JPH0843518A - Coordinate transformation method and display method in radar apparatus - Google Patents

Abstract

PURPOSE:To obtain a coordinate transformation method in which a coordinate-transformation start address indicating the center of a polar coordinate system is generated while it is being updated a plurality of times during one rotation of an antenna, in which the address is written in accordance with the polar coordinate system using the address as the central point and in a true-motion and north-up mode and in which coordinates can be moved smoothly on a display device. CONSTITUTION:A direction arithmetic part 3 adds an antenna direction given by a direction pulse to a track given by a gyro compass, and it finds a polar coordinate direction so as to be sent to a coordinate transformation part 4. A control part 5 operates a coordinate- transformation start address so as to be given to the transformation part 4. The transformation part 4 generates a write address from the address. In this case, a received signal on a buffer memory part 2 is written into an image memory as radar image data in a true-motion and north-up mode. In addition, whenever the counted value of the direction pulse of an antenna, i.e., the antenna direction, is changed by a prescribed angle, the coordinate- transformation start address is updated a plurality of times during one rotation of the antenna according to the track and a speed. Thereby, a sudden image jump and a rotation on a screen are hard to be generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate conversion method and a display control method in a radar device.

[0002]

2. Description of the Related Art A radar device is known as a device for displaying an image of the surrounding environment. For example, a pulse radar device mounted on a ship generates a transmission pulse at a predetermined repetition period and transmits an electric wave from an antenna rotating at a predetermined speed according to the transmission pulse. The reflected wave from the target such as another ship is received by this antenna. The received reflected wave contains the time from the pulse transmission to the reflected wave reception as information about the distance to the target, so by using it together with the azimuth of the antenna at the time of transmission and reception, , A polar coordinate type radar image can be obtained. The user can know the existence and position of the target in the surroundings by looking at the displayed radar image.

On the other hand, as a display for displaying a radar image, a raster scan type CRT or the like has recently been used. Since this type of display is a display in the rectangular coordinate format, it is necessary to perform coordinate conversion processing for converting the received information from the polar coordinate format to the rectangular coordinate format. This coordinate conversion is executed as address control when writing the information obtained by transmission and reception into the image memory. The display displays a radar image based on the information written in the image memory.

FIG. 8 shows the configuration of a radar device according to a conventional example. The apparatus shown in this figure has an A / D converter 10
1, a buffer memory unit 102, an orientation calculation unit 103, a coordinate conversion unit 104, a control unit 105, and an image memory unit 106. An analog reception signal received by an antenna (not shown) is first converted from analog to digital by the A / D conversion unit 101, and the obtained digital reception signal is a predetermined sweep amount (generally one sweep. Means one transmission) Buffer memory unit 102
Is stored.

The received signal on the buffer memory unit 102 is written in the image memory unit 106 as radar image data under the control of the coordinate conversion unit 104. That is, the coordinate conversion unit 104 supplies a coordinate conversion clock (not shown) in addition to the coordinate conversion direction θ _Z given from the direction calculation unit 103 and the coordinate conversion start address (X _S , Y _S ) given from the control unit 105. The write address (X, Y) is generated by using the read address, the radar image data on the buffer memory unit 102 is read in synchronization with the coordinate conversion clock, and the image memory unit 10 is read.
Write to 6. The image memory unit 106 is generally composed of a random access read / write memory and a multiport RAM equipped with a serial access memory.
The control unit 105 generates display addresses in the screen scanning order of the display unit in synchronization with the horizontal synchronizing signal given to the display unit, and reads the radar image data from the image memory unit 106 using the generated display address. The display address is composed of a column address and a row address, and is generated by the procedure of scanning the next column after the scanning of one column is completed. The display displays a radar image based on the read radar image data.

The process of converting the received signal in polar coordinate format into the radar image data in rectangular coordinate format is performed exclusively by the coordinate conversion unit 10.
It is performed by 4. The coordinate conversion unit 104 performs the coordinate conversion calculation based on the following equation (1) based on the coordinate conversion direction θ _Z and the coordinate conversion start address (X _S , Y _S ) to obtain the write address (X, Y). To generate. Note that R
Indicates the distance from the ship and can be known based on the time from the transmission.

[0007]

[Formula 1] X = X _S + R · sin θ _Z Y = Y _S + R · cos θ _Z (1) The coordinate conversion azimuth θ _Z is calculated by the azimuth calculation unit 103 according to the azimuth display mode to be set. Calculate based on. In the azimuth display mode, the head-up mode in which the line connecting the center of the radar image and directly above the display is the bow of the ship, and the north-up mode in which the line connecting the center of the radar image and directly above the display is north , And there is a course-up mode in which the direction of the course that the ship owns can be directed to the line connecting the center of the radar image and directly above the display. The azimuth calculation unit 103 uses the following expression (2) to convert the coordinate conversion azimuth θ according to which azimuth display mode is set.
Calculate _Z. Note that θ _R is a signal that is input as an antenna azimuth signal and indicates the azimuth of the antenna, and is generally obtained by counting azimuth pulses. θ _G is the course of the ship that is input from a gyro compass or the like, and θ _C is the course that the ship is enthusiastic about.

[0008]

[Equation 2] Head up mode θ _Z = θ _R North up mode θ _Z = θ _R + θ _G Course up mode θ _Z = θ _R + θ _G −θ _C (2) On the other hand, start coordinate conversion The address (X _S , Y _S ) is controlled by the control unit 10 according to the set motion mode and azimuth display mode.
5 calculates based on the course and the speed signal. The motion mode includes the relative motion mode in which the position of the ship is fixed on the display, and the true motion in which the position of the ship moves according to the motion of the ship on the display because the fixed target is fixed. There are modes. When the relative motion mode is set, the control unit 10
Reference numeral 5 outputs a constant value as the coordinate conversion start address (X _S , Y _S ) and fixes the own ship image at the center of the radar image, for example. When the true motion is set, the control unit 105
Calculates the coordinate conversion start address (X _S , Y _S ) using the following equation (3). Note that (X _s-1 , Y _s-1 )
Is the ship's position before time t, and V is the ship's speed given by the speed signal. Coordinate conversion start address (X _S ,
Y _s ) is updated once per scan (that is, one scan cycle = t. Scan means one revolution of the antenna).

[0009]

[Expression 3] X _S = X _s-1 + V · sin θ _G · t Y _S = Y _s-1 + V · cos θ _G · t (3)

[0010]

Generally, the update period of the radar image is one scan. Therefore, when the target or the ship itself greatly moves between the previous scan and the current scan, the image of the target largely flies on the radar image (picture skipping). For example, when the own ship moves at high speed, as shown in FIG. 9, picture skipping occurs on the target on the bow line.
This is also the case when the target moves at high speed. Also,
Picture skipping tends to occur more prominently as the range range used is smaller and the amount of relative movement to the target is larger. In addition, when the head-up image is displayed, the land image rotates due to the turning of the ship.

In the state where the picture skipping or the rotation of the land image is occurring, it is difficult to accurately grasp the surrounding situation only by glancing at it. Moreover, in order to grasp the surroundings, it is necessary to continue observing several scan screens. Therefore, if the picture skipping and the rotation of the land image occur remarkably, there is a danger in maneuvering in an emergency.

The present invention has been made to solve the above problems, and the access control of the image memory controls the movement mode and the movement mode even when the ship or target moves at high speed. An object of the present invention is to realize a radar device in which a target moves smoothly on a display regardless of the azimuth mode.

[0013]

In order to achieve such an object, the coordinate conversion method of the present invention writes a received signal obtained by a polar coordinate system into an image memory having a storage space corresponding to the screen of a display. At this time, in the coordinate conversion method of controlling the write address to convert the received signal into radar image data suitable for a display in a rectangular coordinate system, a coordinate conversion showing the center of the polar coordinate system while updating a plurality of times per revolution of the antenna. It is characterized in that a start address is generated, and a write address is generated according to a polar coordinate system having a coordinate conversion start address as a center point and according to a true motion / north-up mode.

The present invention is further characterized in that the coordinate conversion start address is updated according to the direction of the antenna. The present invention is also characterized in that, when the received signal is written in the image memory, the received signal that extends from the storage space of the image memory is written in the remaining storage space of the image memory.

The display control method of the present invention executes the coordinate conversion method of the present invention, generates a read start address while interlocking with the coordinate conversion start address, and generates a read start address, according to an orthogonal coordinate system in which the read start address is an even point. A read address is generated according to the designated motion mode and azimuth display mode, and the radar image data is read from the image memory according to the read address.

The present invention is characterized in that the radar image data read from the image memory is stored in the horizontal scanning memory for one horizontal scanning of the display and then supplied to the display. The present invention is characterized in that writing to the horizontal scanning memory is executed during the non-display period of the display device, and reading from the horizontal scanning memory is executed during the display period.

[0017]

In the coordinate conversion method of the present invention, the coordinate conversion start address indicating the center of the polar coordinate system is updated a plurality of times per revolution of the antenna, and the true coordinate movement is performed according to the polar coordinate system with the coordinate conversion start address as the center point. A write address is generated according to the north-up mode. Therefore, in the storage space of the image memory, the position of the coordinate conversion start address is updated a plurality of times in accordance with the movement of the ship and the like and during one revolution of the antenna. On the other hand, the target written before the update does not change its position in the storage space of the image memory because it is in true motion / north up mode. The relative positional relationship between the position (own ship position) and the target in the storage space gradually changes. As a result, when a radar image is generated based on the information on the image memory, picture skipping and rapid rotation in which the positional relationship between the ship position and the target suddenly changes are unlikely to occur.

In the display control method of the present invention,
The read start address is updated in association with the coordinate conversion start address, and the read is performed according to the designated motion mode and azimuth display mode. Therefore, although the writing is performed in the true movement / north up mode, the display in the desired movement mode and azimuth display mode is possible. Further, in either mode, it is possible to prevent picture skipping and rapid rotation.

In the present invention, the coordinate conversion start address is further updated according to the direction of the antenna. That is, when the antenna rotates by a predetermined amount, the coordinate conversion start address changes accordingly. Therefore, the above process can be realized as a relatively simple process. In the present invention,
When writing the received signal to the image memory, the received signal that extends from the storage space of the image memory is written to the remaining storage space of the image memory. Therefore, a stable radar image can be obtained without loss of past accumulated information due to the pullback process.

In the present invention, the radar image data read from the image memory is stored for one horizontal scanning of the display and then supplied to the display. That is, the present invention can be implemented at low cost by adding a simple and inexpensive horizontal scanning memory. In the present invention, writing to the horizontal scanning memory is executed during the non-display period of the display device, and reading from the horizontal scanning memory is executed during the display period. Therefore, it is not necessary to use a multiport memory as the image memory.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a radar device according to an embodiment of the present invention. Shown in this figure is the configuration around the image memory. The operations of the A / D conversion unit 1 and the buffer memory unit 2 are the same as those of the conventional example.
1 and the buffer memory unit 102.

The first feature of this embodiment is that writing to the image memory unit 7 is always performed in the true motion / north up mode. That is, the azimuth calculation unit 3
Generates a coordinate conversion direction θ _Z by adding the aerial line direction θ _R given as a direction pulse or the like and the course θ _G given from the gyro compass or the like to the coordinate conversion unit 4. The control unit 5 calculates the coordinate conversion start address (X _S , Y _S ) using the above equation (3) and gives it to the coordinate conversion unit 4. The coordinate conversion unit 4 generates the write address (X, Y) using the above equation (1). As a result, the received signal on the buffer memory unit 2 is written on the image memory 7 as radar image data in the true motion / north up mode.

At the time of writing, so-called folding processing is performed. That is, when the own ship is moving, the target or the own ship image arrives at the end point of the storage space of the image memory unit 7 as the coordinate conversion start address (X _S , Y _S ) is updated. In this case, the coordinate conversion start address (X _S , Y _S ) may be pulled back to a certain point in the storage space of the image memory unit 7. However, when the coordinate transformation start address (X _S , Y _S ) is pulled back, the radar image data up to that point is obtained at each point on the earth. Despite being stable, it will disappear. The folding process is a method for preventing such disappearance. As shown in FIG. 2, the folding process is performed by moving the coordinate conversion start address (X _S , Y _S ) so that the radar image projected from the rectangular storage space on one side L of the image memory unit 7 (indicated by a broken line in the figure). This is a process of writing the data of (a, b, c) to other parts (a ', b', c ') of this storage space. By performing such processing,
Despite writing in the true motion mode, continuous processing can be performed without losing the stable radar image data for each point on the earth. Specifically, the return processing is performed by the coordinate conversion start address (X
Performed as processing to ignore carry when _S , Y _S ) overflows or carry address when write address (X, Y) overflows caused by movement of coordinate conversion start address (X _S , Y _S ). To be done.

The second characteristic of this embodiment is that
The coordinate conversion start address (X _S , Y
_s ) is not updated once per scan, but the coordinate conversion start address (X _S , Y _s ) is generated every time the count value of the direction pulse of the antenna, that is, the antenna direction θ _R changes by a predetermined angle.
Is set according to the course θ _G and the speed V. Therefore, in this embodiment, the coordinate conversion start address (X _S ,
Y _s ) is updated multiple times in one scan. Further, because of this need, the antenna direction signal is also input to the control unit 5.

The third feature of this embodiment is that the read control unit 6 generates a read address according to the azimuth display mode and motion mode being used, and the radar image data read from the image memory unit 7 is used as a horizontal scanning memory. It is provided to the display through the section 8.

FIG. 3 is a conceptual diagram showing the storage space of the image memory unit 7 in the reading method according to this embodiment. In the present embodiment, since the writing is performed in the true motion / north up mode, as shown in FIG. 3A, the writing is sequentially performed according to the own vessel course θ _G , the velocity V, and the aerial line direction θ _R. Coordinate conversion start address (X
_The inside of a circle centering on ( _S , Y _S ) is the writing destination of the radar image data. However, since the folding process is performed as described above, the portion of the circle that extends beyond the storage space is folded and written. The reading method will be described below for each mode.

(1) Relative motion / head-up mode In order to read out and display the radar image data written in the true motion / north-up mode in the relative motion / head-up mode in this manner, the radar image data is displayed in a rectangular shape in the storage space. On the other hand, from the rectangle inclined by the course θ _G (broken line in Fig. 3 (a)),
It is necessary to read it. Further, this reading is performed by the vertical synchronization signal V _SYNC and the horizontal synchronization signal H given to the display
_In synchronism with _SYNC , horizontal scanning from R ₁ to R ₂ , horizontal scanning from R ₃ to R ₄ , and so on must be performed in the same manner as the scanning of the display. However, since the folding process is performed as described above, the horizontal scanning is actually performed as shown in FIG.
As shown in (b), the process is repeated in the order of →→→→→. The radar image data thus read is stored in the horizontal scanning memory unit 8 in units of one horizontal scanning line. The horizontal scanning memory unit 8 is composed of a memory such as a FIFO. The storage in the horizontal scanning memory unit 8 is
In the non-display period shown in FIG. 4, the transfer clock CK
It is executed in synchronization with. The radar image data stored in the horizontal scanning memory unit 8 is read in synchronization with the dot clock during the display period and supplied to the display. As a result, a radar image in the relative motion / head-up mode as shown in FIG. 3C is displayed on the screen of the display.
It should be noted that on the display device, a masking process (not shown) such as a circle is actually performed so that an unnecessary portion is not displayed.

When displaying in the relative motion / head-up mode, the read start address (X _R , Y _R ) is generated according to the following equation (4), and the heads (R ₁ , R) of each horizontal scanning line are generated.
_3, ... address), i.e. the vertical read address (X _V, Y _V) was generated according to the following equation (5), addresses in each horizontal scanning line, i.e. horizontal read address (X _H, the Y _H) following It is generated according to the equation (6). However, CK is a value obtained by counting the transfer clock CK from the start of reading each horizontal scanning line, and HCK is the horizontal synchronization signal H.
It is a value obtained by counting _SYNC .

[0030]

X _R = X _S · cos θ _G + Y _S · sin θ _G −L / 2 Y _R = −X _S · sin θ _G + Y _S · cos θ _G + L / 2 (4)

X _V = X _R + HCK · cos (θ _G + π / 2) X _V = Y _R −HCK · sin (θ _G + π / 2) (5)

To [6] _{X H = X V + CK ·} cosθ G Y H = Y V -CK · sinθ G ... (6) 5 and 6, the display state of the target object in relative motion, head-up mode is shown ing. (A) in each figure
The write operation and the read operation to and from the image memory unit 7 are shown. Particularly, the solid line portion indicates the storage space of the image memory unit 7,
The broken lines indicate the read areas. Further, (b) in each figure shows an image on the display. In addition, these figures show the coordinate conversion start address (X _S ,
Y _S ), and therefore the read start address (X _R , Y _R ).
Is assumed to be updated each time the antenna rotates by π / 2 [rad].

In FIG. 5 (1) (a) and (b), θ _R = 0
The state of is shown. In addition, in this figure, the target exists in front of the ship. From this state, the antenna rotates and θ _R
It is assumed that the own ship has moved forward and approached the target at the time of reaching π / 2. At this time, as shown in FIG. 5 (2) (a), the coordinate conversion start address (X _S , Y _S ) (in this case, the own ship position in the storage space) becomes the course θ _G and speed V of the own ship. Will be updated accordingly. In the example of this figure, the coordinate conversion start address (X _S , Y _S ) has moved to the upper right. Also,
The read start address (X _R , Y _R ) is updated in association with the coordinate conversion start address (X _S , Y _S ) while the antenna on the front of the ship on the image memory unit 7 is rotated by the antenna. Since it is not updated until θ _R = 0 again,
As shown in (b), the image of the target approaches the image of the own ship. After this, when the antenna further rotates and reaches θ _R = π, the coordinate conversion start address (X _S , Y _S ) is updated as shown in FIG. 5 (3) (a), and the coordinate conversion start address (X _S , Y _S ) is updated. ) The image of the target gets closer to the image of the ship as shown in (). θ _R
= 3π / 2, the coordinate conversion start address (X _S , Y _S ) is updated as shown in FIG. 6 (4) (a), and as shown in FIG. 6 (4) (b). The image of the mark is closer to the image of the ship. When θ _R = 0, FIG. 6 (5)
As shown in (a), the coordinate conversion start address (X _S ,
Y _S ) is updated, and the position of the target in front of the own ship on the image memory unit 7 is updated. Therefore, as shown in FIG. The positional relationship reflects both the own ship and the movement of the target. Through such a series of processing, the target in front of the own ship smoothly approaches the own ship on the screen.

(2) Relative Movement / North Up Mode Next, when reading and displaying in the relative movement / north up mode, since the writing is performed in the north up mode, equations (4) to The following equations (7) to (9) in which θ _G in (6) is set to 0 are used.

[0033]

## EQU00007 ## X _R = X _S -L / 2 Y _R = Y _S + L / 2 (7)

[Equation 8] _{X V = X R X V =} Y R -HCK ... (8)

In case of reading the display in Equation 9 _{X H = X V + CK Y} H = Y V ... (9) (3) relative movement course up mode relative movement courses up mode, equation (4) to (6 ) of next of theta _G was replaced by theta _G - [theta] _C in the formula (10) is used to (12).

X _R = X _S · cos (θ _G −θ _C ) + Y _S · sin (θ _G −θ _C ) −L / 2 Y _R = −X _S · sin (θ _G −θ _C ) + Y _S・ Cos (θ _G −θ _C ) + L / 2 (10)

X _V = X _R + HCK · cos (θ _G −θ _C + π / 2) X _V = Y _R −HCK · sin (θ _G −θ _C + π / 2) (11)

Equation 12] _{X H = X V + CK ·} cos (θ G -θ C) Y H = Y V -CK · sin (θ G -θ C) ... (12) (4) Shin movement North-up mode True motion -When reading and displaying in the north-up mode, since writing is performed in the north-up mode, basically, the read start address (X
_R , Y _R ) may be fixed and vertical read addresses (X _V , Y _V ) and horizontal read addresses (X _H , Y _H ) may be generated without tilting with respect to the storage space of the image memory unit 7. . That is, equations (7)-(9) can be used (if reset processing is not taken into consideration). However, in the true motion mode, the reset process is performed at the start of the true motion or when the ship moves and reaches the reset point.
The reset process is a process of pulling back the position of the own ship when the own ship reaches a predetermined position in order to prevent the position of the own ship from protruding out of the display area. It is realized by resetting (X _R , Y _R ). Read start address (X _R ,
For the setting of (Y _R ), the distance from the center of the display screen to the reset point is D, and the coordinate conversion start position during reset processing is (X _SO ,
Y _SO ), the following expression (13) is obtained. In this mode, equation (13) is used instead of equation (7).

[0034]

[Formula 13] X _R = X _SO −L / 2 + D · sin θ _G Y _R = Y _SO + L / 2 + D · cos θ _G (13) (5) True movement / course up mode Read display in true movement / course up mode If you want to do, the same formula (4) as in the relative movement / course up mode
Replace θ _G in (6) with θ _G −θ _C and
The reset process is taken into consideration as in the true movement / north up mode. Therefore, in this mode, equations (14) and (1
1) and (12) are used.

[0035]

X _R = X · cos (θ _G −θ _C ) + Y · sin (θ _G −θ _C ) −L / 2 + D · sin (θ _G −θ _C ) Y _R = −X · sin (θ _G −θ _C ) + Y · cos (θ _G −θ _C ) + L / 2 + D · cos (θ _G −θ _C ) ... (14) There is no true motion / head-up mode.

(6) Details of Read Control Unit 6 FIG. 7 shows the details of the read control unit 6.

The read start address (X _R , Y _R ) input from the control unit 5 is latched by the latches 60 and 61 and held until the coordinate conversion start address (X _S , Y _S ) is updated. Further, the control unit 5 sends the rate of change (cos θ, sin θ) of the read address in the horizontal scanning direction to the X _H multiplier 62 or the Y _H multiplier 63, respectively, and the rate of change of the read address in the vertical scanning direction (cos θ + π /
2, sin θ + π / 2) is set in the X _V multiplier 64 or the Y _V multiplier 65, respectively. The controller 5 also transfers the transfer clock CK, the vertical synchronization signal V _SYNC, and the horizontal synchronization signal H.
_{The SYNC} is supplied to the read control unit 6.

The outputs of the latches 60 and 61 are synchronized with the vertical synchronizing signal V _SYNC , and the outputs of the X _V address driver 6 respectively.
6 or Y _V address driver 67. X _V
The multiplier 64 and the Y _V multiplier 65 use the horizontal synchronization signal H _SYNC.
(In X _V multiplier 64 up-counts, Y _V multiplier 65 in down-counting) the counted, the change rate of the read addresses in the vertical scanning direction (cosθ + π / 2, sinθ + π
Multiply the count value by / 2). The X _V address driver 66 and the Y _V address driver 67 are respectively the X _V multiplier 64.
Alternatively, a vertical read address (X _V , Y _V ) is generated by adding the multiplication result in the Y _V multiplier 65 to the outputs of the loaded latches 60 and 61. The generated vertical read address (X _V , Y _V ) is synchronized with the horizontal synchronizing signal H _SYNC , and the X _H address driver 68 or Y _H
It is loaded into the address driver 69.

The X _H multiplier 62 and the Y _H multiplier 63 count transfer clocks (the X _H multiplier 62 counts up,
The Y _H multiplier 63 counts down, and the result is the rate of change of the read address in the horizontal scanning direction (cos θ, s
in θ). X _H address driver 68 and Y _H
The address driver 69 generates the horizontal read address (X _H , Y _H ) by adding the multiplication result to the vertical read address (X _V , Y _V ). The X _H address driver 68 and the Y _H address driver 69 output the generated horizontal read address (X _H , Y _H ) in synchronization with the horizontal synchronization signal H _SYNC . Therefore, with L clocks, the reading along the horizontal scanning lines R _{1 to} R ₂ in FIG. 3A is completed.

The X _V address driver 66 and the Y _V address driver 67 are reset in synchronization with the vertical synchronizing signal V _SYNC , and the read start address (X _R , Y _R ) is loaded again.

As described above, according to this embodiment, in any of the motion modes and the azimuth display modes, the target image on the display is moved smoothly and picture skipping is less likely to occur. It is possible to grasp the surrounding situation with a glance, and it is not necessary to observe the display for several scans. Further, in this embodiment, since writing is performed to the horizontal scanning memory unit 8 during the non-display period and reading is performed during the display period, it is not necessary to use a multiport RAM as the image memory unit 7, and it is inexpensive. A general DRAM may be used. Further, the memory for one horizontal scan of the raster scan (horizontal scan memory unit 8) and the read control unit 6
It is possible to provide a cheap and safe radar device because it can be realized only by adding the.

In the above description, the coordinate conversion start address (X _S , Y _S ) and the read start address (X _R , Y _R ) are set four times for one rotation of the antenna. It is easy to increase. Further, it may be set a plurality of times depending on the course and speed of the ship, regardless of the rotation of the antenna.

[0043]

As described above, according to the coordinate conversion method of the present invention, the coordinate conversion start address indicating the center of the polar coordinate system is updated a plurality of times per revolution of the antenna, and this coordinate conversion start address is set as the center point. According to the polar coordinate system
Since the write address is generated according to the north-up mode, the relative positional relationship between the coordinate conversion address and the target in the storage space will gradually change as the coordinate conversion start address is updated. It makes it harder for picture jumps and sudden rotations where the positional relationship of the markers changes rapidly.
As a result, the surrounding situation can be grasped by only looking at the radar image, and it is not necessary to observe the display for several scans.

Further, according to the display control method of the present invention, the read start address is updated in association with the coordinate conversion start address, and the read operation is performed in accordance with the designated motion mode and azimuth display mode. Despite writing in the exercise / north-up mode, it is possible to display in the desired exercise mode and orientation display mode, and skip or skip suddenly in each exercise mode / azimuth display mode. Can be prevented.

According to the present invention, the coordinate conversion start address is further updated according to the azimuth of the aerial line, so that the above process can be realized as a relatively simple process.
According to the present invention, when the received signal is written in the image memory, the received signal that extends from the storage space of the image memory is written in the remaining storage space of the image memory.
A stable radar image can be obtained without loss of past accumulated information due to the pullback process.

According to the present invention, the radar image data read from the image memory is stored for one horizontal scanning of the display,
Since it is supplied to the display after that, the present invention can be implemented at low cost by adding a simple and inexpensive horizontal scanning memory. According to the present invention, the writing to the horizontal scanning memory is executed during the non-display period of the display, and the reading from the horizontal scanning memory is executed during the display period. Therefore, it is necessary to use the multiport memory as the image memory. , And cheap and general DRAM can be used.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a storage space diagram showing the contents of a return process.

FIG. 3 is a diagram showing a relative movement / reading method according to the present embodiment.
It is a figure which shows a head-up mode as an example, (a) is a memory space figure which shows rotation read, (b) is a memory space figure which shows return read, (c) is a figure which shows a screen.

FIG. 4 is a diagram showing a relationship between horizontal scanning and writing / reading timing.

FIG. 5 is a diagram showing the effect of this embodiment, (1)
(A) is a storage space diagram when the antenna direction is 0, (1)
(B) is a screen diagram when the antenna direction is 0, (2) (a)
Is a storage space map when the antenna direction is π / 2, (2)
(B) is a screen diagram when the antenna direction is π / 2, (3)
(A) is a storage space diagram when the antenna direction is π, (3)
(B) is a screen view when the antenna direction is π.

FIG. 6 is a diagram showing the effect of this embodiment, (4)
(A) is a storage space diagram when the antenna direction is 3π / 2,
(4) (b) is a screen diagram when the antenna direction is 3π / 2,
(5) (a) is a storage space diagram when the antenna direction is 0,
(5) and (b) are screen diagrams when the antenna direction is 0.

FIG. 7 is a block diagram showing a configuration of a read control unit.

FIG. 8 is a block diagram showing a configuration of a conventional example.

FIG. 9 is an explanatory diagram of a picture skipping phenomenon.

[Explanation of symbols]

1 A / D conversion unit 2 Buffer memory unit 3 Azimuth calculation unit 4 Coordinate conversion unit 5 Control unit 6 Readout control unit 7 Image memory unit 8 Horizontal scanning memory unit 60, 61 Latch 62 X _H multiplier 63 Y _H multiplier 64 X _V multiplier 65 Y _V multiplier 66 X _V address driver 67 Y _V address driver 68 X _H address driver 69 Y _H address driver (X _S , Y _S ) Coordinate conversion start address (X _R , Y _R ) Read start address ( X _V , Y _V ) Vertical read address (X _H , Y _H ) Horizontal read address θ _R Antenna direction θ _G Own ship course V Own ship speed H _SYNC Horizontal sync signal V _SYNC Vertical sync signal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Hayakawa 2-10-19 Tairiri, Ueda, Nagano Ueda Nihon Radio Co., Ltd.

Claims (6)

[Claims] 1. When writing a reception signal obtained by a polar coordinate system to an image memory having a storage space corresponding to a screen of a display, by controlling a write address, the reception signal is suitable for a display of an orthogonal coordinate system. In the coordinate conversion method for converting to radar image data, a coordinate conversion start address indicating the center of the polar coordinate system is generated while updating multiple times per revolution of the antenna, and true motion is performed according to the polar coordinate system with the coordinate conversion start address as the center point. A coordinate conversion method characterized by generating a write address according to the north-up mode. 2. The coordinate conversion method according to claim 1, wherein the coordinate conversion start address is updated according to the azimuth of the antenna. 3. The coordinate conversion method according to claim 1, wherein, when the received signal is written in the image memory, the received signal protruding from the storage space of the image memory is written in the remaining storage space of the image memory. Method. 4. The coordinate conversion method according to any one of claims 1 to 3 is executed, a read start address is generated while interlocking updating with the coordinate conversion start address, and the read start address is specified according to an orthogonal coordinate system with an even point. The display control method is characterized in that a read address is generated according to the motion mode and the azimuth display mode, and radar image data is read from the image memory according to the read address. 5. The display control method according to claim 4, wherein the radar image data read from the image memory is stored in a horizontal scanning memory for one horizontal scanning of the display and then supplied to the display. Display control method. 6. The display control method according to claim 4, wherein writing to the horizontal scanning memory is executed during a non-display period of the display, and reading from the horizontal scanning memory is executed during a display period. Display control method.