JPH0868850A - Radar for vessel - Google Patents

Abstract

PURPOSE: To obtain a radar suitably mounted on a high speed vessel in which a radar image equivalent to that subjected to scan correlation processing can be displayed under high speed scanning without sacrifice of azimuth resolution. CONSTITUTION: Radar image frame memories 5a-5d are provided and a frame memory selection circuit 15 repeats the scanning operation for writing a data into one radar image frame memory four times. A luminance control circumt 16 increases the luminance of data being read out early from a radar image frame memory and the data read out from four radar image frame memories are added while being weighted at an adder circuit 17. Consequently, the radar image is presented on a CRT display 10 under a mode similar to that of an image subjected to conventional scan correlation processing. This constitution can increase the rotational speed of an antenna 1 by a factor of about 3 without sacrifice of azimuth resolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device for a ship which stores a radar image signal acquired by a rotating antenna in a rectangular coordinate format in a frame memory, reads it out in a raster scan system, and displays it. The present invention relates to a marine radar device.

[0002]

2. Description of the Related Art FIG. 3 shows a configuration example of a conventional marine vessel radar apparatus. In FIG. 3, the CPU circuit 12 controls each unit and realizes various functions of the device, but basic transmission / reception and display operations are performed as follows.

The antenna 1 is rotationally driven in a horizontal plane.
The transmission / reception control circuit 11 receives a transmission command from the CPU circuit 12 and causes the antenna to transmit pulsed radio waves. Around a ship equipped with the radar device (within the radar range)
A reflected wave from a target such as another ship existing in 1 is received by the antenna 1.

One transmission / reception operation until the antenna 1 transmits at a certain azimuth angle and receives the reflected wave at the end of the radar range is called one sweep. The received signal (radar image signal) acquired by the antenna 1 Sequentially A / D according to the order of reception
The converter circuit 2 digitizes the image data into radar image data, which are sequentially stored in the sweep memory 3 for each sweep by a write clock (not shown) that divides one sweep period.

The radar image data stored in the sweep memory 3 is sequentially read for each sweep by a read clock (not shown) asynchronous with the write clock, and is supplied to the radar image frame memory 5 as write data. The write address of the radar image frame memory 5 is generated in the coordinate conversion circuit 4 as follows.

That is, the bit position of the radar image data stored in the sweep memory 3 is expressed in the polar coordinate format of (R, θ) defined by the distance R from the ship's position to the target and the relative azimuth angle θ. Therefore, in order to display the image on the CRT display 10 by the raster scan method, it is necessary to express the bit position of the radar image data in the (X, Y) orthogonal coordinate format. The coordinate conversion circuit 4 realizes the coordinate conversion of (R, θ) (X, Y) by setting the write address to the radar image frame memory 5 to (X, Y).

Specifically, the reading from the sweep memory 3 is performed sequentially from the origin position of the sweep (own ship position) toward the end of the radar range. Therefore, the number of read clocks corresponds to the data bit position on the sweep memory 3, and indicates the distance R from the own ship position of the target.

The angle signal control circuit 7 is controlled by the CPU circuit 12 such as setting an initial value. The angle signal control circuit 7 receives a pulse-shaped antenna rotation signal from the antenna rotation signal generation circuit 6 in response to the rotation of the antenna 1 and outputs the antenna signal. An angle signal indicating the azimuth of 1 is formed. This angle signal is the relative azimuth angle θ of the target.

Therefore, every time a data bit is read from the sweep memory 3, the coordinate conversion circuit 4 obtains the distance R from the read clock and the angle signal θ from the angle signal control circuit 7 to perform the operation of the equation (1). Run, (R,
The position of the data bit defined by the polar coordinates of (θ) is converted to the position defined by the Cartesian coordinates of (X, Y) with reference to the ship position (X _S , Y _S ), and the position (X, Y ) Is given as a write address to the radar image frame memory 5 to write the data bit read from the sweep memory 3.

[0010]

[Formula 1] X = X _S + R · sin θ Y = Y _S + R · cos θ

The coordinate conversion is performed in this way, and the radar image data for each radar scan is sequentially stored in the radar image frame memory 5. In parallel with the above operation, the radar image frame memory 5 stores the radar image data. Radar image data for each scan is sequentially taken out in accordance with the scan order of raster scan, converted into analog by the D / A conversion circuit 9, and CR
Radar images are displayed on the T-display 10 by the raster scan method.

The marine radar device to which the present invention is directed is provided with a signal processing circuit 8. This signal processing circuit 8
Based on the write address from the coordinate conversion circuit 4 and the antenna rotation signal from the antenna rotation signal generation circuit 6, the frame data from the previous scan and the frame data from the current scan are retrieved from the radar image frame memory 5 and the scan correlation is performed. The processing is executed, and the result is written in the radar image frame memory 5 as the frame data for the current scan. By this processing, the signal-to-noise ratio and the signal-clutter ratio of the radar image displayed on the CRT display 10 by the raster scan method can be improved, and the displayed radar image can have the afterimage effect similar to that of the PPI display.

The CPU circuit 12 controls the graphic control circuit 13 to give an instruction such as a cursor to be displayed, as part of realizing various functions of the marine vessel radar device. As a result, the graphic control circuit 13
Generates graphic data. This graphic data is once stored in the graphic frame memory 14, read out from the graphic frame memory 14, analogized by the D / A conversion circuit 9, and superimposed and displayed on the CRT display 10 with the radar image, which is convenient for the observer. It

[0014]

By the way, in recent years, ships that move at high speed have appeared. However, a radar device mounted on such a high-speed boat requires a high-speed scan several times faster than the conventional one, so that the scan correlation processing is performed. There is a problem that it is difficult to cope with the conventional radar device that performs.

That is, in the scan correlation processing, reading,
Since the calculation and writing operations are executed for all the memory cells of the frame memory, the data update time of each memory cell is equal to the time required for these three reading, calculating and writing operations. Therefore, n memory cells for one sweep requires an update time that is n times the minimum, and a radar device with azimuth resolution (number of antenna rotation pulses) N requires n × N data update time per antenna rotation. Becomes That is, this n × N data update time is the time required for one rotation of the antenna, and if this time is not satisfied, all memory cells of the frame memory cannot be updated.

Then, in order to raise the upper limit of the antenna rotation speed, either the conversion time for one sweep is shortened or the antenna rotation pulse count N is reduced. If the number N is reduced, the azimuth resolution is lowered, and if the conversion time for one sweep is shortened, the access time of the frame memory needs to be shortened, which causes a problem that sufficient time cannot be taken for the scan correlation processing. .

An object of the present invention is to provide a marine radar device suitable for mounting on a high-speed boat, capable of displaying a radar image equivalent to that obtained by performing the scan correlation processing without deteriorating the azimuth resolution under high-speed scanning. To provide.

[0018]

In order to achieve the above object, the marine vessel radar apparatus of the present invention has the following configuration. That is, the marine vessel radar device of the present invention includes a plurality of radar image frame memories that store radar image data in a rectangular coordinate format; a write address of the radar image frame memory; A coordinate conversion circuit that generates information and angle information;
A frame memory selection circuit for receiving one of the plurality of radar image frame memories in order for each scan in response to a rotation reference signal of the antenna and permitting writing of radar image data to the memory; A brightness control circuit for weighting the read data of the plurality of radar image frame memories every time the selection switching signal is input, the brightness decreasing from the present to the past; and the plurality of brightness control circuits according to the weight control signals from the brightness control circuit. And an adder circuit for generating a radar image to be displayed by a raster scan method by weighting and adding signals relating to each read data of the radar image frame memory.

[0019]

Next, the operation of the marine vessel radar apparatus of the present invention constructed as described above will be described. In the present invention, n radar image frame memories are provided, and the number of radar image frame memories is set to 1 by the frame selection circuit.
The operation of writing one radar image frame memory for each scan is repeated n scans, and the brightness control circuit reads the n radar image frame memories by increasing the brightness of the read data of the new radar image frame memory in the order of writing. The data is weighted and added by the addition circuit and displayed.

Thus, the radar image displayed on the display is displayed in the same manner as the conventional scan correlation. That is, in the present invention, a radar image equivalent to the scan correlation processing performed by writing new scan data in the frame memory can be displayed without performing the conventional scan correlation processing, which is necessary in the scan correlation processing. The conversion time is reduced to about 1/3 because the operations of reading the previous data and the current data and performing the correlation calculation are unnecessary. Therefore, the rotation speed of the antenna can be increased about three times as high as the conventional one without deteriorating the azimuth resolution.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a ship radar device according to an embodiment of the present invention. In the present embodiment, in the conventional marine radar device shown in FIG. 3, the signal processing circuit 8 is deleted, and instead of one radar image frame memory 5, there are four radar image frame memories 5a to 5d, and a frame memory selection circuit 15 is provided. The brightness control circuit 16 and the addition circuit 17 are added. FIG. 2 shows an extracted portion of the present invention. Hereinafter, the part according to the present invention will be mainly described with reference to both drawings.

To the four radar image frame memories 5a to 5d, the radar image data read from the sweep memory 3 by a read clock (not shown) is given as write data.

The coordinate conversion circuit 4 generates the write address of the radar image frame memory (5a to 5d) by the distance information and the angle information acquired for each sweep as in the conventional case. The write address generated here is the same for the four radar image frame memories, but is not directly applied to the four radar image frame memories, but will be described later under the control of the frame memory selection circuit 15. Is applied as in.

The frame memory selection circuit 15 receives the rotation reference signal of the antenna and sequentially selects one of the four radar image frame memories for each scan and permits writing of radar image data to the memory. Then, an execution selection switching signal for such a selection operation is given to the brightness control circuit 16.

Specifically, as shown in FIG. 2, the radar image of the first scan is stored in the first radar image frame memory 5a, and the radar image of the second scan is the second radar image frame memory. 5b, the 3rd scan radar image is stored in the 3rd radar image frame memory 5c, and the 4th radar image is 4th
The fifth radar image is stored in the 5th radar image frame memory 5d, the 5th radar image is stored in the 1st radar image frame memory 5a, and the 6th radar image is stored in the 2nd radar image frame memory 5b. , 7
The radar image for the scan is stored in the third radar image frame memory 5c, the radar image for the eighth scan is stored in the fourth radar image frame memory 5d, and so on. It is changed in order.

In parallel with the above operation, the radar image data is taken out from the radar image frame memories (5a to 5d) with the same read clock according to the scanning order of the raster scan, and the D / A conversion circuits (9a to 9d). Is converted into an analog signal and input to the addition circuit 17.

On the other hand, the brightness control circuit 16 receives the selection switching signal from the frame memory selection circuit 15 at the start of the above-described change operation, and therefore, each time the selection switching signal is input, the brightness control circuit 16 stores four radar image frame memories. Each read data is weighted so as to decrease the brightness in order from the present to the past, and the weighting control signal is given to the adder circuit 17.

Specifically, since there are four radar image frame memories in the illustrated example, the weighting may be all the same, but if there are four ways, for example, 4, 3, 2, 1. Since there is no past scan data in the first scan, "4" is given to the read data of the radar image frame memory 5a. In the second scan, since the past scan data is the read data of the radar image frame memory 5a, "4" is given to the read data of the radar image frame memory 5b and "3" is given to the read data of the radar image frame memory 5a. give. Similarly, in the fourth scan, "4" is given to the read data of the radar image frame memory 5d, "3" is given to the read data of the radar image frame memory 5c, and "2" is given to the read data of the radar image frame memory 5b. And "1" is given to the read data of the radar image frame memory 5a.

Then, for example, in the sixth scan, the read data of the radar image frame memory 5b is given "4", the read data of the radar image frame memory 5a is given "3", and the read data of the radar image frame memory 5d is given. "2" is given, and the radar image frame memory 5c
"1" is given to the read data of.

In the adder circuit 17, the signals related to the respective read data of the four radar image frames, that is, the D / A conversion circuits 9a to 9d in the illustrated example, are provided according to the weighting control signal from the brightness control circuit 16 described above. The analog signals are weighted and added to generate a radar image to be displayed by the raster scan method.

Thus, the radar image displayed on the display is displayed in the same manner as the conventional scan correlation. That is, in the present invention, a radar image equivalent to the scan correlation processing performed by writing new scan data in the frame memory can be displayed without performing the conventional scan correlation processing, which is necessary in the scan correlation processing. The conversion time is reduced to about 1/3 because the operations of reading the previous data and the current data and performing the correlation calculation are unnecessary. Therefore, the rotation speed of the antenna can be increased about three times as high as the conventional one without deteriorating the azimuth resolution.

The addition circuit 17 is also adapted to input the graphic signal analogized by the D / A conversion circuit 9e.

[0033]

As described above, the ship radar device of the present invention is provided with a plurality of radar image frame memories,
Since it is possible to display the radar image equivalent to the scan correlation processing just by writing new scan data to the frame memory without performing the conventional scan correlation processing,
The conversion time is reduced to about 1/3 because the operations of reading the previous data and the current data and performing the correlation calculation, which are required in the scan correlation processing, are unnecessary. Therefore, since the rotation speed of the antenna can be increased about three times as high as the conventional one without deteriorating the azimuth resolution, it is possible to provide a radar device suitable for mounting on a high-speed boat that can display a radar image equivalent to that obtained by performing scan correlation processing. There is.

[Brief description of drawings]

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

FIG. 2 is an operation explanatory view showing a characteristic portion of the present invention extracted.

FIG. 3 is a configuration block diagram of a conventional marine radar device.

[Explanation of Codes] 1 Antenna 2 A / D conversion circuit 3 Sweep memory 4 Coordinate conversion circuit 5a to 5d Radar image frame memory 6 Antenna rotation signal generation circuit 7 Angle signal control circuit 9a to 9d D / A conversion circuit 10 CRT indicator 11 transmission / reception control circuit 12 CPU circuit 15 frame memory selection circuit 16 brightness control circuit 17 adder circuit

Claims (1)

[Claims] 1. A plurality of radar image frame memories for storing radar image data in a rectangular coordinate format; a write address of the radar image frame memory is generated by distance information and angle information relating to radar images acquired for each sweep. A coordinate conversion circuit for receiving a rotation reference signal of the antenna, and sequentially selecting one of the plurality of radar image frame memories for each scan and permitting writing of radar image data to the memory;
A brightness control circuit for weighting the read data of the plurality of radar image frame memories in order from the present to the past each time a selection switching signal is input from the frame memory selection circuit; and a weighting from the brightness control circuit. An adder circuit for weighting and adding signals relating to respective read data of the plurality of radar image frame memories in accordance with a control signal to generate a radar image to be displayed in a raster scan system;