JPS62184378A - End position detecting device for radar display - Google Patents

Abstract

PURPOSE:To simplify device constitution and to reduce cost by storing previously data indicating a specific display area and a display end position in an area setting memory and reading it in synchronism with the writing operation of a frame memory, and writing display area data in the frame memory and inhibiting display end position data from being written. CONSTITUTION:At the time of video data is written in the frame memory 5, the display end position is detected and position information for inhibiting data from being written is stored previously in the area setting memory 16. Then, the address of the memory 16 is specified from a scan converter 8 in synchronism with the writing of the video data to the frame memory 5 to read the storage contents, which are supplied to an end position detecting circuit 17. The end position detecting circuit 17 when detecting data '1' on an azimuth ring 18 from the area setting memory 16 outputs a write inhibiting signal to a scan converter 8 to inhibit data from writing a memory area exceeding the azimuth ring 18.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention converts video information for one screen obtained by one rotation of an antenna into an X-Y display address of a display screen and stores it in a frame memory. The present invention relates to a radar display device for reading and displaying, and particularly to a radar display end position detection device for detecting a display area and a display end area when writing a video image by X-Y coordinate conversion.

(Prior art) Conventionally, in a radar display device that displays radar images on a CRT screen using the X-Yi method (television scanning method), a video signal obtained at each trigger cycle is converted to a sampling clock φ1 of a predetermined frequency. The data is synchronously converted into digital video data, and at the same time each video data is converted to a position address (θ) corresponding to the distance information R determined by the antenna rotation angle θ and the number of sampling clocks starting from the trigger pulse.
.

R), so X-Y1i! For reference, use the scan converter to scan the position address (θ, R) on the display screen (X, R).
Y) address, and the video data obtained in real time by specifying this (X, Y) address is written into a frame memory having a storage capacity for one rotation of the antenna.

By the way, in normal radar image display, the radar image is displayed in a circle determined by the bearing ring with the center of the screen as the own ship's position, so the end of the circular display area determined by the bearing ring is detected and the video signal is For example, it is necessary to control the display area to fix the black level.

In conventional devices, this display area control is performed by setting a certain number of dots corresponding to the radius R of the display area determined by the azimuth ring, for example, R = 400 dots, in the case of center display, and then controlling the horizontal blanking of the CRT. When writing video data to the frame memory at the writing timing that corresponds to the period, the number of written dots is compared with the set number of dots, and when the number of written dots reaches the set number of dots, writing is prohibited in the display end area. Detection processing is performed, and this written data is read out from the frame memory in synchronization with the display timing of the CRT, thereby displaying it as a radar image with a radius of 400 dots.

In the case of off-center display, find the coordinates of the display origin that is off-center with respect to the display circle determined by the azimuth ring, calculate the number of dots from this off-center origin to the display circle for each azimuth, and calculate the dots corresponding to the calculated number of dots. A number of video data are written into the frame memory, and the number of dots is changed for each azimuth so that the radar image is displayed off-center within the azimuth ring.

(Problem to be Solved by the Invention) However, in the conventional process of determining the display area by setting the number of dots from the sweep origin and writing video data to the frame memory, the frame memory is It is necessary to compare the number of set dots and the number of written dots for all of the video data for one antenna rotation (one screen) to be written.Especially in the case of off-center display, different settings are required for each azimuth. Because it is necessary to calculate the number of dots and compare it with the number of written dots, the load on the calculation process increases, and faster calculation processing is required, leading to increased complexity and cost of the device. There was a problem.

(Means for Solving the Problems) The present invention has been made in view of such conventional problems, and detects the display end position through a simple comparison process using memory data and displays only the display area. An object of the present invention is to provide a radar display end position detection device that can display radar images.

In order to achieve this object, the present invention provides an area setting memory (memory area for storing azimuth ring display data) having the same memory area as a frame memory for storing video data corresponding to the X-Y address of the display screen. It is also possible to use a frame memory that has a frame memory, and store data indicating a predetermined display area and display end position in this area setting memory in advance, and write data to the area setting memory in synchronization with writing to the frame memory A read operation is performed, and if the successive data is display area data, writing of video data to the frame memory is permitted, and if it is display end position data, writing of video data is prohibited.

(Example) FIG. 1 is a block diagram showing one embodiment of the present invention.

First, to explain the configuration, reference numeral 1 denotes a radar antenna, which is rotated at a constant speed by a drive motor (not shown), emits radar radio waves in synchronization with a trigger pulse from the transmitting/receiving circuit 2, and transmits the received signal of the reflected wave to the transmitting/receiving circuit. Supply to 2. The transmitting/receiving circuit 2 outputs the video signal included in the received signal obtained from the radar antenna 1 to the sampling buffer circuit 3, and the sampling buffer 1 circuit 3 synchronizes with the sampling clock φ1 of a constant frequency determined according to the set distance range. Converts the video signal into digital data and writes it to the built-in buffer memory, and in the write mode of the frame memory 5 corresponding to the horizontal blanking period of the CRT display 12, one sweep from the buffer memory is performed in synchronization with the write clock. data is read out and supplied to the frame memory 5.

On the other hand, the antenna rotation angle θ of the radar antenna 1 is detected by the antenna rotation angle detector 6, and the detected angle θ of the antenna rotation angle detector 6 is converted into digital angle data by the digital angle conversion circuit 7. is supplied to Further, the antenna rotation angle detector 6 outputs an antenna rotation detection signal for each rotation of the radar antenna 1.

The scan converter 8 is the sampling buffer circuit 3
Since the position address of the digital data stored in the buffer memory of is determined by the antenna rotation angle θ and the distance R,
Converts the position address (θ, R) to the X-Y address of the display screen, and supplies the converted X-Y address data to the frame memory 5 at the timing of the write mode corresponding to the horizontal blanking period of the CRT display 12. A write address is designated, and the video data for one sweep obtained from the sampling buffer circuit 3 is written after being converted to an XY address on the display screen.

To explain in more detail, the scan converter 8 is supplied with a trigger pulse φr and a write clock φ2 in addition to the antenna rotation angle θ, and the distance R is determined by the number of write clocks φ2 within the period of the trigger pulse φr. The antenna rotation angle θ is read every trigger pulse φr and
Convert to address.

Position address in this scan converter 8〈θ,
Conversion of the display screen of R) into an XY address can be obtained by calculating the following equation.

Note that XO and Yo are addresses indicating the center position of the display screen, and the distance R that changes depending on time is R(t)=Σ
It is obtained by adding the write clock φ2 as φ2.

In this way, the position address (θ, R) is displayed on the X-Y
The output of the scan converter 8, which is converted into an address, is supplied to the frame memory 5 as a write address via an address switching circuit 9. Therefore, digital video data from the sampling buffer circuit 3 is written into the frame memory 5 by specifying the XY address corresponding to the display screen. The frame memory 5 has a storage capacity for storing video data for one rotation of the antenna, that is, one screen, and uses a rewritable RAM or the like.

Next, writing and reading of the frame memory 5 will be explained in detail as follows.

First, writing and reading from the frame memory 5 is performed based on a read/write signal (hereinafter referred to as "rR/W signal") from the timing pulse generating circuit 13.

That is, the timing pulse generating circuit 13 generates a horizontal synchronizing signal HD and a vertical synchronizing signal VD for display driving the CRT display 12, and as shown in the timing chart of FIG. 2, the blanking of the horizontal synchronizing signal HD Writing to the frame memory 5 is designated at a timing corresponding to the period, reading from the frame memory 5 is designated during the remaining period, and video data is displayed one after another. In addition, when writing between horizontal blanking intervals, instead of writing all the video data for one sweep from the buffer memory of the sampling buffer circuit 3 to the frame memory 5 in one writing, it is written ten times. Video data for one sweep is written over a period of about 10 seconds. Further, the timing pulse generation circuit 13 supplies a read clock to the successive address circuit 14 at the read timing during the horizontal blanking period, and at this time, the address switching circuit 9 receives the read signal R from the timing pulse generation circuit 13. , the X and Y read addresses from the successive address circuit 14 are supplied to the frame memory 5, and the frame memory 5
One screen worth of video data is read out via an OR gate 10, converted into an analog video signal again by a D/A converter 11, and then supplied to a CRT display 12 for display by television sweep.

Next, a configuration for detecting the display end position that determines the display area of the radar image on the CRT display 12 will be described.

First, an area setting memory 16 is provided which stores position information for detecting a display end position and inhibiting writing when writing video data to the frame memory 5. As the area setting memory 16, in addition to a ROM or the like that permanently stores information on the display end position, a ROM or the like that permanently stores azimuth ring display information that determines the display area can be used.

FIG. 3 schematically shows the memory contents of the area setting memory 16 that permanently stores the azimuth ring that determines the display area.
This area setting memory 16 has a storage area for one screen in one-to-one correspondence with the frame memory 5, and has an address (XO) corresponding to the center of the screen.

Data "1" is fixedly stored in a memory area corresponding to the display ring 18, which is a circle with a display radius R centered at YO), and a scale for displaying the radar azimuth scale 20 is provided around the display ring 18. Data has been written, and data in other memory areas is rOJ. Data representing the azimuth ring 18 stored in this area setting memory 16 “
1'' is used as data indicating the display end position in the present invention.

Referring again to FIG. 1, the area setting memory 16 stores data of the display end position formed by the display ring 1B shown in FIG.
is read out in synchronization with writing and reading of frame memory 5, respectively.

In particular, the data of the area setting memory 16 read out in synchronization with the writing of the frame memory 5 is given to the end position detection circuit 17.
When detecting the readout of data "1" from the azimuth ring 18 shown in FIG. Therefore, video data is written to the frame memory 5 by address designation of the scan converter 8 only for the memory area corresponding to the display position of the azimuth ring 18 from the sweep origin, and the video data outside the display ring 18 is written. Writing is prohibited.

On the other hand, since the read data from the area setting memory 16 in synchronization with the read from the frame memory 5 is added to the video data at the OR gate 10, the CRT display 12 displays the azimuth ring with the scale 20 shown in FIG. 3 together with the video image. 1
8 will be displayed simultaneously.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

First, the video signal obtained by receiving the reflected wave of the radar antenna 1 is supplied from the transmitter/receiver circuit 2 to the sampling buffer circuit 3, where it is converted into digital video data at every predetermined distance pitch in synchronization with the sampling clock φ1. minutes of video data is temporarily stored in the built-in buffer memory. The video data stored in the buffer memory of the sampling clock circuit 3 is transferred to the CRT shown in FIG.
Since the write signal W is given to the address switching circuit 9 at the timing of the blanking period of the horizontal synchronization signal HD for the display 12, the write clock φ2 is sent from the scan converter 8 at the timing of the horizontal blanking period.
X calculated based on the distance information R obtained by adding the antenna rotation angle θ and the write clock φ2 output in synchronization with
, Y writes the video data in response to the supply of the write address.

Of course, writing of this video data is performed alternately with successive display in the frame memory 5, and video data for one sweep is written in a plurality of horizontal blanking periods.

On the other hand, in synchronization with the writing of video data to the frame memory 5, the area setting memory 16 receives the address designation from the scan converter 8, reads out the storage contents shown in FIG. 3, and sends the read data to the end position detection circuit 17. give.

When the end position detection circuit 17 detects the reading of data "1" of the azimuth ring 18 from the area setting memory 16, it outputs a write inhibit signal to the scan converter 8, and prevents data from being written to the memory area beyond the azimuth ring 18. prohibited. Due to write prohibition based on the end position data (azimuth ring data) of the area setting memory 16, the azimuth ring 1 is stored in the frame memory 16.
Only the video data inside the frame 8 will be written, and the video image will be displayed on the CRT display 12 within the circular area defined by the display ring 18 by continuously displaying the frame memory 5 in this writing state. Become.

On the other hand, in the case of off-center display, the write address by the scan converter 8 is address-shifted to an arbitrary off-center position, and video data is written in the frame memory at the off-center address. In this case as well, the area setting memory reads the stored data using the write address of the off-centered frame memory 5 (no address shift is applied) as the successive address, and when the azimuth ring data "1" is detected by the end position detection circuit 17 To prevent writing to
Only the video data of the circular display area that is inside the azimuth ring 18 in the off-center state is written to the frame memory 5, and by reading this frame memory 5 as it is, the azimuth ring 18
The video image can be displayed off-center in a circular area determined by .

In the above embodiment, the video image is displayed in a circular area with a radius R determined by the azimuth ring 18 of the area setting memory 16 shown in FIG. The shape of the display area is not limited to the area setting memory 1.
An appropriate shape can be obtained by arranging the addresses of the area setting data rob and rlJ written in 6.

(Effects of the Invention) As explained above, according to the present invention,
- An area setting memory having the same memory area as the frame memory that stores video data corresponding to the Y address is provided, data indicating a predetermined display area and display end position is stored in this area setting memory, and data indicating a predetermined display area and display end position is stored in the area setting memory. A read operation of the area setting memory is performed in synchronization with the writing, and if the read data is display area data, video data is written to the frame memory, and when display end data is obtained, the video data is written to the frame memory. Since writing of data is prohibited, the end position of the display can be detected extremely easily, simplifying the device configuration and reducing costs compared to the conventional method of detecting the end position by comparing the number of set dots and the number of written dots. It is possible to measure a significant reduction in

Further, the shape of the display end area can be freely changed by address arrangement of display area data and display end position data in the area memory.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a time chart showing the write/read timing of the frame memory in FIG. 1, and FIG. This is an explanatory diagram schematically showing the memory contents. 1: Radar antenna 2: Transmission/reception circuit 3: A/D converter 5: Frame memory 6: Antenna rotation angle detector 7: Digital angle conversion circuit 8 Niscan converter 9 Near address switching circuit 10 Nior gate 11: D/A converter 12: CRT display 13: Timing pulse generation circuit 14: Read address circuit 16: Area setting memory 17: End position detection circuit 18: Azimuth ring 20: Angle target

Claims (1)

[Claims] Video information for one rotation of the antenna obtained corresponding to the antenna rotation angle and distance information is converted into an X-Y display address of the CRT screen and stored in a frame memory, and after being stored, the video information is displayed on the CRT screen. In a radar display device that reads and displays in synchronization with the X-Y sweep scan of the screen, it has the same storage area as the frame memory, and stores data indicating the display area and display end area of the CRT screen in the storage area. reading out the stored data in the area setting memory in synchronization with the writing of data into the stored area setting memory and the frame memory; when the read data is display area data, writing the data into the frame memory; and writing the data into the frame memory; A sweep end detection device for PPI display, characterized in that it is provided with means for inhibiting writing when it is data.