JP5225203B2 - Radar apparatus and radar signal processing method - Google Patents

Description

  The present invention is used in a radar apparatus that transmits a transmission wave toward a space, receives a reflected wave reflected by a target object, and suppresses clutter components included in the received reflected pulse, and the apparatus thereof. The present invention relates to a radar signal processing method.

  The flying object guiding radar apparatus generates a modulated pulse signal according to a predetermined pulse repetition frequency PRF (Pulse Repetition Frequency), and transmits a transmission wave based on the modulated pulse signal from an antenna. Then, the radar apparatus receives the reflected wave obtained by reflecting the transmission wave from the target with the antenna, searches for the target, tests and tracks the target, and guides the flying object to the tracked target.

  In the conventional radar apparatus, the pulse repetition frequency is selected so as to satisfy the distance measurement of the maximum detection distance. For this reason, the search, verification, and tracking of the target in the radar apparatus is inevitably performed by a low PRF (Low Pulse Repetition Frequency) method (for example, see Non-Patent Document 1). Here, when a search is performed by transmitting a transmission wave based on a modulated pulse signal generated based on a low PRF, frequency ambiguity is generated. For this reason, the radar apparatus removes clutter components included in the reflected wave by MTI (Moving Target indicator) processing using a multi-Doppler filter (see, for example, Patent Document 1).

  However, in a radar apparatus that must search for a target at high speed, a radar apparatus that rotates antenna directivity at high speed, etc., the time during which the beam is directed in one direction is short. Therefore, when searching for a target by such a radar device using the low PRF method, the clutter suppression processing becomes insufficient because the number of pulse hits in one direction is small in a strong clutter environment, and the target is accurately There is a problem that it is difficult to detect.

  Here, it is conceivable to adopt a method of shortening the pulse repetition period, that is, a high PRF (High Pulse Repetition Frequency) method. By adopting the high PRF method, the number of pulse hits in one direction can be increased, and the clutter suppression capability is improved. However, when searching, verifying, and tracking a target using a modulation pulse generated according to the high PRF method, frequency ambiguity does not occur in the acquired observation data, but range ambiguity occurs. It is impossible to accurately measure the distance of the target. The radar apparatus performs multiple PRF ranging using a plurality of types of high PRF, thereby canceling the range ambiguity and measuring the target. However, in the multi-PRF ranging, there is a problem that distance measurement is likely to be mistaken because similar candidates exist in the combination of received reflected pulses.

JP 2007-271269 A

William H. Long, David H. Mooney, William A. Skillman, "RADAR HANDBOOK Second Edition (CHAPTER 17)", McGRAW-HILL, 17.1-17.25. Sergio Sabatini, Marco Tarantino, "Multifunction Array Radar", Artech House, pp 137-138. William W. Shrader, V. Gregers-hansen, "RADAR HANDBOOK Second Edition (CHAPTER 16)", McGRAW-HILL, 15.1-17.34.

  As described above, in the conventional radar apparatus, when the low PRF method is adopted, if the time during which the beam is directed in one direction is short, the number of pulse hits decreases, and the clutter suppression effect cannot be obtained sufficiently. There is a problem that false detection of the target is likely to occur. In addition, when the high PRF method is adopted, there is a problem that an error is likely to occur in the distance measurement because it is necessary to perform multi-PRF ranging in order to cancel the range ambiguity.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a radar apparatus and a radar signal processing method capable of quickly detecting a target at the time of searching and accurately measuring the distance to the target at the time of verification. There is to do.

  In order to achieve the above object, a radar apparatus according to the present invention includes a transmission pulse generation unit that repeatedly generates a transmission pulse in accordance with a designated PRF (Pulse Repetition Frequency), and a transmission pulse generated by the transmission pulse generation unit. Transmitting / receiving means for transmitting toward and receiving the reflected pulse reflected by the target, switching means for selectively switching derivation of the received reflected pulse, and clutter included in the reflected pulse derived from the switching means Search means for removing a component, searching for the target based on the signal, obtaining the Doppler information of the target when the target is detected in the search, and generating PRF information based on the Doppler information; The clutter component contained in the reflected pulse derived from the switching means is removed and detected by the search means based on the signal. A verification means for verifying a standard; and a control means for designating a PRF for the transmission pulse generating means and controlling the switching means, and the control means performs processing of the reflected pulse in an initial state. A high PRF in which no frequency ambiguity is generated but a range ambiguity is generated is designated to the transmission pulse generation means, and a reflection pulse by the transmission pulse generated according to the high PRF is derived to the search means. When the switching means is switched and the target is detected by the search means and the PRF information is generated, no range ambiguity is generated in the processing of the reflected pulse based on the PRF information. A low PRF in which a Guity is generated is designated to the transmission pulse generating means, and a transmission pulse generated according to the low PRF is specified. The switching means is switched so that a reflected pulse due to a pulse is derived to the verification means.

The radar signal processing method according to the present invention is a radar signal processing method used in a radar apparatus that searches and verifies the target based on a reflected pulse generated when a transmission pulse is reflected by the target. Although the frequency ambiguity does not occur in the pulse processing, the transmission pulse is generated according to the high PRF in which the range ambiguity is generated, and the reflected pulse from the target is subjected to FFT (Fast Fourier Transform) processing to obtain the clutter component. Remove,
The target is searched based on the signal from which the clutter component is removed by the FFT processing, and when the target is detected by the search, the Doppler information of the target is acquired, and the PRF information is generated based on the Doppler information. When the target is detected in the search and the PRF information is generated, based on the PRF information, a low PRF that does not generate range ambiguity but generates frequency ambiguity is generated in the processing of the reflected pulse. Select, generate the transmission pulse according to the low PRF, perform MTI (Moving Target indicator) processing on the reflected pulse from the target to remove the clutter component, and based on the signal from which the clutter component has been removed by the MTI processing The target detected by the search is verified.

  In the radar apparatus and the radar signal processing method configured as described above, the search for the target is performed by the search means according to the high PRF. When the target is detected by the search, a low PRF is selected based on the PRF information acquired by the search, and the target detected during the search is verified according to the low PRF. As a result, the number of pulse hits per beam position in the search increases, and the clutter suppression capability improves. Further, in the search according to the high PRF, range ambiguity occurs, but since the target detected according to the low PRF is verified, the distance to the target can be accurately measured.

  According to the present invention, it is possible to provide a radar apparatus and a radar signal processing method capable of quickly detecting a target at the time of searching and accurately measuring the distance to the target at the time of verification.

It is a block diagram which shows the function structure of the radar apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the processing flow at the time of the search process part of FIG. 1 performing a search process. It is a flowchart which shows the processing flow at the time of the verification and tracking process part of FIG. 1 performing a verification process and a tracking process. It is a flowchart which shows the control flow at the time of the beam scheduler of FIG. 1 controlling a pulse signal production | generation part and a switching part according to the process of a search process part and a test | inspection / tracking process part. It is a schematic diagram which shows the search range of the radar apparatus of FIG. It is a figure which shows typically the removal of the clutter component by the FFT process part of FIG. It is a schematic diagram at the time of selecting PRI suitable for a test process by the search process part of FIG. It is a schematic diagram which shows the MTI blind of the multi-Doppler filter in the MTI processing part of FIG. It is a block diagram which shows the function structure of the radar apparatus concerning the 2nd Embodiment of this invention. It is a flowchart which shows the control flow of the beam scheduler of FIG. It is a schematic diagram of the transmission wave transmitted according to two types of high PRF. It is a block diagram which shows the function structure of the radar apparatus concerning the 3rd Embodiment of this invention. It is a schematic diagram which shows the search range of the radar apparatus of FIG.

  Hereinafter, embodiments of a radar apparatus according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing a functional configuration of a radar apparatus according to the first embodiment of the present invention. The radar apparatus shown in FIG. 1 includes a pulse signal generator 10, an antenna (phased array) 40, a receiver 50, a demodulator 60, a signal processor 70, and a beam scheduler 80, and is based on a reflected wave from a target. Search, verify and track the target.

  The pulse signal generation unit 10 generates a modulated pulse signal in which the pulse is frequency or phase modulated by a preset modulation method by digital processing. At this time, the pulse signal generation unit 10 switches a repetition frequency PRF (Pulse Repetition Frequency) for generating a modulated pulse signal according to an instruction from a beam scheduler 80 described later. In the following, a PRF in which frequency ambiguity is generated in detecting a target based on a reflected wave but no range ambiguity is defined as a low PRF, and no frequency ambiguity is generated, but range ambiguity is not generated. Tee defines the generated PRF as a high PRF.

  The pulse signal generation unit 10 performs quadrature modulation on the baseband modulation pulse signal generated in (1), performs digital-analog conversion, converts the frequency to a transmission frequency, and supplies the converted signal to the antenna 40.

  The antenna 40 includes an element antenna 41, a transmission / reception module 42, and a power feeding circuit 43. The element antenna 41 transmits a signal supplied via the transmission / reception module 42 toward the space as a transmission wave. The transmission wave transmitted from the antenna 40 is reflected by the target and received by the antenna 40 as a reflected wave. The antenna 40 receives the reflected wave at the element antenna 41 and supplies a reception signal based on the received reflected wave to the receiving device 50 via the transmission / reception module 42.

  The receiving device 50 frequency-converts the received signal received into an intermediate frequency band signal, performs analog-digital conversion, and then performs quadrature detection to convert it into a baseband video signal. The baseband video signal is supplied to the demodulator 60.

  The demodulator 60 demodulates the video signal using the modulation method of the pulse signal generator 10 by digital processing. The demodulated video signal is supplied to the signal processing device 70.

  The signal processing device 70 includes a switching unit 71, an FFT (Fast Fourier Transform) processing unit 72, a search processing unit 73, an MTI (Moving Target indicator) processing unit 74, and a verification / tracking processing unit 75. The switching unit 71 derives the supplied video signal to either the FFT processing unit 72 or the MTI processing unit 74 in accordance with an instruction from the beam scheduler 80 described later.

  The FFT processing unit 72 performs FFT processing on the video signal to remove clutter components, and supplies the signal after the clutter signal removal to the search processing unit 73.

  The search processing unit 73 performs a target search process using the signal from which the clutter component has been removed by the FFT processing unit 72. The search processing unit 73 stores in advance a memory 731 for storing the search results, and the relationship between the Doppler information of the target obtained by the search processing and a predetermined PRI (Pulse Repetition Interval) (PRI = 1 / PRF). A table 732 is provided. Here, the predetermined PRI is the most suitable PRI when the verification / tracking processing unit 75 performs the verification process. When the search processing unit 73 shifts to the verification process, the search processing unit 73 notifies the beam scheduler 80 of the shift to the verification process and the PRI for performing the verification process.

  The MTI processing unit 74 removes clutter components included in the video signal by a multi-Doppler filter and outputs the result to the verification / tracking processing unit 75.

  The verification / tracking processing unit 75 performs target verification processing and tracking processing using the signal from which the clutter component has been removed by the MTI processing unit 74. The verification / tracking processing unit 75 includes a memory 751 for recording a verification result and the like.

  The beam scheduler 80 includes a CPU (Central Processing Unit) made of, for example, a microprocessor, and designates a PRF for the pulse signal generation unit 10 according to processing executed by the search processing unit 73 and the verification / tracking processing unit 75. The switching unit 71 is instructed to derive the video signal to be supplied.

  Next, the operation in the above configuration will be described.

  FIG. 2 is a flowchart showing a processing flow when the search processing unit 73 performs the search processing, and FIG. 3 is a flowchart showing a processing flow when the verification / tracking processing unit 75 performs the verification processing and tracking processing. FIG. 4 is a flowchart showing a control flow when the beam scheduler 80 controls the pulse signal generation unit 10 and the switching unit 71 in conjunction with the processing of the search processing unit 73 and the verification / tracking processing unit 75.

  First, the search processing unit 73 performs a search process (step 21).

  When the search processing is performed by the search processing unit 73, the beam scheduler 80 designates a high PRF for the pulse signal generation unit 10 (step 41), and derives the video signal to the FFT processing unit 72 for the switching unit 71. Instructed to do so (step 42). Here, the high PRF is obtained by the following formula based on the target speed.

PRF = 1 / PRI
= Twice the target speed / wavelength of the transmitted wave (1)
For example, when the maximum speed of the target is 2 Mach and the frequency of the transmission wave is 3 GHz, the PRI is 73.3 μs. The pulse signal generator 10 generates a modulated pulse signal according to the designated high PRF. At this time, the beam scheduler 80 causes the pulse signal generation unit 10 to generate a modulated pulse signal 64 times per beam position so that, for example, clutter suppression in the FFT processing unit 72 is performed in 64 banks.

  FIG. 5 is a schematic diagram showing a search range of the radar apparatus according to the first embodiment of the present invention. In this embodiment, the search range is 90 degrees in azimuth and the elevation angle is 60 degrees, and the beams are changed at intervals of 3 degrees. Circles in FIG. 5 indicate each beam position. A transmission wave based on the modulated pulse signal generated by the pulse signal generation unit 10 is transmitted 64 times to each beam position.

  The antenna 40 transmits a transmission wave to each beam position, and receives a reflected wave in which the transmission wave is reflected by a target. The reflected wave received by the antenna 40 is converted into a video signal via the receiving device 50 and the demodulator 60 and supplied to the signal processing device 70.

  FIG. 6 is a diagram schematically illustrating the removal of clutter components by the FFT processing unit 72. The FFT processing unit 72 removes the clutter component from the 64 FFT detected bank information with the value of the bank including the clutter component as zero. The FFT processing unit 72 outputs the signal after the clutter component removal to the search processing unit 73.

  The search processing unit 73 receives the signal from which the clutter component has been removed by the FFT processing unit 72, and stores the bank number and the beam position at that time when the intensity exceeding the preset threshold on the frequency axis is detected as a search result. 731 (step 22). When the transmission of the transmission wave at all beam positions is completed, the search processing unit 73 refers to the search result recorded in the memory 731 and determines whether there is a beam position whose detected intensity exceeds the threshold (step 23). ). When there is a beam position exceeding the threshold (Yes in Step 23), the search processing unit 73 selects a PRI suitable for the verification process based on the table 732 from the bank number (Doppler information) at the beam position (Step 24). .

  FIG. 7 is a schematic diagram when selecting a PRI suitable for the test process. In FIG. 7, for example, five PRIs (PRI1 to PRI5) are registered in the table 732 in advance. The PRI here is a value obtained based on a low PRF that satisfies the following expression.

PRI = 1 / PRF
= Processing distance ÷ (Speed of light / 2) + Pulse width (2)
For example, when the processing distance is 120 km and the pulse width is 50 μm, the PRI is 850 μs.

In table 732, based on the bank number where the intensity exceeding the threshold is detected,
(Detection bank number x 1 bank bandwidth) x Candidate PRI
The PRI in which the decimal of the calculation result is in the range of 0.4 to 0.6 is selected as the PRI suitable for the test process. FIG. 8 is a schematic diagram showing an MTI blind of a multi-Doppler filter in the MTI processing unit 74. As shown in FIG. 8, MTI blinds occur at multiples of PRF. Therefore, by selecting the PRI as shown in FIG. 7, it is possible to match the effective range of the Doppler filter to the Doppler frequency of the target, and to avoid the MTI blind.

  When the search processing unit 73 selects a PRI suitable for the verification process in step 24, the search processing unit 73 notifies the beam scheduler 80 of the PRI selected in step 24 as well as shifting to the verification process (step 25). In addition, the search processing unit 73 gives an instruction to the beam scheduler 80 so as to perform the verification process only on the beam position where the bank having the detected intensity exceeding the threshold exists (step 26). On the other hand, if there is no beam position where there is a bank whose detected intensity exceeds the threshold (No in Step 23), the process proceeds to Step 21 and the search process is repeated.

  The beam scheduler 80 determines whether the search processing unit 73 shifts to the verification process and whether there is a notification of the selected PRI (step 43). When there is a notification from the search processing unit 73 (Yes in Step 43), the beam scheduler 80 sets the high PRF set for the pulse signal generation unit 10 to the low PRF based on the PRI notified from the search processing unit 73. (Step 44), and instructs the switching unit 71 to switch the derivation of the video signal to the MTI processing unit 74 (step 45).

  The pulse signal generator 10 generates a modulated pulse signal according to the newly set low PRF. At this time, the beam scheduler 80 generates a modulated pulse signal for a predetermined number of times per beam position in accordance with the beam position instruction for performing the verification process from the search processing unit 73 (step 46).

  The antenna 40 transmits a transmission wave to a designated beam position, and receives a reflected wave in which the transmission wave is reflected by a target. The reflected wave received by the antenna 40 is converted into a video signal via the receiving device 50 and the demodulator 60 and supplied to the signal processing device 70. The MTI processing unit 74 removes clutter components from the video signal and outputs the video signal to the verification / tracking processing unit 75.

  The verification / tracking processing unit 75 receives the signal from which the clutter component has been removed by the MTI processing unit 74 and measures the distance at which the intensity exceeding the preset threshold is detected on the time axis, thereby detecting the search process. The verified target is verified (step 31). Then, the verification / tracking processing unit 75 records the verification result in the memory 751 (step 32). When the verification process at the designated beam position is completed, the verification / tracking processing unit 75 starts the tracking process for the target confirmed as the target in the verification process (step 33). In the tracking process, the pulse signal generation unit 10 generates a modulated pulse signal according to the same low PRF as in the verification process.

  As described above, in the first embodiment, when searching for a target using the high PRF method and performing target verification, the PRF of the verification beam is selected based on the Doppler frequency acquired during the search. Switching to the low PRF. Thus, since the search is performed by the high PRF method, the number of pulse hits per one beam position is increased, and the clutter suppression capability is improved. That is, even when the beam position is directed in one direction is short, the target can be reliably detected.

  In addition, range ambiguity occurs in the search for a target by the high PRF method, but since it is switched to the low PRF method at the time of verification, it is not necessary to use multi-PRF ranging by a plurality of types of high PRF. Mistakes are reduced.

  Further, since the low PRF at the time of verification is selected based on the Doppler frequency acquired at the time of searching, it is possible to avoid MTI blinds in the MTI processing.

  In the first embodiment, the verification process is performed only on the beam position where the target is detected during the search. Thereby, it becomes possible to perform a test process efficiently.

  Therefore, the radar apparatus according to the present invention can quickly identify a target at the search stage and accurately measure the distance to the target at the verification stage.

[Second Embodiment]
FIG. 9 is a block diagram showing a functional configuration of a radar apparatus according to the second embodiment of the present invention. In FIG. 9, parts common to those in FIG. 1 are given the same reference numerals, and only different parts will be described here.

  The beam scheduler 90 switches the PRF in the pulse signal generator 10 to a different high PRF every time the search processor 73 repeats the search process. FIG. 10 is a flowchart showing a control flow of the beam scheduler 90 of the radar apparatus according to the second embodiment, and FIG. 11 is a schematic diagram of transmission waves transmitted according to two types of high PRF.

  When the search processing is performed by the search processing unit 73, the beam scheduler 90 designates the high PRF 1 for the pulse signal generation unit 10 (step 101), and derives the video signal to the FFT processing unit 72 for the switching unit 71. Instruct to do so (step 102).

  The beam scheduler 90 determines whether the search processing unit 73 shifts to the verification process and whether there is a notification of the selected PRI (step 103). When there is a notification from the search processing unit 73 (Yes in Step 103), the beam scheduler 90 sets the high PRF set for the pulse signal generation unit 10 to the low PRF based on the PRI notified from the search processing unit 73. (Step 104), and instructs the switching unit 71 to switch the derivation of the video signal to the MTI processing unit 74 (step 105).

  On the other hand, the beam scheduler 90 determines whether or not the search processing unit 73 performs the search process again when there is no notification of the transition from the search processing unit 73 to the verification process and the notification of the selected PRI (No in step 103). (Step 106). When search processing is performed again in the search processing unit 73 (Yes in step 106), the PRF of the pulse signal generation unit 10 is switched to another type of high PRF (for example, switching from high PRF1 to high PRF2) (step 107). Then, the process proceeds to step 103. If search processing is not performed again in the search processing unit 73 (No in step 106), the process proceeds to step 103.

  The pulse signal generator 10 generates a modulated pulse signal according to the newly set low PRF. At this time, the beam scheduler 90 generates a modulated pulse signal a predetermined number of times per beam position in accordance with the beam position instruction for performing the verification process from the search processing unit 73 (step 108).

  As described above, in the second embodiment, the beam scheduler 90 switches the PRF of the pulse signal generation unit 10 at the time of searching among a plurality of types of high PRFs. When the radar apparatus employs the high PRF method, a reflected wave cannot be received while a transmission wave is being transmitted, so that a transmission blind as shown in FIG. 11 occurs. Depending on the distance of the target, the reflected wave may not be received by this transmission blind. In the radar apparatus according to the present embodiment, transmission blinds can be avoided by switching between high PRF 1 and high PRF 2 during search.

  In the second embodiment, the example of switching to a different high PRF every time the search process is repeated has been described. However, the present invention can be similarly implemented even when switching to a different high PRF within one beam position.

  In the second embodiment, the example in which two types of high PRFs are switched has been described. However, the types of high PRFs need not be limited to two types, and a plurality of high PRFs may be selected according to the required processing distance. It may be switched using.

[Third Embodiment]
FIG. 12 is a block diagram showing a functional configuration of a radar apparatus according to the third embodiment of the present invention. In FIG. 12, parts that are the same as those in FIG. 1 are given the same reference numerals, and only different parts will be described here.

  The search / verification / tracking processing unit 76 performs target search processing, verification processing, and tracking processing based on the signal from which the clutter component has been removed by the MTI processing unit 74.

  FIG. 13 is a schematic diagram showing a search range of a radar apparatus according to the third embodiment of the present invention. In the present embodiment, the processing by the beam scheduler 100 differs between a low elevation angle (0 to 15 degrees) and a high elevation angle (15 to 90 degrees). At the low elevation angle, the search processing unit 73 performs search processing, and the search / verification / tracking processing unit 76 performs search processing and tracking processing. At high elevation angles, the search / verification / tracking processing unit 76 performs search processing, search processing, and tracking processing.

  The beam scheduler 100 performs processing similar to the flow shown in FIG. 4 at a low elevation angle. That is, the beam scheduler 100 designates a high PRF for the pulse signal generation unit 10 and instructs the switching unit 71 to derive the video signal to the FFT processing unit 72. The search process is performed. When the target is detected by the search processing in the search processing unit 73, the low PRF based on the Doppler frequency acquired by the search processing is specified for the pulse signal generation unit 10, and the switching unit 71 is specified. By instructing the video signal to be derived to the MTI processing unit 74, the search / verification / tracking processing unit 76 performs the verification process. In addition, when the tracking process is performed by the verification / tracking processing unit 75, the beam scheduler 100 designates the same low PRF as that at the time of verification to the pulse signal generation unit 10.

  Further, the beam scheduler 100 designates a low PRF for the pulse signal generation unit 10 and instructs the switching unit 71 to derive a video signal to the MTI processing unit 74 at a high elevation angle. The search / verification / tracking processing unit 76 performs target search processing, verification processing, and tracking processing.

  Next, the search time according to the high PRF method at one beam position is compared with the search time according to the low PRF method. Here, a comparison is made on the assumption of a clutter suppression capability of approximately 60 dB.

The PRI in the search process when adopting the high PRF method is obtained by the equation (1), and is 73.3 μs when the maximum velocity of the target is 2 Mach and the frequency of the transmission wave is 3 GHz. Here, it is assumed that a transmission wave is transmitted 64 times per beam position in order to achieve 60 dB of clutter suppression capability. At this time, the search time per beam position is
73.3 × 64 = about 4.7 ms
It becomes.

On the other hand, the PRI in the search process when adopting the low PRF method is obtained by the equation (2), and is 850 μs when the processing distance is 120 km and the pulse width is 50 μm. Here, in order to achieve a clutter suppression capability of 60 dB, the 3-pulse MTI and 9-pulse Doppler processing is performed per beam position. That is, since 10 pulses are required per beam position, the search time per beam position is
850 × 10 = 8.5 ms
It becomes. Thus, the search process using the high PRF method has a shorter search time than the search process using the low PRF method. That is, by adopting the high PRF method at a low elevation angle, the search time does not increase as compared with the case of adopting the low PRF method.

  As described above, in the third embodiment, the high PRF method is adopted in the search processing at a low elevation angle, and the low PRF method is adopted in the search processing at a high elevation angle. In other words, by adopting a high PRF method for search processing at a low elevation angle, which is assumed to be a strong clutter environment, it is possible to increase the number of pulse hits per beam position, thereby suppressing clutter at a low elevation angle. The performance can be improved. In addition, the range ambiguity that occurs when adopting the high PRF method is eliminated at the time of verification using the low PRF method, so the search time for the high PRF method is the same as when the low PRF method is used. Even if it compares, it does not increase.

[Other Embodiments]
The present invention is not limited to the above embodiments. For example, the radar apparatus in each of the above embodiments may further include a guidance processing unit that guides the flying object to the target after searching, testing, and tracking the target.

  Furthermore, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 10 ... Pulse signal generation part 40 ... Antenna 41 ... Element antenna 42 ... Transmission / reception module 43 ... Feeding circuit 50 ... Reception apparatus 60 ... Demodulation part 70 ... Signal processing apparatus 71 ... Switching part 72 ... FFT processing part 73 ... Search processing part 731 ... Memory 732 ... Table 74 ... MTI processing unit 75 ... Verification / tracking processing unit 751 ... Memory 76 ... Search / verification / tracking processing units 80, 90, 100 ... Beam scheduler

Claims (6)

Transmission pulse generating means for repeatedly generating a transmission pulse according to a designated PRF (Pulse Repetition Frequency);
A transmission / reception means for transmitting the transmission pulse generated by the transmission pulse generation means toward the space and receiving the reflected pulse reflected by the target;
Switching means for selectively switching derivation of the received reflected pulse;
The clutter component included in the reflected pulse derived from the switching means is removed, the target is searched based on the signal, and when the target is detected by the search, the Doppler information of the target is acquired, Search means for selecting a PRI (Pulse Repetition Interval) capable of avoiding an MTI (Moving Target indicator) blind based on Doppler information, and generating direction information about a detection direction in which the target is detected ;
A test unit for removing a clutter component included in the reflected pulse derived from the switching unit and verifying a target detected by the search unit based on the signal;
A control means for designating a PRF for the transmission pulse generating means and controlling the switching means;
The control means includes
In the initial state, no frequency ambiguity is generated in the processing of the reflected pulse, but a high PRF in which range ambiguity is generated is designated to the transmission pulse generating means, and the transmission pulse generated according to the high PRF is used. Switching the switching means so that reflected pulses are derived to the search means;
When the target is detected by the search means and the PRI is selected and the direction information is generated , no range ambiguity is generated in the processing of the reflected pulse based on the PRI , but the frequency ambiguity is not generated. The generated low PRF is designated to the transmission pulse generation means, the transmission pulse generated according to the low PRF is transmitted in the detection direction, and the transmission / reception means is controlled to receive the reflection pulse from the direction. , Switching the switching means so that the received reflected pulse is derived to the verification means,
The search means includes
An FFT processing unit that removes clutter components by performing FFT (Fast Fourier Transform) processing on the reflected pulse of the transmission pulse generated according to the high PRF;
The target is searched based on a signal from the FFT processing unit, and when the target is detected in the search, the Doppler information of the target is acquired, the PRI is selected based on the Doppler information, and the direction A search processing unit for generating information ,
The test means is
An MTI processing unit that performs MTI processing on a reflection pulse by a transmission pulse generated according to the low PRF and removes a clutter component;
A test / tracking processing unit that tests the target detected by the search means based on the signal from the MTI processing unit , records the result of the test, and tracks the target confirmed as the target in the testing process A radar apparatus comprising: When the transmission of the transmission pulse by the transmission / reception unit is equal to or higher than a preset elevation angle, the verification unit removes a clutter component included in the reflected pulse derived from the switching unit, and determines the target based on the signal. search, and if the target by the search is detected, it has rows the detection and target of the assay,
The control means includes
When transmission of the transmission pulse by the transmission / reception means is greater than or equal to a preset elevation angle , range ambiguity does not occur in the processing of the reflected pulse, but low PRF in which frequency ambiguity is generated is sent to the transmission pulse generation means 2. The radar apparatus according to claim 1, wherein the switching means is switched so that a reflected pulse by a transmission pulse designated according to the low PRF is derived to the verification means.   2. The radar apparatus according to claim 1, wherein the control means switches a plurality of types of high PRFs cyclically and designates them to the transmission pulse generation means in an initial state. A radar signal processing method used in a radar device that searches and verifies a target based on a reflected pulse generated when a transmission pulse is reflected by the target,
No frequency ambiguity is generated in the processing of the reflected pulse, but the transmission pulse is generated according to a high PRF in which range ambiguity is generated,
The reflected pulse from the target is subjected to FFT (Fast Fourier Transform) processing to remove clutter components,
Searching for the target based on the signal from which clutter components have been removed by the FFT processing;
When the target is detected in the search, the Doppler information of the target is acquired, and a PRI (Pulse Repetition Interval) that can avoid an MTI (Moving Target indicator) blind is selected based on the Doppler information. Generate direction information about the detected direction of detection ,
When the target is detected in the search and the PRI is selected and the direction information is generated , no range ambiguity is generated in the processing of the reflected pulse but frequency ambiguity is generated based on the PRI. Selecting a low PRF to be generated, generating the transmission pulse according to the low PRF, transmitting the transmission pulse generated according to the low PRF in the detection direction,
The reflected pulse from the target is subjected to MTI processing to remove clutter components,
The target detected in the search is verified based on the signal from which clutter components have been removed by the MTI processing ,
A radar signal processing method , wherein the test result is recorded, and a target confirmed as a target in the verification process is tracked . When the transmission pulse is transmitted in a direction greater than a preset elevation angle,
Range ambiguity does not occur in the processing of the reflected pulse, but the transmission pulse is generated according to a low PRF in which frequency ambiguity occurs,
The reflected pulse from the target is subjected to MTI (Moving Target indicator) processing to remove clutter components,
Searching for the target based on a signal from which clutter components have been removed by the MTI processing;
If the target is detected in the search, the detected target is verified ,
5. The radar signal processing method according to claim 4 , wherein the result of the verification is recorded, and the target confirmed as the target in the verification process is traced . 5. The radar signal processing method according to claim 4 , wherein the high PRF at the time of generating the transmission pulse is cyclically switched from a plurality of types of high PRF.

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