JP2011122839A - Radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar system capable of precisely detecting a target with a low computational load, even when the coherence between polarization channels in a reception signal is reduced. <P>SOLUTION: The radar device includes: two antennas 4, 5 having different polarization characteristics; a polarization switch 2, which continuously outputting a pulse signal a plurality of times to one of the antennas 4, 5 and then continuously outputting it a plurality of times to the other; a Doppler processing means 10 for calculating a Doppler spectrum of the reception signal; a mean power calculation means 11 generating a mean power range Doppler map; a mean total power calculation means 12 generating a mean total power range Doppler map; a CFAR means 13 normalizing a power value of each cell of interest by a mean power of a reference cell; a threshold-processing means 14 detecting a cell having a power value exceeding a threshold; a power ratio calculation means 15 for calculating the power ratio regarding the detected cell; and a determination processing means 16 for executing processing for discriminating between a clutter and the target, on the basis of the power ratio. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radar apparatus that detects a small moving target in a clutter environment.

  A radar device that detects a moving small target using radar, for example, is installed in an aircraft or other platform and observes the surface of the earth and the sea surface by transmitting and receiving radio waves from the sky, and exists near the earth surface and the sea surface. A small target is detected. Here, the small target means a target having a low radio wave reflection intensity, and is not necessarily a target having a small physical size.

  When a radar device mounted on an aircraft or other platform is used to observe the ground surface or the vicinity of the sea surface, a strong echo (hereinafter referred to as ground clutter or sea clutter) is generally called ground clutter or sea clutter from the ground surface or sea surface. Is simply referred to as “clutter”). Therefore, in order to detect an echo (target signal) from a target existing near the ground surface or the sea surface from the received signal, it is necessary to suppress clutter in advance.

As a clutter suppression method in a conventional radar apparatus, a method called MTI (Moving Target Indicator) that suppresses clutter using a Doppler frequency difference between a clutter and a target signal is known (for example, see Non-Patent Document 1). ).
This method assumes a small target that moves like a vehicle or a ship, discriminates a clutter and a target signal based on a speed difference between the background and the target, and suppresses the clutter.

Further, as a clutter suppression method used when detecting a stationary target, a method of suppressing clutter by paying attention to a difference in polarization characteristics between a background and a target is known (see, for example, Non-Patent Document 2). ).
In this method, for example, radio waves are transmitted and received by a combination of two orthogonal polarizations, such as horizontal polarization (H polarization) and vertical polarization (V polarization), and the polarization characteristics between the background and the target. And the component corresponding to the polarization characteristic of the clutter is suppressed from the received signal.

Furthermore, as another clutter suppression method, a method is known in which the Doppler frequency and polarization characteristics of the received signal are analyzed, and components corresponding to the Doppler frequency and polarization characteristics of the clutter are suppressed from the received signal. (For example, refer nonpatent literature 3).
This method generates an adaptive filter in the polarization-time signal to suppress clutter. According to this method, compared to a method such as MTI for a moving target, the clutter can be suppressed by the difference in polarization characteristics between the clutter and the target signal, so that the clutter suppression performance and target detection can be suppressed. Performance is improved.

However, the clutter suppression method described in Non-Patent Document 3 has problems in that prior information on the target polarization characteristic is required and the amount of calculation is very large.
Therefore, with respect to the clutter suppression method described in Non-Patent Document 3, the clutter suppression processing by polarization signal processing is executed after the clutter suppression processing by Doppler processing, thereby reducing the order of the matrix used for the matrix operation. A technique for reducing the amount is shown (for example, see Patent Document 1).

JP 2006-349477 A

M.M. I. Skolnik, “Introduction to Radar Systems”, Third Edition, McGraw-Hill, 2008 L. M.M. Novak, M .; C. Burl, W .; W. Irving, “Optimal polarimetric processing for enhanced target detection”, IEEE Transactions on Aerospace and Electronic Systems, Vol. 29, no. 1, pp. 234-244, Jan. 1993 D. Pastina et al. "Adaptive Polaristic Target Detection with Coherent Radar", IEEE International Radar Conf. 2000, pp. 93-97

However, the prior art has the following problems.
In the clutter suppression method described in Non-Patent Document 1, when the Doppler frequency of the target signal matches the Doppler frequency of the clutter, such as a vehicle stationary on the ground surface or a ship floating on the sea surface, Even if the target is moving, if the Doppler frequency of the clutter spreads and overlaps with the Doppler frequency of the target signal, there is a problem that the target signal is also suppressed. In addition, when the target signal intensity is very small, there is a problem that the target signal may not be sufficiently detected even if clutter is suppressed.

  In addition, in the clutter suppression method described in Non-Patent Document 2, when the polarization characteristics of the background and the target coincide with each other, or when the difference in polarization characteristics is small, the target signal is output even if the clutter is suppressed. There is a problem that it may not be detected sufficiently.

  The clutter suppression methods described in Patent Documents 2 to 4 all suppress clutter based on the difference between the polarization characteristics of the background and the target. A signal processing algorithm has been constructed on the assumption that it is acquired up to. In order to measure the target polarization characteristics, it is necessary to transmit signals of two or more different polarization states, such as horizontal polarization and vertical polarization, for example.

  Therefore, in order to add a function (polarimetry) for measuring polarization characteristics to the pulse Doppler radar, it is necessary to transmit transmission pulses having different polarization states for each pulse, and pulse repetition per polarization channel. There has been a problem that the cycle (PRF: Pulse Repetition Frequency) is lowered.

  Here, during one coherent processing time (CPI: Coherent Processing Interval), transmission pulses having the same polarization state are continuously transmitted, and transmission pulses are transmitted by changing the polarization state when entering the next CPI. Thus, it is conceivable to secure a PRF per polarization channel. In this case, since the PRF does not decrease, the performance for dealing with the high-speed movement target is improved.

  However, since the state of the sea surface, moving target, etc. changes during CPI (the background and the state of the target are time-varying), when transmitting by changing the polarization state of the transmission pulse for each CPI, There is a problem that the coherence between the polarization channels in the received signal decreases.

  The present invention has been made to solve the above-described problem, and can detect a target with high accuracy with a low calculation load even when coherence between polarization channels in a received signal is reduced. An object of the present invention is to obtain a radar apparatus capable of

  The radar apparatus according to the present invention includes two antennas having mutually different polarization characteristics, radiating a pulse signal generated by an oscillator to space, and receiving a scattered wave scattered by an observation target as a reception signal. A polarization switching device provided between the oscillator and the antenna, which continuously outputs a pulse signal to one side of the antenna a plurality of times and then outputs the pulse signal to the other side of the antenna a plurality of times; and a received signal for each range cell FFT processing, Doppler processing means to calculate the Doppler spectrum for each range cell, and for each polarization channel, calculate the average power of the range Doppler map for multiple frames, and generate the average power range Doppler map For the average power calculation means and each resolution cell, calculate the sum of the average power range and Doppler map, Average total power calculation means for generating average total power range / Doppler map, and CFAR for normalizing the power value of each cell of interest with the average power of the corresponding reference cell for the average total power range / Doppler map And a threshold value processing means for detecting a cell having a power value exceeding the threshold value by comparing the power value normalized with the average power of the reference cell with a preset threshold value, and detected by the threshold value processing means. Power ratio calculating means for calculating the cross polarization vs. VV polarization power ratio and the HH polarization vs. VV polarization power ratio, and the cross polarization vs. VV polarization power ratio and the HH polarization vs. VV polarization power. Based on the ratio, there is provided discrimination processing means for executing discrimination processing between the clutter and the target.

According to the radar apparatus of the present invention, the two antennas having different polarization characteristics change the polarization state for each CPI and radiate transmission pulses to the space under the control of the polarization switching device. Thereby, since the PRF per polarization channel does not decrease, it is possible to improve the performance for dealing with a high-speed movement target.
Also, if the background or target state is time-varying, the coherence between the polarization channels in the received signal is reduced, but the discrimination processing means uses only the power ratio between the polarization channels to obtain the clutter and the target signal. Determine.
Therefore, even when the coherence between the polarization channels in the received signal is reduced, it is possible to obtain a radar apparatus that can detect a target with high accuracy with a low calculation load.

It is a block block diagram which shows the radar apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows the operation mode of each time of the horizontal polarization antenna and vertical polarization antenna in the radar apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows the operation mode of each time of the horizontal polarization antenna and the vertical polarization antenna in the conventional radar apparatus. It is explanatory drawing which shows operation | movement of the radar apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows the operation mode of each time of the horizontal polarization antenna and vertical polarization antenna in the radar apparatus which concerns on Embodiment 2 of this invention.

  Hereinafter, preferred embodiments of a radar apparatus according to the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts will be described with the same reference numerals.

Embodiment 1 FIG.
1 is a block diagram showing a radar apparatus according to Embodiment 1 of the present invention.
In FIG. 1, this radar apparatus includes an oscillator 1, a polarization switching device 2, transmission / reception switching devices 3a and 3b, a horizontal polarization antenna 4, a vertical polarization antenna 5, a horizontal polarization receiver 6, and a vertical polarization receiver 7. , A memory 8 and a small target detecting means 9 are provided.

  The oscillator 1 is connected to the horizontal polarization antenna 4 and the vertical polarization antenna 5 through the polarization switching device 2 and the transmission / reception switching devices 3a and 3b. The horizontal polarization antenna 4 and the vertical polarization antenna 5 are connected to the horizontal polarization receiver 6 and the vertical polarization receiver 7 via transmission / reception switchers 3a and 3b, respectively. The horizontal polarization receiver 6 and the vertical polarization receiver 7 are connected to a memory 8, and the memory 8 is connected to a small target detection means 9.

  The small target detecting means 9 includes a Doppler processing (FFT) means 10, an average power calculating means 11, an average total power calculating means 12, a CFAR (Constant False Alarm Rate) means 13, a threshold processing means 14, a cross polarization. A VV polarization power ratio / HH polarization to VV polarization power ratio calculation means 15 and a discrimination processing means 16 are provided.

Here, the small target detection means 9 is constituted by a microprocessor (not shown) having a CPU and a storage means for storing a program, and each block constituting the small target detection means 9 has software stored in the storage means. Is remembered as
Further, the cross polarization vs. VV polarization power ratio / HH polarization vs. VV polarization power ratio calculation means 15 is hereinafter abbreviated as “power ratio calculation means 15”.

Next, the operation of the radar apparatus according to Embodiment 1 of the present invention will be described.
The oscillator 1 generates a pulse signal and outputs it to the polarization switching device 2. The polarization switching unit 2 first outputs the pulse signal from the oscillator 1 to the transmission / reception switching unit 3a. The transmission / reception switch 3 a outputs the pulse signal from the polarization switch 2 to the horizontal polarization antenna 4. The horizontally polarized antenna 4 radiates the pulse signal from the transmission / reception switch 3a to the space.

  The pulse signal radiated into space is scattered by the observation target. The horizontally polarized antenna 4 and the vertically polarized antenna 5 each receive a scattered wave scattered by the observation target and output it to the transmission / reception switchers 3a and 3b. The transmission / reception switchers 3a and 3b output scattered waves from the horizontal polarization antenna 4 and the vertical polarization antenna 5 to the horizontal polarization receiver 6 and the vertical polarization receiver 7, respectively.

The horizontally polarized wave receiver 6 and the vertically polarized wave receiver 7 execute a phase detection process and an A / D change process on the received signals of the scattered waves received by the horizontal polarization antenna 4 and the vertical polarization antenna 5 respectively. Then, a digital reception signal indicating the amplitude and phase of the reception signal is output to the memory 8.
The transmission / reception of the pulse signal described above is repeated N times. The time required for the N times of transmission / reception corresponds to 1 CPI (coherent processing time).

  Next, the oscillator 1 generates a pulse signal again and outputs it to the polarization switching device 2. The polarization switch 2 then outputs the pulse signal from the oscillator 1 to the transmission / reception switch 3b. The transmission / reception switch 3 b outputs the pulse signal from the polarization switch 2 to the vertical polarization antenna 5. The vertically polarized antenna 5 radiates the pulse signal from the transmission / reception switch 3b to the space.

  The horizontal polarization antenna 4 and the vertical polarization antenna 5 receive scattered waves scattered by the observation target, respectively, and the scattered waves are transmitted through the transmission / reception switchers 3a and 3b to the horizontal polarization receiver 6 and the vertical polarization receiver. 7 is output. The horizontal polarization receiver 6 and the vertical polarization receiver 7 perform phase detection processing and A / D change processing on the received scattered wave reception signals, and output digital reception signals to the memory 8.

  By observing 2 CPI (twice CPI), it is possible to observe four combinations of transmission / reception polarization using the horizontally polarized antenna 4 and the vertically polarized antenna 5. Specifically, horizontal polarization transmission / horizontal polarization reception (HH), horizontal polarization transmission / vertical polarization reception (HV), vertical polarization transmission / horizontal polarization reception (VH), and vertical polarization transmission / vertical Four types of polarization reception (VV) can be observed. Here, a set of two CPIs is referred to as a “frame”.

FIG. 2 is a timing chart showing the operation modes at each time of the horizontally polarized antenna 4 and the vertically polarized antenna 5 in the radar apparatus according to Embodiment 1 of the present invention.
As shown in FIG. 2, during 1 CPI, a pulse signal is radiated into space by only one of the horizontally polarized antenna 4 and the vertically polarized antenna 5. Further, the scattered waves scattered by the observation target are simultaneously received by the horizontal polarization antenna 4 and the vertical polarization antenna 5.
That is, since transmission pulses having the same polarization state are continuously transmitted, the PRF per polarization channel does not decrease.

FIG. 3 is a timing chart showing operation modes of the horizontal polarization antenna and the vertical polarization antenna at each time in the radar apparatus described in Patent Document 1 described above.
As shown in FIG. 3, in the conventional radar apparatus, pulse signals are alternately radiated from the horizontal polarization antenna and the vertical polarization antenna to the space. In this case, for example, a pulse signal transmitted from the horizontal polarization antenna 4 and received by the horizontal polarization antenna 4 is observed only every other pulse.
Therefore, regarding the polarization channel of horizontal polarization transmission / horizontal polarization reception (HH), the PRF per polarization channel is reduced to half of the actual pulse transmission / reception frequency.

  Returning to FIG. 1, the memory 8 temporarily stores the digital reception signals output from the horizontal polarization receiver 6 and the vertical polarization receiver 7, and outputs the stored digital reception signals to the small target detection means 9. The small target detecting means 9 detects the small target by Doppler processing or polarization signal processing.

Here, before describing the operation of each means of the small target detecting means 9, the signals input to the small target detecting means 9 will be defined.
First, it is assumed that a range profile is observed for each pulse, and M is the number of range cells at this time. Each time one pulse signal is transmitted, the horizontal polarization antenna 4 and the vertical polarization antenna 5 receive the signal, so that signals for M range cells × 2 polarization channels in total are observed for each pulse. Since transmission / reception of a pulse signal is repeated N times during 1 CPI, signals corresponding to M range cell × 2 polarization channels × N hits are observed during 1 CPI. Furthermore, since one frame includes two CPIs, signals for four polarization channels are observed.

  That is, signals for M range cells × 2 polarization channels × N hits are observed during one frame. By repeating this observation for K frames, signals for M range cells × 2 polarization channels × N hits × K frames are observed. The small target detection means 9 receives signals for this M range cell × 2 polarization channels × N hits × K frames.

Hereinafter, the operation of each unit of the small target detection unit 9 will be described in detail.
The Doppler processing (FFT) means 10 obtains a Doppler spectrum for each range cell by performing FFT processing on signals for 1 CPI (N hits) for each range cell. As a result of the Doppler processing, 4K (4 polarization channels, K frames) M × N range-Doppler maps are generated, and the Doppler processing (FFT) means 10 supplies the range-Doppler map to the average power calculation means 11. Output.

  The average power calculation means 11 calculates the average power of the range-Doppler map for K frames for each polarization channel. That is, the average power calculation unit 11 generates 4 (4 polarization channels) M × N average power range / Doppler maps, and outputs them to the average total power calculation unit 12 and the power ratio calculation unit 15.

  The average total power calculation means 12 calculates the sum of the average power range / Doppler map for four polarization channels for each resolution cell, generates a total power range / Doppler map, and outputs it to the CFAR means 13. Here, the total power of the four polarization channels is referred to as “total power”. The output from the average total power calculating means 12 is one M × N average total power range / Doppler map.

  The CFAR unit 13 applies the CFAR process to the average total power range / Doppler map from the average total power calculation unit 12. The CFAR process is a known technique described in, for example, “Radar Technology (Electronic Information and Communication Society)”. In FIG. 1, CFAR processing refers to processing for normalizing the power value of the target cell with the average power of the reference cell.

FIG. 4 shows a method for setting a target cell, guard cell, and reference cell in the CFAR process.
In FIG. 4, optimal values are set for the number of guard cells and reference cells according to the system. 4 is based on the Cell Average Linear CFAR process, the type of the CFAR process is not limited to this, and for example, the Log CFAR process may be applied.
As a result of the CFAR process, a power value obtained by normalizing the power value of each sample (each target cell) of the M × N average total power range / Doppler map with the average power of the corresponding reference cell is obtained. 13 outputs the normalized power value to the threshold processing means 14.

  The threshold processing means 14 compares the power value normalized by the average power of the reference cell with a preset threshold value, and detects a cell having a power value exceeding the threshold value. As a result of the comparison process, a binary map indicating whether or not each cell of the M × N range / Doppler map is detected is generated, and the threshold processing unit 14 outputs the binary map to the power ratio calculation unit 15.

  Here, in order to enable detection of a small target, the threshold is set low. If the threshold is set lower, the target detection probability is improved, but at the same time, the false detection probability of erroneously detecting clutter is increased. Therefore, the clutter and the target signal are discriminated by processing using the target polarization characteristics shown below.

  The power ratio calculation means 15 calculates the cross polarization-to-VV polarization power ratio and the HH polarization-to-VV polarization power ratio for the cell detected by the threshold processing means 14 and outputs them to the discrimination processing means 16. Specifically, the power ratio calculation unit 15 uses the four average power range / Doppler maps generated by the average power calculation unit 11 and the binary map generated by the threshold processing unit 14 to use the VV bias. Normalize the power of other polarization channels with wave power.

  The discrimination processing means 16 executes discrimination processing between the clutter and the target signal based on the cross polarization vs. VV polarization power ratio and the HH polarization vs. VV polarization power ratio. The threshold value for discrimination is determined in advance by experiments or computer simulation. A plurality of determination threshold values may be prepared so that they can be selected according to the assumed polarization characteristics of the background and the target.

  As described above, in the case of transmitting by changing the polarization state of the transmission pulse for each CPI, the coherence between the polarization channels is reduced, so that the phase information is almost expected to contribute to the discrimination. I can't. Therefore, the discrimination processing means 16 is characterized in that the clutter and the target signal are discriminated using only the power ratio between the polarization channels. Thereby, even if compared with the thing of patent document 1, the amount of calculations can be reduced significantly.

As described above, according to the first embodiment, in a pulse Doppler radar having a polarimetry function, two antennas having different polarization characteristics change the polarization state for each CPI under the control of the polarization switching unit. A transmission pulse is radiated into the space by changing. Thereby, since the PRF per polarization channel does not decrease, it is possible to improve the performance for dealing with a high-speed movement target.
In addition, if the background or target state is time-varying, the coherence between the polarization channels in the received signal decreases, but the discrimination processing means does not use the information on the phase difference between the polarization channels. The clutter and the target signal are discriminated using only the power ratio between them.
Therefore, even when the coherence between the polarization channels in the received signal is reduced, it is possible to obtain a radar apparatus that can detect a target with high accuracy with a low calculation load.

  In the first embodiment, the combination of horizontal polarization and vertical polarization has been described as an example. However, the present invention is not limited to this. Any two polarizations (first polarization and second polarization) are described. May be combined. As a combination of two polarized waves, for example, a combination of a left-handed circularly polarized wave and a right-handed circularly polarized wave can be cited. In addition, on implementation, left-handed circularly polarized wave and right-handed circularly polarized wave can be obtained by using a horizontally polarized wave antenna and a vertically polarized wave antenna to advance the feeding phase difference between both antennas by 90 degrees or by delaying 90 degrees. You may send it.

Embodiment 2. FIG.
In the first embodiment, four combinations of transmission / reception polarizations (polarization channels) using the horizontally polarized antenna 4 and the vertically polarized antenna 5 are observed by observing CPI (1 frame) twice. I explained that I can do it. However, the present invention is not limited to this, and a different polarization channel may be observed to discriminate the clutter from the target signal.
Hereinafter, processing for observing six polarization channels and discriminating between a clutter and a target signal will be described. The block diagram showing the radar apparatus according to Embodiment 2 of the present invention is substantially the same as that shown in FIG.

FIG. 5 is a timing chart showing operation modes at each time of the horizontally polarized antenna 4 and the vertically polarized antenna 5 in the radar apparatus according to Embodiment 1 of the present invention.
In FIG. 5, one frame is composed of a set of three CPIs. In the first and second CPI, as in the first embodiment, only one of the horizontally polarized antenna 4 and the vertically polarized antenna 5 radiates a pulse signal to the space.

  Here, in the third CPI, pulse signals are simultaneously radiated from both the horizontally polarized antenna 4 and the vertically polarized antenna 5 to the space. At this time, the polarization switching unit 2 outputs the pulse signal from the oscillator 1 to both the transmission / reception switching units 3a and 3b. Here, it is assumed that circularly polarized waves are equivalently transmitted by shifting the phases of the pulse signals radiated from the horizontally polarized antenna 4 and the vertically polarized antenna 5 by 90 degrees.

  As a result, the four polarization channels observed in the first embodiment (horizontal polarization transmission / horizontal polarization reception (HH), horizontal polarization transmission / vertical polarization reception (HV), vertical polarization) are observed. Transmission / horizontal polarization reception (VH) and vertical polarization transmission / vertical polarization reception (VV)), circular polarization transmission / horizontal polarization reception (CH) and circular polarization transmission / vertical polarization reception (CV) And 6 channels.

Further, in the first embodiment, the discrimination processing means 16 executes the discrimination processing between the clutter and the target signal based on the cross polarization vs. VV polarization power ratio and the HH polarization vs. VV polarization power ratio. In addition, in the radar apparatus according to the second embodiment of the present invention, the CH polarization to VV polarization power ratio and the CV polarization to VV polarization power ratio can be used.
Therefore, in the radar apparatus according to Embodiment 2 of the present invention, the power ratio calculation means (cross polarization vs. VV polarization power ratio / HH polarization vs. VV polarization power ratio calculation means) 15 shown in FIG. Cross polarization vs VV polarization power ratio, HH polarization vs VV polarization power ratio, CH polarization vs VV polarization power ratio, CV polarization vs VV polarization power ratio calculation means (not shown) is doing.

As described above, according to the second embodiment, two antennas having different polarization characteristics can transmit transmission pulses in different polarization states in three CPIs under the control of a polarization switch. Radiates to. As a result, polarization channels for 6 channels are observed.
The discrimination processing means discriminates the clutter and the target signal based on the power ratio of the polarization channels for 6 channels.
Therefore, when the coherence between the polarization channels in the received signal is reduced, the target can be detected with higher accuracy.

  In the second embodiment, circular polarization is equivalently transmitted by shifting the phase of the pulse signal radiated from the horizontal polarization antenna 4 and the vertical polarization antenna 5 by 90 degrees in the third CPI. explained. However, the present invention is not limited to this, and 45-degree linearly polarized waves may be transmitted with the phases of the horizontally polarized antenna 4 and the vertically polarized antenna 5 aligned. Further, an arbitrary polarization state may be transmitted by arbitrarily setting the amplitude ratio and phase of pulse signals radiated from the horizontal polarization antenna 4 and the vertical polarization antenna 5.

  DESCRIPTION OF SYMBOLS 1 Oscillator, 2 Polarization switching device, 3a, 3b Transmission / reception switching device, 4 Horizontal polarization antenna, 5 Vertical polarization antenna, 6 Horizontal polarization receiver, 7 Vertical polarization receiver, 8 Memory, 9 Small target detection means 10 Doppler processing means, 11 Average power calculation means, 12 Average total power calculation means, 13 CFAR means, 14 Threshold processing means, 15 Power ratio calculation means, 16 Discrimination processing means

Claims (3)

Two antennas having different polarization characteristics, radiating a pulse signal generated by an oscillator into space, and receiving a scattered wave scattered by an observation target as a reception signal;
A polarization switching device provided between the oscillator and the antenna, and continuously outputting the pulse signal to one of the antennas a plurality of times, and then outputting to the other of the antennas a plurality of times;
Doppler processing means for calculating a Doppler spectrum for each range cell by performing FFT processing on the received signal for each range cell;
For each polarization channel, an average power calculating means for calculating an average power of the range-Doppler map for a plurality of frames and generating an average power range-Doppler map;
For each resolution cell, calculate the sum of the average power range / Doppler map, and generate an average total power range / Doppler map;
CFAR means for normalizing the power value of each cell of interest with the average power of the reference cell corresponding to the average total power range / Doppler map;
Threshold value processing means for detecting a cell having a power value exceeding the threshold value by comparing the power value normalized by the average power of the reference cell with a preset threshold value;
Power ratio calculation means for calculating a cross polarization vs. VV polarization power ratio and an HH polarization vs. VV polarization power ratio for the cells detected by the threshold processing means;
Discrimination processing means for executing discrimination processing between a clutter and a target based on the cross polarization vs. VV polarization power ratio and the HH polarization vs. VV polarization power ratio;
A radar apparatus comprising: The polarization switching device continuously outputs the pulse signal to one of the antennas a plurality of times, continuously outputs the pulse signal to the other of the antennas a plurality of times, and then continuously to both of the antennas a plurality of times simultaneously. Output,
The radar apparatus according to claim 1, wherein the discrimination processing unit executes the discrimination processing based on a power ratio of polarization channels for six channels. The polarization switch transmits an arbitrary polarization state by arbitrarily setting the amplitude ratio and phase of the pulse signal when the pulse signal is output to both of the antennas simultaneously and continuously several times. The radar apparatus according to claim 2, wherein:

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