JP2011127961A - Radar apparatus - Google Patents

Abstract

A radar apparatus is provided that correctly calculates a target relative speed when JEM occurs to improve target detection performance.
Means for emitting a transmission signal obtained by pulse-modulating carrier signals having different frequencies at predetermined time intervals, receiving means for receiving a signal reflected by a target, and frequency domain for converting a received signal in a received time domain into a frequency domain Transform means 206, target candidate detection means 207 for detecting a target candidate based on the signal strength in the received signal in the frequency domain, and obtaining the relative speed of the target candidate, phase difference between target candidates detected at different carrier frequencies by the target candidate detection means Tentative relative distance calculating means 208 for obtaining the target candidate tentative relative distance from the phase difference, target determining means 209 for determining the target candidate based on the target candidate tentative relative distance, and relative of the target candidate determined as the target There is a target relative speed calculation means 210 that obtains the speed by the target relative speed obtained by the target candidate detection means.
[Selection] Figure 1

Description

  The present invention relates to a radar apparatus, and more particularly to calculation of a target relative distance when JEM (Jet Engine Modulation) occurs.

  Conventionally, in calculating the target relative distance when JEM occurs, it is assumed that the target Doppler frequency is detected at a higher Doppler frequency than JEM, for example, as shown in FIG. ing.

  The target, JEM Doppler frequency is calculated by subjecting the received video signal of FM (Frequency Modulation) phase C to FFT (Fast Fourier Transform). 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 Examined Patent Publication No. 6-56413 (FIGS. 1, 3, 7, and 8)

  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 the target relative speed is erroneously calculated.

  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 is a radar apparatus that calculates a relative speed with respect to a target and performs target detection, and includes a transmission unit that radiates a transmission signal obtained by pulse-modulating a carrier signal having a different frequency at a predetermined time interval, and a reflection by the target. Receiving means for receiving the transmitted signal returned as a received signal, frequency domain converting means for converting the received signal in the time domain received by the receiving means into a frequency domain, and the frequency domain converting means converted by the frequency domain converting means The target candidate is detected at a different carrier frequency by the target candidate detecting means for calculating the relative speed of the target candidate while performing arithmetic processing based on the signal strength in the received signal in the frequency domain and detecting the target candidate's relative speed A temporary relative distance calculating means for calculating a phase difference of the target candidate and calculating a temporary relative distance of the target candidate from the phase difference; A target determination unit that determines a target candidate based on a provisional relative distance of the target candidate input from, and a target relative speed calculated by the target candidate detection unit based on the relative speed of the target candidate determined as the target by the target determination unit A radar apparatus comprising target relative speed calculation means for calculating the speed.

  According to the present invention, it is possible to provide a radar apparatus that can correctly calculate the target relative speed when JEM occurs.

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 relationship between the radar and target in Embodiment 1 of this invention. It is a figure which shows the relationship between the transmission signal in Embodiment 1 of this invention, and a received signal. It is a figure which shows the target detection process in the frequency domain by the target candidate detection means in Embodiment 1 of this invention. It is a figure which shows the processing content when the cell exceeding a CFAR threshold value gathers as a result of the CFAR process in the target candidate detection means in Embodiment 1 of this invention. It is a figure which shows that several target candidates are detected by the influence of JEM resulting from the jet engine mounted in the target in Embodiment 1 of this invention. It is a figure which shows the operation | movement when the target by the temporary relative distance calculation means in Embodiment 1 of this invention, and JEM1, JEM2 are detected as a target candidate. It is a figure which shows the relationship between the relative distance which can be measured without ambiguity by the relationship between the radar, the target, and JEM in Embodiment 1 of this invention, the relative distance of a target, and two transmission frequencies. It is a figure which shows the temporary relative distance of the target input into the target determination means in Embodiment 1 of this invention, and the target candidate of JEM. It is a figure which shows the determination flow of the target determination means in Embodiment 1 of this invention. It is a figure which shows the case where JEM in Embodiment 1 of this invention generate | occur | produces in the same relative speed as a target. 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 case where the target and JEM in Embodiment 2 of this invention become the same temporary relative distance. It is a figure which shows the ranging result when the initial phase of JEM in Embodiment 2 of this invention differs. It is a figure which shows the relationship between the transmission frequency in Embodiment 2 of this invention, and a transmission signal. It is a figure which shows the influence of the effect of a side lobe and the window function process in Embodiment 2 of this invention. It is a figure which shows the operation | movement when the target and JEM1, JEM2 in the relative distance difference calculation means in Embodiment 2 of this invention are detected as a target candidate. It is a figure which shows the relationship between the radar in Embodiment 2 of this invention, a target, and JEM. It is a figure which shows the relationship between the temporary relative distance and relative distance difference of the target and JEM target candidate in Embodiment 2 of this invention. It is a figure which shows the relative distance difference of the target in Embodiment 2 of this invention, and the target candidate of JEM. It is a figure which shows the determination flow of the target determination means 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 relative distance difference of the target candidate in case the target in Embodiment 3 of this invention is not detected.

  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. The radar apparatus switches the antenna 1, the transmitter 2, the receiver 4, the transmitter 2, and the receiver 4 to transmit the transmission RF (high frequency) signal and receive the reflected RF signal thereby to connect the antenna 1 to the transmission / reception switching. 3 and a signal processor 205A for processing a received video signal obtained by the receiver 4, for example, a computer, and a display 20 for displaying a processing result in the signal processor 205A. The transmitter 2, the transmission / reception switch 3 and the antenna 1 constitute a transmission means, and the antenna 1, the transmission / reception switch 3 and the receiver 4 constitute a reception means.

  Further, the signal processor 205A includes a frequency domain conversion unit 206, a target candidate detection unit 207, a temporary relative distance calculation unit 208, a target determination unit 209, and a target relative speed calculation unit 210.

  FIG. 2 is a diagram for explaining the relationship between the radar and the target, and FIG. 3 is a diagram for explaining the relationship between the transmission signal and the reception signal.

Hereinafter, the operation until the reception video signal is generated will be described with reference to FIGS. 2 and 3, f ₁ and f ₂ are transmission (signal) frequencies, Δf is a frequency interval between f ₁ and f ₂ , T _f is a time for transmitting the same transmission frequency (transmission time), and φ ₀₁ and φ ₀₂ are Initial phases of transmission signals of transmission frequencies f ₁ and f ₂ , R ₁ and R 2 are target relative distances observed at transmission frequencies f ₁ and f ₂ , and φ ₁ and φ ₂ are observations at transmission frequencies f ₁ and f ₂ The target phase in the frequency domain, m is the transmission frequency number.

The transmitter 2 performs pulse modulation on the carrier signal at a transmission time _Tf with a pulse repetition period (hereinafter referred to as PRI) to generate a transmission RF signal and outputs the transmission RF signal to the transmission / reception switch 3. Further, the transmitter 2 during the transmission time T _f, after generating the transmission RF signal of the transmission frequency f _1, during the next transmission time T _f, the transmission frequency f ₁ from the frequency interval Δf is higher by the transmission frequency f ₂ The transmission RF signal is generated. In this way, during the next transmission time _Tf , it operates at a transmission frequency that is higher than the transmission frequency used during the previous transmission time _Tf by the frequency interval Δf. Here, a case will be described in which operation is performed at a transmission frequency that is higher by the frequency interval Δf in the next transmission time, but processing can be performed on the same principle when operation is performed at a transmission frequency that is lower by the frequency interval Δf in the next transmission time.

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 represented by the following equations (1) and (2) is radiated from the antenna 1 into the air. Here, _{Tx f1} (t) is transmitted RF signal of the transmission frequency _{f 1, Tx f2} (t) is transmitted RF signal of the transmission frequency _{f 2,} A represents the amplitude of the transmission RF signal.

The transmitted RF signal radiated into the air is reflected by the target and enters the antenna 1 as a reflected RF signal expressed by the following equations (3) and (4). Here, Rx _f1 (t) is the reflected RF signal at the transmission frequency f ₁ , Rx _f2 (t) is the reflected RF signal at the transmission frequency f ₂ , A ′ is the amplitude of the reflected RF signal, v is the target relative velocity, and R ₁ And R ₂ are target relative distances when transmitting and receiving at each transmission frequency, and c represents the speed of light.

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. The receiver 4 passes the received RF signal input from the transmission / reception switch 3 through a narrow band filter, and after amplification by an amplifier and phase detection by a phase detector (both not shown), the following equation (5 ) Converted into a received video signal represented by (6) and output to the signal processor 205A. _{Here, V f1} (n) is the received video signal of the transmission frequency _{f 1, V f2} (n) is the received video signal of the transmission frequency _{f 2, A S} is the received video signal amplitude, n between a transmission time _{T f} is The pulse number, N represents the number of pulses during the transmission time _Tf , and Δt represents the sampling interval in the time domain (here, the same as the pulse repetition period).

  The signal processor 205A is composed of a computer having a CPU, RAM, ROM, interface circuit and the like (all 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 the RAM or dedicated memory of the computer.

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 expressed by the following equation (7) on the received video signal V _fm (n) in the time domain, and receives the received video signal P _fm (k) converted into the frequency domain. It outputs to the target candidate detection means 207. Here, N _fft represents the number of FFT points. However, 0 is substituted when N _fft > N. Further, the sampling interval ΔF _samp in the frequency domain is expressed by Expression (8). T _pri represents a pulse repetition period (PRI: Pulse Repetition Interval). The frequency domain transforming means 206 samples the received video signal in the frequency domain with high accuracy by performing a fast Fourier transform using the number of FFT points larger than the number of pulses.

Next, processing contents of target detection by CFAR (Constant False Alarm Rate) processing performed in the target candidate detection means 207 will be described. FIG. 4 is a diagram for explaining target detection processing in the frequency domain by the target candidate detection unit 207. More specifically, FIG. 4 is a diagram for explaining a target cell, a guard cell, and a sample cell related to the CFAR process. Here, a case where one target candidate is detected from the received video signal P _fm (k) converted into the frequency domain will be described.

The target candidate detecting unit 207 performs CFAR processing on the received video signal P _fm (k) converted into the frequency domain obtained from the frequency domain converting unit 206 according to the following equation (9) to detect a target candidate. Here, P _{fm, CFAR} (k) is a target candidate detection result by CFAR processing of the received video signal in the frequency domain of the transmission frequency number m, and (abs (P _fm (k))) is the received video converted to the frequency domain. This represents the amplitude of the signal P _fm (k), and 0 is set as the target candidate (1 is set for others).

The CFAR threshold value CFAR_th _m (k) is calculated by the following equation (10). Here, CFAR_cor is the CFAR coefficient, Samp_cell _m (k) is the sample cell, ave (Z (p)) is the average value of the array Z (p) (Z (p) = (abs (Samp_cell _m (k)))) Represents. However, when cells exceeding the CFAR threshold value CFAR_th _m (k) are aggregated, a cell indicating the maximum amplitude value is detected as a target candidate in the aggregate. FIG. 5 is a diagram for explaining the processing contents when cells exceeding the CFAR threshold (indicated by hatching) are gathered as a result of the CFAR processing in the target candidate detection means 207 of this embodiment. The target candidate detecting means 207 calculates the relative speed v ′ of the target candidate detected by the frequency domain cell number k ′ by the following equation (11). Here, f (k ′) represents the frequency of the frequency domain cell number k ′, and f ₀ represents the transmission frequency. The target candidate detection unit 207 outputs the detected target candidate and its relative speed to the temporary relative distance calculation unit 208.

  FIG. 6 is a diagram for explaining that a plurality of target candidates are detected due to the influence of the JEM caused by the jet engine mounted on the target. Even in the case of a single target, a plurality of target candidates may be detected as shown in FIG. 6 due to the influence of the JEM caused by the jet engine mounted on the target. In such a case, it is difficult to calculate the relative speed of the true target.

The provisional relative distance calculation means 208 calculates a provisional relative distance with distance ambiguity (distance uncertain) with high distance resolution in order to distinguish the target and JEM from the target candidates.
The temporary relative distance calculation unit 208 calculates the phase of the target candidate detected at different transmission frequencies input from the target candidate detection unit 207. When a discrete Fourier transform is performed on the received video signal V _f1 (n) expressed by the equation (5) with N _ftt , the result is expressed by the following equation (12).

From the equation (12), it can be seen that the intensity of the received video signal P _f1 (k) converted into the target candidate frequency region of the transmission frequency f ₁ becomes the maximum value when k becomes the following equation (13).

Since c, f ₁ , N _fft , and Δt are known, the received video converted into the frequency domain of the target candidate of the transmission frequency f ₁ is k ₁ where k is the maximum value in the following equation (13). The phase φ ₁ of the signal P _f1 (k ₁ ) is expressed by the following equation (14).

As in the case of the transmission frequency f _1, the phase phi ₂ of the transmission frequency f ₂ of the received video signal converted into the frequency domain of the target candidate P _f2 (k ₂₎ is expressed by the following equation (15).

The provisional relative distance calculation means 208 calculates the phase difference Δφ ₂₁ by the following equation (16) from the above relationship. FIG. 7 is a diagram for explaining the operation when the target and JEM1 and JEM2 are detected as target candidates. When calculating the phase difference, the target candidate detected at the transmission frequencies f ₁ and f ₂ is calculated with the closest relative speed as shown in FIG.

Next, the provisional relative distance calculation means 208 calculates the provisional relative distance from the phase difference Δφ ₂₁ by the following equation (17). However, the maximum distance R _max that can be measured without ambiguity at two transmission frequencies is obtained by the following equation (18), and the distance resolution is obtained by the following equation (19). In the case of a matched filter having signal processing performance with a distance resolution ΔR, a filter with a pass band Δf is necessary, but in this embodiment, a narrow band filter that requires a sufficiently small pass band as compared with the pass band Δf has the same distance. The resolution can be obtained and the scale of the apparatus can be reduced.

FIG. 8 is a diagram for explaining the relationship between the relationship between the radar, the target, and the JEM, the relative distance between the target, and the relative distance that can be measured without ambiguity at two transmission frequencies. The relative distance R ₁ to the target, the relative distance R _1J to the JEM generation source, and the maximum distance R _max that can be measured without ambiguity at the two transmission frequencies are expressed as shown in FIG. The temporary relative distance calculation unit 208 calculates the phase, the phase difference, and the temporary relative distance using the equations (14) to (17) for the target candidates detected by the JEM. Since the JEM generation source is the same, when the initial phases of the JEMs are the same, the phase is represented by the following formulas (20) and (21), the phase difference is represented by the following formula (22), and the provisional relative distance is represented by the following formula (23). .

  The temporary relative distance calculation unit 208 outputs the target candidate temporary relative distance calculated by the above calculation to the target determination unit 209. Here, the phase difference is converted into a temporary relative distance and the target determination is performed, but the target determination based on the phase difference can be performed in the same manner. FIG. 9 is a diagram showing a tentative relative distance between the target input to the target determination unit 209 and the JEM target candidate. The provisional relative distance between the target and the JEM is different as shown in equations (17) and (23). It can also be seen that the JEMs are within a predetermined temporary relative distance range of the temporary relative distance.

  FIG. 10 shows a determination flow of the target determination unit 209. The target determination unit 209 uses the fact that the temporary relative distance between the target and the JEM is different, and in accordance with the processing flow shown in FIG. 10, another target target within the predetermined temporary relative distance range of the target candidate temporary relative distance. When the candidate temporary relative distance does not exist, it is determined as a target, and when it exists, it is determined as JEM.

  FIG. 11 is a diagram for explaining a case where JEM occurs at the same relative speed as the target. As shown in FIG. 11, the JEM may occur at a relative speed that affects the target. Thus, when the influence of JEM is great, the target and the JEM interfere with each other, and the provisional relative distance of the target is expressed by the following equation (24). In this way, the temporary relative distance when the target and the JEM interfere with each other is a temporary relative distance different from the generated JEM other than the target relative speed. The target and JEM are determined according to the processing flow shown. The target determination unit 209 outputs the target and JEM determination result to the target relative speed calculation unit 210.

  The target relative speed calculation unit 210 outputs the relative speed of the target candidate determined as the target input from the target determination unit 209 to the display unit 20 as the target relative speed. When it is determined that the target is a target from the target candidates, the display unit 20 displays the relative speed at time t on the screen as target information.

  As described above, according to this embodiment, the temporary relative distance calculation unit 208 calculates the temporary relative distance between the target and the JEM from the target and JEM observed at different transmission frequencies. Radar device that improves target detection performance and target relative speed calculation performance without calculating an incorrect target relative speed because the target and JEM are determined using the difference between the temporary relative distance of JEM Can be obtained. In addition, in the case of a matched filter having a signal processing performance with a distance resolution ΔR, a filter with a pass band Δf is necessary. In this embodiment, a narrow band filter that has a sufficiently small pass band compared with the pass band Δf has the same distance resolution. And the scale of the apparatus can be reduced. Further, since the scale of the apparatus can be reduced, observation with high resolution can be performed, and the target and JEM can be determined in a short observation time.

Embodiment 2. FIG.
FIG. 12 is a diagram showing a configuration of a radar apparatus according to Embodiment 2 of the present invention. Compared with the configuration in the above embodiment, the signal processor 205B in the configuration in this embodiment includes a frequency domain conversion unit 206B instead of the frequency domain conversion unit 206, and a target determination unit 209B in place of the target determination unit 209. Furthermore, a difference is that a relative distance difference calculating unit 211 is provided between the temporary relative distance calculating unit 208 and the target determining unit 209B.

FIG. 13 is a diagram for explaining a case where the target and the JEM (generated other than the target relative speed) have the same temporary relative distance. In the first embodiment, it is assumed that there is a JEM (JEM generated at a relative speed that does not affect the target) within a predetermined temporary relative distance range of the target temporary relative distance as shown in FIG. Yes. However, in relation to the maximum distance R _max of folding the relative distance of the target can be Anbigyuiti no distance measurement at different transmission frequencies as shown in FIG. 13, the temporary relative distance of the target (JEM occurs in the relative speed affect the target) However, when the temporary relative distance between JEM1 and JEM2 falls within a predetermined temporary relative distance range, the target and JEM cannot be determined in the first embodiment.

  In addition, since the reflection signal from a plurality of blades resonates in JEM, JEM observed at different transmission frequencies may not have the same initial phase. FIG. 14 is a diagram for explaining a distance measurement result when the initial phase of JEM is different. When the initial phase of the JEM is different, as shown in FIG. 14, an offset is added to the phase difference, and the JEMs do not exist within the predetermined temporary relative distance range of the temporary relative distance. This makes it difficult to determine the target and JEM.

  FIG. 15 is a diagram for explaining the relationship between the transmission frequency and the transmission signal in the second embodiment. In the second embodiment, in order to determine the target and the JEM even in the above case, the target and the JEM can be determined using signals observed at different transmission frequencies as shown in FIG. . Hereinafter, the part different from the above embodiment will be described by taking the case of FIG. 13 as an example.

  FIG. 16 is a diagram for explaining the influence of side lobes and the effect of window function processing. As shown in FIG. 16A, when the strength of adjacent target candidates is high, the side lobes of the adjacent target candidates affect the phase of the target candidates, making it difficult to calculate the temporary relative distance correctly. Become.

  The frequency domain transforming unit 206B performs window function processing on the received video signal in the time domain input from the receiver 4 by the following equation (25). Here, W (n) represents a window function. For example, when a Hamming window is used as the window function, it is represented by the following equation (26).

  The frequency domain transforming unit 206B converts the time domain received video signal subjected to the window function processing into the frequency domain, and outputs the received video signal converted into the frequency domain to the target candidate detecting unit 207. As shown in FIG. 16B, the side lobe is reduced by performing the window function process, the influence on the adjacent target candidate is reduced, and the provisional relative distance can be calculated with high accuracy.

The relative distance difference calculating unit 211 detects the temporary relative distance of the target candidate detected at the transmission frequencies f ₁ and f ₂ from the temporary relative distance calculating unit 208 and the target candidate detected at the transmission frequencies f ₂ and f ₃ . A temporary relative distance is input. FIG. 17 is a diagram for explaining the operation of the relative distance difference calculating unit 211 when the target and JEM1 and JEM2 are detected as target candidates. FIG. 18 is a diagram for explaining the relationship between the radar, the target, and the JEM. The target phase difference detected at the transmission frequencies f ₂ and f ₃ is the following equation (27), and the target temporary relative distance detected at the transmission frequencies f ₂ and f ₃ input to the relative distance difference calculating means 211 is It is represented by the following formula (28). Further, the temporary relative distance of the JEM detected at the transmission frequencies f ₂ and f ₃ input to the relative distance difference calculating unit 211 is expressed by the following equation (29).

The relative distance difference calculating means 211 calculates the difference between the temporary relative distance of the target candidate detected at the transmission frequencies f ₁ and f ₂ and the temporary relative distance of the target candidate detected at the transmission frequencies f ₂ and f ₃ by the following equation: Calculated by However, the target case is shown in the following formula (30), and the case of JEM is shown in the following formula (31). The relative distance difference calculation unit 211 outputs the calculated relative distance difference of the target candidates to the target determination unit 209B.

  As described above, the relative distance difference between the target (when JEM is generated but the influence on the target is small) and the target candidate based on JEM is a value within a predetermined relative distance difference range. However, when a JEM that affects the target occurs as shown in FIGS. 19 and 20, the temporary relative distance is wrong, and a relative distance difference different from other target candidates is calculated. FIG. 19 is a diagram showing the relationship between the temporary relative distance between the target and the JEM target candidate and the relative distance difference, and FIG. 20 is a diagram showing the relative distance difference between the target and the JEM target candidate.

  FIG. 21 shows a determination flow of the target determination means 209B. The target determination unit 209B utilizes the fact that the relative distance difference between the target and the JEM is different, and follows the processing flow shown in FIG. 21 so that the relative distances of other target candidates fall within the predetermined relative distance difference range of the target candidate relative distance difference. When there is a difference, it is determined as JEM, and when there is no relative distance difference between other target candidates and there is a target candidate determined as JEM, it is determined as a target and the relative distance difference between other target candidates. If there is no target candidate determined to be JEM, it is determined as a second target candidate. The second target candidate further changes the transmission frequency and continues processing. Then, the target determination unit 209B outputs the determination result of the target and the JEM to the target relative speed calculation unit 210.

  As described above, according to this embodiment, the temporary relative distance between the target observed at different transmission frequencies and the JEM is within the predetermined temporary relative distance range, and it is difficult to determine the target and JEM. Using the signal observed at the frequency, the relative distance difference calculating means 211 calculates the relative distance difference between the target and the JEM, and the target determining means 209B uses the fact that the target is not calculated as a relative distance difference different from the JEM, Therefore, the erroneous target relative speed is not calculated, and a radar apparatus that improves the target detection performance and the target relative speed calculation performance can be obtained. Moreover, although the relative distance difference is used, the same effect can be obtained when the phase difference difference is used.

  Further, in the case of a matched filter having signal processing performance with a distance resolution ΔR, a filter with a pass band Δf is necessary, and in this embodiment, a narrow band filter that requires a sufficiently small pass band as compared with the pass band Δf has the same distance resolution. And the scale of the apparatus can be reduced. Further, since the scale of the apparatus can be reduced, observation with high resolution can be performed, and the target and JEM can be determined in a short observation time.

  Further, by providing the frequency domain transforming unit 206B, the side lobe of the target candidate is reduced by performing the window function processing, the influence on the adjacent target candidate is reduced, and the temporary relative distance can be calculated correctly. It becomes possible.

Embodiment 3 FIG.
FIG. 22 is a diagram showing the configuration of the radar apparatus according to Embodiment 3 of the present invention. The configuration in this embodiment is different from the configuration in the second embodiment in that the signal processor 205C includes a target relative speed calculation unit 210B instead of the target relative speed calculation unit 210.

  FIG. 23 is a diagram for explaining a relative distance difference between target candidates when a target is not detected. The target relative speed calculation means 210 of the above embodiment calculates the relative speed of the target candidate determined as the target as the target relative speed, and when the target relative speed is not determined from the target candidate as shown in FIG. The speed cannot be calculated.

  This embodiment is for calculating the target relative speed even in the above-described case, and hereinafter, a different part from the above-described second embodiment will be described by taking the case of FIG. 23 as an example.

  The target relative speed calculation unit 210B calculates the target relative speed by the following equation (32). The target relative speed calculation unit 210B outputs the calculated target relative speed to the display unit 20.

  As described above, according to this embodiment, even when the target is not included in the target candidates, the target relative speed calculation unit 210B uses the signals measured at different transmission frequencies to calculate the target relative speed from the relative distance difference. The speed can be calculated, and a radar apparatus that improves the target detection performance and the target relative speed calculation performance can be obtained.

  The present invention is not limited to the above-described embodiments, and it goes without saying that all possible combinations thereof are included.

  1 antenna, 2 transmitter, 3 transmission / reception switch, 4 receiver, 205A, 205B, 205C signal processor, 206, 206B frequency domain conversion means, 207 target candidate detection means, 208 temporary relative distance calculation means, 209, 209B Target determination means, 210, 210B Target relative speed calculation means, 211 Relative distance difference calculation means.

Claims (7)

A radar device that calculates a relative speed with a target and performs target detection,
Transmitting means for emitting transmission signals obtained by pulse-modulating carrier signals having different frequencies at predetermined time intervals;
Receiving means for receiving the transmission signal reflected and returned by the target as a reception signal;
A frequency domain transforming means for transforming a time domain received signal received by the receiving means into a frequency domain;
A target candidate detecting means for performing a calculation process based on the signal intensity in the received signal in the frequency domain transformed by the frequency domain transforming means, detecting a target candidate, and calculating a relative speed of the target candidate;
A temporary relative distance calculating means for calculating a phase difference of the target candidates detected at different carrier frequencies by the target candidate detecting means and calculating a temporary relative distance of the target candidates from the phase difference;
Target determination means for determining a target candidate based on the temporary relative distance of the target candidate input from the temporary relative distance calculation means;
Target relative speed calculation means for calculating the relative speed of the target candidate determined as the target by the target determination means as the target relative speed calculated by the target candidate detection means;
A radar apparatus comprising:   The target determination means includes a temporary relative distance of another target candidate within a predetermined distance range of the temporary relative distance of the target candidate from the temporary relative distance of the target candidate input from the temporary relative distance calculation means. The radar apparatus according to claim 1, wherein the radar apparatus determines that the target is a JEM, and determines that the target is a target when there is no provisional relative distance of another target candidate.   Relative distance difference calculation means for calculating a temporary relative distance difference of target candidates obtained at different transmission frequencies based on the temporary relative distance input from the temporary relative distance calculation means, and the target determination means, The radar apparatus according to claim 1, wherein the target candidate is determined based on a relative distance difference between the target candidates input from the relative distance difference calculating unit.   The target determination means includes a relative distance difference of another target candidate within a predetermined distance difference range of the relative distance difference of the target candidate from the temporary relative distance difference of the target candidate input from the relative distance difference calculation means. 4. The method according to claim 3, wherein JEM is determined as a second target candidate when there is no relative distance difference between other target candidates and there is no target candidate determined as JEM. Radar equipment.   The radar apparatus according to claim 3, wherein the target relative speed calculation unit calculates a target relative speed based on a relative distance difference from the relative distance difference calculation unit.   The frequency domain transforming unit performs window function processing on the received signal in the time domain received by the receiving unit in order to reduce the influence from adjacent target candidate signals, and then receives the receiving unit. The radar apparatus according to claim 1, wherein the received signal in the time domain received in step 1 is converted into a frequency domain.   The frequency domain transforming unit transforms the time domain received signal received by the receiving unit into a frequency domain with a score higher than the time domain received signal so that the maximum intensity of the target candidate can be calculated with high accuracy. The radar device according to claim 1, wherein the radar device is a radar device.

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