JP2021067461A - Radar device and radar signal processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar device capable of detecting at a high frame rate. A radar device includes an antenna that receives a reflected wave of a radar signal from a target, a reception processing circuit that generates a beat signal using the reflected wave, an AD conversion circuit that generates a sampling signal of the beat signal, and sampling. The signal is divided into a plurality of time regions, the peak-to-peak value of the sampling signal is calculated for each of the plurality of time regions, and the sample timing that is equal to or higher than a predetermined value is extracted from the peak-to-peak values. , Apply the interference processing circuit that generates the control signal used for the interference processing of the sampling signal based on the extracted sample timing, and the processing to obtain the beat frequency and Doppler shift frequency for the sampling signal using the control signal. Includes a frequency peak detection circuit that produces information about the relative distance and relative speed of the target. [Selection diagram] Fig. 2

Description

The present disclosure relates to a radar device and a radar signal processing method.

In recent years, studies on radar devices using microwaves, millimeter waves, etc., which can obtain high resolution, have been progressing. Examples of the application destination of the radar device include a safe driving support system for a vehicle or an automatic driving system. As the market for these technologies expands, the number of vehicles equipped with radar devices is increasing, so it is highly possible that multiple radar devices with overlapping detection areas exist in the same environment.

Here, when another radar device having the same operating frequency band as the radar device exists in the overlapping detection area, interference occurs between the radar device and the other radar device. The occurrence of interference causes deterioration of radar detection performance such as false detection or non-detection in signal processing of the receiving unit of the radar device.

Here, as a method of suppressing interference, an interference signal is detected by comparing the beat signal and the threshold value using a threshold value set based on the average amplitude calculated from the beat signal which is the difference between the received signal and the transmitted signal. A method of generating a beat signal in which the influence of interference is suppressed has been proposed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2019-100956

The radar device calculates the absolute value of the beat signal, which is a complex signal, in order to obtain the average amplitude of the beat signal. However, since the amount of calculation is large, consideration as an in-vehicle radar device that requires detection at a high frame rate is considered. It was inadequate.

Non-limiting examples of the present disclosure contribute to the provision of a radar device and a radar signal processing method capable of supporting detection at a high frame rate.

The radar device according to an embodiment of the present disclosure generates an antenna that receives a reflected wave of a radar signal from a target, a reception processing circuit that generates a beat signal using the reflected wave, and a sampling signal of the beat signal. The AD conversion circuit and the sampling signal are divided into a plurality of time regions, the peak-to-peak value of the sampling signal is calculated for each of the plurality of time regions, and a predetermined value among the peak-to-peak values is calculated. An interference processing circuit that extracts sample timings having the above values and generates a control signal used for interference processing of the sampling signal based on the extracted sample timing, and the control signal are used for the sampling signal. It includes a frequency peak detection circuit that applies processing for obtaining the beat frequency and the Doppler shift frequency and generates information on the relative distance and relative speed of the target.

It should be noted that these comprehensive or specific embodiments may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium, and any of the systems, devices, methods, integrated circuits, computer programs, and recording media. It may be realized by various combinations.

According to one embodiment of the present disclosure, it is possible to provide a radar device capable of detecting interference at a high frame rate.

Further advantages and effects in one embodiment of the present disclosure will be apparent from the specification and drawings. Such advantages and / or effects are provided by some embodiments and features described in the specification and drawings, respectively, but not all need to be provided in order to obtain one or more identical features. There is no.

The figure which shows an example of the interference wave signal which concerns on Embodiment 1. The figure which shows an example of the structure of the radar apparatus which concerns on Embodiment 1. The figure which shows an example of the interference detection processing which concerns on Embodiment 1. A flowchart showing an example of the interference detection process according to the first embodiment. The figure which shows an example of the structure of the received signal processing part which concerns on Embodiment 1. The figure which shows an example of the output which SF adjustment is not applied in the CFAR part which concerns on Embodiment 1. The figure which shows an example of the output which SF adjustment has been applied in the CFAR part which concerns on Embodiment 1. The figure which shows another example of the interference detection processing which concerns on Embodiment 1. A flowchart showing another example of the interference detection process according to the first embodiment. A flowchart showing another example of the interference detection process according to the first embodiment. The figure which shows an example of the structure of the received signal processing part which concerns on Embodiment 2. The figure which shows an example of the interference removal processing which concerns on Embodiment 2. The figure which shows an example of the output of the Doppler analysis part which concerns on Embodiment 2. The figure which shows another example of the structure of the interference processing part which concerns on Embodiment 2. The figure which shows an example of the structure of the received signal processing part which concerns on Embodiment 3. The figure which shows an example of the structure of the radar apparatus which concerns on Embodiment 4.

(Radar device using FMCW method)
First, a radar device using a frequency modulation continuous wave (FMCW) method will be described. In the FMCW method, the beat signal, which is the difference between the received signal and the transmitted signal, is analyzed in order to calculate the distance to the target object or the relative velocity between the target object and the radar device. When there is an interference source radar device in which the radar device and the detection area overlap, and the frequency bands used by the radar device and the interference source radar device overlap, the radar device uses the transmitted wave of the interference source radar device as a received signal for the radar device. Therefore, there is a possibility that spike noise may occur in the beat signal generated by using the received signal.

FIG. 1 is a diagram showing an example of an interference wave signal according to the present embodiment. FIG. 1 shows an interference signal by an interference source radar device in which the frequency change of the transmission signal with time is slower than that of the radar device. The horizontal axis shows time and the vertical axis shows the frequency of each wave.

In Figure 1, the chirp signal is transmitted every transmission cycle T _r: indicates (dashed radar transmission wave) radar apparatus, during each transmission cycle T _r, repeated chirp signals increases the frequency with a constant slope Output. # m and # m + 1 indicate the chirp number.

The frame period is the time obtained by multiplying the number of times the chirp signal is repeatedly transmitted in one frame by the transmission period T _r and adding the processing time of all the data included in one frame. The frame rate is the reciprocal of the frame period. Therefore, the radar device can shorten the frame period and support a high frame rate by shortening the data processing time.

In FIG. 1, in each transmission cycle, a radar transmission wave transmitted from the radar device and a signal received by the radar transmission wave transmitted by the radar device reflected by the object to be measured (solid line: radar reflected wave reception signal). , Interference signals (single-point chain lines) that come directly from the interference source radar are mixed, and points where frequencies overlap occur in each transmission cycle.

The radar device uses a low-pass filter to remove high-frequency signals other than the desired signal included in the signal from the beat signal generated by the frequency difference (beat frequency) between the radar transmission wave and the radar reflected wave reception signal. To apply. The low-pass filter can remove signals included in the interference signal of FIG. 1 whose frequency difference from the transmission frequency of the radar device is larger than a predetermined threshold value determined by the low-pass filter, but the frequency is the radar reflected wave. Since it is difficult to remove the signal near the point where it overlaps with the received signal (spike noise generation point), the signal near the spike noise generation point including the interference signal is output to the subsequent processing. The spike noise included in the beat signal includes all signals other than the time at which the radar reflected wave reception signal and the interference signal intersect and the modulation frequency, and all signals included in the range in which the frequency difference between the two signals is equal to or less than a predetermined value. Because it is generated by, there is a range in terms of time and frequency.

Further, since the interference signal is not a reflected wave, the propagation path is shorter than that of the radar reflected wave reception signal, so that the attenuation is small. Therefore, the radar device receives the interference signal as a signal having a stronger reception intensity than the radar reflected wave reception signal. Therefore, the interference signal of the interference source radar device in which the used frequency bands overlap appears as spike-like noise in the beat signal of the radar device. By applying the Fourier transform to the spike noise contained in the beat signal, the radar device raises the noise floor of the entire frequency domain and deteriorates the detection performance.

Next, an example of a method for suppressing spike noise will be described (see, for example, Patent Document 1). The radar device first detects an interference signal by comparing the beat signal with the threshold value using a threshold value set based on the average amplitude calculated from the beat signal. Next, the radar device multiplies the window function based on the interference detection result to generate a beat signal in which the influence of the interference is suppressed.

However, the radar device calculates the absolute value of the beat signal, which is a complex signal, in the interference detection process. Since the calculation of the absolute value of the complex signal includes the square of the real part, the square of the imaginary part, the addition, and the calculation of the square root, the amount of calculation increases. Therefore, it is difficult to shorten the frame period of a radar device using the absolute value of the beat signal, and it is difficult to apply it to an in-vehicle radar device that requires detection at a high frame rate.

<Embodiment 1>
According to one aspect of the present disclosure, the amount of interference generated in each time-divided region of the beat signal is calculated, and the scaling factor (hereinafter referred to as SF) in CFAR (Constant False Alerm Rate) processing is adjusted. As a result, it is possible to suppress an increase in the amount of calculation, so that a radar device that supports a high frame rate and can be mounted on a vehicle, for example, is provided.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiment, the same components are designated by the same reference numerals, and the description thereof will be duplicated and will be omitted. The embodiments described below are examples, and the present disclosure is not limited to the following embodiments.

[Radar device configuration]
FIG. 2 is a diagram showing an example of the configuration of the radar device 1 according to the present embodiment. The radar device 1 employs a radar system in which a frequency-modulated Chirp signal is used as a radar transmission signal. In FIG. 2, a method (FCM: Fast chirp modulation) in which a chirp signal is repeatedly transmitted is used.

The radar device 1 of FIG. 2 includes a radar transmitting unit 2 and a radar receiving unit 3. The radar transmission unit 2 includes a radar transmission signal generation unit 102 and a transmission antenna 101. The radar receiving unit 3 includes a receiving antenna 105, a receiving radio unit 106, an AD conversion (Analog-to-digital converter) unit 109, and a received signal processing unit 115. The radar transmission signal generation unit 102 includes a modulation signal generation unit 104 and a voltage controlled oscillator (VCO) 103. The reception signal processing unit 115 includes an interference processing unit 111 and a frequency peak detection unit 110. The frequency peak detection unit 110 includes a beat frequency analysis unit 112, a Doppler analysis unit 113, and a CFAR unit 114.

_{First, the modulation signal generation unit 104 periodically (transmission cycle Tr} ) generates a sawtooth modulation signal (chirp signal) used for controlling the VCO 103. The modulated signal of the sawtooth wave corresponds to the radar transmission wave of FIG.

The VCO 103 generates a radar transmission wave as shown in FIG. 1 based on the output of the modulation signal generation unit 104, and outputs the radar transmission wave to the reception radio unit 106.

Although not shown, the amplifier amplifies the input signal from the radar transmission signal generation unit 102 and outputs it to the transmission antenna 101. The transmitting antenna 101 emits a signal amplified by an amplifier (not shown) into space as a radio wave.

The receiving antenna 105 receives a signal (corresponding to the radar reflected wave reception signal of FIG. 1) in which the radar transmitted wave transmitted from the transmitting antenna 101 is reflected from a reflecting object including the radar measurement target. The signal received by the receiving antenna 105 is amplified by an amplifier (not shown) and then output to the receiving radio unit 106.

Here, the receiving radio unit 106 includes a mixer unit 107 and a low-pass filter (LPF) unit 108. The mixer unit 107 mixes the received signal received by the receiving antenna 105 with the transmitted chirp signal. Further, the LPF unit 108 outputs a beat signal having a frequency corresponding to the delay time of the reflected wave by passing a frequency lower than a predetermined cutoff frequency. The beat signal is a signal including the frequency of the transmission chirp signal and the beat frequency of the reception chirp signal as shown in FIG.

The AD conversion unit 109 converts the beat signal in the mth chirp signal into discrete sampling data d (m, n) that is discretely sampled. Here, m = 1, ..., N C, n = 1, ..., a N _S, m, n are each, also described as an index (sample timing). N _C is the number of chirps contained in one frame, and N _S is the number of AD samples per transmission cycle. The AD conversion unit 109 outputs a real number as sampling data when the mixer unit 107 is a real number mixer, and describes it as an in-phase component (hereinafter referred to as an I signal) when the mixer unit 107 is a quadrature mixer. ) And the quadrature component (hereinafter referred to as Q signal). In this embodiment, an orthogonal mixer will be used for description.

By applying the FFT process to the beat signal d (m, n), the beat frequency analysis unit 112 outputs a frequency spectrum in which a peak appears at the beat frequency according to the delay time of the radar reflected wave. The beat frequency analysis unit 112 may multiply a window function coefficient such as a Han window or a Hamming window during FFT processing. By applying the window function, the side lobes generated around the beat frequency peak can be suppressed.

_{The beat frequency analysis unit 112 outputs the beat frequency response RFT (m, f s} ) specified by the equation (1) from the beat signal obtained by transmitting the mth chirp signal. Here, f _s represents the beat frequency index and corresponds to the FFT index number. Note that f _s = 0, ..., N _S. The smaller the beat frequency index f _s , the smaller the delay time of the radar reflected wave reception signal, that is, the closer the distance from the target to the beat frequency. Incidentally, m = 1, ..., a N _C.

Since the beat frequency index f _{s can be converted into the distance information R (f s} ) using the equation (2), the beat frequency index f _s will be referred to as the distance index f _{s below.} Where Bw is the frequency modulation bandwidth within the range gate of the chirp signal. C ₀ represents the speed of light. The CFAR unit 114 in the latter stage calculates _{the relative position R (f s} ) between the radar device 1 and the target using _{the f s} corresponding to the index of the detected peak signal using the equation (2). it can.

The Doppler analysis unit 113 analyzes the beat frequency response RFT (f _b , m) obtained by the beat frequency analysis unit 112, and outputs speed information. The phase shift of each chirp signal of RFT _z (m, f _s ) is proportional to the speed of the target. _{The Doppler analysis unit 113 obtains the Doppler shift frequency VFT (f c} , f _s ) by applying the equation (3) to all the chirp signals in one frame by using the phase shift for each chirp signal. Where f _c is the Doppler shift frequency index. In the following, the Doppler frequency index f _c will be referred to as the velocity index f _c.

_{The CFAR unit 114 in the subsequent stage uses f c} corresponding to the index of the detected peak signal to calculate the relative velocity V between the radar device 1 and the target from the Doppler shift frequency VFT (f _c , f _s). (F _c ) is calculated using Eq. (4). Here, f _carrier is the carrier frequency.

The interference processing unit 111 includes at least an interference detection unit 301 that detects the occurrence of interference from the IQ signal of the beat signal, for example.

The interference detection unit 301 applies the interference detection process to the mth chirp signal of the discrete sampling data d (m, n) input from the AD conversion unit 109. FIG. 3 is a diagram illustrating an example of the interference detection process according to the present embodiment. FIG. 4 is a flowchart illustrating an example of the interference detection process according to the present embodiment.

FIG. 3 shows the I signal of the 0th chirp (m = 0) of the discrete sampling data d (m, n). In FIG. 3, the horizontal axis represents n (n = 0, ..., 255) (that is, N _S = 255), and the time division number N _AD is 7. The interference detection unit 301 obtains a peak-to-peak (PP) value by calculating the difference between the maximum value and the minimum value for each region divided into seven. The number of time divisions N _AD may be other than 7, and should be set in the range of 3 to 4 to 10.

First, the interference detection unit 301, the I signal of the input discrete sampled data d (m, n), n = 1, ..., dividing the time range represented by N _S in N _AD number, divided Each of the subsequent regions is represented as # 1, ..., #N _AD (step S501). The interference detection unit 301 obtains the maximum value I _{max # i} and the minimum value I _{min # i} for the signal I # i in the region #i (i = 1, ..., N _AD ) (in other words, detects). (Step S502), the PP value I _{pp # i} (= I _{max # i --I min # i} ) is calculated (step S503). If the calculation of the PP value for all the regions is not completed (No in step S504), the interference detection unit 301 moves to the next region # i + 1 (step S505).

After the calculation of the PP value for the entire region is completed (Yes in step S504), the interference detection unit 301 sets _{the minimum PP value from the N AD} PP values to the reference PP value I _{pp # Ref} (step S506). , The maximum PP value is set to the determination target PP value I _{pp # Target} (step S507). For example, in FIG. 3, the determination target PP value I _{pp # Target} is the region # 5, and the reference PP value I _{pp # Ref} is the region # 7. The reference PP value, median N _AD pieces of PP value, or may be set to PP values located x-th in the result of the sort on the basis of the N _AD pieces of PP value magnitude. x is any natural number less than or equal to _{N AD.}

Next, the interference detection unit 301 performs an interference determination (in other words, a PP determination) (step S508). The interference determination is performed by the equation (5) using the _{reference PP value I pp # Ref} and the determination target PP value I _{pp # Target.} Here, SF _pp is a scaling factor that is multiplied by the reference PP value I _{pp # Ref} , and is a parameter that adjusts the interference detection performance. When the interference detection unit 301 satisfies the equation (5), the interference detection unit 301 determines _{that the region #Target for which the determination target PP value I pp} #Target is calculated is the region including the interference. It is desirable to set SF _pp as a value of about 1.8 to 3.

Interference detecting unit 301, the total chirp signals (e.g., N _C number) with respect to, when the interference detection process is completed, and the flow ends (Yes in step S509), the total chirp signal, interference detection If is not completed (No in step S509), interference detection processing is performed on the next chirp signal m + 1 (step S510).

The interference detection unit 301 _{may change the SF pp} from the initial setting value. For example, when SF _pp is large, the number of cases where equation (5) is not satisfied with weak spike noise increases, and the interference detection performance deteriorates, but the desired signal due to reflection from the original target is considered to be interference. It has the advantage of less false detection. On the other hand, when the SF _pp is small, the interference detection unit 301 satisfies the equation (5) even with weak spike noise, so that the interference detection performance can be expected to be improved, but there is a possibility that the desired signal is erroneously detected as an interference signal. is there.

Here, the process related to the interference detection of Patent Document 1 uses the calculation of the absolute value of the complex signal. Therefore, the interference detection unit 301 of the present embodiment, which does not use the calculation of the absolute value, requires a smaller amount of calculation than the processing in the interference detection of Patent Document 1.

For example, the processing of the interference detection unit 301 of the present embodiment that does not use the calculation of the absolute value, which takes from the input of the AD data (for one chirp signal) of the beat signal to the detection of the sample index where the interference occurs. The time can be shortened to about 1/5 of the processing time related to the interference detection of Patent Document 1 using the calculation of the absolute value.

Further, in the process related to the interference detection of Patent Document 1, the spike noise detection threshold value is set by using the average value of the discrete sampling data (beat signal) including the spike noise. Therefore, when the number of spike noises included in the beat signal is large, or when the power of the spike noise is large, the influence of the spike noise on the calculation of the average value of the beat signal becomes large, and the detection threshold value is set when the parameter is set. If it becomes larger than expected, the performance of spike noise detection may deteriorate.

On the other hand, in the present embodiment, interference detection is performed by the equation (5) with the determination target PP value, the reference PP value, and the design parameter SF _PP. Here, since the spike noise is included in a limited time region smaller than the divided region for calculating the PP value of the beat signal, the determination target PP value is a value for evaluating the amplitude of the region containing the spike noise, and is a reference PP value. Is a value for evaluating the amplitude of the desired signal due to reflection from the target. The determination target PP value and the reference PP value are calculated using the maximum value and the minimum value in the divided region of the beat signal, and the sampling data other than the maximum value and the minimum value in the divided region is not used for the interference detection process.

Therefore, in the present embodiment, when the number of occurrences of spike noise included in the divided region of the beat signal is large, it is possible to eliminate the influence of data other than the spike noise having the maximum value on the interference determination process. .. Further, when the beat signal contains spike noise of a large power, in the present embodiment, the detection threshold value shown on the right side of the equation (5) is a fixed value SF _PP that does not depend on the beat signal and an evaluation value of the amplitude of the desired signal. Since it is set as the product of a certain reference PP value, it is not affected by the magnitude of spike noise in the calculation of the detection threshold value, so that deterioration of spike noise detection performance can be suppressed. From the above, in the present embodiment, even for a beat signal in which spike noise is generated frequently in the divided region of the beat signal or the power of spike noise is large, interference is detected without deteriorating the performance. Can be done.

When interference is detected, the interference processing unit 111 can adjust the scaling factor (hereinafter referred to as SF) of the CFAR unit 114 in the subsequent stage to suppress erroneous detection in the CFAR unit 114. , The detected interference itself can also be removed. In the present embodiment, suppression of erroneous detection in the CFAR unit 114 will be described.

FIG. 5 is a diagram showing an example of the configuration of the received signal processing unit 115a according to the present embodiment. An example in which the interference processing unit 111a includes an interference detection unit 301, an interference amount calculation unit 302, and a CFAR-SF adjustment unit 303 will be described. With the configuration of FIG. 5, the SF of the CFAR unit 114 in the frequency peak detection unit 110a can be adjusted according to the presence or absence of interference. Therefore, the CFAR unit 114 sets a large SF value when the amount of interference is large. By doing so, it is possible to reduce the detection of peaks at relatively small levels and suppress false detection of the target.

The interference amount calculation unit 302 calculates the amount of interference that occurs for each frame. For example, the interference amount calculation unit 302, the interference detecting unit 301 with respect to N _C-number of chirp signals included in one frame counts the number of chirp signal it is determined that there is interference. Since each chirp signal includes N _S indexes, the interference amount calculation unit 302 calculates the interference amount Q in _f using (the number of chirp signals determined to have interference) / N _C × N _S. .. As a result, the interference amount calculation unit 302 can suppress an increase in the calculation related to the interference amount.

The interference amount calculation unit 302 may calculate the interference amount in consideration of the number of times of interference and the magnitude of the interference that occurs. This is because it is possible to suppress an increase in the noise floor in the frequency domain depending on the strength of spike noise due to the generated interference. At this time, step S508, which is the interference determination process of the interference detection unit 301, can be omitted, and the interference detection unit 301 sets the reference PP value I _{pp # Ref} and the determination target PP value I _{pp # Target} as the interference amount calculation unit in the subsequent stage. Output to 302.

The interference amount calculation unit 302 uses the reference PP value I _{pp # Ref} for each chirp signal calculated by the interference detection unit 301 and the determination target PP value I _{pp # Target} . When the reference PP value I _{pp # Ref} in the mth chirp signal is I _{pp # Ref} (m) and the determination target PP value is I _{pp # Target} (m), the interference amount calculation unit 302 uses the equation ( 6), as shown in the equation (7), the sum of squares of the reference PP value and the determination target PP value in all chirp signals in the frame is calculated. In Patent Document 1, _{it was necessary to calculate the absolute value of the amplitude of N C} × N _S times, but in the present embodiment, the calculation of the sum of squares _{can be performed N C} times, so that the amount of calculation is Reductions can be made.

_{The interference amount calculation unit 302 calculates the frame determination target PP value Target sum} and the frame reference PP value Ref _sum for the entire frame including all chirp signals by the equations (6) and (7). Next, the interference amount calculation unit 302 calculates the interference amount Q in _f by _{taking the ratio of the frame determination target PP value Target sum} and the frame reference PP value Ref _{sum by the equation (8).} The magnitude of the amount of interference value indicates the strength of the interference of the entire frame including the N _C-number of chirp signals.

_{When the interference amount Q inf} is equal to or greater than the threshold value Q _th , the interference amount calculation unit 302 determines that there is interference in the entire frame, and _{sets the SF offset amount OFS SF} to OFS _SF1 (> 0). If the interference amount Q _inf is less than the threshold Q _th , the SF offset amount OFS _{SF is set} to 0. The interference amount calculation unit 302 _{outputs the SF} offset amount OFS SF to the CFAR unit 114.

Incidentally, the interference amount calculation unit 302, in accordance with the interference amount Q _inf, has been how to increase the SF offset OFS _SF, when the interference amount Q _inf is the threshold Q _th or more, the SF offset OFS _SF If it is set to 0 and the interference amount Q _inf is less than the threshold Q _th , the SF offset amount OFS _SF may be OFS _SF1 (<0).

From the above, the interference processing unit 111a can reduce the erroneous detection by adjusting the SF in the CFAR unit 114 in an environment where the erroneous detection of the target may increase due to the influence of the interference.

Next, the CFAR unit 114 (for example, FIG. 2 or FIG. 5) will be described. CFAR is one of the peak detection processing methods in the frequency domain, and converts the detected peak into distance information and velocity information and outputs it (also referred to as a peak detection unit).

The CFAR unit 114 can reduce the detection of peaks at relatively small levels by setting a large SF value, and can suppress erroneous detection of the target.

The CFAR unit 114 uses the outputs of the Doppler analysis unit 113 and the CFAR-SF adjustment unit 303 to perform CFAR processing that performs noise floor calculation and threshold calculation on the data of each index m and n, and peak signals in the frequency domain. By extracting the distance index and the velocity index that give the above, the relative distance between the measurement target and the radar installation position and the relative velocity are detected (peak detection).

The CFAR unit 114 includes two-dimensional CFAR processing consisting of a distance axis and a Doppler frequency axis (corresponding to a relative velocity), or one-dimensional CFAR processing using the distance axis and one-dimensional CFAR processing using the Doppler frequency axis. CFAR processing may be performed in combination with.

The CFAR unit 114 uses, for example, a value obtained by adding the _{SF offset amount OFS SF} output from the CFAR-SF adjustment unit 303 to the initial value SF. For CFAR processing that combines two-dimensional CFAR processing or one-dimensional CFAR processing, for example, the processing disclosed in Reference 1 can be applied (Reference 1 M. Kronauge, H. Rohling, "Fast two". -dimensional CFAR procedure ", IEEE Trans. Aerosp. Electron. Syst., 2013, 49, (3), pp. 1817-1823).

FIG. 6A is a diagram showing an example of an output to which SF adjustment is not applied in the CFAR unit 114 according to the present embodiment. FIG. 6B is a diagram showing an example of an output to which SF adjustment has been applied in the CFAR unit 114 according to the present embodiment.

In FIGS. 6A and 6B, as an example of the output of the CFAR unit 114, the radar installation position is set to the origin (x, y) = (0, 0), and the position of (x, y) = (10, 0) [m]. Indicates the detected target coordinates when there is an object to be measured equipped with the radar device 1 as an interference source. Since FIGS. 6A and 6B are measurement results by the radar device 1 having a configuration provided with a plurality of antennas, the direction estimation process is performed in addition to the distance information output from the CFAR unit 114, and the coordinates are shown as two-dimensional coordinates. There is.

FIG. 6A shows the target coordinates detected without applying the SF adjustment and without changing the preset SF, and FIG. 6B shows the SF in the CFAR unit 114 as compared with FIG. 6A by applying the SF adjustment. It is the target coordinate detected by enlarging it.

In FIG. 6A, the radar device 1 outputs a detection point with the x-coordinate from about 0 m to about 100 m and the y-coordinate from about -5 m to about 20 m. On the other hand, in FIG. 6B, the radar device 1 has a group in which the x-coordinate is about 0 m to about 30 m and the y-coordinate is about -5 m to about 5 m, and the x-coordinate is about 80 m and the y-coordinate is about 10 m. The detection point is output in the group. That is, in the radar device 1, the false detection point generated in the shower shape could be suppressed by the SF adjustment in the CFAR unit 114. For example, the radar device 1 removes 85% of false positive points when the interference source is located 10 m from the radar installation position.

The radar device 1 according to the present embodiment can avoid the calculation of the absolute value of the complex signal, suppress the performance deterioration depending on the number of occurrences of the spike noise and the magnitude of the spike noise, detect the interference, and can detect the interference. The effect of suppressing false positives can be obtained by adjusting the SF of.

(Modification example 1 of interference detection)
Next, a modification 1 of the interference detection process will be described. FIG. 7 is a diagram illustrating another example of the interference detection process according to the present embodiment. FIG. 8 is a flowchart illustrating another example of the interference detection process according to the present embodiment.

When the DC offset is within a predetermined range between the I signal and the Q signal, the interference detector 301 calculates a single PP value from both the I signal and the Q signal data in the same time domain. May be good.

FIG. 7 shows the I signal (solid line) and the Q signal (dashed line) of the 0th chirp (m = 0) of the discrete sampling data d (m, n). For example, in region # 1, the maximum value I _{max # 1} is the value of the I signal, and the minimum value I _{min # 1} is the value of the Q signal. Since the other processes are the same as those in FIG. 4, the description thereof will be omitted.

First, the interference detection unit 301, the I signal of the input discrete sampled data d (m, n), n = 1, ..., dividing the time range represented by N _S in N _AD number, divided Each of the subsequent regions is represented as # 1, ..., #N _AD (step S701). _{The interference detection unit 301 obtains the maximum IQ max # i} and the minimum IQ _{min # i} for the signal IQ # i in the region #i (i = 1, ..., N _AD ) (in other words, detects). (Step S702), the PP value IQ _{pp # i} (= IQ _{max # i} --IQ _{min # i} ) is calculated (step S703). If the calculation of the PP value for all the regions is not completed (No in step S704), the interference detection unit 301 moves to the next region # i + 1 (step S705).

After the calculation of the PP values for all regions is completed (Yes in step S704), the interference detection unit 301 sets _{the minimum PP value from the N AD} PP values to the reference PP value IQ _{pp # Ref} (step S706). , The maximum PP value is set in the determination target PP value IQ _{pp # Target} (step S707). For example, in FIG. 7, the determination target PP value IQ _{pp # Target} is the region # 5, and the reference PP value IQ _{pp # Ref} is the region # 7.

Next, the interference detection unit 301 performs an interference determination (in other words, a PP determination) (step S708). The interference determination is performed by the equation (10) using the _{reference PP value IQ pp # Ref} and the determination target PP value IQ _{pp # Target.} Here, SF _pp is a scaling factor that is multiplied by the reference PP value IQ _{pp # Ref} , and is a parameter that adjusts the interference detection performance. When the interference detection unit 301 satisfies the equation (10), the interference detection unit 301 determines _{that the region #Target for which the determination target PP value IQ pp # Target} is calculated is the region including the interference.

Interference detecting unit 301, the total chirp signals (e.g., N _C number) with respect to, when the interference detection process is completed, and the flow ends (Yes in step S709), the total chirp signal, interference detection If is not completed (No in step S709), interference detection processing is performed on the next chirp signal m + 1 (step S710).

The radar device 1 in the form of the modification 1 of the interference detection can suppress undetection when the spike noise power of either the I signal or the Q signal is relatively small. _{In addition, I pp # Ref} becomes an undervalue when the time-divided region is smaller than the region for one transmission cycle of the low-frequency signal by the interference judgment considering the two signals that are out of phase. False detection of spike noise can be suppressed.

(Modification example 2 of interference detection)
Next, a modification 2 of the interference detection process will be described. FIG. 9 is a flowchart illustrating another example of the interference detection process according to the present embodiment. In FIG. 9, the radar device 1 merges the interference detection results of the I signal and the Q signal to perform the interference detection process. In FIG. 9, the interference detection unit 301 refers to the Q signal (step S801) in addition to the I signal of the input discrete sampling data d (m, n) in the flowchart of the interference detection process shown in FIG. Step S502 to S508 are applied (step S802, step S803). The interference detection unit 301 uses the interference determination information of the I signal and the interference determination information of the Q signal to determine that there is interference when any one of them detects interference (step S804).

Interference detecting unit 301, the total chirp signals (e.g., N _C number) with respect to, when the interference detection process is completed, and the flow ends (Yes in step S805), the total chirp signal, interference detection If is not completed (No in step 805), interference detection processing is performed on the next chirp signal m + 1 (step S806).

Since the interference detection process of FIG. 9 processes both the I signal and the Q signal separately, the amount of calculation increases, but it occurs only in the Q signal as compared with the case where the interference detection process is performed only in the I signal. Since it is possible to detect the interference that occurs, it is expected that the interference detection performance will be improved.

In the first modification of interference detection, when the I signal and the Q signal include different levels of DC offset, the P-P value may become an excessive value. On the other hand, in the second modification of the interference detection, the interference detection unit 301 calculates the PP value for each of the I signal and the Q signal. Therefore, when the I signal and the Q signal include DC offsets of different levels, It is expected that the interference detection performance will be improved as compared with the first modification.

(Modification example 1 of the interference amount calculation unit)
Next, a modified example of the interference amount calculation unit 302 will be described. In the present embodiment, the interference detection unit 301 uses _{R max as} the index n that takes the maximum value used when calculating _{the reference PP value I pp # Ref} , and uses it when calculating the determination target PP value I _{pp # Target} . The index n that takes the maximum value is set as _{T max, and R max} and T _max , the reference PP value I _{pp # Ref,} and the determination target PP value I _{pp # Target} are output to the interference amount calculation unit 302.

The interference amount calculation unit 302 weights the reference PP value and the determination target PP value by the window function w when calculating the sum of squares. The window function w _Tmax or w _Rmax is a window function when the FFT is applied in the beat frequency analysis unit 112, and the subscript indicates the index. _{The interference amount calculation unit 302 calculates the interference amount Q inf} by the equation (8) after calculating the equations (11) and (12).

Since the radar apparatus 1 according to this embodiment can calculate the amount of interference in consideration of the multiplication of the window function in the beat frequency analysis unit 112, T _max is 0, or, in the case of close into N _S value, interference It is possible to suppress the undetection in the CFAR unit 114 that occurs when the amount is overestimated.

(Modification example of CFAR-SF adjustment part)
Next, a modification of the CFAR-SF adjustment unit 303 will be described. The CFAR-SF adjustment unit 303 receives the interference amount frame determination target PP value Target _sum and the frame reference PP value Ref _sum calculated by the interference amount calculation unit 302 as inputs, and inputs the SF offset amount OFS _SF to the CFAR unit 114. Output.

SF offset amount OFS _SF is calculated by Eq. (13). _{Here, PL 1, PL 2, ...} , PL k and _{OFS PL1, OFS PL2, ...,} OFS PLk is a design parameter. The CFAR-SF adjustment unit 303 sets the value _{obtained by multiplying the reference PP value Ref sum} by PL ₁ , PL ₂ , ..., PL k as the threshold value of Target _sum , and steps according to the value of _{Target sum.} Adjust the value of OFS _{SF to.}

From the above, according to the first embodiment, the beat signal can be divided into a plurality of time domains, interference detection processing can be performed, and the SF used in the CFAR unit 114 can be appropriately adjusted. Since erroneous detection can be suppressed, a radar device 1 corresponding to a high frame rate can be obtained.

<Embodiment 2>
According to one embodiment of the present disclosure, it is possible to suppress an increase in the amount of calculation by detecting and removing interference in each time-divided region of the beat signal. Therefore, the radar device 1 corresponding to a high frame rate Is provided.

FIG. 10 is a diagram showing an example of the configuration of the received signal processing unit 115b according to the present embodiment. The interference processing unit 111b includes an interference detecting unit 301b and an interference removing unit 304, and outputs a control signal to the frequency peak detecting unit 110b. Since the beat frequency analysis unit 112, the Doppler analysis unit 113, and the CFAR unit 114 of the frequency peak detection unit 110b are the same as the processing described in the first embodiment, the description thereof is omitted here.

FIG. 11 is a diagram showing an example of the interference removing process according to the present embodiment. When the interference detection unit 301b determines that there is interference by the interference determination process (process using the equation (5)) for the radar reflected wave reception signal (received chirp signal) containing spike noise, it is shown in FIG. 11 (a). As described above, the index of the larger value among the absolute value of the maximum value and the absolute value of the minimum value used in the PP calculation is output as the _{interference peak time n max.}

FIG. 11A shows a beat signal before applying interference removal to a beat signal for a single chirp. The horizontal axis of each figure of FIG. 11 indicates the sampling index in the AD conversion unit 109. FIG. 11A shows a beat signal including spike noise, and the index that is the maximum value of the determination target PP value calculated by the interference detection unit 301b is n _max = 168.

As shown in FIG. 11B, the interference removing unit 304 uses the interference peak time n _max = 168 output from the interference detecting unit 301b, and the closer the interference peak time is, the closer the value is to 0, and the interference peak. Generates an anti-interference window function whose value approaches 1 as the time goes by.

FIG. 11B shows _{a window function centered on n max} = 168, and here, a Blackman-Harris window is used as an example. The window function can be used for other than the Blackman-Harris window.

Further, the interference removing unit 304 generates a beat signal from which interference has been removed, as shown in FIG. 11 (c), by multiplying the interference removing window function and the beat signal. As a result, the radar device 1 can reduce the influence of spike noise on the post-stage processing and suppress erroneous detection.

FIG. 11 (c) is the result of multiplying the data of FIGS. 11 (a) and 11 (b), and suppresses the value of spike noise around _{n max seen in FIG. 11 (a).} I understand.

FIG. 12 is a diagram showing an example of the output of the Doppler analysis unit 113 according to the present embodiment, the horizontal axis represents the distance index, and the vertical axis represents the electric power at each index in decibel units.

FIG. 12A shows the output when processing by the beat frequency analysis unit 112 and the Doppler analysis unit 113 is applied to the beat signal including spike noise, and FIG. 12B shows the output when the interference elimination unit 304 applies the processing. This is the output when the same processing is applied to the beat signal from which spike noise has been removed.

In FIG. 12 (a) where the interference removing unit 304 is not applied, the noise floor is 79.54 dB, whereas in FIG. 12 (b) where the interference removing unit 304 is applied, the noise floor is reduced by 8.67 dB. , 70.87 dB. In order to avoid including the signal due to the reflection from the object in the noise floor calculation, the data whose Range Index is 70 or more and less than 230 is used when calculating the noise floor.

Based on the above, according to the second embodiment, the beat signal is divided into a plurality of time domains to perform interference detection processing, and the detected interference is removed in each time domain to suppress an increase in the amount of calculation. Further, since the noise floor of the beat signal output from the Doppler analysis unit 113 can be reduced, the radar device 1 corresponding to a high frame rate can be obtained.

(Modification example 1 of the interference processing unit)
A modified example of the interference processing unit 111b will be described. The interference processing unit 111d repeatedly performs the processing of the interference detecting unit 301b and the interference removing unit 304 in the interference processing unit 111b. FIG. 13 is a diagram showing another example of the configuration of the interference processing unit 111d according to the present embodiment. Since the processing in each block of the frequency peak detection unit 110b is the same as that in the second embodiment, the description here will be omitted.

First, the interference detection unit 301d divides the input discrete sampling data d (m, n) _{into N AD} time domains, obtains a PP value for each region, and obtains the maximum PP value. Obtained as the judgment target PP value I _{pp # Target.}

The interference detection unit 301d determines _{whether or not there is interference with respect to the determination target PP value I pp # Target} using the equation (5), and if there is interference, outputs the determination result to the interference removal unit 304d. If there is no interference, the discrete sampling data d (m, n) is output to the frequency peak detection unit 110b in the subsequent stage.

Next, the interference removing unit 304d removes the interference by using, for example, the processing described in the second embodiment, and outputs the processed beat signal to the interference detecting unit 301d again.

Next, the interference detection unit 301d again performs interference detection processing using the P-P value on the beat signal from which the interference input from the interference elimination unit 304d has been removed, and determines the presence or absence of interference. When there is interference, the interference detection unit 301d outputs the determination result and the beat signal whose interference has been removed once to the interference removal unit 304d, and when there is no interference, the beat signal whose interference has been removed once is output to the frequency peak in the subsequent stage. Output to the detection unit 110b.

By performing the above loop processing, the interference processing unit 111d performs interference removal processing on _{all the determination target PP values I pp # Target satisfying the equation (5).}

As a result, when spike noise due to interference is included in a plurality of time domains in the time domain division process of the interference detection unit 301d, the interference detection unit 301d detects other than the spike noise in the region where the PP value is maximum, and the PP value. Spike noise contained in the region where is not the maximum can be detected. Further, the interference removing unit 304d can detect and remove all spike noise even when spike noise is included in a plurality of regions by performing interference detection again on the beat signal from which the interference has been removed. ..

<Embodiment 3>
The radar device 1 according to the present embodiment is a radar device 1 having a configuration in which the configuration of the radar device 1 described in the first embodiment and the configuration of the radar device 1 described in the second embodiment are combined.

FIG. 14 is a diagram showing an example of the configuration of the received signal processing unit 115c according to the present embodiment. The main processing of the interference detection unit 301c, the interference amount calculation unit 302, the CFAR-SF adjustment unit 303, the beat frequency analysis unit 112, the Doppler analysis unit 113, and the CFAR unit 114 is the same as in the first embodiment, and interference removal is performed. The main processing of the part 304c is the same as that of the second embodiment.

The interference processing unit 111c according to the present embodiment is implemented by appropriately adjusting the SF used in the CFAR unit 114 according to the interference amount by the interference detection unit 301c, the interference amount calculation unit 302, and the CFAR-SF adjustment unit 303. The false detection in the CFAR unit 114 can be suppressed in the same manner as in the first aspect of the above. Further, the interference processing unit 111c according to the present embodiment reduces the noise floor of the beat signal output from the Doppler analysis unit 113 by the interference detection unit 301c and the interference elimination unit 304c, as in the second embodiment. Can be done.

Therefore, the CFAR unit 114 of the frequency peak detection unit 110c in FIG. 14 performs peak detection processing in the frequency domain on the beat signal with the reduced noise floor by using an appropriately adjusted SF. False detection can be suppressed.

According to the third embodiment, the output of the CFAR-SF adjustment unit 303 divides the beat signal into a plurality of time domains and performs interference detection processing, whereby an increase in the amount of calculation can be suppressed, and CFAR can be suppressed. Since the SF used in the unit 114 can be adjusted as appropriate, erroneous detection can be suppressed. Further, according to the third embodiment, the noise floor of the beat signal output from the Doppler analysis unit 113 can be reduced by removing the detected interference in each time domain by the output of the interference removing unit 304c. Therefore, it is possible to obtain the radar device 1 corresponding to a high frame rate.

<Embodiment 4>
According to one embodiment of the present disclosure, it is possible to suppress an increase in the amount of calculation by detecting and removing interference in each time-divided region of the beat signal. Therefore, MIMO (Multiple) corresponding to a high frame rate can be suppressed. A radar device 1b using -Input Multiple-Output) is provided.

FIG. 15 is a diagram showing an example of the configuration of the radar device 1b according to the present embodiment. The radar transmission unit 2b includes a plurality of transmission antennas 101-1 to N and a radar transmission signal generation unit 102. The radar receiving unit 3b includes a plurality of receiving antennas 105-1 to Na, a plurality of antenna system processing units 4-1 to Na, a CFAR unit 114b, and a direction estimation unit 116. Since the operations other than the CFAR unit 114b and the direction estimation unit 116 are the same as those of the other embodiments, the description thereof is omitted here.

In the radar transmission unit 2b, each of the plurality of transmission antennas 101-1 to N transmits the chirp signal generated by the radar transmission signal generation unit 102. The radar receiving unit 3b receives the plurality of radar reflected waves reflected by the target from the plurality of transmitted chirp signals by the plurality of receiving antennas 105-1 to Na. Each of the plurality of receiving antennas 105-1 to Na is connected to a plurality of antenna system processing units 4-1 to Na. The plurality of antenna system processing units 4-1 to Na include a reception radio unit 106, an AD conversion unit 109, and a reception signal processing unit 115, and are connected to the CFAR unit 114b and the direction estimation unit 116.

The CFAR unit 114b was included in the frequency peak detection unit 110 in the other embodiment, but in the present embodiment, the CFAR unit 114b has a different configuration from the frequency peak detection unit 110, and a plurality of antenna system processing units 4 A signal from -1 to Na is input, and distance information and speed information are output to the direction estimation unit 116.

The direction estimation unit 116 inputs the output signals from the plurality of antenna system processing units 4-1 to Na, the distance information and the speed information from the CFAR unit 114b, and outputs the positioning result of the target. When the distance between the plurality of receiving antennas 105-1 to Na and the target is sufficiently large, the direction estimation unit 116 can regard the observed wave as a plane wave, and therefore, the position between the receiving antennas 105-1 to Na. By detecting the phase difference, the direction of arrival of the reflected wave is calculated.

When the interference processing unit 111 includes the interference detecting unit 301 (or 301b, 301c, 301d) and the interference removing unit 304 (or 304c, 304d), a plurality of interference detecting units 301 included in the interference processing unit 111 may be used. It may be arranged in each of the antenna system processing units 4-1 to Na, or may be arranged in any one of a plurality of antenna system processing units 4-1 to Na. When it can be considered that the distance between the plurality of receiving antennas 105-1 to Na is sufficiently short, the interference peak time at which spike noise occurs in the beat signal can be regarded as the same for all the receiving antennas 105. Therefore, in the interference removing unit 304 arranged in each of the plurality of antenna system processing units 4-1 to Na, the interference detecting unit 301 is arranged in any one of the plurality of antenna system processing units 4-1 to Na. In this case, the interference peak time extracted from one interference detection unit 301 may be input, or when the interference detection unit 301 is arranged in all of the plurality of antenna system processing units 4-1 to Na, any one of them is used. The interference peak time extracted from one interference detection unit 301 may be input.

Further, when the interference detection unit 301 is arranged in two or more antenna system processing units among the plurality of antenna system processing units 4-1 to Na, the interference detection unit 301 may be used in the plurality of antenna system processing units 4-1 to 1. If the difference in the interference peak time in Na is smaller than the predetermined value, it is determined that the beat signal contains interference, the interference peak time in one of the antenna system processing units is selected, and the interference peak time is output to the interference elimination unit 304. Good.

The interference detection unit 301 performs interference determination using a plurality of antennas by the equation (14), which is an inter-antenna spike noise match determination equation, using _{the interference peak time n max output by the interference detection unit 301.} Here, m _{ant 1} and m _{ant 2} indicate a receiving antenna 105-1 and a receiving antenna 105-2. Th _ant is a design parameter.

The interference detection unit 301 may select a different combination from the Na receiving antennas 105. Further, when three or more antenna system processing units 4 are included, the interference detection unit 301 may repeatedly perform the interference determination described above by changing the combination of the receiving antennas 105. Also, the interference detection unit 301, the difference between the interference peak time between antennas of a plurality of systems are the following cases Th _ant, it is determined that the timing of the interfering match.

From the above, according to the fourth embodiment, in addition to the effects of the first to third embodiments, a plurality of transmitting antennas 101-1 to N, a plurality of receiving antennas 105-1 to Na, and a plurality of antenna system processing units 4- By using 1-Na, the CFAR unit 114b, and the direction estimation unit 116, the direction can be estimated, so that a radar device 1b corresponding to a high frame rate can be obtained.

Although various embodiments have been described above with reference to the drawings, it goes without saying that the present disclosure is not limited to such examples. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, which naturally belong to the technical scope of the present disclosure. Understood. In addition, each component in the above embodiment may be arbitrarily combined as long as the purpose of disclosure is not deviated.

In each of the above embodiments, the present disclosure has been described for an example of configuring using hardware, but the present disclosure can also be realized by software in cooperation with hardware.

In the above description, the notation "... part" used for each component is "... circuitry", "... device", "... unit", or "... unit". It may be replaced with other notations such as "module".

Further, each functional block used in the description of each of the above embodiments is typically realized as an LSI which is an integrated circuit. The integrated circuit may control each functional block used in the description of the above embodiment and include an input and an output. These may be individually integrated into one chip, or may be integrated into one chip so as to include a part or all of them. Although it is referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Further, the method of making an integrated circuit is not limited to LSI, and may be realized by using a dedicated circuit or a general-purpose processor. After manufacturing the LSI, a programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor that can reconfigure the connection or setting of the circuit cells inside the LSI may be used.

Furthermore, if an integrated circuit technology that replaces an LSI appears due to advances in semiconductor technology or another technology derived from it, the functional blocks may be integrated using that technology. For example, the application of biotechnology is possible.

(Summary of this disclosure)
The radar device of the present disclosure includes an antenna that receives a reflected wave of a radar signal from a target, a reception processing circuit that generates a beat signal using the reflected wave, and an AD conversion circuit that generates a sampling signal of the beat signal. The sampling signal is divided into a plurality of time regions, and the peak-to-peak value of the sampling signal is calculated for each of the plurality of time regions, and the peak-to-peak value becomes a value equal to or more than a predetermined value among the peak-to-peak values. An interference processing circuit that extracts sample timing and generates a control signal used for interference processing of the sampling signal based on the extracted sample timing, and the beat frequency and Doppler with respect to the sampling signal using the control signal. It includes a frequency peak detection circuit that applies a process for determining the shift frequency and generates information on the relative distance and relative speed of the target.

In the radar device of the present disclosure, the interference processing circuit generates a scaling factor adjusted according to the extracted sample timing as the control signal.

In the radar device of the present disclosure, the frequency peak detection circuit selects the beat frequency and the Doppler frequency with respect to the target by using the scaling factor with respect to the beat frequency and the Doppler shift frequency obtained from the sampling signal.

In the radar device of the present disclosure, the frequency peak detection circuit is a frequency analysis circuit that applies Fourier conversion processing to the sampling signal to generate a beat frequency response, and the radar device for the beat frequency response. Includes a Doppler analysis circuit that calculates the relative position and relative velocity of the target, and a peak detection circuit that selects the relative position and relative velocity of the target from the beat frequency response using the adjusted scaling factor. ..

In the radar device of the present disclosure, the interference processing circuit generates a window function for suppressing interference corresponding to the extracted sample timing as the control signal.

In the radar device of the present disclosure, the frequency peak detection circuit selects the beat frequency and the Doppler frequency related to the target with respect to the beat frequency and the Doppler shift frequency obtained from the sampling signal multiplied by the window function for suppressing the interference. To do.

In the radar device of the present disclosure, the frequency peak detection circuit includes a frequency analysis circuit that applies a Fourier transform process to the sampling signal multiplied by a window function that suppresses the interference to generate a beat frequency response. A Doppler analysis circuit that calculates the relative position and relative speed with respect to the radar device with respect to the beat frequency response, and a peak detection circuit that selects the relative position and the relative speed of the target from the beat frequency response. Including.

In the radar device of the present disclosure, the interference processing circuit generates a scaling factor adjusted according to the extracted sample timing and a subtraction coefficient corresponding to the extracted sample timing as the control signal.

In the radar apparatus of the present disclosure, the frequency peak detection circuit uses the adjusted scaling factor for the beat frequency and the Doppler shift frequency obtained from the sampling signal multiplied by the subtraction coefficient, and beats for the target. Select the frequency and Doppler frequency.

In the radar device of the present disclosure, the frequency peak detection circuit includes a frequency analysis circuit that applies Fourier conversion processing to the sampling signal multiplied by the subtraction coefficient to generate a beat frequency response, and the beat frequency response. On the other hand, the relative position and the relative speed of the target are selected from the beat frequency response by using the Doppler analysis circuit that calculates the relative position and the relative speed with the radar device and the adjusted scaling factor. Includes a peak detection circuit.

In the radar device of the present disclosure, the interference processing circuit generates a scaling factor adjusted according to the number of extracted sample timings as the control signal.

In the radar device of the present disclosure, the interference processing circuit generates a scaling factor adjusted according to the peak-to-peak value of the extracted sample timing as the control signal.

In the radar device of the present disclosure, the antenna includes a plurality of antenna elements, the reception processing circuit includes a plurality of reception processing subcircuits corresponding to each of the plurality of antenna elements, and the AD conversion circuit includes a plurality of reception processing subcircuits. The interference processing circuit includes a plurality of AD conversion subcircuits corresponding to each of the plurality of reception processing subcircuits, and the interference processing circuit includes a plurality of interference processing subcircuits corresponding to each of the plurality of AD conversion subcircuits. The frequency peak detection circuit includes a plurality of frequency peak detection subcircuits corresponding to each of the plurality of interference processing subcircuits, and the plurality of frequency peak detection subcircuits perform a process of obtaining the Doppler shift frequency. It is applied to each of the sampling signals corresponding to the reflected waves received by each of the plurality of antenna elements, and all of the sampling signals corresponding to the reflected waves received by each of the plurality of antenna elements are integrated to obtain the target. Information on the relative distance and relative speed of the target generated by generating information on the relative distance and relative speed and integrating all of the sampling signals corresponding to the reflected waves received by each of the plurality of antenna elements, and information on the relative distance and relative speed of the target. The target is used by each of the plurality of frequency peak detection subcircuits and an output to which a process of obtaining the Doppler shift frequency is applied to each of the sampling signals corresponding to the reflected waves received by each of the plurality of antenna elements. Further includes a direction estimation circuit to which the direction estimation process of is applied.

In the radar apparatus of the present disclosure, the interference processing circuit generates the control signal by using the sample timing extracted in at least one of the interference processing sub-circuits.

In the radar device of the present disclosure, the interference processing circuit determines the consistency of the sample timings extracted in the plurality of interference processing sub-circuits and generates the control signal.

In the radar device of the present disclosure, the predetermined value is set based on the minimum value among the peak-to-peak values in the plurality of time domains.

In the radar signal processing method of the present disclosure, an antenna receives a reflected wave of a radar signal from a target, generates a beat signal using the reflected wave, generates a sampling signal of the beat signal, and receives the sampled signal. , Divide into a plurality of time regions, calculate the peak-to-peak value of the sampling signal for each of the plurality of time regions, and extract the sample timing that is equal to or more than a predetermined value from the peak-to-peak values. A control signal used for interference processing of the sampling signal is generated based on the extracted sample timing, and a process of obtaining a beat frequency and a Doppler shift frequency is applied to the sampling signal using the control signal. Generates information about the relative distance and relative speed of the target.

The present disclosure is suitable as a radar device mounted on a vehicle and a radar signal processing method thereof.

1, 1b Radar device 2, 2b Radar transmitter 3, 3b Radar receiver 4 Antenna system processing unit 101 Transmit antenna 102 Radar transmission signal generator 103 Voltage control oscillator 104 Modulation signal generator 105 Receive antenna 106 Receive radio unit 107 Mixer 108 LPF unit 109 AD conversion unit 110, 110a, 110b, 110c Frequency peak detection unit 111, 111a, 111b, 111c, 111d Interference processing unit 112 Beat frequency analysis unit 113 Doppler analysis unit 114, 114b CFAR unit 115, 115a, 115b, 115c Received signal processing unit 116 Direction estimation unit 301, 301b, 301c, 301d Interference detection unit 302 Interference amount calculation unit 303 CFAR-SF adjustment unit 304, 304c, 304d Interference removal unit

Claims (17)

An antenna that receives the reflected wave of the radar signal from the target, and
A reception processing circuit that generates a beat signal using the reflected wave,
An AD conversion circuit that generates a sampling signal of the beat signal and
The sampling signal is divided into a plurality of time domains, and the peak-to-peak value of the sampling signal is calculated for each of the plurality of time domains, and the peak-to-peak value becomes a value equal to or more than a predetermined value among the peak-to-peak values. An interference processing circuit that extracts sample timing and generates a control signal used for interference processing of the sampling signal based on the extracted sample timing.
A frequency peak detection circuit that uses the control signal to apply processing to obtain the beat frequency and Doppler shift frequency to the sampling signal to generate information on the relative distance and relative velocity of the target.
Including radar equipment. The interference processing circuit generates a scaling factor adjusted according to the extracted sample timing as the control signal.
The radar device according to claim 1. The frequency peak detection circuit is
With respect to the beat frequency and the Doppler shift frequency obtained from the sampling signal, the beat frequency and the Doppler frequency with respect to the target are selected by using the scaling factor.
The radar device according to claim 2. The frequency peak detection circuit is
A frequency analysis circuit that applies a Fourier transform process to the sampled signal to generate a beat frequency response,
A Doppler analysis circuit that calculates the relative position and relative speed of the radar device with respect to the beat frequency response, and
A peak detection circuit that selects the relative position and the relative velocity of the target from the beat frequency response using the adjusted scaling factor.
2. The radar device according to claim 2. The interference processing circuit generates a window function that suppresses interference corresponding to the extracted sample timing as the control signal.
The radar device according to claim 1. The frequency peak detection circuit selects the beat frequency and the Doppler frequency with respect to the target with respect to the beat frequency and the Doppler shift frequency obtained from the sampling signal multiplied by the window function for suppressing the interference.
The radar device according to claim 5. The frequency peak detection circuit is
A frequency analysis circuit that applies a Fourier transform process to the sampled signal multiplied by the window function that suppresses interference to generate a beat frequency response, and
A Doppler analysis circuit that calculates the relative position and relative speed of the radar device with respect to the beat frequency response, and
A peak detection circuit that selects the relative position and the relative velocity of the target from the beat frequency response, and
5. The radar device according to claim 5. The interference processing circuit generates a scaling factor adjusted according to the extracted sample timing and a subtraction coefficient corresponding to the extracted sample timing as the control signal.
The radar device according to claim 1. The frequency peak detection circuit is
With respect to the beat frequency and the Doppler shift frequency obtained from the sampling signal multiplied by the subtraction coefficient, the beat frequency and the Doppler frequency with respect to the target are selected by using the adjusted scaling factor.
The radar device according to claim 8. The frequency peak detection circuit is
A frequency analysis circuit that applies a Fourier transform process to the sampling signal multiplied by the subtraction coefficient to generate a beat frequency response, and
A Doppler analysis circuit that calculates the relative position and relative speed of the radar device with respect to the beat frequency response, and
A peak detection circuit that selects the relative position and the relative velocity of the target from the beat frequency response using the adjusted scaling factor.
9. The radar device according to claim 9. The interference processing circuit generates a scaling factor adjusted according to the number of extracted sample timings as the control signal.
The radar device according to any one of claims 2 to 10. The interference processing circuit generates a scaling factor adjusted according to the peak-to-peak value of the extracted sample timing as the control signal.
The radar device according to any one of claims 2 to 10. The antenna includes a plurality of antenna elements.
The reception processing circuit includes a plurality of reception processing subcircuits corresponding to each of the plurality of antenna elements.
The AD conversion circuit includes a plurality of AD conversion sub-circuits corresponding to each of the plurality of reception processing sub-circuits.
The interference processing circuit includes a plurality of interference processing subcircuits corresponding to each of the plurality of AD conversion subcircuits.
The frequency peak detection circuit includes a plurality of frequency peak detection sub-circuits corresponding to each of the plurality of interference processing sub-circuits.
The plurality of frequency peak detection sub-circuits
The process of obtaining the beat frequency and the Doppler shift frequency is applied to each of the sampling signals corresponding to the reflected waves received by each of the plurality of antenna elements.
All of the sampling signals corresponding to the reflected waves received by each of the plurality of antenna elements are integrated to generate information on the relative distance and relative velocity of the target.
Information on the relative distance and relative speed of the target generated by integrating all of the sampling signals corresponding to the reflected waves received by each of the plurality of antenna elements, and each of the plurality of frequency peak detection sub-circuits The direction estimation process of the target is applied by using the beat frequency and the output to which the process of obtaining the Doppler shift frequency is applied for each of the sampled signals corresponding to the reflected waves received by each of the plurality of antenna elements. Including further direction estimation circuit,
The radar device according to claim 1. The interference processing circuit generates the control signal using the sample timing extracted in at least one interference processing sub-circuit.
The radar device according to claim 13. The interference processing circuit determines the consistency of the sample timings extracted in the plurality of interference processing sub-circuits and generates the control signal.
The radar device according to claim 13. The predetermined value is set based on the minimum value among the peak-to-peak values in the plurality of time domains.
The radar device according to any one of claims 1 to 15. The antenna receives the reflected wave of the radar signal from the target,
A beat signal is generated using the reflected wave.
A sampling signal of the beat signal is generated,
The sampling signal is divided into a plurality of time domains, and the peak-to-peak value of the sampling signal is calculated for each of the plurality of time domains.
From the peak-to-peak values, sample timings that are equal to or greater than a predetermined value are extracted.
Based on the extracted sample timing, a control signal used for interference processing of the sampling signal is generated.
Using the control signal, a process of obtaining a beat frequency and a Doppler shift frequency is applied to the sampling signal to generate information on the relative distance and relative speed of the target.
Radar signal processing method.

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