JP3990830B2 - Radar video synthesizer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radar video signal synthesizing apparatus, and more particularly to an apparatus for synthesizing a plurality of radar video signals into one radar video signal.
[0002]
[Prior art]
In general, in a radar video synthesizer, a plurality of antennas are arranged at predetermined locations (that is, a plurality of antennas are installed on the same axis), and transmission of radio waves from the antennas and rotation of the antennas are synchronized. Thus, a plurality of received radar video signals are obtained in response to a reflected wave from the object, and a synthesized video signal is generated by synthesizing the plurality of received video signals.
[0003]
[Problems to be solved by the invention]
By the way, in recent years, in ships and the like, the mast structure has a multi-sided structure with a slight inclination due to stealth, and as a result, the mast structure is located behind the radar antenna. Radar radio waves output to the rear side are often shielded by a mast structure. Therefore, it is necessary to provide a plurality of monitoring radars in order to ensure safety behind the vehicle. That is, it is necessary to separately provide a rear monitoring radar in addition to the front monitoring radar and to monitor using a plurality of radars.
[0004]
As described above, in the conventional radar video synthesizing apparatus, it is necessary to install a plurality of antennas on the same axis, and the received video is synchronized with the transmission of radio waves from the antenna and the rotation of the antenna. Because of the need to synthesize signals, as described above, if the antenna rotation and the radar repetition frequency are asynchronous and the antenna installation locations are different between radars, multiple received radar video signals are synthesized. Therefore, it is difficult to obtain a composite radar video signal.
[0005]
In other words, in order to obtain a synthesized radar video signal in a conventional radar video synthesizer, a plurality of antennas must be installed on the same axis, and in addition, a plurality of antennas can transmit radio waves from the antenna. The rotation of the antenna must be synchronized, and therefore there is a problem that it is difficult to obtain a combined radar video signal by combining a plurality of received radar video signals.
[0006]
An object of the present invention is to provide a radar video synthesizing apparatus capable of generating a synthesized radar video signal even when radar antennas are installed at different locations and radio wave transmission and antenna rotation are asynchronous between the antennas. .
[0007]
[Means for Solving the Problems]
According to the present invention, a radar video synthesizing apparatus used when synthesizing radar videos obtained from a plurality of radars, each of which outputs a video signal, an azimuth signal, and a trigger signal. One of the plurality of radars is a reference radar, and for each of the other radars excluding the reference radar, a first means for converting the video signal into orthogonal coordinate data based on the azimuth signal; A second means for converting the orthogonal coordinate data into polar coordinate data in accordance with an azimuth signal from the reference radar; and a video signal from the reference radar and the polar coordinate data are selectively output in accordance with radar switching data. A third hand for outputting the output video signal and the azimuth signal and trigger signal from the reference radar as a radar video composite output. Radar video synthesizer is obtained, characterized in that it comprises and.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
[0009]
Referring to FIG. 1, the illustrated radar video synthesizing apparatus includes a video buffer 1, an S / D conversion circuit 2, a trigger timing adjustment circuit 3, a switching circuit 4, a computer 5, a radar switching RAM 6, a trigger synchronization control circuit 7, an orthogonality. Coordinate-polar coordinate conversion circuit (XY-Rθ conversion circuit) 8, A / D conversion circuit 9, S / D conversion circuit 10, trigger synchronization control circuit 11, input buffer control circuit 12, input buffer 13, input buffer 14, polar coordinate − An orthogonal coordinate conversion circuit (Rθ-XY conversion circuit) 15, an image memory 16, an output buffer 17, an output buffer 18, an output buffer control circuit 19, and a D / A conversion circuit 20 are provided.
[0010]
In the illustrated example, it is assumed that two radars A and B are connected to the radar video composition device. The antennas of radars A and B are installed at different installation locations, and are operated independently of each other, that is, in an asynchronous state. In the illustrated example, radar A is used as a reference, and as described later, the installation position of radar B is corrected using radar A as a reference, and the rotation and repetition period of the antenna are synchronized.
[0011]
Now, the radar A outputs the video A1, the azimuth A2, and the trigger A3, respectively, and the radar B outputs the video B1, the azimuth B2, and the trigger B3, respectively.
[0012]
The trigger A3, the video A1, and the direction A2 are given to the radar video synthesizing apparatus at the timings shown in FIGS. 2A, 2B, and 2C, respectively. The video A1 is temporarily stored in the video buffer 1. Thereafter, it is supplied to the switching circuit 4. The azimuth A2 is converted into a first digital azimuth signal by the S / D conversion circuit 2 and supplied to the XY-Rθ conversion circuit 8 and the radar switching RAM 6. Furthermore, the azimuth A2 is output as the azimuth (reference azimuth). The trigger A3 is supplied to the trigger timing adjustment circuit 3 and the trigger synchronization control circuit 7, and the trigger timing adjustment circuit 3 adjusts the timing of the trigger A3 and outputs it as a trigger (reference trigger). In this timing adjustment, the output timing of the trigger A3 is adjusted so that the timing coincides with the output (video) of the switching circuit 4. The trigger synchronization control circuit 7 receives the trigger A3 and generates a first clock signal in synchronization with the trigger A3.
[0013]
The trigger B3 (see FIG. 2D) is supplied to the trigger synchronization control circuit 11, and the trigger synchronization control circuit 11 generates a second clock signal in synchronization with the trigger B3. The second clock signal is supplied to the A / D conversion circuit 9 and the S / D conversion circuit 10. On the other hand, the video B1 (see FIG. 2E) is supplied to the A / D conversion circuit 9, and the A / D conversion circuit 9 converts the video B1 into digital video in accordance with the second clock signal. This digital video is supplied to the input buffers 13 and 14. The azimuth B2 is given to the S / D conversion circuit 10, and the S / D conversion circuit 10 converts the azimuth B2 into a second digital azimuth signal in accordance with the second clock signal. Then, the second digital azimuth signal is given to the input buffers 13 and 14.
[0014]
As shown in the figure, the input buffer control circuit 12 is provided with the timing based on the trigger A3 and the second clock signal, and the input buffer control circuit 12 receives the input buffer 13 based on the trigger A3 and the second clock signal. And 14 are controlled. That is, as shown in FIGS. 2F and 2G, at the timing of the second clock signal, that is, the trigger B3, the input buffer control circuit 12 alternately inputs the digital video and the second digital azimuth signal to the input buffer. Write to 13 and 14 as write data. In other words, the digital video and the second direction signal are alternately written in the input buffers 13 and 14 within the length of the repetition time of the radar A in synchronization with the trigger B3. At this time, the input buffer control circuit 12 reads out the write data as read data from the input buffers 13 and 14 in synchronization with the trigger A 3 at the write timing of the image memory, and supplies the read data to the Rθ-XY conversion circuit 15. The Rθ-XY conversion circuit 15 converts the read data from polar coordinates (Rθ) to Cartesian coordinates (XY) and stores them as image data in the image memory 16 (FIG. 2 (h)).
[0015]
The image data in the image memory 16 is input to the XY-Rθ conversion circuit 8. The XY-Rθ conversion circuit 8 is supplied with the first clock signal from the trigger synchronization adjustment circuit 7, and is also supplied with the first digital orientation signal from the S / D conversion circuit 2, and the XY-Rθ conversion circuit 8 The image data is subjected to XY-Rθ conversion in accordance with the first digital azimuth signal at the timing of one clock signal and output as converted image data (FIG. 2 (i)).
[0016]
The output buffer control circuit 19 is supplied with the first clock signal from the trigger synchronization adjustment circuit 7, and the output buffer control circuit 19 alternately outputs the converted image data according to the first clock signal to the output buffers 17 and 18. Write to. That is, the output buffer control circuit 19 alternately writes the converted image data into the output buffers 17 and 18 at the read timing of the image memory in synchronization with the trigger A3. At this time, the output buffer control circuit 19 alternately reads the converted image data from the output buffers 17 and 18 in synchronization with the first clock signal (FIGS. 2 (j) and (k)). The converted image data read from the output buffers 17 and 18 is applied to the D / A conversion circuit 17, where it is D / A converted and supplied to the switching circuit 4 as analog video (FIG. 2 (l)).
[0017]
Incidentally, the computer 5 has determined a switching range of the radar A and B, the computer 5 stores the radar switching data indicating the switching range of the radar A and B to the radar switching RAM 6 (Figure 3 (a)). For example, “1” is used for radar A and “0” is used for radar B as radar switching data when switching between two types of radars such as radars A and B. Radar switching data stored in the radar switching RAM6 are read in synchronization with the first of the first digital direction signal from the clock signal and S / D converting circuit 2 from the trigger synchronizing circuit 7, the switching circuit 4 Given. When the radar switching data is “1”, the switching circuit 4 selects the radar A, and when the radar switching data is “0”, the radar B is selected. That is, when the radar switching data is “1”, the switching circuit 4 selects the video A1 and outputs it as the output video. When the radar switching data is “0”, the switching circuit 4 is the D / A conversion circuit 20. An analog video is selected and output as an output video (FIG. 2 (m)). The azimuth A2 of the radar A, the trigger from the trigger timing adjustment circuit 3, and the output video are output as a radar video composite output (FIG. 2 (n)).
[0018]
As described above, radar videos of radars A and B are synthesized on polar coordinates and output. That is, the radar A video shown in FIG. 3B and the radar B video shown in FIG. 3C are combined to obtain the radar video combined output shown in FIG.
[0019]
As described above, when the radar video synthesizing apparatus shown in FIG. 1 is used, for example, as shown in FIG. 4, even if the radar B is placed at a different installation position (x1, y1) from the radar A, once XY If the coordinates are converted to (orthogonal coordinates), and then Rθ (polar coordinates) conversion is performed from the center position aligned with the radar A, the radar B is substantially synchronized with the same antenna rotation trigger as the radar A and the video is output. The radar A video and the radar B video can be easily combined.
[0020]
【The invention's effect】
As described above, according to the present invention, even if the installation of the radar antenna is different and the transmission of the radio wave and the rotation of the antenna are asynchronous between the antennas, the synthesized radar video signal can be generated. Even when the back of the ship is shielded, if other radar antennas are arranged so as to compensate for this shielding, the entire circumference can be monitored without leakage. Also, combine radar videos with different characteristics such as a radar with good distance resolution (short pulse width) at short distances and a far distance (pulse width length, high transmission power) even though distance resolution is poor at long distances. For example, it is possible to operate by taking advantage of the good characteristics of both, such as good near-field resolution and being able to see far distances.
[0021]
In the present invention, a plurality of radar composite videos can be supplied to a commonly used radar indicator such as the PPI system. As a result, the conventional apparatus can also be utilized. Therefore, the system configuration can be made at a low cost.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of a radar video synthesis apparatus according to the present invention.
FIG. 2 is a diagram for explaining video synthesis timing in the radar video synthesis apparatus shown in FIG. 1;
FIG. 3 is a diagram illustrating switching and composition of radar video.
FIG. 4 is a diagram showing a radar video composite output when video of radars having different installation positions are combined.
[Explanation of symbols]
1 Video buffer 2, 10 S / D conversion circuit 3 Trigger timing adjustment circuit 4 Switching circuit 5 Computer 6 Radar switching RAM
7 Trigger synchronization control circuit 8 XY-Rθ conversion circuit 9 A / D conversion circuit 11 Trigger synchronization control circuit 12 Input buffer control circuit 13, 14 Input buffer 15 Rθ-XY conversion circuit 16 Image memory 17, 18 Output buffer 19 Output buffer control Circuit 20 D / A conversion circuit

Claims (6)

A radar video synthesizing apparatus used when synthesizing radar videos obtained from a plurality of radars, wherein a video signal, a direction signal, and a trigger signal are output from each of the plurality of radars. One of them is a reference radar, and a first means for converting the video signal into Cartesian coordinate data based on the orientation signal for each of the other radars excluding the reference radar, and an orientation from the reference radar A second means for converting the orthogonal coordinate data into polar coordinate data in accordance with a signal; and a video signal from the reference radar and the polar coordinate data are selectively output as an output video signal in accordance with radar switching data and output. Third means for transmitting a video signal, an azimuth signal from the reference radar and a trigger signal as a radar video composite output. Radar video synthesizing apparatus according to claim.   2. The radar video synthesizing apparatus according to claim 1, wherein first and second radars are provided as the plurality of radars, the first radar is used as the reference radar, and the first and second radars are provided. A radar video synthesizing apparatus characterized in that each of the radars outputs a first video signal, a second video signal, a first azimuth signal, and a first trigger signal.   3. The radar video synthesizing apparatus according to claim 2, wherein the first means performs A / D conversion on the second video signal in accordance with the second trigger signal to generate a digital video signal. D conversion means, S / D conversion means for S / D converting the second azimuth signal in response to the second trigger signal to generate a second digital azimuth signal, the digital video signal, and the first Buffer means for storing two digital orientation signals, and writing the digital video signal and the second digital orientation signal into the buffer means in response to the second trigger signal, and the buffer in response to the first trigger signal. Reading the digital video signal and the second digital azimuth signal from the first reading means as a digital video signal and a reading digital azimuth signal, respectively, A radar video comprising: first coordinate conversion means for converting the read digital video signal into the orthogonal coordinate data in accordance with the read digital orientation signal; and memory means for storing the orthogonal coordinate data as image data. Synthesizer.   4. The radar video synthesizing apparatus according to claim 3, wherein the second means generates a first digital azimuth signal by performing S / D conversion on the first azimuth signal in accordance with the first trigger signal. S / D conversion means, second coordinate conversion means for converting the image data into the polar coordinate data in accordance with the first digital orientation signal, output buffer means for temporarily storing the polar coordinate data, and the first A second reading means for reading the polar coordinate data from the output buffer means in response to a trigger signal of 1 and reading the polar coordinate data as D / A conversion means for converting the read polar coordinate data into analog data; A radar video synthesizing apparatus comprising: 5. The radar video synthesizing apparatus according to claim 4, wherein the third means includes buffer means for temporarily storing the first video signal and then outputting it as buffer data, and the buffer data in accordance with the radar switching data. And a switching means for selectively outputting the analog data as the output video signal. The radar video synthesizing apparatus according to claim 5, further generating means for generating the radar switching data, RAM for the radar switching data is read out the radar switching data is stored according to the first digital direction signal A radar video synthesizing apparatus characterized in that the radar switching data is given from the RAM to the switching means.

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