JPH0712922A - Radar apparatus - Google Patents

Abstract

PURPOSE:To prevent expanded display of a target attributed to a horizontal beam width. CONSTITUTION:A bearing expansion correcting processing circuit 28 is provided to perform a processing of information received for correcting bearing expansion. The bearing expansion correcting processing circuit 38 records a data concerning individual sweeps to be outputted from an A/D converter 20 at least covering a beam width thetaH to determine an AND between the original data, a sweep data concerning a bearing preceding by thetaH/2 and the sweep data concerning the bearing preceding by the thetaH. The AND thus obtained gives information on the image concerning the bearing preceding by thetaH/2 from which an expansion phenomenon of a target attributed to the beam width thetaH is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azimuth enlargement correction processing circuit for preventing enlargement display of a target due to the beam width of an antenna, and more particularly to a radar device equipped with this circuit.

[0002]

2. Description of the Related Art FIG. 3 shows the configuration of a radar device according to a conventional example.

The device shown in this figure comprises an antenna 12 which is rotationally driven in the horizontal plane by a motor 10. The antenna 12 has a predetermined horizontal beam width θ _H and is shared by the transmitter 14 and the receiver 16. That is, the transmitter 14 generates a pulse-modulated high-frequency signal according to the transmission trigger supplied from the timing controller 18 and indicating the transmission timing, and supplies this to the antenna 12. When this signal is transmitted from the antenna 12, this signal is reflected by the target existing in the beam direction. The antenna 12 receives this reflected wave, and the receiver 16 amplifies and detects the received reflected wave and supplies it to the A / D converter 20.

The A / D converter 20 includes a timing controller 1
According to the transmission trigger supplied from 8, the output of the receiver 16 is converted into a digital signal of 1 or multiple bits and supplied to the memory 22. The D / A converter 24 converts the digital data in the memory 22 into an analog video signal and supplies it to the display 26. The deflection circuit 28 is responsive to the horizontal / vertical synchronization signal supplied from the timing control unit 18 to display the display 2
6 controls screen scanning.

The display 26 is a raster scan type C
When using RT etc., A / D obtained by the receiver 16
It is necessary to convert the polar coordinate format information converted into a digital signal by the converter 20 into rectangular coordinate format information suitable for display on the display unit 26. The coordinate conversion circuit 30 is a circuit for converting polar coordinates into rectangular coordinates.

First, the azimuth signal generator 32 includes the motor 10
The azimuth pulse indicating the rotation of the antenna 12 due to the driving by is generated and is supplied to the relative / true azimuth calculation unit 34. The azimuth pulse is, for example, 4 per rotation of the antenna 12.
096 are generated. In this case, one azimuth pulse is
It shows 0.08 °. The relative / true direction calculation unit 34
This azimuth pulse is counted with the reference azimuth as a reference and converted into a relative azimuth or a true azimuth. In this case, if the heading (when mounted on a ship) is used as the reference bearing, the obtained bearing becomes the relative bearing, and if the true north bearing is used, it becomes the true bearing. In this figure, the reference azimuth is given by the gyro signal from the gyro.

On the other hand, the distance information from the radar device to the target can be obtained as the elapsed time from the transmission based on the transmission trigger supplied from the timing control section 18. The coordinate conversion circuit 30 generates an X, Y orthogonal address based on the distance R thus obtained and the azimuth θ output from the relative / true azimuth calculation unit 34. That is,
X = X0 + Rsinθ and Y = Y0 + Rcosθ are calculated and supplied to the memory control unit 36. However, X
0 and Y0 are the ship positions. The memory control unit 36 writes the output of the A / D converter 20 in the memory 22 in synchronization with the transmission timing. Specifically, the memory 22 is, for example, a frame memory corresponding to the screen of the display unit 26, and the memory control unit 36 has a polar coordinate format output from the A / D converter 20 and stored in a sweep memory (not shown). The data is converted into X, Y generated in the coordinate conversion circuit 30.
It is transferred and stored in the memory 22 based on the orthogonal address. This realizes the conversion from the polar coordinate format to the rectangular coordinate format.

[0008]

In such a radar device, a target is captured and displayed on the screen of the display using a horizontal beam having a width θ _H as shown in FIG. 4 (a), for example. In this case, the size of the target is enlarged and displayed in the azimuth direction by an angle corresponding to approximately the horizontal beam width θ _H in the horizontal plane as compared with the size corresponding to the actual size.

That is, the target 10 shown in FIG.
When 0 is captured while rotating the antenna, the target 100 is captured by the leading edge of the horizontal beam at a certain point in time. The target 100 continues to be captured by the horizontal beam until it escapes from the trailing edge of the horizontal beam. Therefore, on the screen of the display, the target 100
Will be enlarged and displayed by θ _H / 2 before and after that.
That is, the target 100 is enlarged and displayed as indicated by the broken line 110 in this figure.

Further, this phenomenon causes a phenomenon that the size of the display of the target 100 is different depending on the position of the target 100. That is, the size L of the target 100 on the screen is the size obtained by adding the expansion EXP by the horizontal beam width θ _H to the actual size L _R , as shown in FIG. 5B. As a result, as shown in FIG. 5A, the distance from the center (target 100
A phenomenon occurs in which the size of the target 100 changes according to the display position).

As described above, in the prior art, the size of the target is enlarged in the azimuth direction, and the size differs depending on the distance from the ship. Therefore, it is only necessary to look at the display on the display. It was extremely difficult to know the actual shape and size of the target.

The present invention has been made to solve the above problems, and prevents the spread of the target in the azimuth direction due to the beam width of the antenna to prevent the target from being displayed on the screen. The purpose is to enable appropriate reading of the shape and size.

[0013]

In order to achieve such an object, the azimuth enlargement correction processing circuit of the present invention associates the reflected wave received while rotating the antenna with the azimuth of the antenna so that at least the beam width is adjusted. Storage means for storing the entire image information, and the stored image information includes information indicating the presence of a target, and this information is the information captured by the leading edge or the trailing edge of the beam of the antenna. To
A removal means for removing the information from the image information, removing the information captured by the leading edge or the trailing edge of the beam, and then performing display based on the image information to cause a target caused by the beam width. It is characterized by removing the enlargement of the display.

The radar device of the present invention further comprises an antenna having a predetermined beam width, means for repeatedly transmitting signals while rotating the antenna within a predetermined plane, and receiving reflected waves from surrounding targets. It is characterized by comprising a means for displaying an image of the target based on the received reflected wave, and the azimuth enlargement correction processing circuit of the present invention.

Further, according to the present invention, the removing means determines, based on the received reflected wave information and / or the video information stored in the storage means, the video information corresponding to the azimuth to be displayed and this azimuth. Then, by selecting the video information corresponding to the azimuth before and / or after the beam width / 2 and performing the logical product operation of the selected video information, from the video information corresponding to the azimuth to be displayed, AND operation means for removing information captured by the leading or trailing edge of the beam,
It is characterized by including.

The present invention is further characterized in that the selecting means selects the image information based on the number of rotations and the beam width of the antenna and the transmission repetition frequency.

In the azimuth expansion correction processing method of the present invention, the reflected wave received while rotating the antenna is stored as video information over at least the beam width while being associated with the azimuth of the antenna, and the stored video information. Contains information indicating the presence of a target and this information is the information captured by the leading or trailing edge of the antenna beam,
It is characterized in that the enlargement of the target display due to the beam width is removed by removing the information from the video information.

[0018]

In the azimuth enlargement correction processing circuit and method of the present invention, first, the reflected wave received while rotating the antenna is stored as image information over at least the beam width while corresponding to the azimuth of the antenna. Further, when the image information to be displayed includes information indicating the presence of the target and this information is the information captured by the leading edge or the trailing edge of the beam of the antenna, this information is removed from this image information. To be done. Therefore, the display based on the image information is performed after the information captured by the leading edge or the trailing edge of the beam is removed. As a result, it is possible to prevent the target display from expanding due to the beam width, and thus to prevent the display size of the target from changing due to the distance to the target.

Further, as a means for removing the information captured by the leading edge or the trailing edge of the beam of the antenna, a configuration including a selecting means and a logical product calculating means can be used. That is, based on the received reflected wave information and / or the image information stored in the storage means, the image information corresponding to the azimuth to be displayed and the azimuth before and / or after the beam width / 2 with respect to this azimuth. The video information corresponding to is selected, and the logical product operation of the selected video information is performed. Since the image information corresponding to the azimuth before and / or after the beam width / 2 with respect to the azimuth to be displayed is the image information for executing the leading edge or the trailing edge of the beam that implements the azimuth to be displayed, By performing this AND operation, the information captured by the leading or trailing edge of the beam will be removed.

Then, in the present invention, the selection of the video information is executed based on the number of rotations of the antenna, the beam width of the antenna and the transmission repetition frequency. That is, since the azimuth before and / or after the beam width / 2 with respect to the azimuth to be displayed can be calculated and determined based on the number of rotations of the antenna and the transmission repetition frequency, by using these pieces of information, The required video information can be suitably selected.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. The same components as those in the conventional example shown in FIGS. 3 to 5 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 shows the configuration of a radar device according to an embodiment of the present invention. As shown in this figure,
The present embodiment is characterized in that the azimuth enlargement correction processing circuit 38 is provided at the subsequent stage of the A / D converter 20.

FIG. 2 shows an example of the configuration of the azimuth enlargement correction processing circuit 38 in this embodiment. As shown in this figure, the azimuth expansion correction processing circuit 38 includes a sweep memory 40, counting circuits 42 and 44, a horizontal beam width setting circuit 46, a θ _H / 2 · θ _H delay sweep number calculation circuit 4,
8, a selection circuit 50 and an AND 52.

The sweep memory 40 is an A / D obtained by one transmission / reception (one sweep) by the antenna 12.
It is a memory that stores the output of the converter 20 over at least the horizontal beam width θ _H of the antenna 12. Antenna 1
When the rotation speed of 2 is expressed as N (rpm), the rotation angle of the antenna 12 in one second is 360 ° · N / 60 = 6 · N.
Becomes When the transmission repetition frequency (the number of transmissions from the antenna 12 per second) is PRF, the antenna 1
The number of transmissions performed during the rotation of 2 by 1 ° is PRF /
6N times. Therefore, since the number of transmissions in the horizontal beam width θ _H is θ _H · PRF / 6N, the storage capacity of the sweep memory 40 is at least θ _H · PRF / 6N.
Sweep required.

Further, the counting circuit 42 includes the azimuth signal generator 3
The antenna azimuth signal (azimuth pulse) generated by 2 is counted over 1 minute to obtain the rotation speed N of the antenna 12. The counting circuit 44 obtains the transmission repetition frequency PRF by counting the transmission trigger output from the timing control unit 18 for 1 second. Horizontal beam width setting circuit 46
It is for example, a DIP switch 0.1 ° units, the horizontal beam with a width setting circuit 46 θ _{H /} 2 · θ _H delay sweep speed computing circuit 48 of the horizontal beam width theta _H 0.1 °
It can be set in units.

Θ _H / 2 · θ _H delay sweep number calculation circuit 4
8 is the rotation speed N obtained by the counting circuit 42, and the transmission repetition frequency PRF obtained by the counting circuit 44.
And, based on the horizontal beam width θ _H set by the horizontal beam width setting circuit 46, the number of sweeps for the azimuth θ _H / 2 before the current azimuth and the number of sweeps for the azimuth before θ _H are calculated. The θ _H / 2 · θ _H sweep number calculation circuit 48 uses the three inputs of N, PRF and θ _H as an address for RO.
It can be realized as M. The selection circuit 50 inputs two types of sweep numbers (corresponding to θ _H / 2 and θ _H , respectively) calculated by the delay sweep number calculation circuit 48, and reads data from the sweep memory 40 based on this. That is, from the current direction of the antenna 12, θ
A sweep according to the _{H /} 2 prior to orientation, the sweep of the theta _H before orientation, reads information from the sweep memory 40, and outputs it to AND52. Here, B in the figure is information before θ _H / 2, and C is information before θ _H.
AND52 is the information output from the A / D converter 20,
That is, the logical product of the raw information A corresponding to the current orientation of the antenna 12 and the information B and C output from the selection circuit 50 is calculated, and the result is output as D. The output information D is stored in the memory 22 and used for coordinate conversion.

Therefore, according to the present embodiment, even when the information B relating to the θ _H / 2 delay includes the information indicating the presence of the target, the same information is included in A and C. If not, the image of the target is not displayed on the screen of the display 26. That is, it is possible to prevent the display size of the target 100 from being enlarged due to the horizontal beam width θ _H , and to prevent the size from changing with the distance from the ship. The prevention of such an enlarged display is very advantageous in that the user can suitably recognize the size and shape of the target 100 by looking at the screen of the display 26.

[0028]

As described above, according to the present invention,
When the image information contains information indicating the presence of a target and this information is captured from the front or rear edge of the beam, it was removed so that the display can be performed. It is possible to prevent the enlargement of the target display due to the cause, and consequently to prevent the size change due to the distance between the ship and the target, and it is possible to more suitably read the shape and size of the target from the display screen. Further, this processing can be realized by storing the received information, selectively using the received information and / or the stored information, and a logical product operation, and can be realized by a relatively simple circuit configuration. it can. Then, this processing can be realized by selecting the video information based on the rotation speed and beam width of the antenna and the transmission repetition frequency.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a configuration of an azimuth enlargement correction processing circuit according to this embodiment.

FIG. 3 is a block diagram showing a configuration of a radar device according to a conventional example.

FIG. 4 is a diagram for explaining the expansion of a target according to the horizontal beam width θ _H , and FIG.
(B) is a figure which respectively shows the principle of expansion of the target by horizontal beam width (theta) _H.

5A and 5B are views for explaining a change in the size of the target depending on the distance from the own ship. FIG. 5A is a display screen of the target, and FIG. 5B is a distance from the own ship. It is a figure which respectively shows the tendency of the change by R.

[Explanation of symbols]

12 antenna 14 transmitter 16 receiver 18 timing control unit 20 A / D converter 22 memory 26 display 38 azimuth expansion correction processing circuit 40 sweep memory 42, 44 counting circuit 46 horizontal beam width setting circuit 48 θ _H / 2 · θ _H delay sweep number calculation circuit 50 selection circuit 52 AND 100 target θ _H horizontal beam width R distance from own ship to target L size of target on screen _LR actual size of target N antenna rotation Number PRF transmission repetition frequency

Claims (5)

[Claims] 1. A storage means for storing a reflected wave received while rotating an antenna as image information over at least a beam width while associating the reflected wave with an azimuth of the antenna, and showing the presence of a target in the stored image information. If the information is included and the information is captured by the leading edge or the trailing edge of the beam of the antenna, the removing means for removing the information from the video information is provided, and the leading edge or the trailing edge of the beam is provided. An azimuth enlargement correction processing circuit, which removes the enlargement of the target display due to the beam width by performing the display based on the image information after removing the information captured by the edge. 2. An antenna having a predetermined beam width, a means for repeatedly transmitting a signal while rotating the antenna in a predetermined plane to receive a reflected wave from a target in the surroundings, and based on the received reflected wave. A radar device comprising: a means for displaying a video image of a target; and a radar device comprising the azimuth enlargement correction processing circuit according to claim 1. 3. The circuit or device according to claim 1 or 2, wherein the removing means corresponds to the azimuth to be displayed from the information related to the received reflected wave and / or the video information stored in the storage means. By selecting the image information and the image information corresponding to the azimuth before and / or after the beam width / 2 with respect to this azimuth, and performing the logical product operation of the selected image information, the azimuth to be displayed is displayed. And a means for removing the information captured by the leading edge or the trailing edge of the beam from the corresponding image information. 4. The circuit or device according to claim 3, wherein the selecting means selects the image information based on the number of rotations and the beam width of the antenna and the transmission repetition frequency. 5. The reflected wave received while rotating the antenna is stored as video information over at least the beam width while being associated with the azimuth of the antenna, and the stored video information includes information indicating the presence of a target. If the information is captured by the leading edge or the trailing edge of the antenna beam, removing the information from the video information eliminates the enlargement of the target display due to the beam width. An azimuth enlargement correction processing method characterized by the above.