JP2006266734A - Radar image transmitting device and radar image receiving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar image transmitting device capable of reducing a data quantity transmitted between the mountain side and the village side without being influenced by trail processing. <P>SOLUTION: This transmitting device is equipped with a scan converter 1 for outputting only a radar image on a coordinate updated by beam transmission from a radar antenna during a time when scanning of one screen portion is performed, and a transmitting circuit 9 for transmitting the radar image outputted from the scan converter 1, and thereby the radar image on the coordinate updated by beam transmission can be transmitted without using a scanning frame memory. Hereby, the data quantity transmitted between the mountain side and the village side can be reduced. Since transmission is performed in the preceding stage of the trail processing, the transmission quantity is not influenced by the trail processing. Thus, the data quantity transmitted between the mountain side and the village side can be reduced without being influenced by the trail processing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radar image transmitting apparatus and a radar image receiving apparatus that transmit or receive a radar image.

  In the radar device, the place where the equipment such as the antenna, receiver and signal processing is installed (referred to as the mountain side) is separated from the place where the console equipped with a display device for viewing the radar image is installed (referred to as the village side). There are many. However, when a console is also installed on the mountain side for maintenance or the like, it is necessary to perform processing for creating a radar image for display on the mountain side and to transmit the radar image to the village side. The amount of radar image data increases as the display becomes more precise, and there are problems such as an increase in hardware scale and design cost due to an increase in transmission rate.

  To deal with such problems, the radar video is converted from R, θ coordinates to X, Y coordinates, then stored in a frame memory prepared for two planes, and the radar image is transmitted from the mountain side to the village side. In this case, instead of transmitting the entire contents of the frame memory for one screen, the latest scan image data and the previous scan image data are compared to obtain updated coordinates, and only the image data of the updated coordinates is obtained. In some cases, the transmission amount is reduced by encoding and transmitting (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 11-101869

Since the conventional radar image transmission system is configured as described above, it is sometimes called trail processing (trailing processing, persist processing) generally performed on the radar screen. For example, the trail coefficient: k is set for each scan. When the processing is performed so that the display gradually fades and disappears by subtracting it from the amplitude value of the radar image), the radar image with coordinates that do not change the input radar image Therefore, the radar image of the latest scan and the radar image of the previous scan are all different, and the transmission amount cannot be reduced.
Also, because the contents of the display frame memory are transmitted, the image shown on the village side display device and the image shown on the mountain side maintenance display device have the same content, and have different offset values and ranges. There was a problem that it was not possible to set etc.

  The present invention has been made to solve the above-described problems, and a radar image transmission device and a radar image that reduce the amount of data transmitted between a mountain side and a village side without being affected by trail processing. An object is to obtain a receiving device.

  The radar image transmitting apparatus according to the present invention outputs a radar image output from the scan converter that outputs only a radar image of coordinates updated by beam transmission from the radar antenna while scanning for one screen is performed. And a transmission circuit for transmission.

  According to the present invention, by transmitting the radar image output from the scan converter by the transmission circuit, it is possible to transmit the radar image of the coordinates updated by the beam transmission without using the pre-scanning frame memory. Thereby, the amount of data transmitted between the mountain side and the village side can be reduced. In addition, since transmission is performed before the trail processing, the transmission amount is not affected by the trail processing. Thus, there is an effect that the amount of data transmitted between the mountain side and the village side can be reduced without being affected by the trail processing.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a mountain-side device (radar image transmission device) according to Embodiment 1 of the present invention. In the figure, a scan converter 1 includes R, θ coordinates (output from a signal processing unit of a radar device). A radar video consisting of luminance values for polar coordinates) is input and converted into a radar image consisting of luminance values for X and Y coordinates (orthogonal coordinates), and a beam is transmitted from the radar antenna while one screen is scanned. Only the radar image of the updated coordinates is output.

  A display area cutout circuit (first display area cutout circuit) 2 cuts out a display area of the radar image output from the scan converter 1 according to range information and offset information. The display frame memory (first display frame memory) 3 stores a radar image. The trail processing circuit (first trail processing circuit) 4 performs a trail process on the radar image read from the display frame memory 3 according to the TV scanning timing according to the trail coefficient. The comparison / selection circuit (first comparison / selection circuit) 5 compares the luminance value of the radar image cut out by the display area cut-out circuit 2 with the luminance value of the radar image trail-processed by the trail processing circuit 4. Are output to the display frame memory 3.

  The D / A converter (first D / A converter) 6 converts a digital radar image read out from the display frame memory 3 in accordance with the TV scanning timing into analog data. The maintenance display device 7 displays the radar image converted into analog data by the D / A converter 6. The control circuit (first control circuit) 8 sets range information and offset information in the display area extraction circuit 2 and sets trail coefficients in the trail processing circuit 4. The transmission circuit 9 transmits the radar image output from the scan converter 1 to a device on the village side (radar image receiving device).

FIG. 2 is a block diagram showing a village-side device (radar image receiving device) according to Embodiment 1 of the present invention. In FIG. 2, the receiving circuit 11 is a mountain-side device (radar image transmitting device) shown in FIG. The radar image transmitted from the transmission circuit 9 is received.
The display area cutout circuit (second display area cutout circuit) 12 cuts out a display area from the radar image received by the receiving circuit 11 according to range information and offset information. The display frame memory (second display frame memory) 13 stores a radar image. The trail processing circuit (second trail processing circuit) 14 performs a trail process on the radar image read from the display frame memory 13 according to the TV scanning timing according to the trail coefficient. The comparison selection circuit (fifth comparison selection circuit) 15 compares the luminance value of the radar image cut out by the display area cutout circuit 12 with the luminance value of the radar image trail-processed by the trail processing circuit 14, and the larger one Are output to the display frame memory 13. The graphic controller 16 writes drawing data into the graphic frame memory 17 in accordance with a drawing command.

The synthesizing circuit 18 synthesizes the radar image and the drawing data of digital data read from the display frame memory 13 and the graphic frame memory 17 in accordance with the TV scanning timing. The D / A converter (second D / A converter) 19 converts the radar image of the digital data output from the synthesis circuit 18 into analog data. The display device 20 displays the radar image converted into analog data by the D / A converter 19. The control circuit (third control circuit) 21 sets range information and offset information in the display area extraction circuit 12, sets trail coefficients in the trail processing circuit 14, and sets drawing commands in the graphic controller 16. is there.
The mountain-side device (radar image transmitting device) shown in FIG. 1 and the village-side device (radar image receiving device) shown in FIG. 2 constitute a radar image transmission device.

Next, the operation will be described.
In FIG. 1, a scan converter 1 inputs a radar video composed of luminance values for R, θ coordinates (polar coordinates) output from a signal processing unit of a radar apparatus, and consists of luminance values for X, Y coordinates (orthogonal coordinates). Convert to radar image.
For example, when R (distance), θ (angle), and A (luminance value) are set in polar coordinates, X = R · cos θ, Y = R · sin θ, and A = A (luminance value: no conversion) in orthogonal coordinates. Convert.
Further, the scan converter 1 outputs only the radar image of the coordinates updated by beam transmission from the radar antenna while scanning for one screen is performed.
For example, when the screen scan is non-interlaced 60 Hz and the rotation speed of the radar antenna is 1 rotation / 4 seconds, the radar antenna is 1.5 degrees (360 degrees / 4.multidot. 60) Only rotates. For this reason, when only the radar image of the coordinate updated by the beam transmission from the radar antenna is output, the amount of information is about 0.5% compared to outputting the radar image of all coordinates.
The transmission circuit 9 transmits the radar image output from the scan converter 1 to a device on the village side.

Further, in the display area cutout circuit 2, the radar image of the updated portion output from the scan converter 1 is actually displayed in the control circuit 8 according to the range information and offset information set by the operator's operation. Only the display area displayed in 7 is cut out and output.
FIG. 3 is an explanatory diagram for explaining a method of extracting a display area. FIG. 3A shows a case where the display area has no offset, the range is maximum, and all the updated parts are included in the display area. FIG. 3 has an offset, the range is maximum, and all the updated parts are included in the display area. FIG. 3C shows the case where the display area has an offset, and in the range 1/2, a part of the updated parts are included in the display area. (D) shows the case where the display area has an offset, and the update portion is not included in the display area in the range 1/2.
The display frame memory 3 stores a radar image cut out in the display area. Since the display frame memory 3 sequentially stores radar images, the radar image of the entire display area is stored.

In the trail processing circuit 4, the radar image for one screen read out from the display frame memory 3 according to the TV scanning timing is trail-processed in the control circuit 8 according to the trail coefficient set by the operation of the operator.
For example, the luminance value of the radar image read from the display frame memory 3 is multiplied or subtracted by a set trail coefficient and output. By this trail processing, the display on the maintenance display device 7 can be processed so as to gradually fade and disappear.
The comparison / selection circuit 5 performs the following processing on the radar image of the updated portion cut out by the display area cutout circuit 2 and the radar image for one screen subjected to the trail processing by the trail processing circuit 4.
If there is only trail-processed image data for a certain pixel, the trail-processed image data is output. If both the updated portion of the radar image and the trail-processed radar image exist for a certain pixel, the luminance values of both are compared and the larger one is output to the display frame memory 3.
The D / A converter 6 converts the radar image of digital data read from the display frame memory 3 according to the TV scanning timing into analog data, and the maintenance display device 7 displays the radar image.

In FIG. 2, the receiving circuit 11 receives the radar image transmitted from the transmitting circuit 9 of the mountain side apparatus shown in FIG. The received radar image is processed by the display area cutout circuit 12, the display frame memory 13, the trail processing circuit 14, and the comparison / selection circuit 15 in the same manner as the mountain-side device. However, in the control circuit 21, the range information, the offset information, and the trail coefficient can be set independently of the control circuit 8 of the mountain side device by the operation of the operator.
In the control circuit 21, a drawing command is set by an operator's operation, and the graphic controller 16 writes drawing data in the graphic frame memory 17 in accordance with the drawing command.
Further, the synthesizing circuit 18 synthesizes the radar image and the drawing data of the digital data read according to the TV scanning timing from the display frame memory 13 and the graphic frame memory 17, and the D / A converter 19 performs the radar image. Is converted into analog data, and the display device 20 displays the radar image.

As described above, according to the first embodiment, by transmitting the radar image output from the scan converter 1 by the transmission circuit 9, the coordinates of the coordinates updated by the beam transmission can be obtained without using the pre-scan frame memory. Radar images can be transmitted. Thereby, the amount of data transmitted between the mountain side and the village side can be reduced. In addition, since transmission is performed before the trail processing, the transmission amount is not affected by the trail processing. Thus, the amount of data transmitted between the mountain side and the village side can be reduced without being affected by the trail processing.
In addition, it is possible to display on the maintenance display device 7 in a display area corresponding to the range information and offset information set independently on the mountain side, and to display in the display area corresponding to the range information and offset information set uniquely on the village side. 20 and can be displayed in different display areas with different range information and offset information on the mountain side and the village side.

Embodiment 2. FIG.
FIG. 4 is a block diagram showing a mountain-side device (radar image transmission device) according to Embodiment 2 of the present invention. In the figure, a PPI database (first PPI database) 31 records a radar image at normal times. Is. The comparison / selection circuit (second comparison / selection circuit) 32 compares the radar image output from the scan converter 1 with the normal radar image recorded in the PPI database 31, and the scan converter has different coordinates in the radar image. Only the radar image output from 1 is extracted and output. The transmission circuit 9 transmits the radar image output from the comparison / selection circuit 32. Other configurations are the same as those in FIG.

  FIG. 5 is a block diagram showing a village-side device (radar image receiving device) according to Embodiment 2 of the present invention. In the figure, a PPI database (second PPI database) 33 records a radar image at normal times. It is a thing. The display frame memory 13 stores a normal radar image recorded in the PPI database 33. Other configurations are the same as those in FIG.

Next, the operation will be described.
In FIG. 4, the PPI database 31 has a plurality of normal radar images corresponding to the location where the radar device is installed, time, weather conditions, and the like, and the radar image corresponding to the situation during operation is selected. The comparison / selection circuit 32 compares the radar image output from the scan converter 1 with the normal radar image recorded in the PPI database 31, and only the radar image output from the scan converter 1 having different coordinates. Is extracted and output, and the transmission circuit 9 transmits the radar image output from the comparison / selection circuit 32. In this way, the transmission amount can be further reduced.
Also, in FIG. 5, the PPI database 33 similarly has a plurality of normal radar images, and the same radar image as that of the mountain side device is selected. By storing this radar image in the display frame memory 13, it is possible to display coordinates that are not transmitted on the village side.

As described above, according to the second embodiment, the radar antenna is extracted while one screen is scanned by extracting and outputting only the radar image having different coordinates as compared with the radar image in the normal state. Even if the coordinates are updated by beam transmission from, if they are in the same state as normal, they will not be updated. Thereby, the amount of data transmitted between the mountain side and the village side can be further reduced.
As for radar images that are not transmitted from the mountain-side transmission circuit 9, the entire display area can be displayed by using the normal radar images recorded in the PPI database 33.

Embodiment 3 FIG.
FIG. 6 is a block diagram showing a mountain-side device (radar image transmission device) according to Embodiment 3 of the present invention. In the figure, a scan converter 41 includes R, θ coordinates (output from a signal processing unit of the radar device). A radar video composed of luminance values for polar coordinates) is input and converted into a radar image composed of luminance values for X and Y coordinates (orthogonal coordinates). The scan converter 1 shown in FIGS. 1 and 4 outputs only the radar image of the coordinates updated by beam transmission from the radar antenna while scanning for one screen is performed. The scan converter 41 shown in FIG. 6 outputs not only the updated part but all radar images.

  The pre-scan frame memory 42 stores a radar image one scan before the radar image stored in the display frame memory 3. The reverse trail processing circuit 43 performs reverse trail processing on the radar image stored in the display frame memory 3 in accordance with the trail coefficient. The comparison / selection circuit (third comparison / selection circuit) 44 compares the radar image subjected to the reverse trail processing by the reverse trail processing circuit 43 and the radar image stored in the pre-scan frame memory 42, and the radar image has different coordinates. Only the radar image subjected to the reverse trail processing is extracted and output. The transmission circuit 9 transmits the radar image output from the comparison / selection circuit 44. The control circuit (second control circuit) 45 sets range information and offset information in the display area cutout circuit 2 and sets trail coefficients in the trail processing circuit 4 and the reverse trail processing circuit 43. Other configurations are the same as those in FIG.

  FIG. 7 is a block diagram showing a village-side device (radar image receiving device) according to Embodiment 3 of the present invention. In the figure, a control circuit (fourth control circuit) 46 is connected to the trail processing circuit 14 with a trail coefficient. Is set. Other configurations are the same as those in FIG. 2 except that the display area cutout circuit 12 is deleted.

Next, the operation will be described.
In FIG. 6, the scan converter 41 converts the radar image from R, θ coordinates (polar coordinates) to X, Y coordinates (orthogonal coordinates), but outputs all radar images, not just the updated portion by beam transmission. The processing of clipping the radar image at the subsequent stage, performing the trail processing, and displaying it on the maintenance display device 7 is the same as in FIG.
Further, the pre-scan frame memory 42 stores a radar image one scan before the radar image stored in the display frame memory 3.
By the way, the radar image stored in the display frame memory 3 at a certain point of time differs from the radar image stored in the pre-scanned frame memory 42 as follows. When the radar image is output from the display area cutout circuit 2, the radar image output from the display area cutout circuit 2 and the radar image subjected to the trail processing are different by the larger radar image. In addition, when the radar image is not output from the display area cutout circuit 2, the radar image is different for the trail-processed radar image.
Here, since the change in the radar image due to the trail processing is different from the updated portion of the radar image output from the scan converter 41, it is excluded from the radar image transmitted to the device on the village side.

Therefore, the reverse trail processing circuit 43 performs reverse trail processing on the radar image stored in the display frame memory 3 in accordance with the trail coefficient. For example, the set trail coefficient is divided or added to the luminance value of the radar image read from the display frame memory 3. Further, the comparison / selection circuit 44 compares the radar image subjected to the reverse trail processing by the reverse trail processing circuit 43 and the radar image stored in the pre-scanned frame memory 42, and the radar image is subjected to the reverse trail processing at different coordinates. Only the radar image is extracted and output, and the transmission circuit 9 can transmit only the output radar image, that is, the updated portion of the radar image.
Since the radar image is transmitted to the reception circuit 11 on the village side in the display area already cut out on the mountain side, the processing can be performed without providing the display area clipping circuit 12 on the village side.

As described above, according to the third embodiment, the radar image subjected to the reverse trail process and the radar image stored in the pre-scanned frame memory 42 are compared, and different coordinates of the radar image subjected to the reverse trail process are compared. It is possible to extract and transmit only the radar image. Thereby, the amount of data transmitted between the mountain side and the village side can be reduced. Further, since the trail process is performed and the reverse trail process is performed, the transmission amount is not affected by the trail process. Thus, the amount of data transmitted between the mountain side and the village side can be reduced without being affected by the trail processing. Furthermore, it is possible to display on the maintenance display device 7 in a display area corresponding to the range information and offset information set uniquely on the mountain side.
Further, since the transmission is performed in the display area already cut out on the mountain side, the configuration on the village side can be simplified without providing the display area clipping circuit 12 on the village side.

Embodiment 4 FIG.
FIG. 8 is a block diagram showing a mountain-side device (radar image transmission device) according to Embodiment 4 of the present invention. In the figure, a comparison / selection circuit (fourth comparison / selection circuit) 51 is output from a comparison / selection circuit 44. The obtained radar image and the normal radar image recorded in the PPI database 31 are compared, and only the radar image output from the comparison / selection circuit 44 having different coordinates is extracted and output. The transmission circuit 9 transmits the radar image output from the comparison / selection circuit 51. Other configurations are the same as those in FIG.

  FIG. 9 is a block diagram showing a village-side device (radar image receiving device) according to Embodiment 4 of the present invention. In FIG. 9, a PPI database 33 in which a radar image at normal times is recorded is provided. Other configurations are the same as those in FIG.

Next, the operation will be described.
In FIG. 8, in the PPI database 31, a radar image corresponding to the situation at the time of operation is selected as in FIG. The comparison selection circuit 51 compares the radar image output from the comparison selection circuit 44 with the normal radar image recorded in the PPI database 31, and the radar image output from the comparison selection circuit 44 having different coordinates. Only the image is extracted and output, and the transmission circuit 9 transmits the radar image output from the comparison / selection circuit 51. In this way, the transmission amount can be further reduced.
In FIG. 9, the PPI database 33 similarly has a plurality of normal radar images, and the same radar image as that of the mountain side device is selected. By storing this radar image in the display frame memory 13, it is possible to display coordinates that are not transmitted on the village side.

As described above, according to the fourth embodiment, only the radar image with different coordinates is extracted and output as compared with the radar image in the normal state, so that the pre-scanning of the radar image subjected to the reverse trail processing is performed. Even a radar image having coordinates different from the radar image stored in the frame memory 42 is not an updated portion if it is in the same state as normal. Thereby, the amount of data transmitted between the mountain side and the village side can be further reduced.
As for radar images that are not transmitted from the mountain-side transmission circuit 9, the entire display area can be displayed by using the normal radar images recorded in the PPI database 33.

It is a block diagram which shows the mountain side apparatus (radar image transmission apparatus) by Embodiment 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the village | side apparatus (radar image receiver) by Embodiment 1 of this invention. It is explanatory drawing explaining the cutting-out method of a display area. It is a block diagram which shows the mountain side apparatus (radar image transmission apparatus) by Embodiment 2 of this invention. It is a block diagram which shows the apparatus (radar image receiver) of the village side by Embodiment 2 of this invention. It is a block diagram which shows the mountain side apparatus (radar image transmission apparatus) by Embodiment 3 of this invention. It is a block diagram which shows the apparatus (radar image receiver) of the village side by Embodiment 3 of this invention. It is a block diagram which shows the apparatus (radar image transmitter) of the mountain side by Embodiment 4 of this invention. It is a block diagram which shows the apparatus (radar image receiver) of the village side by Embodiment 4 of this invention.

Explanation of symbols

  1, 41 scan converter, 2 display area cutout circuit (first display area cutout circuit), 3 display frame memory (first display frame memory), 4 trail processing circuit (first trail processing circuit), 5 Comparison selection circuit (first comparison selection circuit), 6 D / A converter (first D / A converter), 7 maintenance display device, 8 control circuit (first control circuit), 9 transmission circuit, 11 receiving circuit, 12 display area cutout circuit (second display area cutout circuit), 13 display frame memory (second display frame memory), 14 trail processing circuit (second trail processing circuit), 15 comparison selection Circuit (fifth comparison / selection circuit), 16 graphic controller, 17 graphic frame memory, 18 synthesis circuit, 19 D / A converter (second / A converter), 20 display device, 21 control circuit (third control circuit), 31 PPI database (first PPI database), 32 comparison selection circuit (second comparison selection circuit), 33 PPI database (first) 2 PPI database), 42 Pre-scan frame memory, 43 Reverse trail processing circuit, 44 Comparison selection circuit (third comparison selection circuit), 45 Control circuit (second control circuit), 46 Control circuit (fourth control) Circuit), 51 comparison selection circuit (fourth comparison selection circuit).

Claims (8)

A radar video composed of luminance values with respect to polar coordinates is inputted, converted into a radar image composed of luminance values with respect to orthogonal coordinates, and a radar image with coordinates updated by beam transmission from a radar antenna while scanning for one screen is performed. With a scan converter that only outputs
A radar image transmission apparatus comprising: a transmission circuit that transmits a radar image output from the scan converter. A first display area cutout circuit that cuts out the display area of the radar image output from the scan converter in accordance with the set range information and offset information;
A first display frame memory for storing a radar image;
A first trail processing circuit for performing a trail process on a radar image read out from the first display frame memory in accordance with a TV scanning timing in accordance with a set trail coefficient;
The luminance value of the radar image cut out by the first display area cut-out circuit is compared with the luminance value of the radar image trail-processed by the first trail processing circuit, and the larger radar image is compared with the first radar image. A first comparison / selection circuit for outputting to the display frame memory;
A first D / A converter for converting a radar image of digital data read out from the first display frame memory in accordance with a TV scanning timing into analog data;
A maintenance display device for displaying a radar image converted into analog data by the first D / A converter;
2. The radar image transmitting apparatus according to claim 1, further comprising: a first control circuit that sets range information and offset information in the first display area extraction circuit and sets a trail coefficient in the first trail processing circuit. . A first PPI database that records radar images at normal times;
The radar image output from the scan converter is compared with the normal radar image recorded in the first PPI database, and only the radar image output from the scan converter with different coordinates is extracted. A second comparison / selection circuit for outputting,
3. The radar image transmission apparatus according to claim 2, wherein the transmission circuit transmits the radar image output from the second comparison / selection circuit. A scan converter that inputs a radar video composed of luminance values with respect to polar coordinates, converts the radar video into luminance images composed of luminance values with respect to orthogonal coordinates, and
A first display area cutout circuit that cuts out the display area of the radar image output from the scan converter in accordance with the set range information and offset information;
A first display frame memory for storing a radar image;
A first trail processing circuit for performing a trail process on a radar image read out from the first display frame memory in accordance with a TV scanning timing in accordance with a set trail coefficient;
The luminance value of the radar image cut out by the first display area cut-out circuit is compared with the luminance value of the radar image trail-processed by the first trail processing circuit, and the larger radar image is compared with the first radar image. A first comparison / selection circuit for outputting to the display frame memory;
A first D / A converter for converting a radar image of digital data read out from the first display frame memory in accordance with a TV scanning timing into analog data;
A maintenance display device for displaying a radar image converted into analog data by the first D / A converter;
A pre-scanned frame memory for storing a radar image one scan before the radar image stored in the first display frame memory;
A reverse trail processing circuit for performing reverse trail processing on the radar image stored in the first display frame memory in accordance with a set trail coefficient;
The radar image subjected to reverse trail processing by the reverse trail processing circuit is compared with the radar image stored in the pre-scanned frame memory, and only the radar image subjected to reverse trail processing having different coordinates is extracted. A third comparison and selection circuit for outputting;
A transmission circuit for transmitting a radar image output from the third comparison / selection circuit;
Radar image transmission comprising range information and offset information in the first display area cutout circuit, and a second control circuit for setting a trail coefficient in the first trail processing circuit and the reverse trail processing circuit. apparatus. A first PPI database that records radar images at normal times;
The radar image output from the third comparison / selection circuit is compared with the normal radar image recorded in the first PPI database, and the radar image is output from the third comparison / selection circuit having different coordinates. A fourth comparison / selection circuit that extracts and outputs only the radar image obtained,
5. The radar image transmission apparatus according to claim 4, wherein the transmission circuit transmits the radar image output from the fourth comparison / selection circuit. A receiving circuit for receiving a radar image transmitted from the transmitting circuit of the radar image transmitting apparatus according to claim 2;
A second display area cutout circuit that cuts out the display area of the radar image received by the receiving circuit in accordance with the set range information and offset information;
A second display frame memory for storing a radar image;
A second trail processing circuit that performs a trail process on a radar image read out from the second display frame memory in accordance with a TV scanning timing in accordance with a set trail coefficient;
The luminance value of the radar image cut out by the second display area cut-out circuit is compared with the luminance value of the radar image trail-processed by the second trail processing circuit, and the larger radar image is compared with the second radar image. A fifth comparison / selection circuit for outputting to the display frame memory;
A second D / A converter for converting a radar image of digital data read out from the second display frame memory in accordance with TV scanning timing into analog data;
A display device for displaying a radar image converted into analog data by the second D / A converter;
A radar image receiving apparatus comprising: a third control circuit that sets range information and offset information in the second display area cutout circuit and sets a trail coefficient in the second trail processing circuit. A receiving circuit for receiving a radar image transmitted from the transmitting circuit of the radar image transmitting device according to claim 4;
A second display frame memory for storing a radar image;
A second trail processing circuit that performs a trail process on a radar image read out from the second display frame memory in accordance with a TV scanning timing in accordance with a set trail coefficient;
The brightness value of the radar image received by the receiving circuit is compared with the brightness value of the radar image trail-processed by the second trail processing circuit, and the larger radar image is stored in the second display frame memory. A fifth comparison / selection circuit for outputting;
A second D / A converter for converting a radar image of digital data read out from the second display frame memory in accordance with TV scanning timing into analog data;
A display device for displaying a radar image converted into analog data by the second D / A converter;
A radar image receiving apparatus comprising: a fourth control circuit that sets a trail coefficient in the second trail processing circuit. A second PPI database that records radar images during normal times;
8. The radar image receiving apparatus according to claim 6, wherein the second display frame memory stores a normal radar image recorded in the second PPI database.

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