiving the notification that no multiplying the range window function w _r from range window function selecting section 13a, as shown in the following equation (23), the received data s _{r0 (n,} h ) to not multiplied by the range window function w _r.

Next, the pulse compression unit 21 performs convolution integration of the reference data s _ref (n, h) on the received data s _r (n, h) in the time domain as shown in the following equation (24). The pulse compression of the received data s _r (n, h) is performed (step ST7 in FIG. 6).

The pulse compression unit 21 outputs the received data s _rfm (n, h) after the pulse compression to the map creation unit 22.

Here, pulse compression unit 21 receives the data _s r (n, h) a reference data _s ref (n, h) carrying out the convolution in the time domain, the received data _s r (n, h) the pulse Compressed. However, this is only an example, and the pulse compression unit 21 may perform pulse compression of the received data s _r (n, h) by the following method.
That is, the pulse compression unit 21 converts each of the received data s _r (n, h) and the reference data s _ref (n, h) into a signal in the frequency domain.
Next, the pulse compressor 21 removes a chirp component by performing complex multiplication of the frequency domain signal of the received data s _r (n, h) and the frequency domain signal of the reference data s _ref (n, h). .
Then, the pulse compression unit 21 _obtains the reception data s _rfm (n, h) after the pulse compression by converting the complex multiplied signal into a time domain signal.

When receiving the Doppler window function w _dop from the Doppler window function selection unit 13b, the map creation unit 22 receives the pulse-compressed reception data s _rfm (output from the pulse compression unit 21) as shown in the following equation (25). n, h) is multiplied by a Doppler window function w _dop (step ST8 in FIG. 6).

When the map creator 22 receives a notification from the Doppler window function selector 13b not multiplying the Doppler window function w _dop , the reception data s _rfm (n, h) as shown in the following equation (26). ) _Is not multiplied by the Doppler window function w _dop .

Next, the map creation unit 22 _{converts the} received data s _{rfm, w} (n, h) into a frequency domain in the hit direction, as shown in the following equation (27), so that the range Doppler map s _2D (n , K) (step ST9 in FIG. 6).

In Equation (26), H _fft is the number of FFT data points in the hit direction.
As a method of converting the reception data s _{rfm, w} (n, h) into the frequency domain in the hit direction, a method of _{performing a} fast Fourier transform on the reception data s _{rfm, w} (n, h) in the hit direction can be considered.
_Further, a method of _{performing a} discrete Fourier transform on the received data s _{rfm, w} (n, h) in the hit direction or a method of _{performing a} chirp z-transform on the received data s _{rfm, w} (n, h) in the hit direction can be considered.
The map creator 22 outputs the range Doppler map s _2D (n, k) to the target detector 23.

Clutter suppression processing section 23a receives the range Doppler map _s 2D map creation unit 22 (n, k), the range Doppler map _s 2D (n, k) with respect to the direction determined by the direction determination unit 14 By performing the CFAR processing, clutter is suppressed (step ST10 in FIG. 6).
In the example of FIG. 14A, the clutter suppression processing unit 23a performs the CFAR processing in the Doppler frequency direction on the range Doppler map s _2D (n, k).
In the example of FIG. 14B, the clutter suppression processing unit 23a performs a CFAR process in the range direction on the range Doppler map s _2D (n, k).
The clutter suppression processing unit 23a outputs the range Doppler map s _{2D, CFAR} (n, k) after the CFAR processing to the peak detection processing unit 23b.

Peak detection processing section 23b clutter suppression processing section 23a from the range Doppler map _{s 2D, CFAR (n, k} ) receives the, as the detection processing of a plurality of targets, range Doppler map _{s 2D,} the CFAR (n, k) A detection process of the included peak value is performed (step ST11 in FIG. 6).

In the first embodiment, the direction determining unit 14 that determines the direction in which the constant false alarm rate process is performed on the range Doppler map based on the relative distance between the plurality of targets and the relative Doppler frequency between the plurality of targets. Is provided in the range Doppler map by the target detecting unit 23 performing a constant false alarm rate process on the range Doppler map created by the map creating unit 22 in the direction determined by the direction determining unit 14. The target detection device 10 was configured to suppress clutter. Therefore, the target detection device 10 of the first embodiment can prevent erroneous detection of a target.

Embodiment 2 FIG.
The radar device according to the first embodiment includes a target detection device 10.
In the second embodiment, a radar device including the angle measuring device 60 will be described.

FIG. 15 is a configuration diagram illustrating a radar device including the angle measurement device 60 according to the second embodiment.
FIG. 16 is a configuration diagram illustrating the transmission / reception unit 50 of the radar device according to the second embodiment.
FIG. 17 is a hardware configuration diagram illustrating hardware of the angle measurement device 60 according to the second embodiment.
15 to 17, the same reference numerals as those in FIGS. 1 to 3 denote the same or corresponding parts, and a description thereof will be omitted.
The transmission / reception unit 50 includes a transmission unit 2, M (M is an integer of 1 or more) transmission / reception switches 3-1 to 3-M, M transmission / reception antennas 4-1 to 4-M, and a reception unit 5. I have.
The transmission / reception unit 50 generates a transmission RF signal, radiates the transmission RF signal into space as an electromagnetic wave, and then receives the transmission RF signal reflected on the target as a reception RF signal.
Since the transmission / reception unit 50 includes M transmission / reception switching units 3-1 to 3-M and M transmission / reception antennas 4-1 to 4-M, it can be used as, for example, an adaptive array antenna. Become.

The signal processing unit 20 includes a pulse compression unit 21, a map creation unit 22, a target detection unit 23, and an angle measurement unit 24.
When detecting a plurality of targets, the peak detection processing unit 23b of the target detection unit 23 extracts the respective phases of the plurality of targets, and outputs the respective phases to the angle measurement unit 24.
The angle measuring unit 24 is realized by, for example, an angle measuring circuit 37 shown in FIG.
The angle measuring unit 24 measures angles of a plurality of targets by performing angle measuring processing such as a monopulse angle measuring method using the phase output from the peak detection processing unit 23b.

Next, the operation of the radar apparatus shown in FIG. 15 will be described. Here, parts different from the radar apparatus shown in FIG. 1 will be described.
In the radar device shown in FIG. 1, since the number of transmitting / receiving antennas 4 included in the transmitting / receiving unit 1 is one, the received data s _r0 (n, h) as shown in Expression (8) is obtained from the A / D converter 5b. Is output to the data storage unit 6.

In the radar apparatus shown in FIG. 15, since the number of transmission / reception antennas 4-1 to 4-M provided in the transmission / reception unit 1 is M, reception from the A / D converter 5b as shown in the following equation (28) is performed. The data s _r0 (n, h, m) is output to the data storage unit 6.

In the equation (28), m is the antenna number of the transmitting / receiving antennas 4-1 to 4-M, M is the number of the transmitting / receiving antennas 4-1 to 4-M, and d is the number of the transmitting / receiving antennas 4-1 to 4-M. The interval, θ, is a target angle with respect to the transmitting / receiving antennas 4-1 to 4-M.

The operation of the signal processing condition determining unit 11 is the same as that of the first embodiment, and a description thereof will be omitted.
The pulse compression section 21 acquires the reception data s _r0 (n, h, m) and the reference data s _ref (n, h, m) from the data storage section 6.
Pulse compressor 21, when the range window function selection unit 13a receives the range window function _{w r,} as shown in the following equation (29), the received data _s r0 (n, h, m) to the range window function _{w r} Multiply by

Pulse compressor 21, when receiving the notification that no multiplying the range window function w _r from range window function selecting section 13a, as shown in the following equation (30), the received data s _{r0 (n,} h , m) to not multiplied by the range window function _{w r.}

Next, the pulse compression unit 21 performs convolution integration of the reference data s _ref (n, h, m) on the reception data s _r (n, h, m) in the time domain as shown in the following equation (31). By doing so, pulse compression of the received data s _r (n, h, m) is performed.

The pulse compression section 21 outputs the received data s _rfm (n, h, m) after the pulse compression to the map creation section 22.

Here, by performing pulse compression unit 21 receives the data _{s r (n, h, m} ) reference data _s ref to (n, h, m) convolution integration in time domain, the received data _s r (n, h, m) are pulse-compressed. However, this is only an example, and the pulse compression unit 21 may perform pulse compression of the received data s _r (n, h, m) by the following method.
That is, the pulse compression unit 21 converts each of the received data s _r (n, h, m) and the reference data s _ref (n, h, m) into a signal in the frequency domain.
Next, the pulse compression unit 21 performs a complex multiplication of the frequency domain signal of the received data s _r (n, h, m) and the frequency domain signal of the reference data s _ref (n, h, m), thereby performing chirp. Remove components.
Then, the pulse compression unit 21 converts the complex-multiplied signal into a signal in the time domain, thereby obtaining the reception data s _rfm (n, h, m) after pulse compression.

When receiving the Doppler window function w _dop from the Doppler window function selector 13b, the map creator 22 receives the pulse-compressed received data s _rfm () output from the pulse compressor 21 as shown in the following equation (32). n, h, m) is multiplied by a Doppler window function w _dop .

When the map creating unit 22 receives a notification from the Doppler window function selecting unit 13b not multiplying the Doppler window function w _dop , the reception data s _rfm (n, h) as shown in the following equation (33). , _M ) is not multiplied by the Doppler window function w _dop .

Next, the map creation unit 22 _{converts the} received data s _{rfm, w} (n, h, m) into a frequency domain in the hit direction, as shown in the following equation (34), so that the range Doppler map s _2D Create (n, k, m).

As a method of converting the reception data s _{rfm, w} (n, h, m) into the frequency domain in the hit direction, a method of _{performing a} fast Fourier transform of the reception data s _{rfm, w} (n, h, m) in the hit direction Can be considered.
_Further, a method of _{performing a} discrete Fourier transform on the received data s _{rfm, w} (n, h, m) in the hit direction or a method of _{performing a} chirp z-transform on the received data s _{rfm, w} (n, h, m) in the hit direction can be considered. .
The map creation unit 22 outputs the range Doppler map s _2D (n, k, m) to the target detection unit 23.

Clutter suppressing processor 23a determines, upon receiving from the map generator 22 Range Doppler Maps _{s 2D (n, k, m} ) and range Doppler map _{s 2D (n, k, m} ) with respect to, the direction determination unit 14 By performing the CFAR processing in the set direction, clutter is suppressed.
The clutter suppression processing unit 23a outputs the range Doppler map s _{2D, CFAR} (n, k, m) after the CFAR processing to the peak detection processing unit 23b.

Peak detection processing section 23b clutter suppression processing section 23a from the range Doppler map _{s 2D, CFAR (n, k} , m) receives the, as the detection processing of a plurality of targets, range Doppler map _{s 2D,} CFAR _(n, k , M) is detected.
When detecting a plurality of targets, the peak detection processing unit 23b extracts the respective phases of the plurality of targets and outputs the respective phases to the angle measuring unit 24.

When the angle measurement unit 24 receives the phases of the plurality of targets from the peak detection processing unit 23b, the angle measurement unit 24 measures the plurality of targets by performing angle measurement processing such as a monopulse angle measurement method using the phases of the plurality of targets. Corner.
The angle measurement unit 24 outputs angle measurement values of a plurality of targets to the injection device 100.

Hereinafter, the angle measurement processing of the monopulse angle measurement method by the angle measurement unit 24 will be specifically described.
When performing the angle measurement processing of the monopulse angle measurement method, the angle measurement unit 24 uses the sum signal に shown in the following equation (35) and the difference signal Δ shown in the following equation (36) to The angle error voltage ε shown in the equation (37) is calculated.

In the formula (35) to Formula (37), _{G i} is the i-th target signal in the range Doppler map for the received RF signal of one transmission and reception antennas of the transmitting and receiving antennas 4-1 ~ 4-M. For example, one receiving antenna is, if the transmitting and receiving antenna 4-m, _{G i} is the i-th target signal in the range Doppler map _{s 2D (n, k, m} ).
U _i is the i-th target signal in the range Doppler map for the reception RF signal of another transmission / reception antenna among transmission / reception antennas 4-1 to 4-M. For example, the other one receiving antenna, if the transmitting and receiving antenna _{4- (m + 1), G} i is the i-th target signal in the range Doppler map _{s 2D (n, k, m} + 1).
Ψ is a phase difference between the target signal G _i and the target signal U _i .

The phase difference Ψ is represented by the following equation (38).

In Expression (38), x is a phase center distance between the target signal G _i and the target signal U _i, and θ _i is a target angle.

From Expressions (37) and (38), the target angle θ _i is expressed by Expression (39) below.

Angle measuring unit 24, as angle measurement values of the plurality of targets, using equation (39) calculates an angle theta _i of the plurality of targets.

After calculating the plurality of target angles θ _i , the angle measurement unit 24 calculates the average value θ bar of the plurality of target angles θ _i as shown in the following Expression (40). In the document of the specification, the symbol "-" cannot be attached to the character because of the electronic filing, so that it is represented as "θ bar".

In Equation (40), n _θ is the angle measurement value number of a plurality of targets, and N _θ is the number of angle measurement values of a plurality of targets.

When the angle measurement unit 24 calculates the average value θ bar of the angle measurement values of the plurality of targets, the variance σ _θ ² of the angle measurement values of the plurality of targets is expressed by the following equation (41). .

In addition, the angle measurement unit 24 calculates an average value θ bar of the angle measurement values of the plurality of targets, so that the standard deviation σ _θ of the angle measurement values of the plurality of targets is expressed by the following equation (42). You.

When the angle measurement unit 24 calculates the average value θ bar of the angle measurement values of the plurality of targets, the variance value σ _θ ² is reduced, and the dispersion of the angle measurement values of the plurality of targets is reduced. improves.
The angle measurement unit 24 outputs the average value θ bar of the angle measurement values of the plurality of targets to the injection device 100.
When receiving the average angle measurement value θ bar from the angle measurement unit 24, the injection device 100 calculates, for example, a difference between the average angle measurement value θ bar and the emission angles of a plurality of targets.
Then, the injection device 100 corrects the injection angles of a plurality of targets based on the calculated difference.

In the second embodiment, the radar device is configured to include the angle measuring unit 24 that measures the angle of a plurality of targets from the phase extracted by the target detecting unit 23. Therefore, the radar device according to the second embodiment can measure the angle of the detected target without causing erroneous detection.

In the present invention, any combination of the embodiments, a modification of an arbitrary component of each embodiment, or an omission of any component in each embodiment is possible within the scope of the invention. .

The present invention relates to a target detection device for detecting a target and a radar device.
Further, the present invention is suitable for an angle measuring device that measures an angle of a target.

1} transmission / reception unit, 2 transmission unit, 2a oscillator, 2b pulse modulator, 2c transmitter, 3,3-1 to 3-M transmission / reception switch, 4,4-1 to 4-M transmission / reception antenna, 5 reception unit, 5a Receiver, 5b A / D converter, 6 data storage unit, 10 target detection unit, 11 signal processing condition determination unit, 12 relative value calculation unit, 13 window function selection unit, 13a range window function selection unit, 13b Doppler window function Selection unit, 14 ° direction determination unit, 20 ° signal processing unit, 21 ° pulse compression unit, 22 ° map creation unit, 23 ° target detection unit, 23a２３ clutter suppression processing unit, 23b peak detection processing unit, 24 angle measurement unit, 31 correlation value calculation circuit 32 ° window function selecting circuit, 33 ° direction determining circuit, 34 ° pulse compression circuit, 35 ° map creating circuit, 36 ° target detecting circuit, 37 ° angle measuring circuit, 41 ° Mori, 42 processor, 50 transceiver unit, 60 an angle measuring device, 100 an injection device.

Claims (14)

1. From the received signals of the electromagnetic waves reflected on a plurality of targets, a map creating unit that creates a range Doppler map indicating the distance to the plurality of targets and the Doppler frequency of the plurality of targets,
   Based on the relative distance between the plurality of targets and the relative Doppler frequency between the plurality of targets, a direction determining unit that determines a direction in which to perform a constant false alarm rate process on the range Doppler map,
   By performing a constant false alarm rate process on the range Doppler map created by the map creating unit in the direction determined by the direction determining unit, the clutter included in the range Doppler map is suppressed, and after clutter suppression. And a target detection unit for detecting the plurality of targets from the range Doppler map.
2. The target detection unit,
   If the direction determined by the direction determining unit is the range direction, by performing a constant false alarm rate process on the range Doppler map in the range direction, to suppress clutter included in the range Doppler map,
   If the direction determined by the direction determining unit is the Doppler frequency direction, by performing a constant false alarm rate process on the range Doppler map in the Doppler frequency direction, clutter included in the range Doppler map is suppressed. 2. The target detecting device according to claim 1, wherein:
3. From a plurality of range window functions, select a range window function corresponding to the relative distance, from a plurality of Doppler window functions, a window function selection unit that selects a Doppler window function corresponding to the relative Doppler frequency,
   A pulse compression unit that multiplies the reception signals of the electromagnetic waves reflected by the plurality of targets by a range window function selected by the window function selection unit and performs pulse compression on the reception signals after the range window function multiplication.
   The map generator multiplies the received signal pulse-compressed by the pulse compressor by the Doppler window function selected by the window function selector, and generates the range Doppler map from the received signal after Doppler window function multiplication. The target detecting apparatus according to claim 1, wherein the target is detected.
4. 2. The target according to claim 1, further comprising a relative value calculator that calculates each of the relative distance and the relative Doppler frequency from the injection conditions of the plurality of targets in the injection device that injects the plurality of targets. 3. Detection device.
5. The window function selection unit selects a range window function from among the plurality of range window functions, in which, as the relative distance increases, a main lobe spread in a received signal after the range window function multiplication increases. The target detection device according to claim 1, wherein
6. The window function selector, from among the plurality of Doppler window functions, selects a Doppler window function in which the spread of a main lobe in the received signal after the Doppler window function multiplication increases as the relative Doppler frequency increases. The target detection device according to claim 1, wherein
7. 4. The target detection device according to claim 3, wherein the map creating unit creates the range Doppler map by converting the received signal after the Doppler window function multiplication into a frequency domain in a hit direction.
8. 8. The target detection method according to claim 7, wherein the map creator performs a fast Fourier transform on the received signal after the Doppler window function multiplication in a hit direction to convert the received signal into a frequency domain in a hit direction. apparatus.
9. 8. The target detection method according to claim 7, wherein the map generator converts the received signal after the Doppler window function multiplication into a frequency domain in a hit direction by performing a discrete Fourier transform in a hit direction. apparatus.
10. 8. The target detection method according to claim 7, wherein the map generator converts the received signal after the Doppler window function multiplication into a frequency domain in a hit direction by chirp-z transforming the received signal in a hit direction. apparatus.
11. From the received signals of the electromagnetic waves reflected on a plurality of targets, a map creating unit that creates a range Doppler map indicating the distance to the plurality of targets and the Doppler frequency of the plurality of targets,
    Based on the relative distance between the plurality of targets and the relative Doppler frequency between the plurality of targets, a direction determining unit that determines a direction in which to perform a constant false alarm rate process on the range Doppler map,
    By performing a constant false alarm rate process on the range Doppler map created by the map creating unit in the direction determined by the direction determining unit, the clutter included in the range Doppler map is suppressed, and after clutter suppression. From the range Doppler map, a target detection unit that detects the plurality of targets and extracts a phase of each of the plurality of targets,
    An angle measurement unit that measures the plurality of targets from the phase extracted by the target detection unit.
12. The angle measurement device according to claim 11, wherein the angle measurement unit calculates an average value of the angle measurement values of the plurality of targets.
13. After radiating the electromagnetic wave toward a plurality of targets, receiving the electromagnetic wave reflected and returned to the plurality of targets, a transmitting and receiving unit that outputs a reception signal of the electromagnetic wave,
    From the received signal output from the transmitting and receiving unit, a map creating unit that creates a range Doppler map indicating the distance to the plurality of targets and the Doppler frequency of the plurality of targets,
    Based on the relative distance between the plurality of targets and the relative Doppler frequency between the plurality of targets, a direction determining unit that determines a direction in which to perform a constant false alarm rate process on the range Doppler map,
    By performing a constant false alarm rate process on the range Doppler map created by the map creating unit in the direction determined by the direction determining unit, the clutter included in the range Doppler map is suppressed, and after clutter suppression. A target detection unit configured to detect the plurality of targets from the range Doppler map.
14. The target detection unit extracts a phase of each of the plurality of targets,
    14. The radar device according to claim 13, further comprising an angle measuring unit that measures the angles of the plurality of targets from the phase extracted by the target detecting unit.

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