JP2000292524A - Radar and similar devices - Google Patents

Abstract

[PROBLEMS] To provide a radar device and a similar device capable of eliminating the disadvantages of MAX processing and MIN processing while taking advantage of the stability of the display while taking advantage of the processing stability. SOLUTION: A coordinate conversion unit 4 for converting received data from polar coordinates to rectangular coordinates on a display screen, a MAX extraction unit 6 for obtaining a maximum value among received data corresponding to each pixel of the display screen as MAX data, A MIN extraction unit 9 for obtaining the minimum value among received data corresponding to each pixel on the display screen as MIN data, and a MIX processing unit 8 for averaging MAX data and MIN data to obtain MIX data
And an image memory 1 for storing MIX data as pixel data, and a display 7 for displaying data stored in the image memory 1
And

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device, a sonar device, or the like, which converts a detection signal received in a polar coordinate form into rectangular coordinates, stores the converted signal in an image memory, and then displays it on a raster scanning type display. Related to the device.

[0002]

2. Description of the Related Art In a device for converting a detection signal received in a polar coordinate system into rectangular coordinates and displaying a raster, the detection signal is geometrically dense near the center and coarser toward the periphery. Therefore, when performing coordinate conversion to rectangular coordinates (XY coordinates), as the pixel becomes closer to the sweep start point, more received data corresponds to the same pixel. In this case, simply overwriting the received data sequentially for one pixel always results in only the last written data being the data for that pixel, so data with a higher signal level was received halfway. In this case, there is a disadvantage that the information does not remain. Also, even if the received signal is from the same target,
Since the received signal fluctuates slightly in a short time, the shape of the image changes with each rotation of the antenna, or the same target is not displayed or displayed with each rotation of the antenna as it approaches the center. It becomes something.

In order to solve the above inconvenience, for example,
A process of writing the largest data among all the received data corresponding to the same pixel (hereinafter, this process is referred to as a MAX process) has been conventionally performed. Regarding the MAX processing, for example, Japanese Patent Publication No.
No. 582. In this method, when writing received data to the image memory, a circuit for detecting the first access to the same pixel (hereinafter, this circuit is referred to as FI
RST circuit), and the FIRST circuit
If T is detected, the new data received this time is written. Otherwise (for the second time or later), the size of the already written data is compared with the size of the new data received this time. Rewrite the other data. As a result, since all data corresponding to the same pixel is always referred to, the data becomes stable, and the maximum value data is finally extracted and stored.

[0004]

In the case of the above MAX processing, the received signal is displayed more stably than in the case of the overwriting processing, but unnecessary signals such as sea surface reflection, rain and noise are also highlighted. Also, there is a problem that two adjacent targets may not be displayed separately.

Therefore, a MIN process for writing the smallest data out of all the received data corresponding to the same pixel can be considered. However, the MIN process also has the following disadvantages.

That is, even in MIN processing, MAX
Since the process refers to all the received data corresponding to the same pixel as in the process, the process result has the advantage of being stable, and unnecessary signals such as sea surface reflection, rain, and noise are highlighted. Therefore, there is no drawback such as MAX processing, but there is a drawback that an image smaller than the size of the pixel is not displayed, and even if the target is displayed, it is not displayed when approaching the vicinity of the center. I have. As described above, the possibility that the received signal to be displayed is not displayed becomes extremely high, and therefore, it is inappropriate to use the MIN processing alone.

An object of the present invention is to provide the above-described MAX processing and MIN processing.
It is an object of the present invention to provide a radar device and a similar device which can eliminate the drawbacks of the processing while taking advantage of the display stability of the processing.

[0008]

FIG. 1 shows the configuration of the present invention. Although a radar device is illustrated here, the same applies to a similar device such as another sonar device that converts polar coordinates into rectangular coordinates and displays them.

[0009] theta _n represents a sweep of the antenna direction, referred to herein as the prior sweep the sweep. In addition, the sweep immediately before the preceding sweep is called a subsequent sweep, and θ
_{Expressed as n-1} . Direction of current prior sweep theta _n becomes the row sweep theta _n-1 in the direction after the next. The processing for the sample points on each sweep is performed sequentially for every R clock in the sweep line direction. In the figure, FIRST detecting unit 5 detects whether first access to the pixels on the image memory 1 any sample point j on the preceding sweep theta _n correspond its sample point j. This detection, focusing on the point E on the prior sweep theta _n, corresponding to the sample points of the same prior sweep theta _n on the upstream side of the adjacent sample point D and the following sweep theta _n-1 on the A~C The determination is made based on whether the corresponding pixel at point E matches the pixel. If they do not match, point E is detected as a FIRST sample point, and if they do match, they are not detected as FIRST sample points. When detecting whether the point E is a FIRST sample point, it is necessary and sufficient condition to make a comparison judgment between the point D and the four sample points A to C and the point E. That is, point E is F
The necessary and sufficient conditions to be detected as IRST sample points are as follows:
This is the case where the corresponding pixel at point E does not match all of the corresponding pixels at points A to D.

The MAX processing section includes a FIRST detecting section 5
And a MAX extraction unit 6. The MAX extraction unit 6
The maximum value data (hereinafter, MAX data) at the corresponding pixel at each sample point for one sweep is obtained and stored in the MAX extraction memory 6a. Antenna sweep ahead _n
, The extraction memory 6a sequentially stores the MAX data at each sample point of the preceding sweep θ _n , and the MAX data of each sample point of the succeeding sweep θ _n-1 stored up to that point. Are sequentially output. It is to be noted that the MAX data at each sample point means that when the sample point is a FIRST sample point, new reception data at the sample point is MAX data.
If it is not a sample point, the new received data of the sample point is compared with the data on the MAX extraction memory 6a of another sample point having the same corresponding pixel as the corresponding pixel of the sample point, and the larger data is compared. Are MAX data.

The MIN processing means comprises the FIRST detecting section 5 and the MIN extracting section 9. The MIN extraction unit 9 includes a MIN extraction memory 9a. MIN extraction unit 9
Calculates the minimum value data (MIN data) at each sample point on the preceding sweep θ _n to obtain the MIN extraction memory 9a.
To memorize. When the antenna is switched to the prior sweep theta _n, MIN data will be successively stored in each sample point of the prior sweep theta _n for this extraction memory 9a, line sweep theta _n-1 after which has been stored so far The MIN data of each sample point is sequentially output. The MIN extraction memory 9a also has a storage capacity for one sweep. Also, MIN extraction memory 9a, the sample points on the previous sweep theta _n is F
In the case of the IRST sample point, the new received data of the sample point is stored as MIN data. In the case of not the FIRST sample point, the new received data of the sample point is stored in the same correspondence as the corresponding pixel of the sample point. The smaller data is selected and stored by comparing it with the data on the MIN extraction memory 9a of another sample point having pixels.

The MAX data and MI at each sample point on the preceding sweep θ _n extracted by the MAX
The MIN data at each sample point on the preceding sweep theta _n extracted by the N extraction unit 9 is input to MIX processing unit 8 for performing averaging processing of these data. The averaging process may be a simple averaging process, and a weight may be applied to the MAX data or the MIN data. In the MIX processing unit 8,
An average value of the MAX data and the MIN data is obtained for each sample point, and this value is written to a corresponding pixel on the image memory 1 specified by the coordinate conversion unit 4. The display 7 displays the radar image stored in the image memory 1 as a grayscale image or a color image.

In FIG. 1, when detecting whether point E is a FIRST sample point, comparison with four total sample points A to D is a necessary and sufficient condition. Because the comparison of each sample point is naturally performed in the upstream direction of the sweep line on the same sweep, the preceding sweep θ
_{On n} , there is no need to compare with the next succeeding sample point F, and there is no need to compare with the sample point further upstream than point D. This is because if the corresponding pixels do not match in comparison with the point D, the corresponding pixels of the sample points upstream of the point D naturally do not match. Further, on the succeeding sweep θ _n−1 , it is not necessary to compare the points A and C with the sample points in the upstream and downstream directions of the sweep line. If the corresponding pixel at point C and the corresponding pixel at point E do not match, the corresponding pixel at the sample point downstream of point C does not match the corresponding pixel at point E, and similarly, points E and A
If the corresponding pixels at the points do not match, the corresponding pixels at the sample point upstream of the point A and the corresponding pixels at the point E do not naturally match. As described above, the point E is a point D which is an adjacent sample point in the upstream direction on the preceding sweep θ _n , the sample point B at the same sample position as the point E on the succeeding sweep _n−1 , and two points before and after it. A total of four sample points A and C, which are two sample points, are necessary and sufficient comparison sample points when detecting whether the point E is a FIRST sample point.

The configuration shown in FIG. 1 operates as follows.

Assuming now that the antenna direction is at θ _n (preceding sweep) and the sample point is at point E, FIRST
Detector 5 performs comparison determination with the sample between the sample point and E point of A~D prior sweep theta _n and trailing sweep θ _n-1. That is, the matching determination of the corresponding pixel of each sample point is performed. If the corresponding pixel of the sample point E does not match all of the corresponding pixels of the sample points A to D, the point E is a FIRST sample point. When the FIRST detecting unit 5 detects that the point E is a FIRST sample point, the MAX extracting unit 6 and the MIN extracting unit 9 write the received data at the point E directly to the MAX extracting memory 6a and the MIN extracting memory 9a, respectively. . Point E is FI
If it is not the RST sample point, the MAX extraction memory of the received data of the point E and the other sample points (for example, points A, B, and D) having the same corresponding pixels as the corresponding pixels of the points A to D 6a, the larger data is selected and rewritten in the MAX extraction memory 6a, and the received data at the point E and another sample having the same corresponding pixel as the corresponding pixel at the point E are selected. MI of point (for example, point A, B, D)
The data in the N extraction memory 9a is compared, and the smaller data is selected and rewritten in the MIN extraction memory 9a. In this way, MAX extraction memory 6a, the MIN extraction memory 9a, MAX data for each sample point on the preceding sweep theta _n, MIN data is stored.

[0016] MAX extraction memory 6a, data MIN extraction memory 9a is inputted to the MIX processing unit 8, where the average processing of each sample point on the preceding sweep theta _n is performed. A typical method of averaging is a method of taking a simple average of MAX data and MIN data. The data subjected to the averaging process in the MIX processing unit 8 is used as MIX data in the image memory 1.
, That is, the position of the pixel whose coordinates have been converted by the coordinate conversion unit 4. The display 7 raster-displays the radar image stored in the image memory 1 as a grayscale image or a color image.

The MIX processing unit 8 performs an averaging process on the MAX data and the MIN data. This process is performed by the MAX extraction unit 6 and the MIN extraction unit 9 that refer to all the reception data corresponding to the same pixel. Because of the output averaging process, the result of this averaging process is as stable as when only the MAX extracting unit 6 is used alone or when the MIN extracting unit 9 is used alone. In addition, unnecessary signals are not highlighted as in the case where only the MAX extracting unit 6 is used, and a received signal to be displayed is not displayed as in the case where only the MIN extracting unit 9 is used. Can be avoided. Also, in a sweep between two adjacent targets, if there is no data even once, the two targets can be displayed separately. When only the MAX extracting unit 6 is used, or when the MIN extracting unit 9 is used.
When only the processing is used, the quality of the processing result largely depends on the level of the input signal. Depending on the state, it is necessary to perform a delicate gain adjustment operation. Therefore, an optimum display can be obtained without depending much on the level of the signal level and without frequently performing the gain adjustment operation.

In the configuration shown in FIG. 1, the MAX processing section is composed of the FIRST detection section 5 and the MAX extraction section 6, and the MIN processing section is composed of the FIRST detection section 5 and the MIN extraction section 9. , And the MIN processing unit are not limited to these configurations. MAX processing unit,
If the maximum value or the accuracy can be reduced slightly from the reception data corresponding to each pixel of the display screen, a function of obtaining a value near the maximum value as MAX data may be provided.
The N processing unit may have a function of obtaining a minimum value or a value near the minimum value as the MIN data from the received data corresponding to each pixel on the display screen if the accuracy can be slightly reduced.

[0019]

FIG. 2 is a block diagram of a control unit of a radar apparatus according to an embodiment of the present invention.

The detected analog signal from the antenna 10 is
The signal is converted into a digital value by the receiving circuit 11 and the A / D converter 12, and is sampled by a sampling clock (not shown) having a period corresponding to the detection range. The sampled data for one sweep is stored in the primary memory 13 in real time. The primary memory 13 is provided because the sampling rate is high. The primary memory 13 temporarily stores the received data in real time, and then reads out the data stored in the same-level memory 13 with the R clock to read the image data in the subsequent stage. Write to. In some cases, the secondary memory 14 is provided to improve the drawing efficiency in the image memory. By the secondary memory 14,
Even while the received data is stored in the primary memory, data can be continuously drawn on the image memory using the data read from the secondary memory 14.

Although the detection signal is obtained in a polar coordinate system, the image memory is in a rectangular coordinate system. Therefore, a coordinate conversion circuit 15 for converting polar coordinates into rectangular coordinates (XY coordinates) is provided. The coordinate conversion circuit 15 includes, for example, the angle θ of the antenna with respect to the bow direction and the primary memory 1
From the read position R (determined by the R clock) of the third memory (or the secondary memory 14), an address indicating a pixel of the image memory arranged in orthogonal coordinates is created. Specifically, it is configured by hardware realizing the following equation.

X = Xs + R · sin θ Y = Ys + R · cos θ where X, Y: rectangular coordinates Xs, Ys: center coordinates R: distance from center θ: angle of transformed coordinates FIRST detection circuit 16 has been described with reference to FIG. As described above, the circuit for detecting whether a certain sample point has accessed the corresponding pixel for the first time or the second or subsequent access, the R clock indicating the position of the sample point on the sweep, the preceding sweep θ _n and , A detection operation is performed based on the subsequent sweep θ _n−1 obtained from the latch circuit 22.

The output of the FIRST detection circuit 16 is MA
It is input to an X extraction circuit 17 (corresponding to the MAX extraction unit 6 in FIG. 1) and a MIN extraction circuit 18 (corresponding to the MIN extraction unit 9 in FIG. 1). As described with reference to FIG. 1, the MAX extraction circuit 17 has a MAX extraction memory 100 that stores MAX data at each sample point having a capacity of one sweep, and stores the MAX data at each sample point every cycle. Output. Similarly, the MIN extraction circuit 18 stores the MIN data at each sample point having a capacity of one sweep.
It has an IN extraction memory 200 and outputs MIN data at each sample point every cycle. MIX processing circuit 19
(Corresponding to the MIX processing unit 8 in FIG. 1)
7 and the output of the MIN extraction circuit 18 are averaged. The image memory 20 (corresponding to the image memory 1 in FIG. 1)
One screen of display data is stored and is stored in a CRT 21 which is a raster scanning type display (corresponding to the display 7 in FIG. 1).
To be displayed.

FIG. 3 shows the relationship between FIRST and the rest in the same pixel. The pixel I in the figure has a sample point a,
Although b and c correspond to each other, if the sweep rotation direction is clockwise (clockwise) as shown in the figure, point a is detected as a FIRST sample point, and points b and c are detected as second and subsequent sample points. Is detected. Now, assuming that the data size of each sample point is a = 4, b = 3, and c = 6, when the antenna is facing the sweep line θ _n−1 , when the point a is detected as FIRST, MAX extraction memory 1
Data 4 is first stored at a position corresponding to point a of 00. The data 4 is also stored in the MIN extraction memory 200 at a position corresponding to the point a. One cycle later,
Since point b is detected as the second or subsequent access to the same pixel, data 4 and data 3 are compared. As a result of the comparison, since the data 4 is large, the data 4 is stored at the position corresponding to the point b in the MAX extraction memory 100, and the MI
Data 3 is stored at a position corresponding to point b in the N extraction memory. Subsequently, when the antenna is facing up sweep line theta _n, the data 6 c point are compared. Since data 4 is stored at the positions of points a and b of the MAX extraction memory 100 (the MAX extraction memory 100 has a capacity of one sweep, and when comparing the data 6 at the point c, The data and the data at the point a are output through the shift circuit, and the data at the point b and the data at the point c are compared, which will be described later.)
The point data 6 is compared, and 6 is larger than 4, so 6 is stored in the MAX extraction memory at a position corresponding to point c. Further, data 3 is stored at the positions of points a and b in the MIN extraction memory 200, and since this 3 is smaller than 6, the data 3 is also stored at the position of point c of the MIN extraction memory 200. You.

As a result, in the MIX processing circuit 19 of FIG. 2, point a: (4 + 4) / 2 = 4 point b: (4 + 3) /2=3.5 point c: (6 + 3) /2=4.5 Become.

Since the pixels corresponding to the points a to c in the image memory 20 are the same, the same pixels are assigned to the pixels 4, 3.5, 4..
5 are sequentially overwritten, and finally 4.5 is written.

FIG. 4 shows a block diagram of the MAX extraction circuit 17. MAX extraction memory 100 stores the maximum value data for each sample point on the preceding sweep theta _n. When it is detected that point E in FIG. 1 is a FIRST sample point, new data which is an output of the primary memory 13 (see FIG. 2) is unconditionally stored. The larger of the data selected in 104 and the new data is stored. The comparator 105 compares the data selected by the selector 104 with the new data output from the primary memory 13, and outputs 1 to the selector 106 if the new data is larger. The selector 106 selects the B terminal of the selector 106 when the logical sum of the output of the comparator 105 and FIRST is 1, and otherwise selects the A terminal to which the output of the selector 104 is connected. Therefore, if the point E in FIG. 1 is a FIRST sample point, new data is selected by the selector 106 and the extraction memory 1
00, but if the point E is not a FIRST sample point, the comparator 105 compares the output of the selector 104 with the new data, and the larger data is selected by the selector 106 to extract the data from the extraction memory 100. Is output to The output of the selector 106 is delayed by one cycle by the latch 107, so that the output of the latch 107 outputs the data (the maximum value at the point D) written to the extraction memory 100 at the point D. The output of the latch 107 is input to the selector 104 as the maximum value data at the point D.

In the MAX extraction memory 100, reading is performed in the first half of one cycle, and MAX data is written in the second half. The outputs of the MAX extraction memory 100 are latches 101 to 1
03, points A and B on the following sweep θ _n-1
The MAX value at point C is output. These values are input to the selector 104.

The selector 104 outputs the data having the largest value among the data at points A to D.
It is valid only when the point is not FIRST. Which data is output is determined by the priority encoder 109. The priority encoder 109 has a function of generating a selection signal of the selector 104. now,
Assuming that all of A to D have the same coordinates at point E, the maximum value is determined at point E from the new data from the primary memory 13 and the total of five data at points A to D. Therefore, the largest value among the points A to D is always the data determined last. The order of determination is the order of A, B, C, and D, which are the order of processing of the sample points, so that the data at point D is the data that is determined last.
Therefore, the largest data among the points A to D is the data at the point D. This means that the comparator 105 does not need to compare all of the new data with the other four data. Therefore, the four coincidence data from the FIRST detection unit 16 are assigned a priority (point D has the first priority) in the order of A, B, C, and D by the priority encoder 109, and the data among the points A to D A signal for selecting the largest data among points having the same pixel as the point E can be supplied to the selector 104. Note that the priority encoder 109 is effective only when not in FIRST, and in FIRST, new data is unconditionally written to the extraction memory 100 as the maximum value. FIG. 5 shows a configuration diagram of the MIN extraction circuit 18. The configuration differs from the MAX extraction circuit shown in FIG. 4 in that the comparator 105 compares the smallest data among the data at points A to D with the new data and selects the smaller data. It is a point. Others are the same.

FIG. 6 shows a configuration example of the MIX processing circuit 19. The adder 30 adds the outputs of the MAX extraction circuit and the MIN extraction circuit in a binary number and shifts them by one bit to the left.
0. By this processing, MAX data and M
An average value of IN data can be obtained.

FIG. 7 et seq. Are diagrams for explaining the effect of the above configuration.

Now, when the sample data at the sample point corresponding to the same pixel is expressed as “1” and “not present” as 0, it is always 1 or 0.
The processing, the MIN processing, and the MIX processing all have the same result. However, in the case where 1 and 0 are mixed, if the conventional overwriting process is performed, it becomes 1 or 0 because it is determined by the last written data, and is not stable. When only the MAX process is performed, the value becomes 1 and is stabilized. However, when the gain is large, the unnecessary signal is highlighted and the image becomes difficult to see.
In the case of only the MIN process, the value becomes 0 and becomes stable. However, 0 means that it is not displayed, and if the gain is small, the received signal to be displayed is not displayed. But MIX
When the processing is performed, the value becomes 0.5, so that the highlighted display can be softened even when the gain is large, and the reception signal to be displayed is not prevented from being displayed. In the above description, the case where the data is 1 or 0 has been described as an example. However, the same applies to the case where the reception level is processed with a plurality of values.

FIG. 7A shows an example of a signal receiving state when the gain is set to a small value, and FIG. 7B shows a case when the gain is set to a large value. The hatching indicates the presence of the received signal, and when the gain is large compared to the case where the gain is small, the signal is spread in the azimuth direction. Here, the signal has two values of “present” and “absent”. Also, it is assumed that there are countless sweep directions (corresponding to a case where the antenna rotation speed is low). Further, distances (Rn, Rn + 1,...) At equal intervals from the center are set as sample points. Therefore, although there are innumerable sample points, in the figure, a circle means a sample point at which that pixel is accessed last.

FIG. 8 shows a display example when the MAX processing is performed. Pixels indicated by halftone dots in the figure are all pixels that display 1. In the MAX processing, if the gain is set to be large,
The area where the received signal did not exist is also highlighted and the image becomes very difficult to see.

FIG. 9 is a display example when the MIN processing is performed. In this case, if the gain is set to be small, the received signal to be displayed is not displayed.

FIG. 10 is a display example at a certain point in time when the overwriting process is simply performed. In the case of the overwriting process, the display pixel becomes 1 or 0 for each sweep and is not stable. FIG. 11 is a display example when a MIX processing unit is provided. In the figure, pixels indicated by halftone dots indicate 1 and pixels indicated by hatching indicate 0.5. In this case, the display becomes stable regardless of whether the gain is set to be small or the gain is set to be large, and the received signal to be displayed is not displayed when the gain is set to be small. In the case of (1), the received signal can be identified because there is a difference between the data of the portion where the received signal exists and the data of the portion where the received signal does not.

[0037]

According to the present invention, since the MAX processing and the MIN processing refer to all the received data corresponding to the same pixel, the averaging processing of both results (MIX processing)
Are stable. Therefore, the display image does not become unstable as in the conventional overwriting process.

When only the MAX processing is performed, the unnecessary signal is highlighted, and when the MIN processing is performed only, the received signal to be displayed is not displayed. However, the present invention does not have such a disadvantage.

If there is at least one case where there is no data between two adjacent targets, there is a high possibility that the two targets can be displayed separately. As can be seen from FIGS. 8 to 10, in the conventional processing method, the quality of the processing result depends on the input signal level and the set gain. However, in the present invention that performs the MIX processing, the signal level does not depend on the magnitude of the signal level or the set gain as much as in the past,
Therefore, an optimum display can be obtained without frequently performing the gain adjustment operation.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the operation of a FIRST detection unit and a MAX extraction unit.

FIG. 2 is a configuration diagram of a radar device according to an embodiment of the present invention.

FIG. 3 is a diagram showing FIRST in the same pixel and other relations;

FIG. 4 is a configuration diagram of a MAX extraction circuit.

FIG. 5 is a configuration diagram of a MIN extraction circuit;

FIG. 6 is a configuration diagram of a MIX processing circuit.

FIGS. 7A and 7B are diagrams showing signal states when the gain is small and the gain is large.

FIGS. 8A and 8B are display examples of a small gain and a large gain when only MAX processing is performed.

FIGS. 9A and 9B are display examples when the gain is small and the gain is large when only the MIN processing is performed;

FIGS. 10A and 10B are display examples when the gain is small and the gain is large when only the overwriting process is performed;

FIGS. 11A and 11B are display examples when the MIX processing is performed and the gain is small and the gain is large.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshihiro Kitano 9-52, Ashihara-cho, Nishinomiya-shi, Hyogo F-term in Furuno Electric Co., Ltd. (Reference) 5J070 AA14 AC01 AC02 AC11 AH19 AH31 AH50 AJ03 AJ05 AJ14 AK13 AK17 AK19 AK22 AK39 BG02 BG06 BG15

Claims (3)

[Claims] 1. A coordinate conversion means for converting received data from polar coordinates to rectangular coordinates on a display screen, a MAX processing means for obtaining a substantially maximum value of received data corresponding to each pixel on the display screen as MAX data, M to find the substantially minimum value of the received data corresponding to each pixel of the screen as MIN data
IN processing means; MIX processing means for averaging MAX data and MIN data to obtain MIX data;
And an image memory for storing MIX data as pixel data. 2. The MAX processing means according to the following (1) to
(3), wherein the MIN processing means includes the following (1):
The radar device and the similar device according to claim 1, comprising (4) and (5). (1) and any sample point j on the preceding sweep theta _n, performs the preceding sweep theta _n and on consistency determination of the corresponding pixels between the plurality of adjacent sample points on the trailing sweep theta _n-1, sample point j FIRST detecting means for detecting the sample point j as a FIRST sample point when the corresponding pixel of the above does not match all of the corresponding pixels of the other sample points. (2) Stores the maximum value data at each sample point for one sweep (3) An arbitrary sample point j on the preceding sweep θ _n is FI
In the case of the RST sample point, the received data of the sample point is written, and in the case of not the FIRST sample point, the data on the maximum value extraction memory of another sample point having the same corresponding pixel as the corresponding pixel of the sample point and the sample point MAX extracting means for selecting the larger data by comparing the received data with the received data and writing the selected data in the maximum value extraction memory, so that the data at each sample point in the maximum value extraction memory is used as the MAX data. (4) 1 sweep (5) An arbitrary sample point j on the preceding sweep θ _n is FI
In the case of the RST sample point, the received data of the sample point is written, and in the case of not the FIRST sample point, the data on the minimum value extraction memory of another sample point having the same corresponding pixel as the corresponding pixel of the sample point and the sample point MIN extracting means for selecting the smaller data by comparing the received data with the received data and writing the selected data into the minimum value extracting memory, so that the data of each sample point on the minimum value extracting memory becomes MIN data. 3. A preceding sweep θ _n and a following sweep θ
The radar device and the like device according to claim 2, wherein the plurality of neighboring sample points on _n-1 are the following four sample points. (1) An adjacent sample point in front (in the sweep line upstream direction) of an arbitrary sample point j (2) A sample point on the succeeding sweep θ _{n-1 in which} the distance from the sweep start point is the same as the sample point j ( 3) Two sample points before and after the sample point of (2) above