JPS63282678A - Image obtaining method utilizing artificial satellite - Google Patents

Abstract

PURPOSE:To obtain a high resolving power image without being affected by a cloud, by discovering the position of a moving body by a wide range type synthetic aperture radar and controlling a high resolving power synthetic aperture radar so as to obtain an image wherein said position is magnified. CONSTITUTION:An artificial satellite is loaded with a wide range type synthetic aperture radar 3, a high resolving power synthetic aperture radar 4, an image data transmitting apparatus 5, the beam direction control apparatus 12 for the antenna of the radar 4 and a command apparatus 11 sending out the command from the ground applying indication to the apparatus 12. Then, said satellite is arranged so that the front in an advance direction is observed by the radar 3 and the image of the radar 3 is regenerated on the ground to confirm the present position of a moving body. Next, the position of the moving body is transmitted to the artificial satellite and the image at the indicated position is obtained by the radar 4 arranged so as to set the rear in the advance direction to a beam direction and a high resolving power image is obtained while the moving body is searched. By this method, the position of the moving body is searched within a wide range without being affected by a cloud and the high resolving power image in the vicinity of said image can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] Obtain images of the earth by mounting optical sensors and radio sensors on artificial satellites, transmit them to the ground, receive image data on the ground, and reproduce images of the earth. This invention relates to an image acquisition method using artificial satellites.

[Conventional technology]

As seen in the past examples of Landsat satellites and SeaSat satellites in the United States, and ocean observation satellites in Japan,
Artificial satellites are being used as an effective means of observing the Earth over a wide area.

Figure 2 shows a device that uses conventional artificial satellites to obtain images of the earth. In Figure 9, (1) is the earth, (2)
) is an artificial satellite orbiting the earth, (3) is a sensor that acquires images of the earth, (51 is an image data transmission device for transmitting images acquired by sensor (3) to the ground, (6)
is an earth station that receives and reproduces image data from artificial satellites,
(7) is the image data receiving device i that constitutes the earth station (6).
k, f81 is the image reproducing device A. The direction of travel 9 is the direction of the earth. Note that FIG. 2 shows other devices 9 in the artificial satellite, such as a power supply device and an attitude control device.

Tracking and telemetry command equipment, gas jet equipment, or structure are required.

Since it is not directly relevant to the explanation of this invention, it is omitted. In order to obtain an image of the Earth with such a device, a satellite is flown in a pre-selected orbit (usually a sun-synchronous orbit).9 The swath width of sensor A (3) is For example, a synthetic aperture radar is used to detect an image of the earth (in the field of view of the sensor on the earth's surface perpendicular to the direction of travel), and the data is transmitted to the ground and reproduced by the system shown in FIG. 9 Data is normally transmitted from satellites to the ground using radio waves.

[Problem that the invention seeks to solve]

When using the above device to acquire images of a target area on the ground that is dispersed over many locations, if the location is fixed, images can be acquired sequentially by commanding the satellite to obtain the location in advance. . However, if the ground target moves 2 For example, if you want to quickly acquire an image of a ship moving in the ocean, it is unknown where the ship has moved from the previously acquired position, so using the above method, the same ground trace as the previous one is used. Even if a satellite were to come over the ship and take an image, it would not be able to capture an image of the ship.

In other words, the efficiency of use of artificial satellites is that it is necessary to acquire images over a wide range of moving targets.

It must be said that data processing on the ground is extremely inefficient and uneconomical. Furthermore, in the case of optical sensors.

If there are clouds, images of the ground surface beneath the clouds cannot be obtained, and the frequency of image acquisition is greatly affected by the weather.

This invention was made in order to improve these conventional problems, and uses a wide-area synthetic aperture radar and a high-resolution synthetic aperture radar to acquire images over a wide area while transferring AI1'. I Find the position of the object and quickly determine the moving position of the target object without being affected by controlling the off-nadir angle of the high-resolution synthetic aperture radar to quickly obtain an enlarged image of the position. The aim is to obtain high-resolution images while

[Means for solving problems]

This invention applies wide-area synthetic aperture radar to artificial satellites.

(narrow range type) high-resolution synthetic aperture radar, a device for transmitting image data thereof, and a beam direction control device for varying the beam direction of the antenna of the high-resolution synthetic aperture radar;
Equipped with a command device that receives, decodes, and sends commands from the ground that give instructions to the control device, the radio wave emission direction of the wide-area synthetic aperture radar can be determined based on the radio wave emission direction of the high-resolution synthetic aperture radar. It is placed so that it is in front of the camera.

[Effect]

In this invention, a wide-area synthetic aperture radar and a high-resolution synthetic aperture radar are mounted on the same or separate artificial satellites,
A wide-area synthetic aperture radar is arranged to observe the front in the direction of travel, and the current position of the moving target object is confirmed by reproducing the image of this synthetic aperture radar on the ground. This system transmits images to an artificial satellite and obtains an image at a specified position using a high-resolution synthetic aperture radar placed so that the beam direction is backward relative to the direction of travel, and acquires high-resolution images while searching for a moving target object. Therefore, when the target object mentioned above is a ship sailing on the sea without being affected by rain or clouds, it is possible to search for the ship's position over a wide range and to obtain high-resolution images of the vicinity of that position. You will be able to obtain it.

〔Example〕

Is Figure 1 the view of the earth according to this invention? ! 111 device.

In Figure 1, (3) is a synthetic aperture radar, which is a wide-area synthetic aperture radar, (4) is a synthetic aperture radar B, which is a high-resolution synthetic aperture radar, and 02 is a beam for varying the antenna beam direction of synthetic aperture radar B. Directional control device, [9]
is a target position determination device that finds the extent l to be enlarged by the high-resolution synthetic aperture radar from the reproduced image, al is an image acquisition command device that instructs the high-resolution synthetic aperture radar to the image acquisition target position, and the negative is the image acquisition Command devices °a and b, which receive commands from the command device cICj and send commands to the visual field direction control device α2, are visual field directions. Other than A, this device is the same as the device shown in FIG.

Synthetic aperture radar A (3) is a wide-area synthetic aperture radar, so images of the earth (1) in this range are sent to image data transmission device (5), image data reception device (7), and via image reproduction device (8). ) can be played. Where the target object has moved in this reproduced image is displayed on a display or the like and visually confirmed. At this time, a computer compares the previous image of the same ground surface with the current image to detect changes, and when the amount of change in a certain area exceeds a predetermined threshold (it is divided into multiple stages and displayed) ), if a target position determination device (9) that displays the area on a display or the like is used, it becomes easy to visually confirm changes in the target position. Next, since the image obtained here has a large swath width, detailed recognition of the target object is often insufficient in terms of resolution, so the current position of the moving target object is confirmed by the above method. Then, a partially enlarged image is taken using the two-synthesis radar B (4), that is, the high-resolution synthetic aperture radar. By indicating the acquisition position on a display etc., the image acquisition command device αO sends the image from the earth station (6) to the satellite (2).
A predetermined signal is sent to the command device U of
) is executed by sending this command signal to the beam direction control device 0z, which controls the beam direction of the beam direction to be directed as instructed. This beam direction control can be performed by varying the off-nadir of the antenna used in the 9-synthesis radar B (4) or by using a phased array antenna.

2 Synthetic aperture radar Acquisition and reproduction of images of people (3).

The satellite flies for the time (about several tens of seconds to several tens of minutes) that is the sum of the time required to arrive at the confirmation of the change and the time required to orient the Lorada B (4) in the target direction during one synthesis. If two synthetic aperture radars are mounted on the same satellite, two synthetic aperture radars A
The beam direction in (3) is.

From the beam direction of synthetic aperture radar B (4), 2 synthetic aperture radar people (3) are placed in front of the synthetic aperture radar B (4) in the traveling direction of 9 artificial satellites (1) by the distance that the above satellite flies. It is necessary to set it so that If two synthetic aperture radars are mounted on separate satellites, the distance between them should be maintained in their orbits.

Also, Fig. 1 shows other devices that make up the artificial satellite.

For example, a power supply device, an attitude control device 9 a position determining device.

Although there are telemetry devices, they are omitted because they are not directly relevant to the explanation of this invention. Furthermore, here, a synthetic radar A131 is used as a sensor for earth observation. Although the synthetic aperture radar B (4) is explained above, this does not preclude installing another 61+1 sensor, such as an optical sensor, on the same satellite.If the optical sensor is used together, the high-resolution synthetic aperture radar B By controlling the viewing direction of the optical sensor in the same way as the target control in (4),
In weather without rain or clouds, various spectrum images ranging from visible light to infrared light can also be obtained.

〔Effect of the invention〕

As described above, the image acquisition method according to the present invention is as follows.

Since the moving target object is searched for using wide-area synthetic aperture radar, it is possible to search over a wide area without being affected by rain or clouds. Furthermore, since the position is specified and the high-resolution synthetic aperture radar is controlled to take an image at the specified position, it is possible to obtain a high-resolution image of the moving object, and the more information-value-rich images can be obtained within the life of the satellite. It is possible to build an economical image acquisition system with increased frequency.

In the above example where two synthetic aperture radars are mounted on the same satellite, the orbital positions of the two satellites are determined not only for moving targets but also for fixed targets.

Since the attitude angle has an error, the beam direction of the synthetic aperture radar will deviate from the predicted position. This also means that the beam direction of the satellite is determined only by the relative directional accuracy with respect to the wide-area synthetic aperture radar, thereby avoiding the difficulty of achieving attitude control accuracy for the two satellites.

[Brief explanation of the drawings] Fig. 1 is a diagram for explaining the image acquisition method using the artificial satellite of the present invention, and Fig. 2 is a diagram for explaining the image acquisition method using the conventional artificial satellite. It is a diagram. In the figure, (3) is a synthetic aperture radar A, f4) is a synthetic aperture radar B, (Ill is a command device, 0z is a beam direction control bag W, f9+ is a target position determination device, and aυ is an image acquisition command device. Note that the same or equivalent parts in FIG. 9 are designated by the same reference numerals.

Claims (2)

[Claims] (1) An image acquisition method using a satellite that acquires an image of the earth's surface by installing a synthetic aperture radar on the satellite, transmits it to the ground, and reproduces the image on the ground. , a wide-area synthetic aperture radar, a (narrow-area) high-resolution synthetic aperture radar, a device for transmitting their image data to an artificial satellite, and a beam direction control device for varying the beam direction of the high-resolution synthetic aperture radar antenna. Equipped with a command device that receives, decodes, and sends commands from the ground that give instructions to the control device, the radio wave emission direction of the wide-area synthetic aperture radar can be adjusted from the radio wave emission direction of the high-resolution synthetic aperture radar to the satellite's progress. The earth station is located forward in the direction and consists of an image data transmitting device, an image data receiving device, an image reproducing device, a target position determination device, and an image acquisition command device. First, the image data receiving device and the image reproducing device reproduce the wide-area synthetic aperture radar image, and from the image, the partial area to be acquired by the high-resolution synthetic aperture radar is found visually or by a target position determination device, and the image is acquired. directing the antenna beam of the high-resolution synthetic aperture radar in a direction passing the target position by instructing the beam direction control device via the command device and the command device;
An image acquisition method using an artificial satellite, characterized by acquiring an image in which a partial area of a wide-area synthetic aperture radar is enlarged using a high-resolution synthetic aperture radar. (2) The wide-area synthetic aperture radar and (narrow-area) high-resolution synthetic aperture radar are mounted on separate satellites,
These two satellites are placed in almost the same orbit, and the satellite equipped with the wide-area synthetic aperture radar is flown ahead of the satellite equipped with the high-resolution synthetic aperture radar, and images are acquired using the wide-area synthetic aperture radar. An image acquisition method using an artificial satellite according to claim 1, wherein an image is obtained by enlarging a partial area of the image with a high-resolution synthetic aperture radar flying with a time delay.