JP5595238B2 - Radar equipment - Google Patents

Description

  The present invention relates to a radar apparatus that performs target detection when JEM (Jet Engine Modulation) occurs.

  For example, in this type of conventional radar apparatus disclosed in Patent Document 1 below, in target detection and target relative distance calculation when a JEM occurs, the target Doppler frequency is detected at a higher Doppler frequency than JEM. Assumed.

In a conventional radar apparatus, a target and JEM Doppler frequency is calculated by performing FFT (Fast Fourier Transform) on an FM (Frequency Modulation) phase C received video signal. Also, the beat frequency of the target and JEM is calculated by performing FFT on the received beat signal of FM phase B. If the FM phase C Doppler frequency is smaller than the FM phase B beat frequency, the ranging circuit calculates the target relative speed. Further, when the calculated relative distance is smaller than the JEM distance, the distance determination circuit outputs the true target relative distance to the display.
By assuming that the target Doppler frequency is detected at a frequency higher than that of JEM, the relative distance of JEM is not mistakenly set as the target relative distance, and improvement of the target relative distance and target detection performance can be expected.

Japanese Patent Publication No. 6-56413 (especially FIGS. 1, 3, 7, and 8)

Enrico Piazza, “Radar Signals Analysis and Modellization in the Presence of JEM Application to Civilian ATC Radars”, pp.35-pp.40, IEEE AES Systems Magazine, January 1999

  However, in the conventional radar apparatus, since it is assumed that the target Doppler frequency is detected at a frequency higher than that of JEM, the target Doppler frequency is detected at a frequency lower than JEM, and the target beat frequency is higher than that of JEM. When detected at a low frequency, the target relative distance is calculated, but there is a problem that the target relative speed is erroneously calculated. In addition, since a plurality of transmission frequencies are used, there is a problem that the apparatus scale becomes large and the processing becomes complicated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a radar apparatus that correctly calculates a target relative speed when a JEM occurs and improves target detection performance. .

The present invention relates to a radar device that calculates a relative speed with respect to a target, calculates a relative speed with respect to the target, and performs target detection, and transmits a transmission signal obtained by pulse-modulating a carrier signal having a predetermined frequency at a predetermined time interval. A transmission / reception unit that radiates and receives the transmission signal reflected by the target as a reception signal; a frequency domain conversion unit that converts a reception signal in the time domain received by the transmission / reception unit into a frequency domain; and the frequency domain A target candidate detection unit that performs calculation processing based on signal strength in the received signal in the frequency domain converted by the conversion unit to detect a target candidate and calculates a relative speed of the target candidate; and a detection by the target candidate detection unit JEM interval calculation means for calculating an average value of the relative speed intervals of the target candidates as a JEM interval, and a difference calculated by the JEM interval calculation means. Based on the increase or decrease of the JEM intervals time that the target acceleration target when increased, the desired motion determining means for target determines that deceleration target if decreased, the target at different times calculated by the target candidate detecting means Based on the candidate's relative speed, the target candidate acceleration calculating means for calculating the acceleration of the target candidate, the target motion determination result input from the target motion determination means, and the acceleration of the target candidate input from the target candidate acceleration calculation means The target and the target relative speed of the target are determined based on the target candidate, and when the target candidate motion input from the target motion determination unit is an acceleration target, the target candidate acceleration input from the target candidate acceleration calculation unit is greater than zero. Of the candidates, the target candidate having the minimum acceleration is determined as the target, and when the motion of the target candidate is a deceleration target, the target candidate acceleration calculation means is input. Among the acceleration of the target candidate is less than zero target candidate, in the radar apparatus characterized by absolute value is and a target determining means for determining a target the target candidate with the smallest negative acceleration.

  According to the present invention, it is possible to provide a radar apparatus in which the target relative speed when JEM occurs is correctly calculated and the target detection performance is improved.

It is a figure which shows the structure of the radar apparatus concerning Embodiment 1 of this invention. It is a figure which shows the processing flow of the signal processor of FIG. It is a figure for demonstrating the relationship between a radar and a target. It is a figure for demonstrating the received video signal and processing content in this invention. It is a figure for demonstrating the sampling interval of the received video signal in this invention. It is a figure for demonstrating the influence of the side lobe in this invention, and the effect of a window function process. It is a figure for demonstrating the target detection process by the target candidate detection means of FIG. It is a figure which shows the processing content when the cell which exceeds a CFAR threshold value gathers as a result of CFAR processing in the target candidate detection means of FIG. It is a figure which shows that the some target candidate resulting from the jet engine mounted in the target is detected. It is a figure which shows the concept of the target determination in JEM environment in Embodiment 1 of this invention (in the case of 1 target). It is a figure which shows the relationship between a target speed and a rotation frequency. It is a figure which shows the processing flow of the target exercise | movement determination in the target exercise | movement determination means of FIG. It is a figure which shows the determination flow in the target determination means of FIG. It is a figure which shows the structure of the radar apparatus concerning Embodiment 2 of this invention. It is a figure which shows the processing flow of the signal processor of FIG. It is a figure which shows the concept of the target determination in the JEM environment in Embodiment 2 of this invention (in the case of 2 targets). It is a figure for demonstrating the target candidate detection in the target candidate detection means of FIG. It is a figure which shows the concept of PRI conversion and target candidate grouping in Embodiment 2 of this invention. It is a figure for demonstrating the parameter of PRI conversion in Embodiment 2 of this invention. It is a figure for demonstrating the processing content of the target candidate grouping in Embodiment 2 of this invention. It is a figure which shows the concept of the combination of the target candidate group of each time in Embodiment 2 of this invention. It is a figure which shows the structure of the radar apparatus concerning Embodiment 3 of this invention. It is a figure which shows the processing flow of the signal processor of FIG. It is a figure which shows the concept of the target determination in the JEM environment in Embodiment 3 of this invention. It is a figure which shows the processing flow of the target exercise | movement determination in the target exercise | movement determination means of FIG. It is a figure which shows the determination flow of the target determination means of FIG.

  Hereinafter, a radar device according to the present invention will be described with reference to the drawings according to each embodiment. In each embodiment, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

Embodiment 1 FIG.
1 is a diagram showing a configuration of a radar apparatus according to Embodiment 1 of the present invention. In FIG. 1, a transmitter 2 and a receiver 4 are connected to an antenna 1 that transmits a transmission RF signal and receives a reflected RF signal via a transmission / reception switch 3. A signal processor 205A is further connected to the receiver 4. For example, the signal processor 205A configured by a computer includes a frequency domain conversion unit 206, a target candidate detection unit 207, a JEM interval calculation unit 208, a target motion determination unit 209, a target candidate acceleration calculation unit 210, a target determination, which are shown as functional blocks. Means 211 are provided. A display device 20 is further connected to the signal processor 205A.

  The configuration for performing transmission signal generation and transmission control on the transmitter 2 side is not directly related to the present invention, and thus detailed illustration and description thereof will be omitted.

  FIG. 2 is a diagram showing a processing flow of the signal processor 205A, and the same reference numerals as those in FIG. 3 is a diagram for explaining the relationship between the radar and the target, FIG. 4 is a diagram for explaining the received video signal and processing contents, and FIG. 5 is a diagram for explaining the sampling interval of the received video signal.

First, an operation until a reception video signal is generated will be described with reference to FIGS. 4 and 5, _TCPI is an FFT (Fast Fourier Transform) interval for converting the received video signal into the frequency domain, n is a CPI (Coherent Pulse Interval) number, N is the number of CPI, and m is A pulse number in one CPI, M is the number of pulses in one CPI, and T _pri is a pulse repetition period (PRI).

The transmitter 2 modulates the carrier signal with a pulse repetition period to generate a transmission RF signal and outputs the transmission RF signal to the transmission / reception switch 3.
The transmission / reception switch 3 outputs the transmission RF signal input from the transmitter 2 to the antenna 1. As a result, the transmission RF signal Tx (t) represented by the equation (1) is radiated from the antenna 1 into the air. Here, A represents the amplitude of the transmission RF signal, f ₀ represents the transmission frequency, and φ ₀ represents the initial phase of the transmission signal.

The transmitted RF signal radiated into the air is reflected by the target and enters the antenna 1 as a reflected RF signal Rx (t) expressed by the equation (2). Here, A ′ is the amplitude of the reflected RF signal, R (t) is the target relative distance at time t, R ₀ is the target initial relative distance, v (t) is the target relative speed at time t, and c is the speed of light. However, the target relative speed v (t) at time t is expressed by Expression (3) using the target initial relative speed v ₀ and the target relative acceleration a.

Therefore, the antenna 1 receives the incident reflected RF signal and outputs it to the transmission / reception switch 3 as a received RF signal. The transmission / reception switch 3 outputs the reception RF signal input from the antenna 1 to the receiver 4. Then, the receiver 4 passes the received RF signal input from the transmission / reception switch 3 through a narrowband filter, and after amplification and phase detection (not shown in each part), the received video signal represented by Expression (4) V (t) is converted and output to the signal processor 205A. Here, A _S represents the amplitude of the received video signal. Further, the received video signal is expressed by Expression (5) using the time n as the CPI number n and the pulse number m in one CPI. However, the target relative speed v (n, m) at each time is expressed by Equation (6).

  The signal processor 205A is composed of a computer having a CPU, a RAM, a ROM, and an interface circuit (both not shown), and the CPU performs arithmetic processing according to a program stored in the ROM. The processing result of the signal processor 205A is recorded in a computer (for example, RAM).

Hereinafter, processing contents of each unit will be described.
The frequency domain conversion means 206 converts the received video signal in the time domain input from the receiver 4 into the frequency domain.
The frequency domain transforming means 206 performs fast Fourier transform represented by the equation (7) on the received video signal V (n, m) in the time domain, and receives the received video signal F _V (n, k) transformed into the frequency domain. ) Is output to the target candidate detection means 207 (see FIG. 4). Here, M _ftt represents the number of FFT points. However, 0 is substituted when M _fft > M. Further, the sampling interval ΔF _samp in the frequency domain is expressed by Expression (8). The frequency domain transforming means 206 performs fast Fourier transform using the number of FFT points larger than the number of pulses in order to sample the received video signal in the frequency domain with high accuracy (see FIG. 5).

  FIG. 6 is a diagram for explaining the influence of side lobes and the effect of window function processing in the present invention. As shown in FIG. 6A, when the FFT is performed without performing the window function processing, when there is a concern that the target is buried in the side lobe of the JEM, the frequency domain transforming unit 206 calculates the window by the equation (9). The target detection performance is improved by performing function processing. Here, Wind (m) represents a window function. For example, when a Hamming window is used as the window function, it is represented by Expression (10).

  Further, as shown in FIG. 6B, by performing window function processing, the side lobes of the target candidates consisting of the target and the JEM are reduced, the influence on the adjacent target candidates is reduced, and the target lobe target of the JEM is reduced. The target detection performance is improved.

  Next, processing contents of target (candidate) detection by CFAR (Constant False Alarm Rate) processing performed in the target candidate detection means 207 will be described. FIG. 7 is a diagram for explaining target detection processing in the frequency domain by the target candidate detection unit 207. More specifically, FIG. 7 shows a cell of interest in the frequency domain related to CFAR processing, guard cells on both sides of the cell of interest, and sample cells further outside the guard cell.

The target candidate detection unit 207 performs CFAR processing on the received video signal F _V (n, k) converted into the frequency domain obtained from the frequency domain conversion unit 206 according to Expression (11), and detects the target candidate. Here, F _{V, CFAR} (n, k) represents a target candidate detection result by CFAR processing of the received video signal in the frequency domain, and “0” is set as the target candidate (others are “1”).

Also, the CFAR threshold value CFAR_th (n, k) is calculated by the equation (12). Here, CFAR_cor is the CFAR coefficient, Samp_cell (n, k) is the sample cell, for example, ave (Z (p)) is the average value of the array Z (p), and abs (Z (p)) is the array Z (p) Represents an absolute value. However, when cells exceeding the CFAR threshold value CFAR_th _m (k) are collected, a cell indicating the maximum amplitude value is detected as a target candidate in the set. FIG. 8 is a diagram showing the processing contents when cells exceeding the CFAR threshold (cells indicated by diagonal lines) are gathered as a result of the CFAR processing in the target candidate detection means 207 of this embodiment.
The target candidate detection means 207 calculates the relative speed v ′ of the target candidate detected by the frequency domain cell number k ′ using the equation (13). Here, f (k ′) represents the frequency of the frequency domain cell number k ′.
The target candidate detection unit 207 outputs the detected target candidate and its relative speed to the JEM interval calculation unit 208.

The following operation of the first embodiment will be described as a case of one target.
Even when there is one target, a plurality of target candidates (targets, JEM1-3) may be detected as shown in FIG. 9 due to the influence of JEM caused by the jet engine mounted on the target. Thus, even when there is one target, a plurality of target candidates are detected due to the influence of JEM, and it is difficult to calculate the relative speed of the true target.
Hereinafter, the operation of each means up to the target speed measurement calculation method in the JEM environment will be described with reference to the target determination conceptual diagram of FIG. Here, FIG. 10 assumes a target having the same number of target candidates (targets, JEM1-3) at different times and having a difference in JEM interval larger than the speed change amount. For the sake of explanation, the target is outlined and JEM is displayed in black (the same applies to FIGS. 9, 16, 18, 20, 21, and 24).

The JEM interval calculating unit 208 calculates the JEM interval Δv (n) from the average of the relative speeds of the target candidates with respect to the relative speed of the target candidates input from the target candidate detecting unit 207 using the equation (14). However, the relative speed of the target candidate input from the target candidate detection means 207 is combined with the expression of FIG. Here, p is a target candidate number, and P is the number of target candidates.
The JEM interval calculation unit 208 outputs the calculated JEM interval Δv (n) to the target motion determination unit 209.

In order to explain the operation of the target motion determination means 209, first, the relationship between the target speed and the blade rotation frequency and the relationship between the JEM interval, the target speed and the blade rotation frequency will be described.
The present invention is directed to a moving target that generates JEM. A moving target equipped with a jet engine, a propeller engine, or the like is assumed as a moving target that generates JEM. Here, it demonstrates as a movement target carrying a jet engine. The target propulsive force can be obtained by jetting air that the jet engine flows from the front to the rear. Therefore, in order to move at higher speed, it is necessary to increase the amount of air flowing in. By increasing the rotation frequency of the blade as shown in FIG. 3, it becomes possible to obtain more air flowing in, and the target can move at a higher speed. When the target decelerates, the opposite is true, so the blade rotation frequency is lowered in order to reduce the inflowing air that is the driving force. FIG. 11 shows the relationship between the target speed and the rotational frequency of the target blade. The higher the target speed, the higher the rotational frequency.

Further, it is known that the JEM Doppler frequency interval Δf is expressed by the equation (16) (see the above non-patent document). Here, _nb is the number of blades, and ω _r is the blade rotation frequency [rpm]. The JEM interval Δv can be calculated from the JEM Doppler frequency interval Δf by Equation (17).

Based on the principle of operation of the jet engine and the principle of generation of the JEM interval, the target motion determination means 209 uses the JEM interval Δv (0), Δv obtained at different times based on the target motion determination processing flow shown in FIG. Using (1), it is determined whether the target motion is an acceleration target (Δv (0) <Δv (1)) or a deceleration target (Δv (0)> Δv (1)). When Δv (0) = Δv (1), the process proceeds to target motion determination at the next different time. For the situation shown in Figure 10, the desired motion determining means 209, from JEM intervals Δv time t = 0 (0), for JEM intervals JEM intervals Δv of time _{t = T CPI} (1) is large, the acceleration target judge.
The target motion determination unit 209 outputs the obtained target motion determination result, which is an acceleration target or a deceleration target, to the target determination unit 211.

  The target candidate acceleration calculation unit 210 calculates the target candidate relative acceleration a (n, p) from the relative speed of the target candidate obtained by the target candidate detection unit 207 using the equation (18). The target candidate acceleration calculation unit 210 outputs the calculated relative acceleration of the target candidate to the target determination unit 211.

The target determination unit 211 performs target determination using the target motion determination result input from the target motion determination unit 209 and the relative acceleration of the target candidate input from the target candidate acceleration calculation unit 210 according to the determination flow of FIG. Do. In the situation shown in FIG. 10, the target determination unit 211 is determined as an acceleration target by the target motion determination unit 209. Therefore, among the target candidates whose target candidate acceleration is calculated to be greater than 0 by the target candidate acceleration calculation unit 210. (If not, the process proceeds to target determination at the next different time.) The target candidate having the minimum acceleration is set as the target. The target determination unit 211 determines that the target candidate relative speed determined as the target is the target relative speed. When a target having a presumed relative acceleration is detected, a range of relative acceleration is set in advance, and a target candidate having the minimum acceleration in the range is set as a target.
Further, when the target motion determination result is a deceleration target, among the target candidates whose target candidate relative acceleration is calculated to be smaller than 0 by the target candidate acceleration calculation unit 210 (if there is not, the process proceeds to target determination at the next different time) A target candidate having a negative acceleration with the smallest absolute value is targeted.
The target determination unit 211 outputs the relative speed of the target candidate determined as the target to the display device 20 as the target relative speed.

  The display 20 displays the target relative speed at time t on the screen as target information.

  As described above, according to the first embodiment, even when a JEM occurs, the JEM interval is calculated by the JEM interval calculation means 208 from the target and the target candidates of the JEM, and the target motion determination means 209 is the acceleration target. JEM interval is increased, while the deceleration target is determined to be an acceleration target or a deceleration target from the JEM intervals of target candidates at different times by using the fact that the JEM interval is reduced. When the target candidate detection means 207 calculates the relative acceleration of the target candidate, and the target determination means 211 uses the target motion determination result and the target candidate relative acceleration to determine that the target motion is an acceleration target, the acceleration is If the target candidate having the minimum acceleration is selected as a target among the target candidates greater than 0, and the target motion is determined to be a deceleration target, the target candidate having an acceleration of less than 0 is selected. Since a target candidate having a negative acceleration with the smallest absolute value is determined as a target, and the relative speed determined as the target is determined as the target relative speed, even when JEM occurs, the JEM is determined as the target relative speed. It is possible to obtain a radar apparatus in which target detection performance and target relative speed calculation performance are improved without error.

In addition, since it is not necessary to use a plurality of transmission frequencies, the scale of the apparatus can be reduced.
The frequency domain transforming unit 206 can obtain a radar apparatus that improves the target relative speed calculation performance by performing a fast Fourier transform using the number of FFT points larger than the number of pulses. Furthermore, the frequency domain transforming unit 206 can obtain a radar device that improves the target detection performance by suppressing the influence of the side lobe of the target candidate by performing the window function.

Embodiment 2. FIG.
FIG. 14 is a diagram showing a configuration of a radar apparatus according to Embodiment 2 of the present invention. The difference from the radar apparatus according to the first embodiment shown in FIG. 1 is that the signal processor 205B replaces the target candidate detection means 207 with the target candidate detection means 207B and replaces the JEM interval calculation means 208 with the JEM interval calculation. And a target candidate grouping unit 212 and a target candidate group combination unit 213 between the JEM interval calculation unit 208B and the target motion determination unit 209. FIG. 15 is a diagram showing a processing flow of the signal processor 205B, and the same reference numerals as the means for executing in FIG.

  FIG. 16 is a conceptual diagram of target determination in the JEM environment in the case of two targets in the second embodiment, FIG. 17 is a diagram for explaining target candidate detection of the target candidate detection unit 207B, and FIG. 18 is PRI conversion and target candidate FIG. 19 is a diagram for explaining parameters of PRI conversion, FIG. 20 is a diagram for explaining processing contents of target candidate grouping, and FIG. 21 is a concept of combinations of target candidate groups at each time. FIG.

In the first embodiment, one target is assumed as shown in FIG. 10, and the other cases are premised on the occurrence of JEM due to one target. However, when two targets v _{1, T} (0) and v _{2, T} (0) are assumed as shown in FIG. 16, it is difficult to accurately calculate the JEM interval, and it is difficult to determine the target. .
Therefore, in the second embodiment, in order to enable determination of a target even when two targets are assumed, the JEM interval is calculated by using the fact that the JEM periodicity is different for each target. Make a decision. Hereinafter, parts different from the first embodiment will be described with reference to FIGS.

  As shown in the first embodiment, the frequency domain transforming unit 206 performs fast Fourier transform using the number of FFT points larger than the number of pulses in order to sample the received video signal in the frequency domain with high accuracy. In addition, by using a larger number of FFT points than the number of pulses, it is possible to detect JEM intervals with high accuracy by detecting more target candidates.

  The target candidate detecting means 207B sets the relative speed of the target candidate that aggregates the maximum values from the aggregated target candidates. In addition, as shown in FIG. 17, the target candidate detection unit 207B outputs all the target candidates to the JEM interval calculation unit 208B even when the target candidates are gathered. By increasing the number of target candidates, when the JEM interval calculation means 208B calculates the JEM periodicity, the integrated value of the target JEM interval increases, and the JEM interval calculation accuracy improves.

The processing contents of the JEM interval calculation unit 208B and the target candidate grouping unit 212 will be described with reference to FIG.
The JEM interval calculation unit 208B performs PRI conversion using, for example, equation (19) to calculate the JEM periodicity with respect to the relative speed of the target candidate input from the target candidate detection unit 207B. Here, with reference to FIG. 19, Δv _k is the JEM interval to be investigated represented by the equation (20), D (k) is the integral value of the JEM interval Δv _k , Δv _I is the interval of the JEM interval to be investigated, and Δv _min Is the minimum value of the JEM interval to be examined, and K is the number of JEM intervals to be investigated.

  When the relative speed of the target candidate has periodicity, the periodicity, that is, the integrated value of the speed of the JEM interval becomes high. Based on the PRI conversion result, the JEM interval calculation unit 208B sets a JEM interval equal to or greater than a preset threshold value as the target candidate JEM interval. Further, the JEM interval calculation unit 208B sets the number of JEM intervals equal to or greater than the threshold as the target candidate group number. In order to set the threshold value, the threshold value may be set by the CFAR process used in the target candidate detection unit 207B. The JEM interval calculation process of the JEM interval calculation means 208B is effective even when there is one target and when there are a plurality of targets.

The target candidate grouping unit 212 uses the JEM interval input from the JEM interval calculation unit 208B to perform the target candidate input from the target candidate detection unit 207B as shown in FIGS. 20 (a) and 20 (b). Group target candidates into groups. The target candidate grouping means 212 first determines a target candidate that is the origin of grouping. In FIG. 20, the minimum relative speed of the target candidate is set. Next, it is examined whether there are target candidates periodically at JEM intervals from the relative speed. In FIG. 20A, the JEM interval is investigated with Δv ₁ (0). As a result, the number of target candidates 1 that periodically existed in the JEM interval Δv ₁ (0) is stored. Next, the JEM interval calculation unit 208B changes the JEM interval to Δv ₂ (0) and similarly investigates the periodicity. As shown in (b) of FIG. 20, the target candidate number 4 that periodically exists in the JEM interval Δv ₂ (0) is stored.

The target candidate grouping unit 212 compares the number of target candidates that existed periodically between the JEM intervals Δv ₁ (0) and Δv ₂ (0), and the target candidate number is larger, that is, the JEM interval Δv ₂ ( The target candidates that appear periodically at 0) are defined as target candidate groups with a JEM interval Δv ₂ (0) as JEMs resulting from the targets. For non target candidate group of JEM intervals Δv ₂ (0), and an investigation JEM intervals Δv ₁ (0), when the target candidate is present, the target candidate group of JEM intervals Δv ₁ (0) .
The target candidate grouping unit 212 outputs the target candidate group to the target candidate group combination unit 213.

  As shown in FIG. 21, the target candidate group combination means 213 combines target candidate groups between times by combining the target candidate groups having similar numbers of target candidates. The target candidate group combination unit 213 outputs the target candidate group at each time and the combination between the times to the target exercise determination unit 209. The target motion determination means 209 determines the target motion based on the JEM interval based on the combination between the target candidate group at each time and the time input from the target candidate group combination means 213. Even in the case of a plurality of targets, since the target candidate groups are divided and the combinations between the times are determined, the subsequent processing can be similarly performed.

As described above, according to the second embodiment, the JEM interval calculation unit 208B calculates the JEM interval using the periodicity of the JEM, and the target candidate grouping unit 212 groups the target candidates using the JEM interval. The target candidate group combining means 213 combines the target candidate groups between times using the target candidate number of target candidate groups, and after the combination, processing can be performed independently as in the case of one target. Even in the case of a plurality of targets, it is possible to obtain a radar apparatus with improved target detection performance and target relative speed performance.
Further, in the frequency domain transforming means 206, by using the number of FFT points larger than the number of pulses, the target candidate detecting means 207B detects many target candidates, and as a result, by using a large number of target candidates, the JEM interval calculating means Since the JEM interval by 208B can be calculated with high accuracy, a radar apparatus with improved target relative speed calculation performance can be obtained.

Embodiment 3 FIG.
FIG. 22 is a diagram showing the configuration of the radar apparatus according to Embodiment 3 of the present invention. The difference from the radar apparatus according to the second embodiment shown in FIG. 14 is that the signal processor 205C replaces the target motion determination unit 209 with the target motion determination unit 209B and replaces the target candidate acceleration calculation unit 210 with the target candidate. The acceleration calculating means 210B and the target determining means 211B are provided instead of the target determining means 211. FIG. 23 is a diagram showing a processing flow of the signal processor 205C, and the same reference numerals as those in FIG.

  FIG. 24 is a conceptual diagram of target determination in the JEM environment in the third embodiment, FIG. 25 is a diagram illustrating a processing flow of target motion determination in the target motion determination unit 209B, and FIG. 26 is a diagram illustrating a determination flow of the target determination unit 211B. It is.

In the target motion determination unit 209 and the target candidate acceleration calculation unit 210 of the first and second embodiments, the JEM interval and relative acceleration of the target candidate are calculated using the JEM interval and relative speed of the target candidate at two different times. If the observation error such as noise is large, the target candidate JEM interval and the relative acceleration calculation accuracy may be deteriorated.
Therefore, in the third embodiment, it is possible to calculate the target candidate's JEM interval and relative speed with high accuracy even when the observation error such as noise is large.
In addition, in order to improve target determination accuracy, the target determination unit 211B determines JEM in addition to target determination.
In the third embodiment, parts different from the second embodiment will be described by taking the configurations of FIGS. 22 and 23 as examples.

FIG. 24 shows a case where JEM intervals of target candidates of three different times 0, T _CPI and 2T _CPI are assumed. Time _{t = (n-1) T} CPI of the target candidate JEM intervals Delta] v (n) can be expressed by Equation (21). Here, W _J is the rate of change of the target candidate JEM interval. Also, in equation (21), the target candidate JEM interval Δv ′ (n) at time t = (n−1) _{TCPI and} the target candidate JEM interval Δv ′ (0) at time t = 0 are modeled linearly. "'" Is added to indicate that the action has been taken.
Desired motion determining means 209B, using the least squares method, calculates a change rate W _J of JEM intervals target candidate by the formula (22).

The target motion determination means 209B uses the calculated JEM interval change rate W _J based on the target motion determination processing flow shown in FIG. 25 to determine whether the target motion is an acceleration target (0 <W _J ) or deceleration. It is determined whether the target (0> W _J ). For 0 = W _J moves to a desired motion for the subsequent different times. For the situation shown in Figure 24, the desired motion determining means 209B, the change rate W _J of JEM intervals target candidates is calculated larger than 0, it is determined that the acceleration target.
The target motion determination unit 209B outputs the obtained target motion determination result of the acceleration target or the deceleration target to the target determination unit 211B.
Since the change rate W _J of the JEM interval of the target candidate is calculated by the equation (22) by the least square method using the JEM interval Δv (n) of more times, the influence of the observation error such as noise is reduced, The target motion can be determined with high accuracy.

The relative speed v ″ (n, p) of the target candidate of time t = (n−1) _TCPI can be expressed by Expression (23). Here, a ″ (p) is the relative acceleration of the target candidate. Further, in the equation (23), the relative speed v ″ (n, p) of the target candidate at time t = (n−1) _TCPI , the relative speed v ″ (0, p) of the target candidate at time t = 0. ) Is appended with “'' to indicate that it is modeled linearly.
The target candidate acceleration calculating unit 210B calculates the relative acceleration a ″ (p) of the target candidate obtained by the target candidate detecting unit 207B using the equation (24). The target candidate acceleration calculation unit 210B outputs the calculated relative acceleration of the target candidate to the target determination unit 211B.

  Since the relative acceleration a ″ (p) of the target candidate is calculated by the equation (24) based on the least square method using the relative speed v ″ (n, p) of the target candidate at more times, noise and the like The influence of the observation error is reduced, and the relative acceleration of the target candidate can be calculated with high accuracy.

The target determination unit 211B performs target determination using the target motion determination result input from the target motion determination unit 209B and the target candidate relative acceleration input from the target candidate acceleration calculation unit 210B according to the determination flow of FIG. Do. Moreover, the target determination means 211B determines JEM among target candidates. In the situation shown in FIG. 24, since the target determination unit 211B is determined as an acceleration target by the target motion determination unit 209B, the target candidate whose target candidate acceleration is calculated to be smaller than 0 by the target candidate acceleration calculation unit 210B, that is, The deceleration target is determined as JEM. Next, among the target candidates whose remaining target candidate accelerations are calculated to be greater than 0 (if there is no target determination at the next different time), the target candidate having the minimum acceleration is set as the target. The target determination unit 211B determines that the target candidate relative speed determined as the target is the target relative speed. When a target having a presumed relative acceleration is detected, a range of relative acceleration is set in advance, and a target candidate having the minimum acceleration in the range is set as a target.
When the target motion determination result is a deceleration target, the target candidate whose target candidate acceleration is calculated to be greater than 0 by the target candidate acceleration calculation unit 210B, that is, the acceleration target is determined as JEM. Next, among the target candidates whose remaining target candidate accelerations are calculated to be less than 0 (if there is no target determination at the next different time), the target candidate having the negative acceleration with the smallest absolute value is set as the target. .
In this way, since the target determination unit 211B determines JEM from the target candidates, the JEM is not erroneously determined as the target, and the detection performance is improved. Further, the number of target candidates is reduced, the target determination load is reduced, and the apparatus scale can be reduced.

As described above, according to the third embodiment, the target motion determination means 209B calculates the change rate of the JEM interval of the target candidate by the least square method, and based on the change rate of the JEM interval of the target candidate, Thus, the influence of the observation error such as noise is reduced, and a radar apparatus for determining the target motion with high accuracy can be obtained. In addition, the target candidate acceleration calculating unit 210B calculates the relative acceleration of the target candidate from the relative speeds of the target candidates at a plurality of times by the least square method, so that the influence of the observation error such as noise is reduced, and the target candidate is highly accurate. Can be obtained. The target motion determination unit 209B and the target candidate acceleration calculation unit 210B can calculate the target motion and the relative acceleration of the target candidate with high accuracy, and an apparatus for performing target determination with high accuracy can be obtained.
In addition, since the target determination unit 211B determines a target candidate that performs a motion different from the target motion among the target candidates as a JEM, the JEM is not erroneously determined as a target, the detection performance is improved, and the target The processing load of determination is reduced, and the scale of the apparatus can be reduced.

  The present invention is not limited to the above-described embodiments, and it is needless to say that all possible combinations of these embodiments are included.

  1 antenna, 2 transmitter, 3 transmission / reception switch, 4 receiver, 205A, 205B, 205C signal processor, 206 frequency domain conversion means, 207, 207B target candidate detection means, 208, 208B JEM interval calculation means, 209, 209B Target motion determination means, 210, 210B Target candidate acceleration calculation means, 210, 210B Target candidate acceleration calculation means, 211, 211B Target determination means.

Claims (8)

A radar device that calculates a relative speed with a target and performs target detection,
Transmitting and receiving means for radiating a transmission signal obtained by pulse-modulating a carrier signal of a predetermined frequency at a predetermined time interval, and receiving the transmission signal reflected by the target as a reception signal;
A frequency domain transforming means for transforming a time domain received signal received by the transmitting / receiving means into a frequency domain;
Target candidate detection means for performing a calculation process based on the signal intensity in the received signal in the frequency domain transformed by the frequency domain transformation means, detecting a target candidate, and calculating a relative speed of the target candidate;
JEM interval calculating means for calculating an average value of relative speed intervals of the target candidates detected by the target candidate detecting means as JEM intervals;
A desired motion determining means target acceleration target, the target when decreased is determined that deceleration target when the basis of the increase or decrease of the JEM intervals different times calculated by JEM interval calculating unit, increases,
Target candidate acceleration calculating means for calculating the acceleration of the target candidate based on the relative speeds of the target candidates at different times calculated by the target candidate detecting means;
Based on the target motion determination result input from the target motion determination means and the acceleration of the target candidate input from the target candidate acceleration calculation means, the target and the target relative speed of the target are determined and input from the target motion determination means When the motion of the target candidate is an acceleration target, the target candidate having the minimum acceleration is determined as the target among the target candidates whose acceleration of the target candidate input from the target candidate acceleration calculating unit is greater than 0, and the motion of the target candidate Target determination means for determining, as a target, a target candidate having a negative acceleration with a minimum absolute value among target candidates for which the acceleration of the target candidate input from the target candidate acceleration calculation means is smaller than 0 when When,
A radar apparatus comprising:   The JEM interval calculating means calculates the JEM interval from the integrated value of the JEM interval by PRI conversion with respect to the relative speed in consideration of the periodicity of the relative speed of the target candidate detected by the target candidate detecting means. Item 2. The radar device according to Item 1. Frequency domain transform unit, radar apparatus according to claim 1 or 2, wherein the conversion to the frequency domain at more points than the number of the received signal in the time domain received signal of the received time domain transmission and reception means . Frequency domain transform section, after performed by adding a window function processing on the received signal of the received time domain by the transmission and reception means, from claim 1, characterized in that to convert the received signal in the time domain to the frequency domain 4. The radar device according to any one of up to 3 . Based on the JEM interval of the target candidates at different times, the target motion determination means determines the acceleration target when the JEM interval increases and the target motion when the JEM interval decreases with time. The radar device according to any one of claims 1 to 4, wherein The target motion determination means calculates the change rate of the target candidate JEM interval by the least square method based on the JEM interval of the target candidate at different times. If the change rate of the JEM interval is greater than 0, the target motion determination means The radar apparatus according to any one of claims 1 to 4 , wherein a deceleration target and a movement of the target are determined when the speed is small. Target candidate acceleration calculation means, either on the basis of the relative speed of the target candidates of different times calculated by the target candidate detecting section, from claim 1, characterized in that to calculate the acceleration of the target candidate by the least squares method to the 6 The radar apparatus according to claim 1. The target determination means further selects a target candidate having an acceleration whose target candidate acceleration input from the target candidate acceleration calculation means is smaller than 0 as JEM when the motion of the target candidate input from the target motion determination means is an acceleration target. judgment, when the movement of the target candidate is deceleration target, the target candidate acceleration of target candidates inputted from the target candidate acceleration calculation means has a greater than zero acceleration claim 1, wherein determining that JEM The radar apparatus according to any one of 7 to 7 .

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