JP3162660B2 - Scan correlation processing method - 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 apparatus mounted on a moving body such as a ship and provided with a raster scan type display such as a CRT or an LCD. The present invention relates to a scan correlation processing method executed to suppress the influence of clutter (collectively) and emphasize reflected waves (referred to as “echoes” in the present application) from targets such as other ships, land, and buoys.

[0002]

[Prior Art and Problems] PPI (Plan Position I)
The ndicator display is a display mode widely used in marine radar devices and the like, and is a mode in which the presence and position (distance and direction) of a target on a horizontal plane are two-dimensionally displayed. The PPI display can be further classified into several display modes by focusing on the movement of the position of the moving object on the screen on the screen and the azimuth setting on the screen.

[0003] Attention has been paid to the movement of a moving body (hereinafter also referred to as "own ship") for mounting, but this is for the sake of simplicity of description and is not intended to limit the application of the present invention to ships. In this case, it can be classified into a true motion (TM) mode and a relative motion (RM) mode. The TM mode is a display mode in which each display position on the screen is fixedly associated with each position on the earth surface. Therefore, the actual behavior (true motion) of the ship is displayed on the screen.
This is useful when you want to know what kind of behavior your ship is exhibiting from a fixed object such as land. On the other hand, RM
The mode is a display mode in which the position of the own ship is fixed on the screen. When this display mode is used, the radar image is displayed with the own ship as a reference or main body. Therefore, R
The M mode is useful when it is desired to grasp the behavior of another ship or the like as seen from the own ship, for example, at the time of a hulling.

When attention is paid to the azimuth setting on the screen, the PPI display is displayed in a North Up (NU).
P), course up (CUP), and head up (HUP). Of these, the NUP mode is a mode in which the radar image is displayed in a fixed orientation so that north is always on the screen. The CUP mode is a mode in which the radar image is displayed in a fixed orientation so that the course of the ship at the time of the most recent course reset is always on the screen. Here, the course reset is a process of initially setting information relating to the course of the ship to a display processing circuit (specifically, a coordinate conversion circuit that determines an address for writing correlation data to a radar video frame memory). . The HUP mode is a mode in which the azimuth related to the display of the radar image is changed according to the turning of the own ship so that the bow of the own ship is always on the screen.

When performing PPI display, TM /
The display mode is a combination of any one of RM and NUP / CUP / HUP. However, some combinations cannot be realized in principle, and some combinations have low practicality. Therefore, the combinations used in practical use are specific combinations. The most frequently used are RM mode and H
This is a mode combining the UP mode, that is, the RM / HUP mode. In this mode, there is obtained a display having no great difference from the view from the bow of the own ship, that is, a display without a sense of incongruity for the shipbuilder. Therefore, it is widely used in many ships, especially small fishing boats whose course is frequently changed. Next, TM
Mode combined with the NUP mode, that is, TM /
In the NUP mode, just like a map or a chart, a fixed object such as a land is displayed fixed and the display always faces north, so that the position of the own ship on the map or the chart, the presence or absence of a land, and the like are known. This is also useful when it is desired to distinguish between a fixed target and a moving target.

Meanwhile, in order to improve the quality of a display screen in a radar device, scan correlation processing for suppressing clutter and enhancing echo has been conventionally performed. That is,
While the echo from the target has an almost stable signal strength, the signal strength of clutter, which is a reflection from the sea surface or weather particles, is not stable, and therefore the radar reception signal obtained in a certain scan has In general, there is no strong correlation between this clutter and the clutter in the radar reception signal obtained in the next scan. The scan correlation process is a process that focuses on such a fact to improve the screen quality and realize an easily viewable screen. In particular,
A received signal (called “past data” in the present application) of a past scan stored as digital data in a memory is combined with data (called “current data” in the present application) relating to a received signal in the current scan. This is a process for obtaining data (referred to as “correlation data” in the present application) in which clutter is suppressed and echoes are emphasized.

In a radar apparatus for ships and the like, radio transmission / reception is performed by radar antennas while rotating the beam direction in a horizontal plane (deck plane). One transmission / reception is performed by one sweep in the beam direction. One rotation is called one scan. Therefore, since the received signal obtained by the radar device is essentially a signal in a polar coordinate format, when using a raster scan type display, that is, a display that displays an image by scanning in the horizontal and vertical directions, A coordinate conversion process from the polar coordinate format to the rectangular coordinate format is required, and the coordinate conversion process includes a write address for writing data relating to a received signal to a radar video frame memory having a storage space corresponding to the screen of the display. It can be realized by operation. The above scan correlation processing is realized by reading data on the radar video frame memory as past data, combining the read past data with the current data, and writing the resulting correlation data to the address from which the past data was read. it can. In the present application, of the accesses to the radar video frame memory, the access necessary for executing the coordinate conversion and the scan correlation processing, that is, the reading of the past data and the writing of the correlation data, are referred to as “correlation data writing” or simply “writing”. "
The address on the radar video frame memory accessed at that time is called a “write address”. Also, accessing the radar video frame memory and reading the correlation data for PPI display on the screen of the raster scan display is called “raster scan read” or simply “read”.
An address on the radar video frame memory accessed at that time is called a “read address”.

One of the problems with the prior art is that the scan correlation process cannot be performed accurately in the most frequently used mode, RM / HUP mode. For example, it is assumed that echoes from the same fixed target, for example, land, are obtained in a plurality of consecutive scans. RM / HU
In the P mode, the address at which the data relating to the echo from the fixed target is to be written is a rectangular coordinate value determined according to the distance from the own ship and the relative azimuth with respect to the own ship's traveling azimuth, so that the own ship moves or turns. When the distance from the own ship and the relative azimuth with respect to the own ship's traveling direction change in accordance with the above, the write address also changes. Therefore, even if the data is echo data from the same fixed target, the write address for writing the data changes every scan.
In other words, the position or direction of the echo from the fixed target on the past data used in the scan correlation process is different from the position or direction of the echo from the fixed target on the current data to be subjected to the scan correlation process. become. Therefore, the effect of emphasizing the echo from the fixed target on the current data using the past data is described in RM /
In the HUP mode, it cannot be fully demonstrated. In particular, this problem becomes more remarkable when the moving or turning speed of the ship is high or when the rotation speed of the antenna beam is low.

As an example of solving this problem and performing accurate scan correlation processing even in the RM / HUP mode, there is a configuration described in Japanese Patent Publication No. Hei 6-93020. The configuration described in this publication introduces a function division in which a radar video frame memory is divided into two, one of which is used for scan correlation processing and coordinate conversion, and the other is used for providing a display screen. Configuration. That is, scan correlation processing is performed using the data on the first radar video frame memory as past data, and the resulting correlation data is written into the first and second radar video frame memories, and the second radar video frame memory is written. For raster scan reading. In this configuration, by writing the correlation data to the first radar video frame memory in the TM mode and writing the correlation data to the second radar video frame memory in the RM / HUP mode, Eliminate problems. More specifically,
Even if the distance from the own ship to the fixed target and the relative direction of the fixed target with respect to the own ship traveling direction change as the own ship moves or turns, the correlation data writing in the TM mode is performed. On the radar video frame memory, the position of the data related to the echo from the fixed target is kept fixed, so that the above-mentioned echo enhancement effect is not lost.

However, in the configuration described in Japanese Patent Publication No. Hei 6-93020, since the correlation data in the TM mode is written in the first radar video frame memory, when the own ship is moving. Until the next writing / updating, the display position of the image does not change even if the own ship moves. Since this is distorted in the positional relationship with the target, etc.,
In Japanese Patent Publication No. Hei 6-93020, accurate display was difficult.

[0011]

SUMMARY OF THE INVENTION One of the objects of the present invention is to enable accurate scan correlation processing even in RM / HUP mode. An object of the present invention is to enable a written image to be accurately displayed regardless of the movement of the ship when displaying in the RM / HUP mode. In order to achieve such an object, in the present invention, a plurality of radar video frame memories are provided, and the plurality of frame memories are sequentially used for display, and are not used from the state of being used for display. When switching to the state, a course reset is performed on the correlation data write address.

First, the present invention is based on the assumption that past data, which is correlation data obtained in a past scan, is stored in a radar image according to a correlation data write address specified in synchronization with a radar transmission / reception operation. By reading out the past data read from the frame memory and combining the read out past data with the current data which is a received signal in the current scan, correlation data in which clutter is suppressed and echo is emphasized compared to the current data is generated, and the generated current data is generated. This is a scan correlation processing method in which correlation data for scanning is written to a radar video frame memory in accordance with the above-described write address. By executing the scan correlation processing method, the radar video frame memory in which the correlation data is written is subjected to raster scan reading for PPI display by a raster scan type display mounted on a moving body.

Next, the first feature of the present invention is that a plurality of radar video frame memories are prepared. In the present invention, one radar video frame memory is sequentially selected from one of the plurality of radar video frame memories at one to a plurality of scan intervals, and is provided for raster scan reading. Therefore, according to the present invention, in any scan, one of the plurality of radar video frame memories is used to provide a display screen, and the rest is used to store a non-display screen. In one scan, a certain radar video frame memory is used for providing a display screen, but in the next scan, the radar video frame memory is switched to non-display screen storage, and another radar video frame memory is used for providing a display screen. Is performed, or the function is changed.

A second feature of the present invention is that each of the plurality of radar video frame memories is used for providing a display screen when it comes out of a state provided for raster scan reading. At the time when the state shifts from the state of being used to the state used for storing the non-display screen, the writing address of the correlation data is reset. In this reset processing, the position of the moving body at the time of execution is returned to a predetermined position in the storage space, and the course at the time of execution is in the storage space corresponding to the upward direction on the PPI display screen. Perform so that it faces the direction. In other words, this reset process is a process of updating the fixed correspondence between each address on the radar video frame memory and each position on the earth surface when switching from the display screen providing state to the non-display screen storing state. It is.

As described above, in the present invention, the correlation data write address is reset for each of a plurality of radar video frame memories which are sequentially subjected to raster scan reading. Therefore, at the time of transition from the non-display screen storage state to the display screen provision state, the own ship position and the own ship traveling direction in the storage space of the radar video frame memory related to the shift are after the correlation data write address reset. It reflects only the effects of own ship movement and turning up to that point. Since the reset processing of the correlation data write address is performed at a relatively short time interval equivalent to several scans, the position of the own ship on the radar video frame memory at the time of transition from the non-display screen storage state to the display screen provision state. The own ship traveling direction substantially keeps own ship position and own ship traveling direction at the time of reset.

At the point in time when one or more scans have elapsed from this point, the other radar video frame memories are switched from the non-display screen storage state to the radar video frame memories that were in the display screen providing state until then. Move to the display screen providing state. As for the other radar video frame memory, the correlation data write address is reset at a time later than the radar video frame memory in the display screen providing state up to this time. Accordingly, when the other radar video frame memory shifts from the non-display screen storage state to the display screen provision state, the deviation of the own ship position and the own ship traveling azimuth (course of course) previously appearing on the PPI display screen of the display unit. At least a part of the deviation from the reset time is canceled, and the own ship position and the own ship traveling direction on the screen become closer to the position (for example, the center) and the direction (for example, on the screen) at the time of the course reset.

As described above, in the present invention, although the display is not the same as that of the conventional RM / HUP mode, the display is practically hardly distinguished practically (however, by the more accurate scan correlation processing). Display (improved image quality) is realized.

Further, when attention is paid to an arbitrary radar video frame memory, each address on the radar video frame memory and each position on the earth surface are maintained until the correlation data write address is reset and reset again. , And the correlation data is written in TM /
This is performed according to the write address in the CUP mode. In the present invention, since the correlation data is written into each radar video frame memory in accordance with the write address in the TM mode, the RM / H is substantially used as described above.
Despite the UP mode being realized, the problem that the echo enhancement effect due to the scan correlation processing is lost due to the movement of the own ship is the same as the configuration described in the above-mentioned publication.
Will not occur. Further, in the present invention, the configuration or function of a plurality of radar video frame memories is equivalent to each other, and two radar video frame memories with fixed function sharing are provided as in the configuration described in the above-mentioned publication. Absent. In other words, in the present invention, the number of radar video frame memories can be increased to three or more as necessary. In such a case, there is room for executing the reset processing of the correlation data write address except at the time of transition from the display screen providing state to the non-display screen storage state. It is possible to obtain an image closer to such display (however, the image is improved by more accurate scan correlation processing). In addition, the addition of the radar video frame memory only requires the addition of the same one that has been conventionally used, and does not burden the designer.

Further, in the present invention, the own ship position on each radar video frame memory is reset to a predetermined position at a relatively short time interval. Therefore, the display position of the own ship does not greatly deviate from the position corresponding to the actual own ship position, and distortion can be prevented, even though the write address according to the TM mode is used.

Further, in a more preferable configuration of the present invention, the read start address related to the raster scan read is moved by the same amount in the direction as the moving body in the storage space. Thus, it is possible to prevent the image display position from being shifted due to the movement of the own ship.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a marine pulse radar apparatus according to an embodiment of the present invention. In the figure, an antenna 10 is provided at a location with a good view on its own ship, and transmits a radar pulse by radio in response to a transmission trigger generated by a transceiver control circuit 14 under the control of a CPU circuit 12.
When a target such as another ship or land exists in the transmission direction of the radar pulse, the radar pulse is reflected by the target and an echo is received by the antenna 10. Antenna 10
Is driven so that its beam direction rotates in the horizontal plane (in the deck plane). By monitoring the reception signal during one rotation of the beam of the antenna 10, that is, during one scan, It is possible to obtain information on the presence or absence and position of the target.

The A / D conversion circuit 16 converts the signal received by the antenna 10 into digital data, and a sweep memory 18 at the subsequent stage temporarily stores the digital data for at least one sweep. The data on the sweep memory 18, that is, the current data, is supplied to the scan correlation processing circuits 20A and 20B, and is subjected to the scan correlation processing using the past data. The correlation data generated by the scan correlation processing circuit 20A by the scan correlation processing is written to the radar video frame memory A, and the correlation data generated by the scan correlation processing circuit 20B is written to the radar video frame memory B.

The correlation data on the radar video frame memories A and B may be used as past data in a scan correlation process in a later scan, and may be used as a raster scan type display such as a CRT display 22.
Sometimes used for PI screen display. In this embodiment, the selection circuits 24A, 24B and 26 are provided for switching between the past data supply source and the display data supply source. The read data selection circuit 24A sends the past correlation data, that is, the source of the past data to the scan correlation processing circuit 20A.
This is a means for switching between the radar image frame memories A and B. The read data selection circuit 24B supplies the past correlation data, that is, the source of the past data to the scan correlation processing circuit 20B between the radar image frame memories A and B. It is means for switching. Further, the display selection circuit 26 includes a CPU
Correlation data is raster-scan-read from one of the radar video frame memories A and B while appropriately switching the radar video frame memory to be subjected to raster scan read-out in response to the display switching control signal from the circuit 12. The raster scan read address is controlled by the CPU circuit 12.

The D / A conversion circuit 28 converts the raster scan read data into an analog video signal,
It is supplied to the display 22. At this time, graphic data (video data indicating characters, symbols, etc.) written by the graphic control circuit 30 on the graphic frame memory under the control of the CPU circuit 12 is transmitted to the D / A conversion circuit 28 or its peripheral circuits. Is superimposed on the correlation data read by the raster scan, that is, the radar video data to be displayed.

The write address of the correlation data to the radar video frame memory A (the read address of the past data) is determined by the coordinate conversion circuit 34A, and the write address of the correlation data to the radar video frame memory B (= the past data is read). The read address is generated by the coordinate conversion circuit 34B. The formula used to generate the write address is

X = XC + Rsin θ Y = YC + Rcos θ This formula is a formula for coordinate conversion for converting the data related to the received signal from the polar coordinate format to the rectangular coordinate format, and at the same time, gives the write address of the correlation data (= read address of the past data) and performs the scan correlation process. This is an expression for realizing, and also an expression for giving an object of reset processing which is one of the features of the present invention. In this equation,
(X, Y) indicates a write address to be generated, and (XC, YC)
Represents the write start address, and R and θ represent the distance from the ship to the target on the radar video frame memory and the target direction with reference to the upward direction on the screen. The circuits 36 to 42 in the figure give information necessary for the calculation by this equation.

First, the antenna rotation signal generating circuit 36 determines the relative azimuth θA of the beam of the antenna 10 with respect to the advancing direction of the ship.
Is generated. The gyro interface circuit 38 receives, for example, a signal indicating the traveling direction θG of the ship based on true north from a gyro compass (not shown). The speed information input circuit 40 inputs information on the movement of the own ship, for example, information on the speed of the own ship from a navigation device or the like. The gyro interface circuit 38 and the speed information input circuit 40 input these signals and information in response to a command from the CPU circuit 12. The angle signal control circuit 42
An angle signal corresponding to the display mode instructed by the PU circuit 12, that is, a signal indicating θ in the above equation is generated based on an antenna rotation signal and a signal from a gyro compass, and is supplied to the coordinate conversion circuits 34A and 34B. The coordinate conversion circuits 34A and 34B generate a write address (X, Y) using θ given as an angle signal from the angle signal control circuit 42, and input the speed information input circuit 40 to the own ship position. (XC, YC) is set or updated using information on the change of

A characteristic operation of the present embodiment is that the user operates the CPU circuit 12 as a display mode as RM / HU.
This is the operation when the P mode is designated. When the RM / HUP mode is instructed from the CPU circuit 12, the angle signal control circuit 42 obtains θ according to the equation θ = θA + θG-θC, and converts the angle signal indicating this θ into the coordinate conversion circuit 34.
A and 34B. Coordinate conversion circuits 34A and 34
B receives this angle signal and generates a write address (X, Y). Here, in the above equation, θC is C
This is the value of θG when the PU circuit 12 commands the reset of the correlation data write address. Therefore, θ immediately after reset
Is equal to θA, which is exactly the same as the conventionally known HU
It becomes equal to θ in the P mode. In the present embodiment,
The reset of the correlation data write address of the radar video frame memory A and the reset of the correlation data write address of the radar video frame memory B are alternately instructed for each scan. Therefore, in the present embodiment, θ for generating the correlation data write address for the radar video frame memory A and θ for finding the correlation data write address for the radar video frame memory B are set every scan. Alternately (thus every two scans when focusing on one radar video frame memory), θA, ie, the conventional HU
The traveling direction in the P mode will be reset.

The coordinate conversion circuits 34A and 34B further include:
When a write address reset is instructed, the information input from the speed information input circuit 40, that is, the information relating to the change in the position of the ship, is used to write the start address of the correlation data to the corresponding radar video frame memory, ie, ( XC, Y
C) is returned to a predetermined position on the screen, for example, an address corresponding to the center. Thereby, the radar video frame memory A
And B in the storage space are alternately returned to a predetermined position, for example, the center position, for each scan.

Further, in the RM / HUP mode, the CPU circuit 12 supplies a display switching control signal to the display selection circuit 26 to cause the radar video frame memories A and B to be alternately subjected to raster scan reading for each scan. . Further, this operation is performed in synchronization with the reset of the correlation data write address. That is, for the radar video frame memory that has been switched from the state targeted for raster scan readout to the state not targeted for raster scan readout, at the time of this switchover, the raster scan readout is performed so that the correlation data write address is reset. Is switched in synchronization with the resetting of the correlation data write address. Furthermore, the read data selection circuits 24A and 24B supply past correlation data in the radar video frame memory which is not currently subjected to raster scan reading to the scan correlation processing circuits 20A and 20B as past data. , Perform a switching operation. In addition, the start address of the raster scan reading is controlled according to the information input from the speed information input circuit 40 and indicating the change in the position, so that the display position on the screen does not shift under the control of the CPU circuit 12. Is done.

FIGS. 2 to 6 show transitions for the radar video frame memories A and B when the RM / HUP mode command is issued. In these figures, the dashed rectangles indicate the expansion of the storage space of each radar video frame memory, and the solid circles present in the dashed rectangles indicate the storage areas where the correlation data is written at each time. Further, a black circle representing the center of the solid line circle is an address used as a writing start address of the correlation data in the above-mentioned equation, and a solid straight line extending from the black circle represents the own ship at each time point. Indicates the heading direction. White circles indicate initial values (reset values) of the write start address of the correlation data. Further, “display screen” in the figure represents a radar video frame memory that is targeted for raster scan reading, and “non-display screen” represents a radar video frame memory that is not targeted. Further, the area indicated by the solid rectangular frame with respect to the radar image frame memory on the side indicated as “display screen” is an area to be read by raster scan, and its upper left coordinate value, for example, (HDX
(C, HDYC) is a start address of raster scan reading.

In the examples shown in FIGS. 2 to 6, first, the RM
When display in the / HUP mode is started, reset processing of the correlation data write address is performed for both the radar video frame memories A and B. That is, the center position (XC, YC) of the storage space of each radar video frame memory is initially set at the writing start address, and the direction corresponding to the screen direction on each of the radar video frame memories A and B is set to the ship's traveling direction. Is initialized, (HDXC, HDYC) is initialized to the start address of the raster scan readout for the radar video frame memory A used for the display screen during the first one of these scans.

After this initial setting, correlation data is written on each of the radar video frame memories A and B for one scan. At this time, the read data selection circuits 24A and 24A
B operates so that the past correlation data on the radar video frame memory B is supplied as the past data to the scan correlation processing circuits 20A and 20B. Further, in general,
Since the ship to be mounted gradually moves and turns, the own ship position and the own ship traveling direction change in the storage space of each radar video frame memory. The CPU circuit 12 makes the display selection circuit 2 based on the information obtained from the speed information input circuit 40 and the information provided from the gyro interface circuit 38 in order to make the display on the screen follow the movement of the ship.
6 and gradually shifts the read start address for raster scan read.

FIG. 3 shows the stored contents at the time when this one scan is completed. At this point, the correlation data writing start address is (X1, Y1), the traveling direction of the own ship is θ1, and the raster scan reading start address is (HDX1, HDY1). At this point, the CPU circuit 12 supplies a display switching control signal to the display selection circuit 26 to switch the raster scan readout target from the radar video frame memory A to the radar video frame memory B, and at the same time, to the angle signal control circuit 42 A command to reset the correlation data write address for the radar video frame memory A is issued. Then, as shown in FIG. 4, the radar video frame memory A
Is changed to non-display screen storage, the radar video frame memory B is changed to display screen provision, and the correlation data write start address in the storage space of the radar video frame memory A returns to the initial value (XC, YC). Your ship's heading returns to the top of the screen.

After the switching of the raster scan readout target and the reset processing of the correlation data write address are performed as described above, during one scan, the radar video frame memory B
Are used for providing a display screen, that is, as a target of raster scan reading. Each read data selection circuit operates so that the past correlation data in the radar video frame memory A is used as the past data in each scan correlation processing circuit. At the time when this scan is actually finished, as shown in FIG. 5, the correlation data writing start address is shifted on both the radar video frame memory A and the radar video frame memory B, and the ship's traveling direction is changed. Is also displaced. However, regarding the radar video frame memory A, since the correlation data writing address is reset at a time before one scan, the correlation data writing start address and the traveling direction of the own ship on the radar video frame memory B are determined. Compared with the shift, those on the radar video frame memory A are smaller shifts.

At this time, the CPU circuit 12 instructs the display selection circuit 26 to switch the raster scan readout target from the radar video frame memory B to the radar video frame memory A, and outputs the correlation related to the radar video frame memory B. A command is issued to the angle signal control circuit 42 to reset the data write address. Then, as shown in FIG. 6, the correlation data writing start address on the radar video frame memory B moves to the center, the own ship traveling direction moves upward on the screen, and the radar video frame memory A Began to be used for providing display screens. As a result, the own ship position on the screen of the CRT display 22 is returned from (X3, Y3) shown in FIG. 5 to (X2, Y2) shown in FIG. θ2 =
It will be pulled back from θ2 + θ1 to θ2.

Therefore, according to the present embodiment, the conventional RM
A display similar in appearance to the / HUP mode can be realized. Further, at that time, the radar video frame memory A
And B are written using the write address in the TM mode, so that inaccuracies do not occur in the scan correlation processing. Further, since the correlation data writing start address, that is, the own ship position is returned to the initial position, for example, the center, before reaching the end of the storage space of the radar video frame memories A and B, the non-display screen storage is performed. Scan correlation processing is performed using the data in the radar video frame memory used for the past as past data, so that the correlation data is written at the write address related to the TM mode. In addition, it is possible to prevent distortion due to displacement of the own ship position.

Furthermore, in this embodiment, two radar video frame memories A and B are provided, but three or more radar video frame memories may be provided. Furthermore, in this embodiment, since a scan correlation processing circuit and a coordinate conversion circuit are provided corresponding to each radar video frame memory, for example, when performing display in the TM mode, any one set of The TM mode can be realized by using the radar video frame memory, the scan correlation processing circuit, and the coordinate conversion circuit. At that time, if the correlation data is written on the remaining radar video frame memory (but the write address is shifted), when the own ship position reaches the end of the storage space and the pullback processing is required. By simply switching the radar video frame memory to be used, it is possible to prevent the loss of past data and continue to enjoy the effect of scan correlation processing. In implementing the present invention, it is not necessary to provide a scan correlation processing circuit for each radar video frame memory.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a marine pulse radar device according to an embodiment of the present invention.

FIG. 2 is a storage space diagram showing an operation of the present embodiment.

FIG. 3 is a storage space diagram showing an operation of the present embodiment.

FIG. 4 is a storage space diagram showing the operation of the present embodiment.

FIG. 5 is a storage space diagram showing the operation of the present embodiment.

FIG. 6 is a storage space diagram showing the operation of the present embodiment.

[Explanation of symbols]

A, B radar video frame memory, 12 CPU circuit, 20A, 20B scan correlation processing circuit, 22C
RT display, 24A, 24B read data selection circuit, 2
6 display selection circuit, 34A, 34B coordinate conversion circuit, 4
2 Angle signal control circuit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-43519 (JP, A) JP-A-5-203725 (JP, A) JP-A 8-271615 (JP, A) JP-A-7- 92250 (JP, A) JP-A-8-43518 (JP, A) JP-A-5-288845 (JP, A) JP-A-4-212082 (JP, A) (58) Fields investigated (Int. Cl. ^7, DB name) G01S 7/24 G01S 7/32 G01S 7/295 - 7/298

Claims (2)

(57) [Claims] 1. A past data, which is a correlation data obtained by a past scan, is read from a radar video frame memory in accordance with a correlation data write address specified in synchronization with a radar transmission / reception operation, and the read past data is stored in a current frame. By combining the data with the current data as a received signal in the scan, correlation data is generated in which clutter is suppressed and echo is emphasized compared with the current data, and the generated correlation data for the current scan is written according to the write address. A scan correlation processing method for writing in a radar image frame memory, wherein the scan for providing the radar image frame memory in which the correlation data is written is subjected to raster scan reading for PPI display by a raster scan type display mounted on a moving body. In the correlation processing method, the radar video frame memory A plurality of radar image frame memories are prepared, and one radar image frame memory is sequentially selected from the plurality of radar image frame memories at one to a plurality of scan intervals and subjected to the raster scan readout. The raster scan reading is performed such that the position of the moving body at that time returns to a predetermined address in the storage space and the course at that time points in the direction corresponding to the upward direction of the PPI screen in the storage space. A scan correlation processing method, wherein a write address of the correlation data is reset at a time when the correlation data is out of a provided state. 2. The scan correlation processing method according to claim 1, wherein the read start address for the raster scan read is moved by the same amount in the same direction as the movement of the moving body in a storage space. Scan correlation processing method.