JP3034369B2 - Radar image display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a radar image display device for converting echo data from a polar coordinate format to a rectangular coordinate format and displaying the converted data.

[0002]

2. Description of the Related Art Conventionally, a radar device is mounted on a ship or the like. The radar device includes a radar image display device for displaying the presence of a target (such as another ship) around a ship or the like.

FIG. 1 shows a configuration of a conventional radar image display apparatus. The device shown in this figure
An antenna 1, an A / D conversion circuit 2, and a sweep memory 3 are provided. The aerial 1 is installed at a location of good view of a ship, and is rotationally driven by a motor (not shown) or the like. The antenna 1 transmits a radio wave at a predetermined repetition cycle and receives a reflected wave from a target existing in the vicinity. The signal obtained by the antenna 1 is converted into digital data by the A / D conversion circuit 2, and the echo data obtained by this conversion is stored in the sweep memory 3.

[0004] The echo data stored in the sweep memory 3 is basically data in a polar coordinate format. That is, the reception time of the reflected wave from the antenna 1 indicates the distance at which the target exists, and the sweep memory 3 stores the echo data in time series, so that the storage position of the data in the sweep memory 3 reaches the target. Represents the distance of
The azimuth of the antenna 1 at the time when the echo data is obtained represents the azimuth up to the target. Therefore, it can be said that the echo data stored in the sweep memory 3 is data in a polar coordinate format.

Further, in this device configuration, a coordinate conversion circuit 4 is provided for converting the echo data stored in the sweep memory 3 into data in a rectangular coordinate format. The coordinate conversion circuit 4 converts the echo data stored in the sweep memory 3 into a rectangular coordinate format by an address operation of the radar video frame memory 5 and stores the data in the radar video frame memory 5. In this coordinate conversion, the outputs of the antenna rotation signal generation circuit 6 and the angle signal control circuit 7 are used.

That is, the antenna rotation signal generating circuit 6
Generates an antenna rotation signal indicating the rotation of the antenna 1 and supplies it to the angle signal control circuit 7. Angle signal control circuit 7
Generates an angle signal indicating the azimuth of the antenna 1 based on the antenna rotation signal, and supplies it to the coordinate conversion circuit 4.
The coordinate conversion circuit 4 uses the storage position of the echo data in the sweep memory 3, that is, the distance R to the target, and the azimuth θ of the antenna 1 represented by the angle signal, and writes the write address to the radar video frame memory 5. Is generated based on the following equation.

X = XS + R × sin θ Y = YS + R × cos θ Here, XS and YS indicate own ship positions.

The addresses X, Y obtained in this way are
Then, when the radar image frame memory 5 is accessed and the echo data is written, the echo data in the polar coordinate format is converted into the data in the rectangular coordinate format. The data in the rectangular coordinate format stored in the radar video frame memory 5 is converted into an analog signal by the D / A conversion circuit 8 and used for the screen display of the raster scan type CRT display 9. That is, the CRT display 9 is a display in a rectangular coordinate system, and the coordinate conversion circuit 4 can be said to be a circuit for converting the coordinate of the echo data into a format suitable for the display 9.

The transmission / reception operation in the antenna 1 is controlled by a transceiver control circuit 10. The CPU circuit 11 controls operations of the transceiver control circuit 10, the angle signal control circuit 7, and the graphic control circuit 12. The graphic control circuit 12 generates an image such as a cursor to be superimposed on a radar image (image related to data stored in the radar image frame memory 5) on the screen of the CRT display 9, and stores the generated image in the graphic frame memory 13. Circuit. Graphic frame memory 13
Is converted into an analog signal by the D / A conversion circuit 8 in the same manner as the data stored in the data video frame memory 5, and is supplied to the screen display of the CRT display 9.

In addition, in this apparatus configuration, a radar video multiplex writing prevention circuit 14 for preventing multiplex writing of the radar video frame memory 5 is provided. The radar video multiplex write protection circuit 14 is a circuit that, when the same address of the radar video frame memory 5 is accessed by the coordinate conversion circuit 4, prohibits writing to the address. That is, while the antenna 1 makes one revolution,
When the same address of the radar video frame memory 5 is accessed by the coordinate conversion circuit 4, writing related to the access is prohibited.

[0011]

However, with the conventional configuration, it has been difficult to enable high-speed rotation of the antenna while maintaining sufficient azimuth resolution.

That is, one transmission / reception (1
The time required to convert the echo data obtained by the sweep) from the polar coordinate format to the rectangular coordinate format is the time required to write one dot data of the radar video to the radar video frame memory and the number of dots belonging to the radius of the radar video. Is determined by the product of This time, that is, one sweep conversion time, is determined by the antenna rotation speed (rpm) as shown in the following equation.
The upper limit is set.

60 / ｛1 sweep conversion time (sec) ×
Number of pulses of antenna rotation signal (per rotation) 回 転 Therefore, as required in recent years especially for high-speed ships, when trying to increase the antenna rotation speed by two to three times compared with the conventional device, one sweep conversion time is required. It is necessary to shorten the number or reduce the number of pulses of the antenna rotation signal. However, when the number of pulses of the antenna rotation signal is reduced, the antenna 1
The number of sweeps per rotation decreases, and the azimuth resolution deteriorates. Also, when trying to reduce the one-sweep conversion time, the access time to the radar video frame memory becomes a bottleneck.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and realizes a high speed antenna rotation without deteriorating the azimuth resolution, that is, by shortening one sweep conversion time. The purpose is to do.

[0015]

In order to achieve the above object, according to the present invention, a coordinate conversion circuit performs coordinate conversion in an order from a peripheral portion to a center portion of a radar image, and a multi-write preventing circuit performs the coordinate conversion. When the writing is prohibited, the coordinate conversion of the sweep is stopped.

[0016]

According to the present invention, the echo data is written into the frame memory by the coordinate conversion circuit in the order from the periphery to the center of the radar image. If writing to the frame memory is performed in such an order, multiple writing to the same address of the frame memory occurs at a certain dot close to the center of the radar image. This writing is prohibited by the multiple write protection circuit. The coordinate conversion circuit is
In response to the write prohibition, the coordinate conversion of the sweep is stopped. Therefore, writing in the vicinity of the center of the radar image is partially omitted, and as a result, one sweep conversion time is reduced. Therefore, it is possible to speed up the rotation of the antenna without deteriorating the azimuth resolution.

[0017]

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

FIG. 2 shows a method of writing echo data to the radar video frame memory 5 according to the present invention in comparison with the conventional method. The apparatus according to the present invention is sufficient for the apparatus configuration to be the same as the conventional apparatus configuration shown in FIG. 1. The difference from the conventional apparatus is that the writing to the radar video frame memory 5 is performed as shown in FIG. The order is different, and the point is that the coordinate conversion circuit 4 stops the coordinate conversion of the echo data related to the sweep when the writing to the radar video frame memory 5 is prohibited by the radar video multiplex writing prevention circuit 14.

That is, in the conventional method shown in FIG. 2A, the own ship position (X
(S, YS), and ends with the coordinates (XE, YE) of the peripheral part. In such an operation, multiple accesses to the radar video frame memory 5 have occurred for echo data near the own ship position (XS, YS). In the conventional method, even when such multiple access occurs, it is necessary to write the echo data at an address corresponding to a position separated from the own ship position (XS, YS). The coordinate conversion operation was performed for all the sweeps.

On the other hand, in the present invention, the coordinate conversion circuit 4
Is performed so that the coordinate conversion operation by the above starts from the coordinates (XE, YE) of the peripheral portion and ends at the own ship position (XS, YS) at the central portion. The coordinate conversion circuit 4 includes a sweep memory 3
2 is read out, and coordinate conversion is performed in the order shown in FIG.

In this process, when the coordinate conversion of the echo data of one sweep is started, the writing is rarely inhibited by the radar image multiplex writing prevention circuit 14. However, the write address in a certain sweep is the antenna 1
If the address is accessed by the previous sweep within the same rotation, the writing is inhibited by the radar video multiplex writing prevention circuit 14. After such write prohibition, even if the coordinate conversion is continued, only the write is similarly prohibited, so that the coordinate conversion circuit 4 stops the subsequent coordinate conversion. That is, the writing of the echo data of the sweep to the radar video frame memory 5 is stopped.

Therefore, in this embodiment, in particular, the own ship position (X
The time required for writing in the vicinity of (S, YS) is omitted, and the one-sweep conversion time is reduced. At this time, it is not necessary to reduce the number of pulses of the antenna rotation signal, and the azimuth resolution does not deteriorate.

[0023]

As described above, according to the present invention,
Since one sweep conversion time is shortened by changing the coordinate conversion direction, it is possible to realize a high-speed antenna rotation without deteriorating the azimuth resolution, and to realize an antenna high-speed rotation type radar device for a high-speed boat.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an apparatus configuration according to an embodiment of the present invention and a conventional example.

FIG. 2 is a diagram showing a writing method to a frame memory in one embodiment of the present invention in comparison with a conventional method.
2A shows the conventional system, FIG. 2B shows the system of the present invention,
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 3 Sweep memory 4 Coordinate conversion circuit 5 Radar video frame memory 9 CRT display 14 Radar video multiplex writing prevention circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-50080 (JP, A) JP-A-61-50081 (JP, A) JP-A-61-50082 (JP, A) JP-A-54-50 8492 (JP, A) JP-A-62-113078 (JP, A) JP-A-1-210885 (JP, A) JP-A-3-103784 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/64 G01S 13/00-15/96

Claims (1)

(57) [Claims] 1. A sweep memory for storing echo data obtained by one sweep in a time-series manner, a frame memory for storing data relating to a radar image in a rectangular coordinate format, and a storage position of an echo data and an antenna rotation signal. A coordinate conversion circuit for determining the address of the frame memory, writing the echo data by accessing the address, and converting the one-sweep echo data stored in the sweep memory into a rectangular coordinate format; A radar image display device comprising: a multiple write protection circuit that inhibits writing when the same address of the frame memory is accessed by the coordinate conversion circuit. The coordinate conversion is performed in the order leading to A coordinate conversion of the sweep is stopped when writing is prohibited by the radar image display device.