JP2006168421A - Flying object monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flying object monitoring device capable of sorting and monitoring only a flying object only specified as a monitoring object. <P>SOLUTION: This flying object monitoring device has a sound detecting part 11 detecting sounds generated in a monitoring area, and is constituted to measure a sound pressure level and a frequency of the sounds detected by the sound detecting part 11, and judge that the flying object 14 to be monitored is flying if the sound pressure in a preset specific frequency is larger than a set level. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flying object monitoring apparatus capable of accurately detecting and monitoring a flying object to be monitored that has arrived in a monitoring object area.

  In general, there are cases in which shooting is performed from the sky using a helicopter or Cessna for the purpose of spying for outdoor work or experiments performed in a laboratory or test facility. If it is detected that such a helicopter and Cessna for the purpose of photographing are detected, it is possible to hide the experimental scenery and body from the photographing.

  The following problems can be considered when monitoring such flying objects. The flying objects that fly above are not only helicopters and Cessna, but also passenger aircraft, clouds, and birds. Therefore, in a system that simply detects what is flying, an alarm is issued in response to all of the above, and if the experiment is stopped or the body is hidden in accordance with this alarm, the necessary time is lost. For this reason, it is necessary to separate the flying objects to be navigated.

  Here, radar detection is effective as means for detecting a flying object. However, installation is often difficult due to cost and size of deployment. In addition, monitoring by an image is performed by arranging cameras around, but since an object moving in the sky is moving not only by an aircraft but also by birds and clouds, there is a high possibility that these will be erroneously detected. Furthermore, in the case of an image, when the sun enters the back, there are cases where it cannot be detected due to the influence of backlight.

  In addition, a monitoring system using an infrared camera that captures and captures a flying object by capturing a heat source of the flying object has also been proposed (see, for example, Patent Document 1). In this aircraft monitoring system, a flying object that has entered a predetermined monitoring area is captured by any one of four infrared cameras, and the flying object is monitored by shooting the flying object based on the heat source.

However, in the above-described aircraft monitoring system, since the flying object is monitored by detecting the heat source with the infrared camera, all the flying objects having the heat source are captured. For example, it has been a problem to react to jet aircraft and large aircraft.
JP 2001-253398 A

  As described above, the conventional technology cannot select and monitor specific flying objects such as helicopters and Cessna.

  An object of the present invention is to provide a flying flying object monitoring apparatus capable of selecting and monitoring only flying objects specified as monitoring targets.

  The flying object monitoring apparatus according to the present invention includes a sound detection unit that detects a sound generated in a monitoring region, and a sound pressure level and a frequency of the sound detected by the sound detection unit. And a processing device that determines that the flying object to be monitored is flying if the pressure is equal to or higher than a set level.

  Further, the flying object monitoring apparatus of the present invention has a sound detection unit having directivity for detecting sound generated in the monitoring region, and turns the sound detection unit having this directivity with respect to the monitoring region. The swivel that can detect the angle, and the sound pressure level and frequency of the sound input to the sound detection unit are measured. If the sound pressure of a specific frequency set in advance is equal to or higher than the set level, there is a flying object to be monitored. And a processing device that determines the flying direction of the monitoring target flying object from the turning angle of the swivel at which the sound pressure at a specific frequency is equal to or higher than a set level.

  Further, the flying object monitoring device of the present invention, a sound detection device provided with a plurality of sound detection units having directivity for detecting the sound generated in the monitoring region, facing each direction covering the monitoring region, The sound pressure level and the frequency of the sound input to the plurality of sound detection units are respectively measured, and the sound detection unit whose sound pressure at a preset specific frequency is equal to or higher than the set level is specified to cause the flying object to be monitored. And a processing device that determines the flying direction of the monitoring target flying object from the installation direction of the specified sound detection unit.

  In the present invention, the processing device may be configured such that the frequency analysis detected by the sound detection unit is seen in the time direction, the pattern of the peak change of the sound is captured, and added as a discrimination element of the monitoring target flying object.

  The present invention further includes a camera that can be turned in any direction within the monitoring area, and a control unit that changes the shooting direction of the camera in the flying direction of the flying object detected by the processing device. It is good.

  In the present invention, the first camera capable of turning in any direction within the monitoring area, the second camera having a zoom function capable of turning in any direction within the monitoring area, and the processing device detect First control means for changing the shooting direction of the first camera in the flying direction of the flying object, and the position and size of the flying object in the image shot by the first camera as an image frame And a second control unit for controlling the shooting direction and zoom function of the second camera in correspondence with the position and size of the flying object detected by the image determination unit. May be provided.

  In the present invention, the image recognition means for extracting the appearance features of the flying object photographed by the camera, the storage means for storing the appearance features extracted by the image recognition means, and the image recognition means extracted. A configuration may be further provided with matching means for detecting matching between the appearance features and the appearance features stored in the storage means.

  Furthermore, in the present invention, an infrared camera that detects a heat source and monitors a flying object may be used in combination, and only a flying object having a heat source may be determined as a monitoring target.

  According to the present invention, it is possible to detect and monitor only the flying object specified as the monitoring target in advance among the flying objects flying in the monitoring area, without erroneously detecting the flying object other than the monitoring target, Necessary time loss such as abortion of experiments due to false detections can be prevented.

  Hereinafter, an embodiment of the flying object monitoring apparatus according to the present invention will be described in detail with reference to FIGS.

  FIG. 1 shows an apparatus configuration. Reference numeral 11 denotes a sound detection unit, which includes an omnidirectional microphone provided on a monitoring tower 13 provided near the monitoring building 12. The microphone 11 detects sound generated in a preset monitoring area. Therefore, when a flying object 14 (a helicopter or a Cessna (not shown)) 14 to be monitored flies within the monitoring area, a sound of a certain level or higher including a sound generated by these is detected.

  FIG. 2 represents the function of this device in blocks. The processing device 15 measures the sound pressure level and frequency of the sound detected by the microphone 11 serving as a sound detection unit. If the sound pressure at a specific frequency set in advance is equal to or higher than the set level, the monitoring target flying object, for example, illustrated It is determined that the noise is generated by the helicopter 14, and information that the helicopter 14 has come into the monitoring area is output to the alarm device 16.

  In the above configuration, as shown in FIG. 1, when the heicopter 14 comes into the monitoring area, the average value of the sound input to the microphone 11 increases. The sound data detected by the microphone 11 is measured by the processing device 15 for sound pressure and frequency as shown in FIG. 3, and a level increase of some specific frequencies is detected. That is, it is determined that the sound object of the specific frequency set in advance is equal to or higher than the set level and is determined to be the monitoring target flying object 14, and an alarm is generated from the alarm device 16.

  Here, even if the level of the sound input from the microphone 11 is increased, the sound is not necessarily generated from the monitoring target flying object (helicopter or Cessna) 14. For example, when the cause of the sound level increase is a jet aircraft, the high frequency increases when the increase result for each frequency is confirmed. On the other hand, helicopters increase several frequencies, a low frequency and a high frequency, by the rotation of a large rotor. In addition, since Cessna is equipped with a propeller that rotates at high speed, some of the specific low frequencies rise as peaks due to the continuous propeller rotation sound.

  Therefore, in the processing device 15, some peak frequencies generated by these monitoring target flying objects (helicopter and Cessna) 14 are specified in advance, and when the peak positions of the sound frequencies captured by the microphone 11 coincide, It is determined that the noise is generated by the flying object 14 and, as described above, information that the monitoring target flying object (helicopter or Cessna) 14 has come into the monitoring area is output to the alarm device 16.

  In addition, although there is lightning in other loud sound levels, lightning can be excluded from detection because there is no periodic sound.

  Next, the embodiment shown in FIGS. 4 and 5 will be described. In the embodiment of FIGS. 1 to 3 described above, the direction in which the monitoring target flying object (helicopter or Cessna) 14 enters cannot be determined. Therefore, this embodiment adds a direction detection function.

  In this embodiment, as shown in FIG. 4, a microphone having specific directivity is used as the sound detection unit 21 that detects sound generated in the monitoring area. The microphone 21 having directivity is driven to turn by the turntable 23 so that the sound collection range covers the monitoring area. The turntable 23 detects and outputs the turning angle of the directional microphone 21.

  As shown in FIG. 5, information on the sound detected by the directional microphone 21 and a turning angle signal from the turntable 23 are input to the processing device 25. The processing device 25 measures the sound pressure level and frequency of the sound input from the directional microphone 21, and determines that the monitoring target flying object 14 has come if the sound pressure at a specific frequency set in advance is equal to or higher than the set level. To do. Further, the flying direction of the monitoring target flying object 14 is determined from the turning angle of the turntable 23 when the sound pressure of the specific frequency is equal to or higher than the set level.

  In this way, sound is measured while the directional microphone 21 is turned by the turntable 23. For this reason, the sound of the flying object to be monitored (helicopter or Cessna) 14 is detected, and an alarm is issued from the alarm device 16 to the site. Moreover, since the directional microphone 21 is used to turn, the flying direction can be detected from the turning angle when the monitoring target flying object 14 is detected. Therefore, the detection warning of the monitoring target flying object 14 including the flying direction can be performed. In addition, by knowing the direction of flight, it is easy to hide even when hiding in a hurry.

  Next, the embodiment shown in FIGS. 6 and 7 will be described. In the embodiment shown in FIGS. 4 and 5 described above, the surrounding sound is measured by turning the directional microphone 21, so that the place where the sound is input to the turning microphone 21 is specified, which is insensitive. Time will occur. Therefore, in this embodiment, measurement is always possible in the shortest time so that no dead time occurs.

  In this embodiment, a directional microphone 21 having a specific directivity is used as a sound detection unit for detecting a sound generated in the monitoring area, as in the embodiments of FIGS. 4 and 5. As shown in FIG. 6, the sound detection device is configured by installing a plurality of radiating areas 21 toward each direction so that the directivity range 21 a covers the monitoring area. .

  As shown in FIG. 7, information on sounds detected by the plurality of directional microphones 21 is input to the processing device 35. The processing device 35 measures the sound pressure level and frequency of the sound input from the plurality of directional microphones 21. Then, the directional microphone 21 that detects sound information whose sound pressure at a preset specific frequency is equal to or higher than a set level is specified to detect the flying of the flying object 14, and from the installation direction of the specified directional microphone 21. The flying direction of the monitoring target flying object 14 is determined.

  Thus, since the entire circumference is always measured using a plurality of directional microphones 21, the flying direction of the monitoring target flying object 14 can be determined in a short time without causing a dead time. Therefore, the monitoring target flying object 14 including the flight direction can be detected in a short time, and an alarm can be issued by the alarm device 16.

  Next, the embodiment shown in FIG. 8 will be described. In this embodiment, a time element is added to the frequency analysis. That is, in each of the above-described embodiments, the frequency analysis of the sound detected by the microphone 11 (or 21) is performed as shown in FIG. 8A. In this embodiment, the frequency analysis is performed as shown in FIG. ), The pattern of the change in the sound peak as seen in the time direction is captured and added as a discriminating element for the monitoring target flying object 14.

  In this way, by detecting the frequency analysis in the time direction, detection is performed with a pattern of change in sound peak due to rotation of the propeller and the rotor. In the case of a rotating body, the sound level is not always constant but pulsates. Therefore, detection using this characteristic enables detection with fewer false detections.

  Next, the embodiment shown in FIGS. 9 and 10 will be described. In this embodiment, a monitoring camera 36 shown in FIG. 9 is added to the above-described embodiment (FIG. 4 or 6) in which the flying object 14 is detected by the directional microphone 21 including the flying direction. As shown by 10, this is combined with detection by the directional microphone 21.

  In FIG. 9, the camera 36 is installed separately from a microphone (not shown) on the monitoring tower 13 and is configured to be capable of turning in any direction within the monitoring area. In addition, the camera 36 includes control means 37 that changes the shooting direction toward the flying direction of the flying object 14 based on the detection result of the processing device 25 having the flying direction detection function. The image of the flying object 14 photographed by the camera 36 is displayed on the display device 38 via the processing device 25.

  That is, the monitoring camera 36 can control the shooting direction up, down, left, and right, and by connecting the control unit 37 that controls the direction of the camera 36 to the processing device 25 that detects the flying object 14 by sound, the microphone 21. If the flying object 14 and the flying direction thereof are detected by the sound detection, the surveillance camera 36 is directed in the direction in which the flying object 14 has come. Since the video imaged by the monitoring camera 36 is displayed on the display device 38, the flying object 14 detected by sound can be confirmed by the video of the monitoring camera 36. Therefore, it is possible to confirm that the object detected by sound is definitely the flying object 14 to be monitored and to generate an alarm by the alarm device 16.

  Next, the embodiment shown in FIGS. 11 to 13 will be described. In this embodiment, the monitoring camera 36 of the above embodiment is used as a first camera for detecting a flying object, and a second camera 39 is provided for image enlargement.

  Here, each of the first camera 36 and the second camera 39 is configured to be capable of turning in an arbitrary direction within the monitoring area. However, as shown in FIG. The second camera 39 is set to capture a wide-angle image, and has a zoom function capable of enlarging the image.

  Here, for the first camera 36, as in the above-described embodiment, the shooting direction is changed to the flying direction of the flying object 14 based on the detection result of the processing device 25 having the flying direction detection function. First control means 37 is provided. Further, the video of the flying object 14 photographed by the first camera 36 is displayed on the display device 38 via the processing device 25 and also given to the image determination means 41.

  The image determination means 41 detects the position and size of the flying object 14 in the image based on the image captured by the first camera 36 as shown in FIG. Is output to the second control means 42. The second control unit 42 controls the shooting direction and zoom function of the second camera 39 in accordance with the position and size of the flying object 14 detected by the image determination unit 41. That is, as shown in FIG. 11, the shooting direction and zoom function of the second camera 39 are controlled so that the image of the flying object 14 shot by the second camera 39 becomes a full image frame.

  In other words, the moving object determination device (first camera 36 and image determination means 41) in the image and the second camera 39 for enlargement are added. Then, after the flying object 14 is captured by the first camera 36, the position and size of the moving flying object 14 are determined from the longitudinal correlation of the image frames in the image of the camera 36. The second camera 39 for enlargement having a zoom function is controlled to the telephoto side from the determined position information and size information, and the flying object 14 is enlarged and photographed. An image captured by the second camera 39 is also displayed on the display device 38.

  A series of these flows will be described with reference to FIG. First, the flying of the flying object 14 and its flying direction are detected by the microphone 21, and it is determined that the flying object 14 to be monitored has entered the monitoring area (step 101). Based on the detection result, the shooting direction of the first camera 36 set on the wide-angle side is controlled to face the flying direction of the flying object 14 (step 102), and the flying object 14 is shot at a wide angle (step 103). From the image captured by the first camera 36, the position and size of the moving flying object 14 are determined by the front-rear correlation of the image frames in the image (step 104). From the determined position and size of the flying object 14, the second camera 39 having a zoom function is controlled to the telephoto side, and the shooting direction is controlled so as to be within the image frame of the enlarged flying object 14 image. The flying object 14 is enlarged and photographed (steps 105 and 106). Then, an image captured by the second camera 39 is displayed on the display device 38 (step 107).

  In this way, by constantly performing sound and movement determination and performing camera control, it is possible to stably photograph the flying object 14 moving at high speed. In addition, since the second camera 39 does not need to predict the movement because the whole image is taken and determined by the first camera 36, an enlarged image is taken even when the flying object 14 suddenly changes its direction. Is possible.

  Next, the embodiment shown in FIG. 14 will be described. In this embodiment, it is configured to determine whether the detected flying object 14 has come in the past.

  In FIG. 14, the operations from step 101 to step 106, that is, the operations until the flying object 14 is magnified by the second camera 39 according to the imaging result of the flying object by the first camera 36 are shown in FIG. The form is the same.

  In this embodiment, as a function of the processing device 25, although not shown, an image recognition unit, a storage unit for image information extracted by the image recognition unit, and a matching unit for detecting matching of image information are added. ing. The image recognition means extracts the appearance of the monitoring target (either color, pattern, shape, or a combination thereof) from the image of the flying object 14 photographed by the second camera. The storage means stores the appearance information extracted by the image recognition means. The matching unit compares the appearance information extracted by the image recognition unit with information stored in the storage unit in the past, and detects the degree of matching between them.

  That is, as shown in FIG. 14, the flying object 14 is magnified and photographed by the second camera 39 (step 106), and then the appearance feature of the monitoring target is extracted from the photographed image (step 108). This extracted feature is matched with the past feature stored in the storage means (step 109), and it is determined whether or not the flying object detected this time is new (step 110). As a result of matching, if the degree of matching with a past feature is equal to or greater than a threshold value, it is determined that it has come in the past.

  Note that the image captured by the second camera 39 is displayed on the display device 38 (step 107), which is the same as in the above embodiment.

  In this way, since the appearance features such as the color, pattern, and shape of the monitoring image are extracted from the captured image and stored, the extracted pattern information can be used to determine whether the monitoring target that has come repeatedly is flying. It is possible to make a judgment by matching.

  Next, the embodiment shown in FIGS. 15 and 16 will be described. In this embodiment, an infrared camera 45 that detects a heat source and monitors a flying object is used in combination, and only a flying object having a heat source is determined as a monitoring target. That is, as shown in FIG. 15, an infrared camera 45 is added to the embodiment shown in FIG. 12, and as a function of the processing device 25, although not shown, brightness determination means that reacts with infrared rays is added.

  Here, in the embodiment shown in FIG. 12, when a flying object is detected in response to sound and the camera 21 is pointed in that direction, if a bird happens to fly in the sky in front of it, this is mistakenly detected. There is a possibility of tracking birds as monitoring targets. In addition, there is a possibility that a cloud moving by wind is determined as a monitoring target.

  In order to prevent such erroneous detection, the infrared camera 45 is used to confirm that the heat source (aviation engine) is a flying object and to perform monitoring. This series of operations will be described with reference to FIG.

  In FIG. 17, the operations from step 101 to step 104 are the same as those in FIG. That is, the flying of the flying object 14 and its flying direction are detected by the microphone 21, the shooting direction of the first camera 36 set on the wide angle side is directed to the flying direction of the flying object 14, and the flying object 14 is shot at a wide angle. Then, a moving flying object is determined from the image captured by the first camera 36. However, as described above, if a bird happens to fly in the sky in front of the flying object to be monitored, it may be erroneously determined that this bird is the monitoring target.

  Therefore, the infrared camera 45 is controlled (step 111), and the flying object is photographed (step 112). As is well known, the infrared camera 45 captures a heat source (in this case, an aircraft engine) and takes a picture while tracking the heat source. Therefore, even if a bird is flying in front of the monitoring target, the bird is not erroneously detected and tracked as a monitoring target, and only the flying object (helicopter or Cessna) to be monitored is tracked and photographed. Then, the position and size of the photographing target flying object 14 are determined from the photographed image of the infrared camera 45 (step 113).

  Thereafter, as in FIG. 13, the second camera 39 is controlled to the telephoto side based on the determined position and size of the flying object 14 so as to be within the image frame of the image of the enlarged flying object 14. The shooting direction is controlled to magnify the flying object 14 (steps 105 and 106). Then, an image captured by the second camera 39 is displayed on the display device 38 (step 107).

  In addition, as a method of capturing a flying object having a heat source with the infrared camera 45, for example, a plurality of infrared cameras are prepared, the entire monitoring area is covered with the plurality of infrared cameras, and the flying object is within the monitoring area. When flying, it is captured by any one of the infrared cameras, and thereafter, the flight positions of the flying object having the heat source may be tracked and captured by using a plurality of infrared cameras with reference to the capture positions. In addition to this, for example, a single infrared camera that can cover the entire monitoring area is provided, and the direction is controlled in conjunction with the first camera 36 on the wide-angle side to capture a flying object having a heat source. It may be configured to perform a tracking operation.

  As described above, since the infrared camera 45 is used in combination, only the flying object having the heat source is determined as the monitoring target. Therefore, it is erroneously determined that the bird flying by the sky or the cloud moving by the wind is the monitoring target. In other words, the monitoring accuracy and reliability can be improved.

It is an apparatus block diagram which shows one Embodiment of the flying flying object monitoring apparatus by this invention. It is a functional block diagram showing apparatus structure of one Embodiment same as the above. It is a characteristic view showing the relationship between the sound pressure of the sound data for monitoring object flying object determination in one Embodiment same as the above, and a frequency. It is an apparatus block diagram which shows embodiment which turns the sound detection part in this invention. It is a functional block diagram showing the apparatus structure of embodiment shown in FIG. 1 shows an embodiment using a plurality of sound detection units according to the present invention, (a) shows a sound collection range of the sound detection unit alone, and (b) shows sound collection when a plurality of sound detection units are arranged. The range is shown. It is a functional block diagram showing the apparatus structure of embodiment shown in FIG. An embodiment in which the frequency analysis of sound of the present invention is viewed in the time direction will be described. (A) shows the relationship between sound pressure and frequency, and (b) shows the relationship with time. It is an apparatus block diagram which shows embodiment which used the camera of this invention together. It is a functional block diagram showing the apparatus structure of embodiment shown in FIG. It is a figure explaining the camera picked-up image in embodiment using the 1st camera of the wide angle side of this invention, and the 2nd camera of a telephoto side. It is a functional block diagram showing the apparatus structure of embodiment described in FIG. It is a flowchart explaining the operation | movement of embodiment described in FIG. It is a flowchart explaining the operation | movement of embodiment which added the matching function with the past image of this invention. It is a functional block diagram showing the apparatus structure of embodiment which further added the infrared camera of this invention. It is a flowchart explaining the operation | movement of embodiment described in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Sound detection part 14 Flying object 15 and 25 of monitoring object Processing apparatus 21 Sound detection part 23 which has directivity 23 Turntable 36 Cameras (1st camera)
37 Control means (first control means)
39 Second camera 41 Image determination means 42 Second control means 45 Infrared camera

Claims (8)

A sound detection unit for detecting sound generated in the monitoring area;
A processing device that measures the sound pressure level and frequency of the sound detected by the sound detection unit, and determines that the flying object to be monitored is flying if the sound pressure at a specific frequency set in advance is equal to or higher than the set level;
A flying object monitoring apparatus characterized by comprising: A sound detection unit having directivity for detecting sound generated in the monitoring area;
A turntable capable of turning the sound detection unit having the directivity with respect to the monitoring area and detecting the turning angle;
The sound pressure level and frequency of the sound input to the sound detection unit are measured, and if the sound pressure of a specific frequency set in advance is equal to or higher than the set level, it is determined that the flying object to be monitored is flying, and the sound of the specific frequency A processing device that determines the flying direction of the flying object to be monitored from the turning angle of the turntable at which the pressure is equal to or higher than a set level;
A flying object monitoring apparatus characterized by comprising: A plurality of sound detection units having directivity for detecting sound generated in the monitoring area, and a sound detection device installed toward each direction covering the monitoring area;
The sound pressure level and the frequency of the sound input to the plurality of sound detection units are respectively measured, and the sound detection unit whose sound pressure at a preset specific frequency is equal to or higher than the set level is specified to cause the flying object to be monitored. And a processing device for determining the flying direction of the monitoring target flying object from the installation direction of the specified sound detection unit,
A flying object monitoring apparatus characterized by comprising:   4. The processing apparatus according to claim 1, wherein the processing device captures a pattern of a change in sound peak by looking at a frequency analysis detected by the sound detection unit in a time direction, and adds the pattern as a discriminating element of a monitoring target flying object. The flying object monitoring apparatus according to any one of the above. A camera capable of turning in any direction within the surveillance area;
4. The flying flying object monitoring apparatus according to claim 2, further comprising control means for changing the shooting direction of the camera to the flying direction of the flying object detected by the processing device. A first camera capable of turning in any direction within the surveillance area;
A second camera having a zoom function capable of turning in any direction within the monitoring area;
First control means for changing the shooting direction of the first camera to the flying direction of the flying object detected by the processing device;
Image determining means for detecting the position and size of a flying object in an image photographed by the first camera in relation to an image frame;
The second control means for controlling the shooting direction and zoom function of the second camera in correspondence with the position and size of the flying object detected by the image determination means. The flying object monitoring apparatus according to claim 2 or claim 3. Image recognition means for extracting features of the appearance of the flying object photographed by the camera;
Storage means for storing features of the appearance extracted by the image recognition means;
7. The flying device according to claim 5, further comprising: a matching unit that detects a match between the appearance feature extracted by the image recognition unit and the appearance feature stored in the storage unit. Flight object monitoring device.   The flying vehicle monitoring apparatus according to claim 5 or 6, wherein an infrared camera that detects a heat source and monitors a flying object is used in combination, and only a flying object having a heat source is determined as a monitoring target.

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