JP3421269B2 - Radar signal processing equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar signal processing device, and more particularly to a radar signal processing device suitable for suppressing clutter in signal processing of pulse radar and improving target detection probability and false alarm probability. Regarding

[0002]

2. Description of the Related Art FIG. 8 is a functional block diagram of a conventional radar signal processing device 10 disclosed in Japanese Patent Laid-Open No. 3-248077. In FIG. 8, 12 is a low-pass filter (LP
F), 14 is a clutter map update filter, 16 is a clutter map memory, 18 is a zero Doppler signal target detection circuit, 20 is a threshold averaging cell control circuit,
22 is an MTI (Moving Target Indicator) circuit, 24 is a Doppler filter, and 26 is a CFAR (Constant False A).
Larm Rate) circuits 26 and 28 are target detection determination circuits.

Next, the operation will be described. By processing the radar signal by the low-pass filter 12, a zero Doppler signal, that is, a signal with a Doppler shift near zero is extracted. The zero Doppler signal is averaged by the clutter map update filter 14 for a certain period of time, and stored in the clutter map memory 16 for each azimuth and range cell. At this time, the clutter map update filter 14 updates the contents every time a fixed period of time elapses, and sequentially obtains new average values. If the target is stably at the same position with zero Doppler, the clutter map value at that position will be a relatively large value.

The output from the clutter map memory 16 is
In the zero Doppler signal target detection circuit 18, it is compared with a preset threshold. As a result, if the clutter map value is large compared to the threshold, then that value is targeted for zero Doppler. In this case, the value is removed from the clutter map and sent to the target detection decision circuit 28.

On the other hand, the radar signal is also sent to the MTI circuit 22. The MTI circuit 22 removes the zero Doppler signal from the radar signal and extracts the non-zero Doppler signal. The non-zero Doppler signal is supplied to the Doppler filter 24, the S / N ratio is improved for each Doppler bank, and then sent to the CFAR circuit 26 for each Doppler bank. Those which are judged by the CFAR circuit 26 to exceed the CFAR threshold are sent to the target judgment circuit 28.

Threshold averaging cell control circuit 20
, The clutter map memory 16 determines that the zero doppler signal target detection circuit 18 determines the target as clutter, except for the target determined as the target. For the range cell determined to be clutter, if the range cell hits the reference cell of the CFAR circuit 26, the value of the reference cell is replaced with the blank value. Also, if the range cell hits the cell of interest, the threshold of the CFAR circuit 26 is forcibly increased.

Zero Doppler signal target detection circuit 18
And the output of the CFAR circuit 26 are both
The target detection / judgment circuit 28 compares it with a predetermined threshold. As a result, if it is determined that the threshold is larger than the threshold, it is output as the target.

Since the conventional apparatus is configured as described above, the existence of the target is only present when the amplitude level of the zero Doppler signal is continuously input for several scans when the clutter map is created. It was recognized and the effect of that signal was removed from the clutter map. Therefore, in the conventional apparatus, a target according to swirling case 1 (amplitude value change for each scan) often applied to an aircraft or a target with a relatively low level is recognized as clutter, and as a result, a detection probability (hereinafter, “ Pd ”).

Further, for a clutter having a considerably high level in a certain scan, the high level may be maintained even on average. According to the conventional device, such clutter may be erroneously recognized as a target, and as a result, the false alarm probability (hereinafter referred to as “Pfa”) may increase.

Further, in the conventional device, the clutter whose center Doppler is not zero Doppler, such as weather clutter and sea clutter (hereinafter referred to as "moving clutter").
However, since the clutter map cannot be created, the suppression effect on those moving clutter cannot be expected. Therefore, to deal with mobile clutter,
In addition to the system configuration shown in FIG. 8, a clutter map for mobile clutter had to be created.

Further, in the conventional CFAR circuit, the threshold is determined only by the amplitude of the signal. In this case, in order to reduce the false alarm probability Pfa, it is necessary to increase the threshold of the CFAR circuit, while in order to increase the detection probability Pd, it is necessary to decrease the above threshold. Therefore, in the conventional device, the improvement (reduction) of the false alarm probability Pfa and the improvement (enhancement) of the detection probability Pd cannot be realized at the same time.

The present invention has been made in order to solve the above problems, and it is possible to recognize the characteristics of clutter having various Doppler frequencies separately from the target and suppress only the clutter. In addition, it is an object of the present invention to provide a radar signal processing device capable of suppressing the false alarm probability Pfa to a low level without lowering the detection probability Pd as compared with the conventional CFAR device.

[0012]

The invention according to claim 1 is
Normal system circuit that performs processing for clutter-free area,
A radar signal processing device comprising an MTI system circuit that performs processing for a clutter region, wherein the normal system circuit performs CFAR processing based on the value of a target cell and the values of a plurality of reference cells for each Doppler bank. A circuit for performing, and based on the average value of the values of the plurality of reference cells, while recognizing the clutter intensity at the position of the cell of interest for each Doppler bank, a clutter map creation circuit that accumulates the recognized clutter intensity in a clutter map, The MTI system circuit includes a pre-canceller that removes a signal in a predetermined Doppler frequency band from a radar reception signal, a Doppler filter that makes the signal processed by the pre-canceller into a signal for each Doppler bank, and for each Doppler bank. , The value of the cell of interest, the values of multiple reference cells, and the CFA
A CFAR circuit group that performs CFAR processing based on the R coefficient, and further, based on the clutter intensity for each Doppler bank stored in the clutter map, the CF
CFA for calculating the CFAR coefficient used in the AR circuit group for each combination of the position of the cell of interest and the Doppler bank
An R coefficient calculation circuit, processing results of the normal circuit,
A selection circuit for selectively using the processing result of the MTI system circuit according to the clutter intensity stored in the clutter map.

According to a second aspect of the present invention, in a radar signal processing device, when the value of the cell of interest is larger than the threshold set based on the value of the reference cell, the value of the cell of interest is targeted. C to pass as
The CFAR circuit for performing the FAR process and the CFAR process
The value of the cell of interest that has passed and the records before and after the cell of interest
Of the pulse received by the radar using
Calculate the normalized pulse area and find the normalized pulse area.
If the pulse shape is within the fixed range,
And a pulse shape verification circuit for determining the pulse shape due to the pulse .

According to a third aspect of the present invention, in the radar signal processing apparatus according to the first aspect, the CFAR processing executed by the normal circuit is compared with a threshold value set based on a value of a reference cell. When the value of the cell of interest is large, the process includes passing the value of the cell of interest as a target. When the value of the cell of interest passes the CFAR process, the value of the cell of interest and the By using the values of the front and rear range cells, the shape of the pulse received by the radar is provided with a pulse shape verification circuit that determines whether or not it can be regarded as the shape of the pulse caused by the target, and further, the clutter map creation circuit is The value corresponding to the position and Doppler bank where the presence of the target is verified by the pulse shape verification circuit is the basis of the clutter intensity. If stored in Arensuseru, it is characterized in that to create a clutter map without using the value.

The invention according to claim 4 is the radar signal processing device according to any one of claims 1 to 3, wherein a plot creation circuit for creating a plot corresponding to an object estimated to be a target, and a position And a fixed clutter map creation circuit that creates a clutter map for fixed clutter with no fluctuation in Doppler frequency and no spread in Doppler frequency, and a clutter map created by the fixed clutter map creation circuit and comparison with the plot And a fixed clutter removing circuit for removing the plot caused by the fixed clutter from the plot.

According to a fifth aspect of the present invention, in the radar signal processing device according to the third aspect, the pulse shape verification circuit verifies whether or not the pulse can be regarded as a target when determining the pulse shape. At the same time, whether or not the pulse can be regarded as a clutter candidate is tested, and even if the signal has passed the CFAR processing of the MTI system circuit, the signal that is tested as a clutter candidate by the pulse shape verification circuit is: It is characterized by being rejected as not a target.

According to a sixth aspect of the present invention, there is provided a radar signal processing device, wherein when the value of the cell of interest is larger than the threshold value set based on the value of the reference cell, the value of the cell of interest is set. C to pass as a target
The CFAR circuit for performing the FAR process and the CFAR process
The value of the cell of interest that has passed and the records before and after the cell of interest
Of the pulse received by the radar using
Calculate the normalized pulse area and find the normalized pulse area.
If the pulse shape is within the fixed range,
Pulse shape verification circuit based on a neural network for determining the pulse shape caused by the dot pattern.

The invention according to claim 7 is the invention according to claim 2 or 3.
In the radar signal processing device according to the description, when the presence of a target is verified in the pulse shape verification circuit for the signal of the cell of interest, the signal corresponds to the same range as the signal, and a signal belonging to an adjacent Doppler bank and , The signal is used to recognize the pulse shape in the Doppler direction, and by performing pulse verification in the Doppler direction based on the recognized pulse shape in the Doppler direction, the signal of the cell of interest is a signal caused by the target. It is characterized by comprising a circuit for determining whether or not

The invention according to claim 8 is the radar signal processing device according to claim 3, wherein in the clutter map creating circuit, a signal for a combination of a certain range cell and a certain Doppler bank is output by the pulse shape verification circuit. When it is determined that the target is not a target, a signal for the combination is added to the basic data to create a clutter map.

According to a ninth aspect of the present invention, there is provided a radar signal processing device including a normal system circuit for performing processing for the clutter free region and an MTI system circuit for performing processing for the clutter region. , A circuit that performs CFAR processing based on the value of the cell of interest and the values of the plurality of reference cells for each Doppler bank, and the average value of the values of the plurality of reference cells for the target cell of the Doppler bank. And a clutter data creation circuit for recognizing the clutter intensity at a position, wherein the MTI system circuit comprises:
A pre-canceller that removes a signal in a predetermined Doppler frequency band from a radar reception signal, a Doppler filter that makes the signal processed by the pre-canceller a signal for each Doppler bank, and for each Doppler bank, the value of the cell of interest and multiple A CFAR circuit group that performs a CFAR process based on a value of a reference cell and a CFAR coefficient is provided, and a CFAR circuit group that is used in the CFAR circuit group based on the clutter intensity recognized by the clutter data creation circuit.
A CF coefficient calculation circuit for calculating an AR coefficient;
The CFAR coefficient calculated by the AR coefficient calculation circuit is
A clutter that synchronizes the processing timing, a processing result of the normal system circuit, and a processing result of the MTI system circuit so that the CFAR circuit group of the MTI system circuit can be directly used in real time as they are. And a selection circuit which is selectively used according to the clutter intensity stored in the map.

The tenth aspect of the present invention is the radar signal processing apparatus according to the first or ninth aspect, further comprising a shape determination circuit for recognizing the Doppler characteristic of clutter, and the precanceller of the MTI system circuit is the According to the Doppler characteristic, a radar signal supplied to the MTI system circuit has a function of forming a null suitable for the clutter.

The invention according to claim 11 is the radar signal processing device according to claim 9, wherein the circuit that performs CFAR processing in the NORM system circuit calculates an average value of reference cell values for each Doppler bank. Together with the M
The CFAR circuit group of the TI system circuit is characterized by performing the CFAR process using an average value of the values of the reference cells calculated by the NORM system circuit.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Hereinafter, with reference to the drawings, a radar signal processing device 30 according to a first embodiment of the present invention
Will be described. In FIG. 1, 32 is an FFT circuit,
34 is a pulse shape verification circuit group including a plurality of pulse shape verification circuits provided for each Doppler bank, 36 is a bank selection circuit for selecting a Doppler bank, 38 is an MTI video in the clutter area, and a clutter-free area Then, a video selection circuit for selecting a normal system (hereinafter referred to as "NORM system") video, 40 is an MTI circuit, 42 is a Doppler filter circuit, 44 is a CFAR circuit group including a plurality of CFAR circuits provided for each Doppler bank. Four
6 is a bank selection circuit for selecting a Doppler bank,
Reference numeral 48 is a clutter map creation circuit, 50 is a clutter map for moving clutter such as weather clutter, and 52.
Is a CFAR coefficient calculation circuit for calculating an MTI CFAR coefficient, and 54 is an MTI CFAR coefficient generated for each combination of the Doppler bank and the distance area.

Further, 56 is a plotting circuit for taking a correlation between a plurality of signals included in the video selected by the video selecting circuit 38 and grouping the signals for which correlation is recognized to produce a plot, and 58 is a clutter described later. Map 6
2 is a fixed clutter removing circuit for eliminating plots that can be correlated with 2. 60 is a fixed clutter map generating circuit for accumulating as plots the fixed clutter among the plots generated by the plot generating circuit 56 whose position and Doppler do not change. It is a clutter map that accumulates the maps created by the map creation circuit 60.

FFT circuit 32, pulse shape verification circuit group 3
4 and the bank selection circuit 36 are NORM video generation blocks. On the other hand, the MTI circuit 40, the Doppler filter 42, the CFAR circuit group 44, and the bank selection circuit 46 are MTI video creation blocks. In the radar signal processing device of this embodiment, the FFT circuit 3
2, pulse shape verification circuit group 34 and bank selection circuit 3
In block 6, the NORM system video in the case of clutter-free is created, and the characteristics of the moving clutter are recognized in the FFT circuit 32, the pulse shape verification circuit group 34, the clutter map creation circuit 48 and the clutter map 50.

The CFAR coefficient calculation circuit 52 uses the clutter map 50, which is created by the clutter map creation circuit 48 and then accumulated, for each Doppler bank and
The CFAR coefficient is calculated for each range region, that is, for each combination of the Doppler bank and the range region. At this time, in a certain Doppler bank and range cell,
The smaller the value of the clutter map 50, the smaller the CFAR coefficient for the combination. In other words, the larger the value of the clutter map 50 corresponding to a certain Doppler bank and range cell due to the influence of moving clutter, the larger the CFAR coefficient for that combination. As a result, no matter which Doppler bank the mobile clutter is in, the CFAR coefficient of that bank is large, and the probability of false alarms from the MTI system is reduced.

The bank selection circuits 36 and 46 are circuits for collectively combining the data of respective video systems divided into a plurality of Doppler banks. As a method of collecting data corresponding to a plurality of banks into one, for example, a method of selecting a maximum value from a plurality of data for each range cell, a method of adding amplitudes of the plurality of data as they are, or the like is used. .

In the radar signal processing device 30 of this embodiment, as described above, the NORM for the clutter-free area is used.
System video and MTI system video for the clutter area are processed in parallel, and both are input to the video selection circuit 38.

The video selection circuit 38 uses the clutter map 5
With reference to the region of 0, a region where the maximum intensity of the map 50 (the maximum value of the intensity stored for each Doppler bank) is relatively large is determined to be a clutter region, while the other regions are determined to be clutter-free regions. to decide. Then, when it is determined that a certain area is the clutter area, the video selection circuit 38 selects the MTI video as the video of the area. Further, when it is determined that a certain area is the clutter-free area, the video selection circuit 38 selects the NORM video as the video of the area.

The selected video is displayed in the plot creation circuit 5
6 is supplied. In the plot creation circuit 56, the video supplied from the video selection circuit 38 is correlated with the sweep direction and the elevation direction. Further, in the plot creation circuit 56, signals that are recognized to be correlated with each other are grouped, and a plot corresponding to the target is created.

The plot created by the plot creation circuit 56 is compared with the data of the clutter map 62 in the fixed clutter removal circuit 58. The clutter map 62 stores data about point-shaped grand clutters (hereinafter referred to as “point clutters”) such as small islands. As a result of the above comparison, the plot determined to be point clutter by the fixed clutter removing circuit 58 is rejected as point clutter.

Clutter map 62 for point clutter
Is created by the following method in the fixed clutter map creation circuit 60 based on the plot output from the plot creation circuit 56. That is, the plot creation circuit 56
If there is a plot with almost the same intensity at the same position during a predetermined learning period, the plot is determined to be point clutter, and the position of the plot, Doppler, and amplitude intensity are registered in the clutter map 62. .

Next, the pulse shape verification circuit group 34 will be described in detail with reference to FIG. FIG. 2 is a functional block diagram showing the functions of the pulse shape verification circuit group 34, focusing on one Doppler bank. In the following description, FIG.
A circuit represented by reference numeral 64 is referred to as a pulse shape verification circuit. The pulse shape verification circuit group 34 includes a pulse shape verification circuit 64 for each of the plurality of Doppler banks.

In FIG. 2, 66 and 68 are m continuous reference cells, 70, 72 and 74 are addition circuits, 76 is a CFAR cell of interest, 78 and 80 are cells used for pulse area calculation, and 82 is a reference. A multiplication circuit that multiplies by 1/2 m to calculate the average value of cells, 84 is a multiplication circuit that multiplies a coefficient K to calculate the threshold of CFAR, and 86 is the threshold of CFAR calculated by the multiplication circuit 84 A comparison circuit for comparing the value of the cell 76 and adding a detection mark if the value of the cell of interest 76 is larger, 88 is a pulse area calculation circuit for calculating the pulse area from the cell of interest 76 and range cells around it by a method described later. , 90 indicates that the pulse area calculated by the pulse area calculation circuit 88 is a target, not noise or clutter. That is the target test circuit to test.

In FIG. 2, the number of cells referred to by the pulse area calculation circuit 88 for calculating the pulse area is three (the cell of interest 76 and the cells 78 and 80 before and after it). , A value that should be appropriately set according to the relationship between the pulse width of the radar transmission wave and the sampling rate of A / D conversion used for processing the radar reception wave.

Further, in FIG. 2, the pulse shape verification circuit 64
Is to execute the CFAR process of the CA (Cell Averaging) -CFAR system, the pulse shape verification circuit 6
The CFAR processing executed in 4 is not limited to this, and the CF shape processing circuit 64 may be made to execute other CFAR processing such as a GO (Greatest Of) -CFAR method or a LOG-CFAR method.

In the case of NORM system, the signals received by the radar receiver and A / D converted are integrated by the FFT circuit shown in FIG. 1, and then, in order for each Doppler bank, reference cells 66 and 68 shown in FIG. To enter. Figure 2
In the case of the CA-CFAR as shown in FIG. 5, after all the values of the reference cells 66 and 68 are added by the adder circuits 70 and 72, the added value is multiplied by the reciprocal 1 / 2m of the reference cell number in the multiplier circuit 82. To be done. As a result, in the multiplication circuit 82, the average value of the values of all the reference cells is calculated.

The average value calculated by the multiplication circuit 82 is multiplied by the coefficient K of CFAR in the multiplication circuit 84. Through the above multiplication processing, the CFAR threshold used in the pulse shape verification circuit 64 is calculated. The threshold calculated in the multiplication circuit 84 is used as the comparison circuit 8
6 is supplied.

In the pulse shape verification circuit 64, in order to confirm the existence of the target, in addition to the CFAR processing executed by the comparison circuit 86 and the like, a target detection processing in the target verification circuit 90 is executed as described later. Therefore, the threshold of CFAR calculated by the multiplication circuit 30 can be set to a value lower than the value required to obtain the desired false alarm probability Pfa. In the CFAR processing executed by the comparison circuit 86 or the like, the lower the threshold used, the higher the detection probability Pd can be for detecting the target. Therefore, the radar signal processing device 30 of the present embodiment
According to the above, a high detection probability Pd can be obtained in the pulse shape verification circuit 64.

In the comparison circuit 86, the target cell 76 and the CFA are
The R threshold is compared. As a result, when the value of the cell of interest 76 is larger than the threshold, it is determined that the target is detected in the cell of interest 76, and the pulse area calculation circuit 88 is triggered.

The pulse area calculation circuit 88 includes a comparison circuit 86.
It is a circuit that operates only when a trigger is applied from. That is, the pulse area calculation circuit 88, in response to the above-mentioned trigger, extracts the amplitude values stored in the cell of interest 76 at that time and the cells 78 and 80 before and after it. Then, the extracted value is substituted into the following equation to calculate the normalized pulse area.

[0042]

[Equation 1]

However, in the above formula 1, a _d (*) is the signal amplitude value of a certain range cell * in a certain Doppler bank d. Further, r is a range of the cell of interest 76, and h is a constant determined by the pulse width and the A / D conversion rate (corresponding to the number of cells to be referred to before and after the cell of interest 76 when calculating the pulse area). . In this embodiment, h is set to 1.

The amplitude value caused by the target is the cell 7 of interest.
In the case of being stored in No. 6, the value calculated according to the equation 1 becomes a substantially constant value if the pulse shape and the A / D conversion rate are determined. For example, in a pulse compressed by a linear chirp signal, if the pulse width is about twice the A / D sampling rate, the calculation is performed using Equation 1 using the amplitude values of the cell of interest 76 and the one range cells 78 and 80 before and after the cell of interest. The standardized pulse area used is about 2.4.

On the other hand, when the value stored in the cell of interest 76 is noise and happens to pass through CFAR (when it is judged by the comparison circuit 86 to happen to be the target).
Has a high probability that the area of the standardized pulse calculated by Equation 1 is less than 2.4.

The above situation is shown in FIG. FIG. 3 is an example of a signal waveform in the range direction of a certain Doppler bank. Figure 3
In the figure, 92 is the waveform of the radar echo caused by the target, 94 is noise with a relatively large value, and Ts is the width of A / D sampling. In the case of the radar echo caused by the target, the pulse shape is A as shown by the dotted line 92.
This shape is constant since it has been / D sampled. However, in the case of the noise 94, the correlation is small in the range direction, so even if a large value happens to occur, the amplitude of the signal in the range before and after that will hardly occur.

If the value of the cell of interest 76 passes CFAR under the condition that the amplitude of the cell due to clutter is stored in the cell of interest 76, does the area of the standardized pulse exceed 2.4? , Or less than 2.4 is high.
Therefore, when the area of the normalized pulse falls within a range defined by a certain threshold, it can be determined that the value of the cell of interest 76 is due to the target.

In the apparatus of this embodiment, when the target verification circuit 90 shown in FIG. 2 can determine that the value of the cell of interest 76 is due to the target by the above processing (target verification), the value is displayed in the NORM video. Output. In the above target test, there is almost no probability that the actual target will be rejected. Therefore, according to the above target test, only the false alarm probability Pfa can be reduced while maintaining the detection probability Pd. Therefore, according to the device of this embodiment, the false alarm probability Pfa and the detection probability Pd of the NORM system can be simultaneously improved.

The clutter map generation circuit 48 recognizes the average value of the reference cells output from the multiplication circuit 82 included in the pulse shape verification circuit 64 of a certain Doppler bank as the clutter intensity of the target cell 76 in that Doppler bank, and Update the clutter map values for the range and the Doppler bank by averaging the averages over several scans. Since the clutter normally has a spread in the range direction, the values of the clutter map may be set (ranged) to some extent (average) in the range direction, the azimuth direction, etc., instead of each range.

However, each map value of the clutter map is
When the values of a plurality of reference cells as the basis include a value recognized as a target by the pulse shape test, it is created based on the values of other reference cells excluding the values. By the above operation, it is possible to prevent the map value of the clutter map from being pulled to the target value and accidentally becoming a large value.

The CFAR coefficient calculation circuit 52 uses the CTI used in the MTI system for each combination of position and Doppler bank according to the value of the clutter map created as described above.
The FAR coefficient L is calculated. CFAR coefficient calculation circuit 52
Specifically, when the clutter map value is large, a large CFAR coefficient L is set for the position and bank corresponding to that value, while when the clutter map value is small, that value is set. Set a small CFAR coefficient L for the position and bank corresponding to.

Next, referring to FIG. 4, the CFAR circuit group 4
4 will be described. FIG. 4 is a functional block diagram of a plurality of CFAR circuits 96 included in the CFAR circuit group 44. The CFAR circuit group 44 includes a CFAR circuit 96 for each of the plurality of Doppler banks.

In FIG. 4, 98 and 100 are m continuous reference cells, 102, 104 and 106.
Is an addition circuit, 108 is a target cell of CFAR, and 110 is a multiplication circuit that multiplies the calculated value of the addition circuit 106 by L / 2m in order to calculate the multiplication value of the average value of the reference cell and the CFAR coefficient L. In the CFAR circuit 96, the multiplication value calculated in the multiplication circuit 110 as described above is used as the threshold of CFAR.

In FIG. 4, 112 is a multiplication circuit 110.
CFAR Threshold Calculated in Step 10 and Cell of Interest 10
The comparison circuit compares the value of 8 with the value of 8 and if the value of the cell of interest 108 is larger, it is determined that the target exists in the range of the cell of interest 108. The comparison circuit 112 uses the above-mentioned C
When it is determined by the FAR processing that the value of the cell of interest 108 is due to the target, that value is output to the MTI video.

The false alarm probability Pfa of the CFAR circuit 96 is C
The higher the FAR threshold, that is, CFA
It decreases as the R coefficient L increases. In addition, the CFAR circuit 9
The detection probability Pd of 6 is improved as the CFAR threshold is lower, that is, the CFAR coefficient L is smaller. In the present embodiment, as described above, the CFAR coefficient L can be set to a large value when the map value of the clutter map is large, while the CFAR coefficient L can be set to a small value when the map value is small.

That is, the apparatus of this embodiment suppresses the false alarm occurrence probability Pfa by setting the CFAR coefficient L to a large value when the value of the cell of interest 108 tends to be a large value due to the influence of clutter. When the value of the cell of interest 108 is not affected by clutter, the CFAR coefficient L can be set to a small value to improve the detection probability Pd.

In the radar signal processing device 30 of this embodiment, in the MTI system, (1) the CFAR coefficient is appropriately set according to the clutter strength as described above, and
(2) False alarm probability P due to clutter near zero Doppler being suppressed in advance by the MTI circuit 40.
fa can be made even lower than the NORM system value. Also, in the MTI system, a CF corresponding to a certain position
Even if clutter exists at that position, the AR coefficient is set to a small value as long as the clutter and the Doppler bank are different. Therefore, the MTI system can detect the target with the same detection probability Pd as the NORM system.

The NORM video and the MTI video created by the above-described operation are both supplied to the video selection circuit 38. Then, in the video selection circuit 38, NORM video is selected in the clutter area where the clutter map 50 has a large value, and MTI video is selected in the other clutter-free areas. Therefore, the design values Pd and Pfa of the NORM system can be obtained in the clutter-free region, while the PTI and Pfa in which the clutter is sufficiently suppressed can be obtained by the MTI system in the clutter region.

Even after the above-described operation, point clutter that cannot be fundamentally distinguished from the target echo, such as a small island, remains. In order to eliminate this, the fixed clutter removing circuit 58 performs a process of correlating the plot created by the plot creating circuit 56 with the clutter map 62 and deleting the plot having the correlation of the position and the Doppler bank. In addition, the clutter map 62 includes the fixed clutter map creation circuit 60.
Values averaged with a time constant longer than that of the clutter map creation circuit 48 are stored for each combination of position and Doppler bank.

In the above embodiment, the pulse shape verification circuit 64 has a threshold of CFAR which is obtained based on the average value of the reference cells 66 and 68, and
The process of comparing the value of the cell of interest 76 with the value of the comparison circuit 86 is "C" in the normal circuit according to claim 1.
It corresponds to "FAR processing". Further, in the above embodiment, the MTI circuit 40 corresponds to the "precanceller" described in claim 1 and the video selection circuit 38 corresponds to the "selection circuit" described in claim 1.

Further, in the above embodiment, the portion of the pulse shape verification circuit 64 that performs the CFAR processing is the same as the "CFAR circuit" in claim 2 , and the pulse area of the pulse shape verification circuit 64 is the same. The calculation circuit 88 and the target verification circuit 90 correspond to the “pulse shape verification circuit” described in claim 3 , respectively.

Embodiment 2. Next, a radar signal processing device according to a second embodiment of the present invention will be described. The radar signal processing device according to the present embodiment will be described with reference to the functional configuration diagram used in the description of the first embodiment.

The radar signal processing apparatus of this embodiment is NO
In the target verification circuit 90 of the RM system (see FIG. 2), the calculated value of Expression 1 is slightly smaller than the reference value of the standard pulse area (hereinafter, referred to as “low threshold”) and the reference value. Compared with a slightly higher threshold (hereinafter referred to as "high threshold"). As a result of the above comparison, the target verification circuit 90 sets the value of the cell of interest 76 as a noise candidate when the calculated value of Expression 1 is smaller than the low threshold, and
When the calculated value of Expression 1 is larger than the high threshold, the value of the target cell 76 is set as the clutter candidate.

In the radar signal processing apparatus of this embodiment, when the value of the target cell 108 (see FIG. 4) is detected as the target through the CFAR processing in the MTI system processing, the range of that cell is detected. And the Doppler bank with those made noise or clutter candidates in the NORM system. If they are the same, the value of the cell of interest 108 is rejected unless it is the target. According to the above processing, the clutter suppressing performance in the MTI system can be further improved as compared with the case of the first embodiment.

Embodiment 3. Next, a radar signal processing device according to a third embodiment of the present invention will be described. The radar signal processing device according to the present embodiment will be described with reference to the functional configuration diagram used in the description of the first embodiment.

The radar signal processing apparatus according to the present embodiment is different from the apparatus according to the first embodiment in that the pulse area calculation circuit 88 and the target verification circuit 90 (see FIG. 2) perform the pulse shape verification using the equation 1. On the other hand, the pulse shape is verified by a neural network. According to the pulse shape test using the neural network, the pulse shape test can be performed more flexibly as compared with the pulse shape test using Expression 1. Therefore, according to the device of the present embodiment,
Clutter suppression performance can be further improved as compared with the case of the first embodiment.

Fourth Embodiment Next, a radar signal processing device according to a fourth embodiment of the present invention will be described. The radar signal processing device according to the present embodiment performs the target test similarly to the device according to the first embodiment, and calculates the pulse area in the Doppler direction for the signals of the range cell and the Doppler bank recognized as the target. The above calculation is performed using the signal recognized as the target and the signal of the range cell of the bank adjacent to the Doppler bank of the signal in the same manner as the calculation of the pulse area in the range direction according to Expression 1.

The radar echo caused by the target has almost no spread in the Doppler direction. Therefore, when the value of the pulse area in the Doppler direction is within a certain range, the apparatus of this embodiment finally recognizes the signal as the target. According to the above processing, it is possible to realize a more excellent target detection accuracy as compared with the radar signal processing device according to the first embodiment.

Embodiment 5. Next, a radar signal processing device according to a fifth embodiment of the present invention will be described with reference to FIG. In the radar signal processing device of the present embodiment, the target cell 7
When 6 is recognized as the target by the target verification circuit 90, the value obtained by dividing the total sum of the amplitude values of the reference cells 66 and 68 by 2 m in the clutter map creation circuit 48, that is, as in the first embodiment, that is, ,
The average value of the amplitude values of the reference cells is used as the basic data of the clutter map values corresponding to the range and Doppler bank of the cell of interest 76.

In addition, in the radar signal processing apparatus of this embodiment, when the target cell 76 is rejected by the target verification circuit 90, the amplitude value of the target cell 76 and the cells 78 and 80 before and after the target cell 76 are created as a clutter map. Sent to circuit 48. In this case, the clutter map creation circuit 48 uses the average value of the reference cells 66 and 68 and the cell 7 described above.
6. Average the values of 78 and 80 with appropriate weighting.
More specifically, the calculation according to the following Expression 2 is performed, and the calculated value is used as the basic data of the clutter map value.

[0071]

[Equation 2]

Here, B _d (k) and A _d (k) are the total values of the forward reference cells (68 in this embodiment) when the cell of interest in a certain Doppler bank d is k,
And the total value of the rear reference cells (66 in this embodiment). Further, in Expression 2, m is the number of front or rear reference cells. Other symbols are the same as in the case of the formula 1. In the present embodiment, h is set to 1.

By creating a clutter map using the calculated value of equation 2 as basic data, when the target cell 76 has no target, the amplitude value corresponding to the range and Doppler bank of the target cell 76 is reflected in the map. The clutter map can be created more accurately. Therefore, according to the radar signal processing device of the present embodiment, it is possible to perform target detection with higher accuracy than the device of the first embodiment.

Sixth Embodiment Next, a radar signal processing device according to a sixth embodiment of the present invention will be described. The radar signal processing apparatus of this embodiment is realized by removing the fixed clutter map creation circuit 60, the fixed clutter removal circuit 58, and the clutter map 62 from the system configuration shown in FIG. The radar signal processing device of this embodiment is a radar signal processing device suitable for use in a situation where there are few fixed clutters. Under such circumstances, the target detection process can be performed with high accuracy even if the above-mentioned three circuits are removed. Further, by removing those circuits, the scale of the radar signal processing device can be reduced. Therefore, according to the structure of the present embodiment,
It is possible to realize a small-scale radar signal processing device capable of accurately detecting a target in a situation where there are few fixed clutters.

Embodiment 7. Next, a radar signal processing device 120 according to a seventh embodiment of the present invention will be described with reference to FIG. In the radar signal processing apparatus according to the first embodiment, scheduling is performed such that the circuits up to the NORM type pulse shape verification circuit group 34 are operated prior to the MTI system and thereafter the MTI system CFAR is operated for each range cell. Then, the CFAR coefficient L supplied to the MTI-based CFAR circuit group 44 can be set to a real-time value.

The MTI-based CFAR circuit group 44 uses the CFAR coefficient L supplied in real time to generate a CFAR
When performing the processing, it is possible to obtain an excellent clutter suppressing ability as compared with the case where the CFAR circuit group 44 performs the CFAR processing based on the map value of the clutter map 48. If the CFAR coefficient can be supplied to the MTI system in real time, the clutter map creation circuit 48 and the clutter map 50 can be omitted. Therefore, by performing the scheduling described above, it is possible to further improve the clutter suppression capability and further reduce the device scale.

FIG. 5 is a functional block diagram of the radar signal processing device 120 of this embodiment. In FIG. 5, 122
Is a clutter data creation circuit, and 124 is an MTI system scheduler for controlling the operation of MTI system processing. The operation will be described below.

When data of a certain range is processed by the FFT circuit 32 and the pulse shape verification circuit group 34 in the NORM system, the same data is accumulated in the MTI system scheduler 124. In the pulse shape verification circuit group 34, it is determined whether or not the value of the cell of interest is the target. As a result, the value that has passed the test is the bank selection circuit 3
Sent to 6. The value that has passed the test is the bank selection circuit 36.
At the same time, the clutter data corresponding to the range is created by the clutter data creation circuit 122, and based on the clutter data creation circuit 122, the CFAR coefficient calculation circuit 52 creates the CF of the range.
The AR coefficient L is determined and stored as the CFAR coefficient 54.

The MTI system scheduler 124 uses the MTI system circuit, that is, the MTI system, to store the data of the range accumulated only when the maximum value of the clutter data created by the clutter data creation circuit 122 for each bank is larger than a certain value. Circuit 40, Doppler filter 42, and C
It is supplied to the FAR circuit group 44. At this point in time, the CFAR coefficient 54 used in the CFAR circuit group 44 has already been changed, so that the MTI CFAR process in the range operates normally. When the maximum value of the clutter data is sufficiently small, the MTI system scheduler 124 discards the data of the range and prepares for the input of the data of the next range.

In the present embodiment, the video selection circuit 38
Selects the MTI system video only in the range region where the MTI system scheduler 124 supplies the data to the MTI system, and selects the NORM system video in the other range region. As a result, MTI video is selected in the clutter area and NORM video is selected in the clutter-free area.

By the way, in the above embodiment, M
The TI-based CFAR circuit 96 calculates the average value of the values of the reference cells, and calculates the CFAR coefficient L as the calculated value.
Although the CFAR threshold is calculated by multiplying by, the threshold calculation method is not limited to this. That is, the device 120 of the present embodiment
Then, the NORM type pulse shape verification circuit 64 and the MTI
Since the CFAR circuit 96 of the system operates in synchronization, MT
The I-system CFAR circuit 96 can perform desired processing using the average value calculated by the NORM-system pulse shape verification circuit 64. By causing the MTI CFAR circuit 96 to use the calculated value of the NORM pulse shape verification circuit 64 as described above, the calculation load can be reduced and the scale of the apparatus can be reduced.

Eighth Embodiment Next, a radar signal processing device according to an eighth embodiment of the present invention will be described with reference to FIG. FIG. 6 shows a radar signal processing device 130 of this embodiment.
The functional block diagram of is shown. The device 130 of this embodiment is
Similar to the device 30 of the first embodiment, the clutter map 50 is created by the NORM system processing. In the present embodiment, the value of the clutter map 50 is supplied to the CFAR coefficient calculation circuit 52 and the shape determination circuit 132.

The shape determination circuit 132 recognizes the center Doppler of the clutter and the spread of the Doppler frequency using the value of the clutter map 50. Shape determination circuit 13
A Doppler filter with a null 134 is connected to 2. A radar signal is supplied to the Doppler filter 134 with null. Doppler filter with null 134
Is a Doppler filter capable of digging a null into a specific frequency band, that is, a filter that blocks a signal belonging to a specific frequency band while dividing a radar signal into signals of a plurality of Doppler banks.

In the present embodiment, the shape determination circuit 132
Is to dig a null that suppresses the signal near the center Doppler of the clutter in the range region that is the target of processing.
It issues an instruction to the Doppler filter 134 with null. In the MTI system processing, since the central Doppler frequency of the clutter is dug, the signal for each Doppler bank input to the CFAR circuit group 44 is the signal with the clutter component removed. Therefore, according to the radar signal processing device 130 of the present embodiment, it is possible to further improve the clutter suppression capability as compared with the device 30 of the first embodiment.

Ninth Embodiment Next, a ninth embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a functional block diagram of the radar signal processing device 140 of this embodiment. The radar signal processing device 140 of the present embodiment uses the MTI
A system scheduler 124, a shape determination circuit 132, and a Doppler filter 134 with a null are provided. The MTI system scheduler 124 functions similarly to the case of the seventh embodiment. Further, the shape determination circuit 132 and the Doppler filter with null 134 function as in the case of the eighth embodiment.

In the radar signal processing device 140 of this embodiment, the data used for creating the clutter map in the NORM system and the Doppler filter with null 1 in the MTI system.
Since the data processed by 34 is the same as the data processed by 34, it is possible to dig an optimum null with higher accuracy than the device 130 of the eighth embodiment. Therefore, according to the device 140 of the present embodiment, the clutter suppressing ability can be further improved as compared with the device 130 of the eighth embodiment.

In the above embodiment, the radar signal processing device 140 is constructed based on the device 30 of the first embodiment, but the technique of this embodiment is different from the device 120 of the seventh embodiment. Can also be applied.

Embodiment 10. Next, a tenth embodiment of the present invention will be described. The radar signal processing apparatus according to the present embodiment has an elimination Doppler moving type MTI circuit in place of the Doppler filter with null 134 in the system configuration shown in FIG. It is realized by arranging the usual Doppler filter of. According to the above configuration, the device 14 of the ninth embodiment
The same effect as 0 can be obtained, and the clutter suppressing ability can be improved.

Eleventh Embodiment Next, an eleventh embodiment of the present invention will be described. The radar signal processing device according to the present embodiment has the system configurations according to the first to tenth embodiments.
The MTI-based CFAR circuit 96 (see FIG. 4) is used for NORM.
Similar to the pulse shape verification circuit 64 (see FIG. 2) of the system, it is realized by using the pulse shape verification type. According to the above configuration, the clutter suppressing ability can be further improved as compared with the devices according to the first to tenth embodiments.

[0090]

Since the present invention is constructed as described above, it has the following effects. Claim 1
According to the described invention, the clutter intensity is detected for each Doppler bank, and the threshold of the CFAR circuit for processing the clutter region is appropriately set for each combination of the range region and the Doppler bank based on the clutter intensity. be able to. Therefore, according to the present invention, the false alarm probability and the detection probability can be maintained at appropriate levels in the clutter region having any Doppler frequency. Further, in the present invention, since the clutter map is created by using the data created during the processing of the normal system circuit that performs the processing for the clutter-free area, the scale of the circuit that performs the clutter map creation processing can be reduced. You can

According to the second aspect of the present invention, the range cell that has passed the CFAR process is tested based on the value (amplitude value) of the cell and the cells before and after the range cell to determine whether or not it is the target. You can Therefore, according to the present invention, a high detection probability can be secured while suppressing the false alarm probability to a sufficiently small value.

According to the third aspect of the present invention, the clutter map can be created based only on the signal that does not include the range cell signal in which the target exists. For this reason,
According to the present invention, it is possible to accurately create a clutter map.

According to the fourth aspect of the present invention, it is possible to reliably remove from the plots recognized as targets the plots whose position and Doppler frequency hardly change, that is, plots that can be estimated to be caused by point clutter. Therefore, according to the present invention, the false alarm probability can be further reduced while maintaining the detection probability.

According to the fifth aspect of the present invention, at the time of determining the pulse shape, it can be verified whether or not the pulse can be regarded as a target and at the same time, whether or not the pulse can be regarded as a clutter candidate. Further, according to the present invention, even a signal that has passed through the MTI type CFAR circuit, that is, a signal recognized as a target in the MTI type circuit, a signal having the same range and Doppler bank as that signal is tested as a clutter candidate. If so, the signal is excluded from the target. Therefore, according to the present invention, the false alarm probability can be further suppressed.

According to the sixth aspect of the invention, the pulse shape can be determined by the neural network circuit. Therefore, according to the present invention, the cause of the pulse shape included in the radar signal can be tested flexibly and accurately.

According to the seventh aspect of the present invention, the pulse shape in the range direction and the pulse shape in the Doppler direction are taken into consideration in examining the cause of the pulse included in the radar signal. For this reason, according to the present invention, it is possible to enhance the accuracy of inspection of the cause of the pulse and to realize a more excellent target detection accuracy.

According to the eighth aspect of the present invention, when it is determined that the target does not exist in the cell of interest, the signal of the cell of interest also has the range and Doppler corresponding to the cell when the clutter map is created. Used as basic data for map values in banks. Therefore, according to the present invention, it is possible to accurately create the clutter map.

According to the ninth aspect of the invention, the timing at which the CFAR processing for the specific range area is started in the processing of the MTI system circuit is synchronized with the timing at which the CFAR coefficient for the specific range area is calculated. be able to. Therefore, according to the present invention, the MTI
The accuracy of target detection in the CFAR circuit of the system can be improved, and the scale of the device can be reduced since the clutter map memory is not required.

According to the tenth aspect of the present invention, it is possible to detect the center Doppler frequency of the clutter, cancel the signal in the vicinity thereof in advance, and supply it to the CFAR circuit of the MTI system. Therefore, according to the present invention, the false alarm probability of the MTI system can be suppressed to be sufficiently small.

According to the eleventh aspect of the invention, the CFAR circuit of the MTI system can determine the threshold of CFAR without calculating the average value of the reference cells. Therefore, according to the present invention, the scale of the device can be reduced without deteriorating the detection probability and the false alarm probability.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a radar signal processing device according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram of a pulse shape verification circuit included in a pulse shape verification circuit group included in the radar signal processing device shown in FIG.

FIG. 3 is an example of a signal waveform handled by the radar signal processing device shown in FIG.

FIG. 4 is a CF included in the radar signal processing device shown in FIG.
It is a functional block diagram of a CFAR circuit included in an AR circuit group.

FIG. 5 is a functional block diagram of a radar signal processing device according to a seventh embodiment of the present invention.

FIG. 6 is a functional block diagram of a radar signal processing device according to an eighth embodiment of the present invention.

FIG. 7 is a functional block diagram of a radar signal processing device according to a ninth embodiment of the present invention.

FIG. 8 is a functional block diagram of a conventional radar signal processing device.

[Explanation of symbols]

30; 120; 130; 140 radar signal processing device,
32 FFT circuit, 34 pulse shape verification circuit group, 40 MTI circuit, 44 CFAR circuit group, 48 clutter map creation circuit, 50, 6
2 clutter map, 52 CFAR coefficient calculation circuit, 56 plot creation circuit, 58 fixed clutter removal circuit, 60 fixed clutter map creation circuit,
64 pulse shape verification circuit, 70, 72, 74,
102, 104, 106 Adder circuit, 88 Pulse area calculation circuit, 90 Target verification circuit, 9
6CFAR circuit, 122 clutter data creation circuit, 124 MTI system scheduler, 132 shape determination circuit, 134 Doppler filter with null.

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-63-142280 (JP, A) JP-A-9-145829 (JP, A) JP-A-3-92783 (JP, A) JP-A-64- 1989 (JP, A) JP 11-23696 (JP, A) JP 3-248077 (JP, A) JP 2-287177 (JP, A) JP 5-223918 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01S ⁷ /00-7/42 G01S 13/00-13/95

Claims (11)

(57) [Claims] 1. A radar signal processing device comprising a normal circuit for performing a process for a clutter-free region and an MTI system circuit for performing a process for a clutter region, wherein the normal system circuit is provided for each Doppler bank. CFA based on the value of the cell of interest and the values of multiple reference cells
A clutter map that recognizes the clutter intensity at the position of the cell of interest for each Doppler bank based on a circuit that performs R processing and the average value of the values of the plurality of reference cells, and that accumulates the recognized clutter intensity in a clutter map. The MTI system circuit includes a pre-canceller that removes a signal in a predetermined Doppler frequency band from a radar reception signal, a Doppler filter that makes the signal processed by the pre-canceller a signal for each Doppler bank, and a Doppler For each bank,
The value of the cell of interest, the values of multiple reference cells, and CF
And a CFAR circuit group that performs CFAR processing based on the AR coefficient, and further, based on the clutter strength for each Doppler bank stored in the clutter map, sets the CFAR coefficient used in the CFAR circuit group to the target cell. The CFAR coefficient calculation circuit for calculating each position and the Doppler bank, the processing result of the normal system circuit, and the processing result of the MTI system circuit according to the clutter strength stored in the clutter map. A radar signal processing device comprising: a selection circuit that is selectively used. 2. A CFAR circuit for performing a CFAR process of passing a value of a cell of interest as a target when the value of the cell of interest is larger than a threshold value set based on the value of a reference cell, said CFAR circuit. The value of the cell of interest that has passed through the process and the values of the range cells before and after the cell of interest are used to calculate the normalized pulse area of the pulse received by the radar, and the normalized pulse area is within a predetermined range. A radar signal processing device comprising: a pulse shape verification circuit that determines the shape of the pulse to be the shape of the pulse caused by the target when it fits. 3. A CFA implemented in the normal circuit
The R process includes a process of passing the value of the cell of interest as a target when the value of the cell of interest is larger than the threshold set based on the value of the reference cell, and the value of the cell of interest is the CFAR. Whether or not the shape of the pulse received by the radar can be regarded as the shape of the pulse caused by the target by using the value of the cell of interest and the values of range cells before and after the cell of interest when passing through the processing. Further, the clutter map creation circuit, the clutter map creation circuit, the value corresponding to the position and Doppler bank where the existence of the target is verified by the pulse shape verification circuit, the clutter strength as a basis of the reference. The clutter map is created without using the value stored in the cell. Da signal processor. 4. A plot creation circuit for creating a plot corresponding to an object estimated to be a target, and a fixed clutter for creating a clutter map for fixed clutter with no fluctuation in position and Doppler frequency and no spread in Doppler frequency. A map creation circuit, a clutter map created by the fixed clutter map creation circuit, and a fixed clutter removal circuit that removes a plot caused by fixed clutter from the plot based on comparison with the plot. The radar signal processing device according to any one of claims 1 to 3, characterized in that: 5. The pulse shape verification circuit verifies whether or not the pulse can be regarded as a target when judging the pulse shape, and at the same time, verifies whether or not the pulse can be regarded as a clutter candidate. 4. The radar signal according to claim 3, wherein even if the signal has passed through the CFAR processing of the system circuit, the signal that has been verified as a clutter candidate by the pulse shape verification circuit is rejected as not a target. Processing equipment. 6. A CFAR circuit for performing a CFAR process of passing the value of a cell of interest as a target when the value of the cell of interest is larger than a threshold value set based on the value of a reference cell, and the CFAR circuit. The value of the cell of interest that has passed the processing,
By using the value of the before and after of Ren Jiseru cell of interest, to the radar
Calculate the normalized pulse area of the received pulse and
If the graded pulse area is within the specified range,
The shape of the pulse as the shape of the pulse caused by the target
A radar signal processing device, comprising: a pulse shape verification circuit based on a neural network; 7. When the presence of a target is verified in the pulse shape verification circuit for the signal of the cell of interest, a signal corresponding to the same range as the signal and belonging to an adjacent Doppler bank and the signal are identified. Using, while recognizing the pulse shape in the Doppler direction, by performing a pulse test in the Doppler direction based on the recognized pulse shape in the Doppler direction, whether the signal of the cell of interest is a signal originating from the target or not. The radar signal processing device according to claim 2 or 3, further comprising a circuit for determining. 8. The clutter map creation circuit adds a signal for a combination of a range cell and a Doppler bank to the basic data when the pulse shape verification circuit determines that the signal for the combination is not a target. The radar signal processing device according to claim 3, wherein a clutter map is created. 9. A radar signal processing device comprising: a normal system circuit that performs processing for the clutter-free region; and an MTI system circuit that performs processing for the clutter region, wherein the normal system circuit is provided for each Doppler bank. CFA based on the value of the cell of interest and the values of multiple reference cells
A circuit for performing R processing, and a clutter data creation circuit for recognizing the clutter intensity at the position of the cell of interest for each Doppler bank based on the average value of the values of the plurality of reference cells. A precanceller that removes a signal in a predetermined Doppler frequency band from a radar reception signal, a Doppler filter that makes the signal processed by the precanceller a signal for each Doppler bank, and for each Doppler bank,
The value of the cell of interest, the values of multiple reference cells, and CF
A CFAR circuit group that performs CFAR processing based on the AR coefficient, and further, based on the clutter intensity recognized by the clutter data creating circuit, C used in the CFAR circuit group.
A CFAR coefficient calculation circuit for calculating a FAR coefficient, and a CFAR coefficient calculation circuit for calculating the FAR coefficient
The coefficient is used for the processing of the CFAR circuit group of the MTI system circuit,
A scheduler for synchronizing processing timings so that they can be used as they are in real time, a processing result of the normal system circuit, and a processing result of the MTI system circuit are selectively used according to the clutter strength stored in the clutter map. A radar signal processing device comprising: a selection circuit. 10. A shape determination circuit for recognizing a Doppler characteristic of clutter is provided, and a pre-canceller of the MTI system circuit is suitable for the clutter for a radar signal supplied to the MTI system circuit based on the Doppler characteristic. 10. The radar signal processing device according to claim 1, further comprising a function of forming a null. 11. The CFAR in the NORM system circuit
The circuit that performs the processing calculates the average value of the reference cell values for each Doppler bank, and the CFAR circuit group of the MTI system circuit uses the average value of the reference cell values calculated by the NORM system circuit. The radar signal processing device according to claim 9, wherein the CFAR process is performed.