JP2010236872A - Image processing device and radio communication device and image processing method and image processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire an on-ground radar image similar to that in the case where no radio communication devices are used, while using a radio communication device for emitting a radio wave actively, and to highly accurately correct the radar image based on the position of the radio communication device. <P>SOLUTION: A synthetic aperture radar 200 transmits a chirp-modulated transmission pulse at each pulse repetition interval PRI, and receives a signal reflected on the ground as a reception signal. An RFID tag 300 transmits a chirp-modulated emission pulse at each another repetition pulse interval PRI', and allows the synthetic aperture radar 200 to receive it as a part of its received signal. An image processing device 401 regenerates an ordinary on-ground radar image by performing range compression or the like of the received signal at each pulse repetition interval PRI. Moreover, an image reflecting the RFID tag 300 is regenerated by performing range compression or the like of the received signal at each pulse repetition interval PRI', and based on this image and position information of the RFID tag 300, the on-ground radar image is corrected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image processing device, a wireless communication device, an image processing method, and an image processing program. The present invention particularly relates to a method for detecting position information of a synthetic aperture radar image using an asynchronous active RFID (Radio Frequency Frequency Identification) tag.

  Conventionally, as a method for detecting a specific position on the ground surface from a synthetic aperture radar (SAR) reproduction image, a corner reflector (reflector) that reflects a pulse wave from the synthetic aperture radar is previously installed on the ground surface. In some cases, the position of the point is specified by surveying (for example, see Patent Documents 1 and 2). As another method, there is a method in which a point having a high reflection intensity is identified from a reproduced image, and the position information of the point is read from a map and collated (for example, see Patent Document 3).

  Conventionally, the ARC (Active Radar Calibrator) that receives and records the transmission radio wave from the synthetic aperture radar, calculates the characteristics of the received signal, generates a replica (replica) of the received signal, and returns it to the synthetic aperture radar. There is a device. By analyzing the received signal recorded in the ARC, it is possible to investigate the performance and deterioration of the transmission radio wave of the synthetic aperture radar. In addition, although ARC is brightly displayed as “one point” on the synthetic aperture radar image, since the ARC is installed by humans, the accurate position of the installation location is measured to accurately detect at least one pixel on the synthetic aperture radar image. Can be used for image correction and the like. Further, since the intensity of the radio wave returned from the ARC has been determined by prior calibration, the brightness of the synthetic aperture radar image is backscattered based on the brightness of the ARC (one point) reflected on the synthetic aperture radar image. It can be converted into strength.

JP 2001-91650 A Japanese Patent Laid-Open No. 2004-157397 JP 2003-173449 A

  In the conventional method of using the corner reflector or ARC, the local adjustment (procedure for obtaining permission from the administrative body, corporation, individual, etc. that manages the installation location) or GPS ( It is necessary to conduct field surveys using a global positioning system), etc., and to determine the direction of pulse wave emission from the synthetic aperture radar according to the direction of the corner reflector and ARC. There was a problem that it took time and effort. In addition, the conventional method using a map has a problem that it is not easy to detect an accurate position from a synthetic aperture radar image because the accuracy of reading position information is not sufficient.

  For example, the present invention obtains a radar image of the ground similar to the case where a radio communication device is not used while using a radio communication device that actively radiates radio waves, and obtains a radar image based on the position of the radio communication device. The purpose is to correct with high accuracy.

An image processing apparatus according to an aspect of the present invention includes:
A radar mounted on an air vehicle, which generates a chirp-modulated first pulse signal for each predetermined pulse repetition interval PRI and transmits it to the ground, and receives a signal obtained by reflecting the transmitted first pulse signal on the ground as a received signal. A signal acquisition unit that acquires the received signal from a radar that receives as:
A wireless communication apparatus installed on the ground, which generates and transmits a chirp-modulated second pulse signal for each pulse repetition interval PRI ′ different from the pulse repetition interval PRI ′ of the first pulse signal transmitted by the radar. An information acquisition unit that acquires position information indicating a geographical position of a wireless communication device that causes the radar to receive the transmitted second pulse signal as part of the received signal;
The received signal acquired by the signal acquisition unit is range-compressed for each pulse repetition interval PRI, the range-compressed received signal is azimuth-compressed to generate a first compressed signal, and the ground radar image is generated from the generated first compressed signal. An image reproducing unit for reproducing the image by a processing device;
The received signal acquired by the signal acquisition unit is range-compressed at each pulse repetition interval PRI ′, the range-compressed received signal is azimuth-compressed to generate a second compressed signal, and the image is generated from the generated second compressed signal. The relative position of the wireless communication device in the radar image reproduced by the reproduction unit is specified, and the image reproduction unit is based on the specified relative position and the geographical position indicated by the position information acquired by the information acquisition unit And an image processing unit that corrects the radar image reproduced by the processing device.

  PRI ′> PRI.

The radar transmits a signal chirp-modulated at a predetermined chirp rate k (−1 ≦ k <0 or 0 <k ≦ 1) as the first pulse signal,
The wireless communication apparatus performs a chirp modulation on a signal obtained by chirp modulation at a chirp rate k ′ (−1 ≦ k ′ <0 or 0 <k ′ ≦ 1) different from the chirp rate k of the first pulse signal transmitted by the radar. Send it as a two-pulse signal,
The image reproduction unit performs range compression on the reception signal acquired by the signal acquisition unit at a chirp rate k for each pulse repetition interval PRI, and azimuth compresses the range compressed reception signal to generate the first compressed signal,
The image processing unit performs range compression on the reception signal acquired by the signal acquisition unit at a chirp rate k ′ at each pulse repetition interval PRI ′, and azimuth-compresses the range-compressed reception signal to generate the second compressed signal. It is characterized by doing.

The wireless communication device transmits a signal indicating an identifier of the wireless communication device as the second pulse signal,
The information acquisition unit stores the acquired position information in a storage device in association with the identifier of the wireless communication device,
The image processing unit further acquires an identifier of the wireless communication device from the generated second compressed signal, reads position information corresponding to the acquired identifier from the storage device, and the specified relative position and the read position information are The radar image reproduced by the image reproduction unit is corrected based on the indicated geographical position.

The wireless communication device generates the position information based on a positioning signal from a positioning satellite,
The information acquisition unit acquires position information generated by the wireless communication device.

The wireless communication device transmits a signal indicating the position information as the second pulse signal,
The information acquisition unit acquires the position information from the second compressed signal generated by the image processing unit.

The wireless communication device includes an environmental sensor for observing the surrounding environment, and transmits a signal indicating the observation result of the environmental sensor as environmental information as the second pulse signal,
The image processing unit further acquires the environment information from the generated second compressed signal, and processes the radar image reproduced by the image reproduction unit based on the acquired environment information.

A wireless communication device according to one aspect of the present invention includes:
A wireless communication device installed on the ground,
A radar mounted on an air vehicle, which generates a chirp-modulated first pulse signal for each predetermined pulse repetition interval PRI and transmits it to the ground, and receives a signal obtained by reflecting the transmitted first pulse signal on the ground as a received signal. The second pulse signal subjected to chirp modulation is generated and transmitted for each pulse repetition interval PRI ′ different from the pulse repetition interval PRI of the first pulse signal, and the transmitted second pulse signal is transmitted to the radar receiving as A transmission unit that causes the radar to receive the signal as a part of the reception signal is provided.

An image processing method according to one aspect of the present invention includes:
The signal acquisition unit of the image processing apparatus is a radar mounted on an air vehicle, and generates a chirp-modulated first pulse signal for each predetermined pulse repetition interval PRI and transmits it to the ground. Obtains the received signal from a radar that receives a signal reflected on the ground as a received signal,
The information acquisition unit of the image processing device is a wireless communication device installed on the ground, and the second pulse signal subjected to chirp modulation is different from the pulse repetition interval PRI of the first pulse signal transmitted by the radar. Generating and transmitting at every interval PRI ′, obtaining position information indicating a geographical position of a wireless communication device that causes the radar to receive the transmitted second pulse signal as a part of the received signal;
The image reproduction unit of the image processing device performs range compression on the reception signal acquired by the signal acquisition unit at each pulse repetition interval PRI, and generates a first compressed signal by azimuth compressing the range compressed reception signal. The ground radar image is reproduced from the first compressed signal by the processing device,
The image processing unit of the image processing device performs range compression on the reception signal acquired by the signal acquisition unit for each pulse repetition interval PRI ′, and azimuth compresses the range compressed reception signal to generate a second compressed signal, The relative position of the wireless communication device in the radar image reproduced by the image reproduction unit is identified from the generated second compressed signal, and the geographical position indicated by the identified relative position and the position information acquired by the information acquisition unit The radar image reproduced by the image reproduction unit is corrected by a processing device based on the position.

An image processing program according to an aspect of the present invention includes:
A radar mounted on an air vehicle, which generates a chirp-modulated first pulse signal for each predetermined pulse repetition interval PRI and transmits it to the ground, and receives a signal obtained by reflecting the transmitted first pulse signal on the ground as a received signal. A signal acquisition process for acquiring the received signal from a radar receiving as
A wireless communication apparatus installed on the ground, which generates and transmits a chirp-modulated second pulse signal for each pulse repetition interval PRI ′ different from the pulse repetition interval PRI ′ of the first pulse signal transmitted by the radar. Information acquisition processing for acquiring position information indicating a geographical position of a wireless communication device that causes the radar to receive the transmitted second pulse signal as a part of the received signal;
The received signal acquired by the signal acquisition process is range-compressed at each pulse repetition interval PRI, the range-compressed received signal is azimuth-compressed to generate a first compressed signal, and the ground radar image is generated from the generated first compressed signal. Image reproduction processing for reproducing the image by a processing device;
The reception signal acquired by the signal acquisition process is range-compressed at each pulse repetition interval PRI ′, the range-compressed reception signal is azimuth-compressed to generate a second compressed signal, and the image is generated from the generated second compressed signal. The relative position of the wireless communication device in the radar image reproduced by the reproduction process is specified, and the image reproduction process is performed based on the specified relative position and the geographical position indicated by the position information acquired by the information acquisition process. The computer is caused to execute image processing for correcting the radar image reproduced by the processing device using a processing device.

  PRI ′> PRI.

The radar transmits a signal chirp-modulated at a predetermined chirp rate k (−1 ≦ k <0 or 0 <k ≦ 1) as the first pulse signal,
The wireless communication apparatus performs a chirp modulation on a signal obtained by chirp modulation at a chirp rate k ′ (−1 ≦ k ′ <0 or 0 <k ′ ≦ 1) different from the chirp rate k of the first pulse signal transmitted by the radar. Send it as a two-pulse signal,
In the image reproduction process, the reception signal acquired by the signal acquisition process is range-compressed at a chirp rate k for each pulse repetition interval PRI, the range-compressed reception signal is azimuth-compressed to generate the first compressed signal,
In the image processing, the reception signal acquired by the signal acquisition processing is range-compressed at a chirp rate k ′ at each pulse repetition interval PRI ′, and the range-compressed reception signal is azimuth-compressed to generate the second compressed signal. It is characterized by that.

The wireless communication device transmits a signal indicating an identifier of the wireless communication device as the second pulse signal,
The information acquisition process stores the acquired position information in a storage device in association with the identifier of the wireless communication device,
The image processing further acquires an identifier of the wireless communication device from the generated second compressed signal, reads position information corresponding to the acquired identifier from the storage device, and indicates the specified relative position and the read position information. The radar image reproduced by the image reproduction process is corrected based on the geographical position.

The wireless communication device generates the position information based on a positioning signal from a positioning satellite,
In the information acquisition process, the position information generated by the wireless communication device is acquired.

The wireless communication device transmits a signal indicating the position information as the second pulse signal,
In the information acquisition process, the position information is acquired from the second compressed signal generated by the image processing.

The wireless communication device includes an environmental sensor for observing the surrounding environment, and transmits a signal indicating the observation result of the environmental sensor as environmental information as the second pulse signal,
In the image processing, the environment information is further acquired from the generated second compressed signal, and the radar image reproduced by the image reproduction processing is processed based on the acquired environment information.

  According to one aspect of the present invention, since the image processing apparatus uses a wireless communication apparatus that transmits a chirp-modulated signal at different pulse repetition intervals from the radar, the received signal of the radar is transmitted at the same pulse repetition interval as the radar. By performing range compression, a ground radar image similar to the case where the wireless communication device is not used can be obtained, and the received signal of the radar is subjected to range compression at the same pulse repetition interval as that of the wireless communication device. Can be identified, and the radar image can be corrected with high accuracy based on the identified relative position and the geographical position of the wireless communication device.

1 is an overall configuration diagram of an image processing system according to Embodiment 1. FIG. 1 is a block diagram illustrating a configuration of an RFID tag according to Embodiment 1. FIG. 3 is a diagram illustrating a configuration example of an ID setting unit of an RFID tag according to Embodiment 1. FIG. 6 is a diagram illustrating a procedure of radiation pulse generation processing by the RFID tag according to Embodiment 1. FIG. 1 is a block diagram illustrating a configuration of an image processing device according to Embodiment 1. FIG. 2 is a diagram illustrating an example of a hardware configuration of an image processing apparatus according to Embodiment 1. FIG. 3 is a flowchart illustrating an operation of the image processing apparatus according to the first embodiment. FIG. 10 is a diagram illustrating a procedure of normal SAR reproduction processing and SAR reproduction processing for tag information extraction by the image processing apparatus according to the first embodiment. 6 is a diagram illustrating an example of transmission / reception timing of the synthetic aperture radar according to Embodiment 1. FIG. 6 is a diagram showing an example of rearrangement of received signals in normal SAR reproduction processing according to Embodiment 1. FIG. 6 is a diagram showing an example of rearrangement of received signals in normal SAR reproduction processing according to Embodiment 1. FIG. It is a figure which shows an example of the transmission / reception timing of the synthetic aperture radar and RFID tag which concern on Embodiment 1. FIG. 6 is a diagram showing an example of rearrangement of received signals in normal SAR reproduction processing according to Embodiment 1. FIG. 6 is a diagram illustrating an example of rearrangement of received signals in SAR reproduction processing for tag information extraction according to Embodiment 1. FIG. 6 is a diagram illustrating an example of rearrangement of received signals in SAR reproduction processing for tag information extraction according to Embodiment 1. FIG. It is a figure which shows an example of the tag information extraction result which concerns on Embodiment 1. FIG. 6 is a diagram illustrating an example of image association in SAR reproduction processing for tag information extraction according to Embodiment 1. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is an overall configuration diagram of an image processing system 100 according to the present embodiment.

  In FIG. 1, an image processing system 100 includes a synthetic aperture radar 200 (SAR), an RFID (Radio Frequency Frequency Identification) tag 300, and a synthetic aperture radar image processing facility 400. Although two RFID tags 300 are shown in this figure, there may be one or three or more RFID tags 300.

  First, the synthetic aperture radar 200 will be described.

  Synthetic aperture radar 200 is an example of a radar mounted on a flying object such as an artificial satellite or an aircraft. The synthetic aperture radar 200 irradiates a microwave (electromagnetic wave having a wavelength of about 1 mm to 1 m) toward the ground surface at a right angle (range direction) to the traveling direction (azimuth direction) of the flying object, and returns from the observation object. Receives the bounce of electromagnetic waves. Since an image of the ground surface can be obtained from the received signal, the synthetic aperture radar 200 is also called an image radar or an imaging radar. Synthetic aperture radar 200 is effective for collecting information at night, when it is difficult to use an optical sensor, during rainy or cloudy weather, or when the ground surface is covered with volcanic plume.

  Normally, the synthetic aperture radar 200 irradiates the ground surface with a pulse wave with a beam width (observation width) of about 10 km when mounted on an aircraft and about 60 km when mounted on an artificial satellite, and receives the reflected wave. By doing so, the data of the ground surface is acquired in a band shape. Since the resolution in the azimuth direction is determined by the beam width, and the beam width is inversely proportional to the antenna length, conventional radar has attempted to increase the resolution by increasing the actual aperture length of the antenna. However, since the platform is limited, in the synthetic aperture radar 200, the antenna length is equivalently increased by signal processing to achieve high resolution. In other words, the synthetic aperture radar 200 improves the resolution in the azimuth direction by synthesizing received signals by signal processing and acquiring data with a large antenna.

  In the present embodiment, the synthetic aperture radar 200 performs chirp modulation (changes the frequency in a linear function) at a predetermined chirp rate k (−1 ≦ k <0 or 0 <k ≦ 1) during the flight of the flying object. Therefore, a transmission pulse (also referred to as linear frequency modulation) (first pulse signal) is generated at every predetermined pulse repetition interval PRI. The synthetic aperture radar 200 transmits the generated transmission pulse from the synthetic aperture radar antenna 201 to the ground. The synthetic aperture radar 200 receives a signal obtained by reflecting the transmitted pulse transmitted on the ground as a reception signal by the synthetic aperture radar antenna 201. When the RFID tag 300 is installed on the ground in the region where the transmission pulse is transmitted from the synthetic aperture radar antenna 201, the synthetic aperture radar 200 receives the radiation pulse (second pulse signal) from the RFID tag 300 as a reception signal. Are received by the synthetic aperture radar antenna 201. Synthetic aperture radar 200 outputs a reception signal in which a radiation pulse from RFID tag 300 and a reflected wave from the ground including the point where RFID tag 300 is installed is mixed as synthetic aperture radar observation data. Synthetic aperture radar observation data is data in which signal information such as amplitude and phase of a received signal is recorded in time series, for example. When the flying object is an artificial satellite, the synthetic aperture radar observation data is transmitted to the synthetic aperture radar image processing facility 400 by air transmission (so-called downlink). When the flying object is an aircraft, a data recorder for recording synthetic aperture radar observation data is mounted inside the aircraft, and the data recorder is transported to the synthetic aperture radar image processing facility 400 after landing.

  In the present embodiment, other types of radars may be used instead of the synthetic aperture radar 200 as long as the transmission pulses as described above can be generated and transmitted.

  Next, the RFID tag 300 will be described.

  The RFID tag 300 is an example of a wireless communication device installed on the ground. The RFID tag 300 is a tag in which ID information (identifier) or the like is embedded. Usually, a tag exchanges information with an RFID reader / writer by wireless communication at a short distance (several centimeters to several meters, depending on a frequency band) using an electromagnetic field or radio waves. There are two types of tags: passive tags called passive tags and active tags called active tags. In this embodiment, the RFID tag 300 is an active tag. The RFID tag 300 is preferably a specific low-power radio station that does not require a radio station license.

  In the present embodiment, the RFID tag 300 has an arbitrary chirp rate k ′ (−1 ≦ k ′ <0 or 0 <k ′ ≦ 1) (may be the same as or different from the chirp rate k of the synthetic aperture radar 200). May be generated for each pulse repetition interval PRI ′ different from the pulse repetition interval PRI of the transmission pulse transmitted by the synthetic aperture radar 200. The RFID tag 300 transmits the generated radiation pulse from the antenna unit 301 to the synthetic aperture radar 200. As described above, the synthetic aperture radar 200 receives the radiation pulse from the RFID tag 300 as a part of the reception signal. That is, the RFID tag 300 causes the synthetic aperture radar 200 to receive the transmitted radiation pulse as a part of the reception signal. For example, if the center frequency of the radiation pulse is set so as to substantially coincide with the center frequency of the transmission pulse, the synthetic aperture radar 200 can inevitably receive the radiation pulse.

  In the present embodiment, other types of wireless communication devices may be used instead of the RFID tag 300 as long as the above-described radiation pulse can be generated and transmitted.

  The RFID tag 300 receives a GPS signal (positioning signal) from a GPS satellite group 101 including a plurality of GPS (global positioning system) satellites by a GPS receiver 302. The RFID tag 300 measures its geographical position based on the received GPS signal. The RFID tag 300 generates position information indicating the measured position, and outputs the generated position information. The position information is information indicating, for example, the latitude / longitude, altitude, etc. of the point where the RFID tag 300 is installed.

  FIG. 2 is a block diagram showing a configuration of the RFID tag 300.

  2, in addition to the antenna unit 301 described above, the RFID tag 300 includes an ID setting unit 303, a signal processing unit 304, an external device interface unit 305, a network interface unit 306, a timer unit 307, a power supply control unit 308, and a transmission unit 309. , An amplification unit 310, an RF filter unit 311, and a power supply unit 312. The RFID tag 300 includes an external device 321 such as the GPS receiver 302 described above and a router 322.

  The ID setting unit 303 sets ID information of the RFID tag 300. The ID setting unit 303 can be configured by a dip switch as shown in FIG. 3, for example. In this example, the ID setting unit 303 is configured so that the ID information is 12 bits and one bit of ID information can be set for each dip switch.

  The signal processing unit 304 includes a CPU (Central Processing Unit), a memory, and the like. The signal processing unit 304 reads the ID information set by the ID setting unit 303 by the CPU and stores it in the memory. Further, the signal processing unit 304 acquires information from the external device 321 via the external device interface unit 305, processes the information by the CPU as necessary, and stores the information in a memory. For example, the signal processing unit 304 acquires a GPS signal from the GPS receiver 302 via the external device interface unit 305, and generates the above-described position information by the CPU based on the acquired GPS signal (that is, navigation data). The generated position information is stored in the memory. The signal processing unit 304 transmits (outputs) information such as position information stored in the memory to the synthetic aperture radar image processing facility 400 via the network interface unit 306 and the router 322. Further, the signal processing unit 304 generates a radiation pulse by executing a radiation pulse generation process, which will be described later, by the CPU. The signal processing unit 304 uses the timer unit 307 to generate a radiation pulse at each pulse repetition interval PRI ′. At this time, the signal processing unit 304 can read arbitrary information from the memory and generate a radiation pulse with the read information. The signal processing unit 304 transmits the generated radiation pulse from the antenna unit 301 via the power supply control unit 308, the transmission unit 309, the amplification unit 310, and the RF filter unit 311.

  In the present embodiment, the signal processing unit 304 reads ID information from the memory by the CPU, and generates a radiation pulse on which the read ID information is placed. That is, in this embodiment, the RFID tag 300 transmits a signal indicating ID information of the RFID tag 300 as a radiation pulse. At this time, for example, the RFID tag 300 transmits a radiation pulse not bearing ID information first, and then transmits a radiation pulse bearing ID information. If the ID information is 12 bits, the RFID tag 300 transmits 12 radiation pulses carrying each bit after the first radiation pulse. The first radiation pulse is transmitted to inform the position of the RFID tag 300, and the signal intensity is set higher than the other radiation pulses. On the other hand, the radiation pulse carrying each bit of the ID information is transmitted to inform the bit value, and the signal strength is set according to the bit value (for example, if the signal strength is 0) Weak or strong, and vice versa). Note that the RFID tag 300 may transmit a plurality of bits on one radiation pulse, or may transmit only a radiation pulse having ID information. Further, the bit value may be represented by other than the signal strength.

  The power supply unit 312 supplies power to each unit.

  FIG. 4 is a diagram illustrating a procedure of radiation pulse generation processing by the RFID tag 300.

In step S101 (reference function parameter determination) and step S102 (range inverse reference function generation) in FIG. 4, the signal processing unit 304 determines the range inverse reference function r (t) based on an appropriate chirp rate k ′ and pulse width τ ′. Create
r (t) = A × [cos {πk ′ (t−τ ′) ² } + i × sin {πk ′ (t−τ ′) ² }} (where 0 ≦ t ≦ τ)
Here, t is time. τ ′ is the pulse width of the radiation pulse. i is an imaginary unit. That is, i = √ (−1). As described above, k ′ is the chirp rate of the radiation pulse. The case of k ′> 0 is called up-chirp (increasing the frequency in a linear function), and the case of k ′ <0 is called down-chirp (increasing the frequency in a linear function). k ′ and τ ′ may be the same as or different from the chirp rate k and pulse width τ of the transmission pulse transmitted by the synthetic aperture radar 200, respectively. In the present embodiment, the RFID tag 300 radiates a radiation pulse at a cycle (pulse repetition interval PRI ′) that is completely different from the cycle of the transmission pulse (pulse repetition interval PRI) transmitted by the synthetic aperture radar 200. Therefore, the radiation pulse radiated from the RFID tag 300 is not clearly displayed on an image obtained by a normal SAR reproduction process described later (the radiation pulse is not subjected to range compression or azimuth compression). That is, by setting PRI ′ ≠ PRI, the radiation pulse is controlled so that the amplitude does not exceed a certain level when the range compression process and the azimuth compression process are executed in the normal SAR reproduction process described later.

  In step S103 (transmission information generation), the signal processing unit 304 reads ID information to be transmitted (or arbitrary information including position information and other information as will be described later) from the memory, and if necessary, CPU To perform a conversion process to obtain a bit string (transmission time-series data).

  In step S104 (Fourier transform), the signal processing unit 304 Fourier transforms r (t) created in step S102 by the CPU. Here, a result of Fourier transform of r (t) is denoted as R (f).

  In step S105 (Fourier transform), the signal processing unit 304 performs Fourier transform on the bit string of the ID information obtained in step S103 by the CPU. Here, the bit string of the ID information is denoted as x (t). A result of Fourier transform of x (t) is denoted as X (f).

In step S106 (multiplication), the signal processing unit 304 multiplies X (f) obtained in step S105 by R (f) obtained in step S104 by the CPU. Here, as described below, X (f) multiplied by R (f) is denoted as Y (f).
Y (f) = X (f) × R (f)

  In step S107 (inverse Fourier transform), the signal processing unit 304 performs inverse Fourier transform on Y (f) obtained in step S106 by the CPU. Here, Y (f) obtained by inverse Fourier transform is denoted as y (t).

  After step S107, the signal processing unit 304 transmits y (t) to the transmission unit 309, performs baseband conversion (converts the center frequency to a value receivable by the synthetic aperture radar 200), and the synthetic aperture radar. Radiate to 200.

  The signal processing unit 304 repeatedly performs the above-described radiation pulse generation process at regular intervals. This interval is the pulse repetition interval PRI '. As described above, the pulse repetition interval PRI ′ does not coincide with the pulse repetition interval PRI of the synthetic aperture radar 200.

  Next, the synthetic aperture radar image processing facility 400 will be described.

  The synthetic aperture radar image processing facility 400 is installed on the ground and includes an image processing device 401. Synthetic aperture radar image processing equipment 400 may be installed on a flying object on which synthetic aperture radar 200 is mounted.

  FIG. 5 is a block diagram illustrating a configuration of the image processing apparatus 401.

  5, the image processing apparatus 401 includes a signal acquisition unit 402, an information acquisition unit 403, an image reproduction unit 404, and an image processing unit 405. The operation of each part will be described later.

  The image processing apparatus 401 includes hardware such as a processing apparatus 411, a storage apparatus 412, an input apparatus 413, and an output apparatus 414. Hardware is used by each unit of the image processing apparatus 401. For example, the processing device 411 is used for performing calculation, processing, reading, writing, and the like of data and information in each unit of the image processing device 401. The storage device 412 is used for storing the data and information. The input device 413 is used to input the data and information, and the output device 414 is used to output the data and information.

  FIG. 6 is a diagram illustrating an example of a hardware configuration of the image processing apparatus 401.

  In FIG. 6, an image processing apparatus 401 is a computer, and includes an LCD 901 (Liquid / Crystal / Display), a keyboard 902 (K / B), a mouse 903, an FDD 904 (Flexible / Disk / Drive), and a CDD 905 (Compact / Disc / Drive). ) And a hardware device such as a printer 906. These hardware devices are connected by cables and signal lines. Instead of the LCD 901, a CRT (Cathode / Ray / Tube) or other display device may be used. Instead of the mouse 903, a touch panel, a touch pad, a trackball, a pen tablet, or other pointing devices may be used.

  The image processing apparatus 401 includes a CPU 911 that executes a program. The CPU 911 is an example of the processing device 411. The CPU 911 includes a ROM 913 (Read / Only / Memory), a RAM 914 (Random / Access / Memory), a communication board 915, an LCD 901, a keyboard 902, a mouse 903, an FDD 904, a CDD 905, a printer 906, and an HDD 920 (Hard / Disk) via a bus 912. Connected with Drive) to control these hardware devices. Instead of the HDD 920, a flash memory, an optical disk device, a memory card reader / writer, or other storage medium may be used.

  The RAM 914 is an example of a volatile memory. The ROM 913, the FDD 904, the CDD 905, and the HDD 920 are examples of nonvolatile memories. These are examples of the storage device 412. The communication board 915, the keyboard 902, the mouse 903, the FDD 904, and the CDD 905 are examples of the input device 413. The communication board 915, the LCD 901, and the printer 906 are examples of the output device 414.

  The communication board 915 is connected to a LAN (Local / Area / Network) or the like. The communication board 915 is not limited to a LAN, but is an IP-VPN (Internet, Protocol, Private, Network), a wide area LAN, an ATM (Asynchronous / Transfer / Mode) network, or a WAN (Wide / Area / Network) It does not matter if it is connected to. LAN, WAN, and the Internet are examples of networks.

  The HDD 920 stores an operating system 921 (OS), a window system 922, a program group 923, and a file group 924. The programs in the program group 923 are executed by the CPU 911, the operating system 921, and the window system 922. The program group 923 includes programs that execute the functions described as “˜units” in the description of the present embodiment. The program is read and executed by the CPU 911. The file group 924 includes data, information, and signal values described as “˜data”, “˜information”, “˜ID (identifier)”, “˜flag”, and “˜result” in the description of this embodiment. And variable values and parameters are included as items of “˜file”, “˜database”, and “˜table”. The “˜file”, “˜database”, and “˜table” are stored in a storage medium such as the RAM 914 or the HDD 920. Data, information, signal values, variable values, and parameters stored in a storage medium such as the RAM 914 and the HDD 920 are read out to the main memory and the cache memory by the CPU 911 via a read / write circuit, and extracted, searched, referenced, compared, and calculated. It is used for processing (operation) of the CPU 911 such as calculation, control, output, printing and display. During the processing of the CPU 911 such as extraction, search, reference, comparison, calculation, calculation, control, output, printing, and display, data, information, signal values, variable values, and parameters are temporarily stored in the main memory, cache memory, and buffer memory. Remembered.

  The arrows in the block diagrams and flowcharts used in the description of this embodiment mainly indicate input / output of data and signals. Data and signals are recorded in memory such as RAM 914, FDD904 flexible disk (FD), CDD905 compact disk (CD), HDD920 magnetic disk, optical disk, DVD (Digital Versatile Disc), or other recording media Is done. Data and signals are transmitted by a bus 912, a signal line, a cable, or other transmission media.

  In the description of the present embodiment, what is described as “to part” may be “to circuit”, “to device”, “to device”, and “to step”, “to process”, “to”. ~ Procedure "," ~ process ". That is, what is described as “˜unit” may be realized by firmware stored in the ROM 913. Alternatively, what is described as “˜unit” may be realized only by software, or only by hardware such as an element, a device, a board, and wiring. Alternatively, what is described as “to part” may be realized by a combination of software and hardware, or a combination of software, hardware and firmware. Firmware and software are stored as programs in a recording medium such as a flexible disk, a compact disk, a magnetic disk, an optical disk, and a DVD. The program is read by the CPU 911 and executed by the CPU 911. That is, the program causes the computer to function as “to part” described in the description of the present embodiment. Or a program makes a computer perform the procedure and method of "-part" described by description of this Embodiment.

  FIG. 7 is a flowchart showing the operation of the image processing apparatus 401 (the image processing method according to the present embodiment and the processing procedure of the image processing program according to the present embodiment). Note that the operation of the image processing apparatus 401 may be executed as offline batch processing or real-time processing.

  In step S201 (signal acquisition processing) in FIG. 7, the signal acquisition unit 402 acquires the synthetic aperture radar observation data (reception signal) output from the synthetic aperture radar 200 from the synthetic aperture radar 200 and stores it in the storage device 412. To do. Here, when the flying object on which the synthetic aperture radar 200 is mounted is an artificial satellite, the signal acquisition unit 402 directly receives the synthetic aperture radar observation data transmitted from the artificial satellite to the synthetic aperture radar image processing facility 400. When the flying object on which the synthetic aperture radar 200 is mounted is an aircraft, the signal acquisition unit 402 reads the synthetic aperture radar observation data from the data recorder conveyed to the synthetic aperture radar image processing facility 400.

  In step S202 (information acquisition processing), the information acquisition unit 403 receives (acquires) information such as position information transmitted from the RFID tag 300 via the router 322 via the network via the network, and stores the information. 412 is stored. At this time, the information acquisition unit 403 acquires the ID information of the RFID tag 300 by receiving the ID information of the RFID tag 300 together with the position information from the RFID tag 300, for example, and uses the acquired position information of the RFID tag 300. The information is stored in the storage device 412 in association with the ID information.

  In step S <b> 203 (image reproduction processing), the image reproduction unit 404 reads the synthetic aperture radar observation data acquired by the signal acquisition unit 402 from the storage device 412. The image reproduction unit 404 reproduces a ground radar image by executing a normal SAR reproduction process described later on the read synthetic aperture radar observation data by the processing device 411.

  In step S <b> 204 (image processing), the image processing unit 405 reads the synthetic aperture radar observation data acquired by the signal acquisition unit 402 from the storage device 412. The image processing unit 405 performs SAR reproduction processing for tag information extraction described later on the read synthetic aperture radar observation data by the processing device 411, and the RFID tag in the radar image reproduced by the image reproduction unit 404 300 relative positions are specified. At this time, the image processing unit 405 acquires ID information of the RFID tag 300 as a result of the tag information extraction, and reads position information corresponding to the acquired ID information from the storage device 412. The image processing unit 405 corrects the radar image reproduced by the image reproduction unit 404 by the processing device 411 based on the relative position of the identified RFID tag 300 and the geographical position indicated by the read position information.

  FIG. 8 is a diagram illustrating a procedure of normal SAR reproduction processing and SAR reproduction processing for tag information extraction performed by the image processing apparatus 401.

  First, the range compression process in the normal SAR reproduction process will be described.

  In step S301 (data rearrangement for each PRI) in FIG. 8, the image reproduction unit 404 rearranges the synthetic aperture radar observation data acquired by the signal acquisition unit 402 in the azimuth direction (vertical) for each pulse repetition interval PRI.

As shown in FIG. 9, when synthetic aperture radar 200 transmits a transmission pulse at every pulse repetition interval PRI, the transmission pulse is backscattered on the ground surface and returns to synthetic aperture radar 200. Synthetic aperture radar 200 receives this as a received signal. As shown in FIG. 10, the synthetic aperture radar 200 receives a reception signal at each pulse repetition interval PRI. Here, the reception signals received by the synthetic aperture radar 200 are referred to as reception signal 1, reception signal 2,..., Reception signal M in order at each pulse repetition interval PRI. In step S301, the image reproduction unit 404 extracts received signals from the synthetic aperture radar observation data, and arranges them for each PRI in the azimuth direction as shown in FIG. 10 (stores them in the storage device 412). As a result, the received signal 1, the received signal 2,..., The received signal M are arranged in order in the azimuth direction, and two-dimensional data with the number of data N × M is obtained as shown in FIG. Remembered). Here, N = PRI / T _CLK . T _CLK is a clock period of A / D (analog / digital) conversion in the synthetic aperture radar 200.

  The image reproduction unit 404 performs the range compression process of steps S302 to S306 for each of the M pieces of data (received signal 1, received signal 2,..., Received signal M) of the two-dimensional data obtained in this way. Executed to obtain M range-compressed data. Then, the image reproduction unit 404 performs the azimuth compression processing in steps S307 to S311 on the M consecutive data subjected to the range compression, and as a result, a reproduction image is obtained.

In step S302 (range reference function generation), the image reproduction unit 404 creates the following range reference function by the processing device 411.
r (t) = A × [cos {πk (t−τ) ² } + i × sin {πk (t−τ) ² }] (where 0 ≦ t ≦ τ)
Here, as described above, k is the chirp rate of the transmission pulse, and τ is the pulse width of the transmission pulse. Others are the same as described above.

  In step S303 (Fourier transform, complex conjugate), the image reproduction unit 404 performs Fourier transform on r (t) created in step S302 by the processing device 411 to create R (f).

  In step S304 (Fourier transform in the range direction), the image reproduction unit 404 performs Fourier transform on the data x (t, s) obtained in step S301 in the range direction by the processing device 411 to obtain X (f, s). . Here, t is a time variable in the range direction (radio wave transmission direction of the synthetic aperture radar 200), and s is a time variable in the azimuth direction (advancing direction of the synthetic aperture radar 200).

In step S305 (multiplication), the image reproduction unit 404 multiplies X (f, s) obtained in step S304 by the complex conjugate of R (f) obtained in step S303 by the processing device 411 as follows. Let Y (f, s).
Y (f, s) = X (f, s) x R (f) * (* is a complex conjugate)

  In step S306 (inverse Fourier transform in the range direction), the image reproduction unit 404 performs inverse Fourier transform on Y (f, s) obtained in step S305 in the range direction by the processing device 411, and the first observation signal y (t, s).

  Next, azimuth compression processing in normal SAR reproduction processing will be described.

  In step S307 (azimuth reference function generation), the image reproduction unit 404 creates the azimuth reference function u (s) by the processing device 411. The formula is omitted.

  In step S308 (Fourier transform, complex conjugate), the image reproduction unit 404 performs Fourier transform on u (s) created in step S307 by the processing device 411 to create U (f).

  In step S309 (Fourier transformation in the azimuth direction), the image reproduction unit 404 performs Fourier transformation in the azimuth direction by the processing device 411 on the first observation signal y (t, s) obtained in step S306, and V (t, f). And

In step S310 (multiplication), the image reproduction unit 404 multiplies V (t, f) obtained in step S309 by the complex conjugate of U (f) obtained in step S308 by the processing device 411 as follows. Let W (t, f).
W (t, f) = V (t, f) × U (f) * (* is a complex conjugate)

  In step S311 (inverse Fourier transform in the azimuth direction), the image reproduction unit 404 performs inverse Fourier transform in the azimuth direction on W (t, f) obtained in step S310 to obtain w (t, s). . This is a normal playback image.

  As shown in FIG. 12, the RFID tag 300 transmits a radiation pulse at a period (pulse repetition interval PRI ') different from the period (pulse repetition interval PRI) at which the synthetic aperture radar 200 transmits a transmission pulse. The synthetic aperture radar 200 receives the radiation pulse as a part of the reception signal, but cannot receive the radiation pulse in a period that is not the reception timing (that is, the transmission timing). Therefore, a part of the radiation pulse is lost in the synthetic aperture radar 200. As shown in FIG. 13, the synthetic aperture radar 200 receives only a part of the radiation pulse at each pulse repetition interval PRI. Here, the received signals received by the synthetic aperture radar 200 are sequentially received signal 1, received signal 2,..., Received signal M ′ at every pulse repetition interval PRI ′ (however, some of them are missing) ) In step S301, the image reproduction unit 404 extracts received signals from the synthetic aperture radar observation data, and arranges them for each PRI in the azimuth direction as shown in FIG. 13 (stores them in the storage device 412). As a result, a part of the received signal 1, another part of the received signal 1, another part of the received signal 1 and a part of the received signal 2 are sequentially arranged in the azimuth direction. Line number and pulse number of radiation pulse are not synchronized. Therefore, the radiation pulse of the RFID tag 300 is regarded as simple noise as it is, and neither the range compression nor the azimuth compression is performed in the normal SAR reproduction processing.

On the other hand, in step S401 of the SAR reproduction process for extracting tag information to be described next, the image processing unit 405 extracts the received signal from the synthetic aperture radar observation data, and PRI in the azimuth direction as shown in FIG. Are arranged (stored in the storage device 412). As a result, the reception signal 1, the reception signal 2,..., The reception signal M ′ are sequentially arranged in the azimuth direction, and the line number in the azimuth direction and the pulse number of the radiation pulse are synchronized. Then, as shown in FIG. 15, two-dimensional data with the number of data N ′ × M ′ is obtained (stored in the storage device 412). Here, N ′ = PRI ′ / T _CLK . T _CLK is a clock period of A / D conversion in the synthetic aperture radar 200 as described above. When range compression and azimuth compression are performed in this state, information (bit string) of the RFID tag 300 is reproduced as an image. On the contrary, since the normal observation signal is a signal transmitted / received at the period PRI, it is a discontinuous signal when rearranged for each PRI ′, and neither the range compression nor the azimuth compression is performed. The reception signal 1, the reception signal 2,..., And the reception signal M ′ are partially missing, but only the pulse width (range resolution) after range compression is deteriorated, and the effect thereof is not big. In order to suppress the range resolution, it is desirable that PRI ′ is longer than PRI.

  Next, the range compression process in the SAR reproduction process for extracting tag information will be described.

  In step S401 (data rearrangement for each PRI ′) in FIG. 8, as described above, the image processing unit 405 uses the synthetic aperture radar observation data acquired by the signal acquisition unit 402 in the azimuth direction for each pulse repetition interval PRI ′. Rearrange (vertically) to obtain the above two-dimensional data. The image processing unit 405 executes the range compression processing of steps S402 to S406 for each of the M ′ data (received signal 1, received signal 2,..., Received signal M ′) of the two-dimensional data, Obtain M ′ pieces of compressed data. Then, the image processing unit 405 performs the azimuth compression processing of steps S407 to S411 on the M ′ continuous data subjected to the range compression, and as a result, a reproduced image is obtained.

In step S402 (range reference function generation), the image processing unit 405 creates the following range reference function by the processing device 411.
r ′ (t) = A × [cos {πk ′ (t−τ) ² } + i × sin {πk ′ (t−τ) ² }} (where 0 ≦ t ≦ τ)
Here, as described above, k ′ is the chirp rate of the radiation pulse of the RFID tag 300, which is known or is obtained from the chirp rate k of the transmission pulse of the synthetic aperture radar 200 by a known calculation method. And τ ′ is the pulse width of the radiation pulse, and is known or is obtained from the pulse width τ of the transmission pulse of the synthetic aperture radar 200 by a known calculation method. Others are the same as described above.

  In step S403 (Fourier transform, complex conjugate), the image processing unit 405 performs Fourier transform on r ′ (t) created in step S402 by the processing device 411 to create R ′ (f).

  In step S <b> 404 (Fourier transform in the range direction), the image processing unit 405 performs Fourier transform on the synthetic aperture radar observation data x (t, s) acquired by the signal acquisition unit 402 in the range direction by the processing device 411, and X ( f, s). Here, as described above, t is a time variable in the range direction (radio wave transmission direction of the synthetic aperture radar 200), and s is a time variable in the azimuth direction (advancing direction of the synthetic aperture radar 200).

In step S405 (multiplication), the image processing unit 405 multiplies X (f, s) obtained in step S404 by the complex conjugate of R ′ (f) obtained in step S403 by the processing device 411 as follows. , Y ′ (f, s).
Y ′ (f, s) = X (f, s) × R ′ (f) * (* is a complex conjugate)

  In step S406 (inverse Fourier transform in the range direction), the image processing unit 405 performs inverse Fourier transform in the range direction on Y ′ (f, s) obtained in step S405 by the processing device 411, and obtains the second observation signal y ′ ( t, s).

  Next, the azimuth compression process in the SAR reproduction process for extracting tag information will be described.

  In steps S407 to S411, the image processing unit 405 performs the same processing as the normal azimuth compression processing in steps S307 to S311 by the processing device 411 to obtain w ′ (t, s). This is a reproduced image from which tag information has been extracted.

  Thus, in the present embodiment, when normal SAR reproduction processing (range compression, azimuth compression) is performed, the reflected wave from the ground surface is imaged, but the radiation pulse from the RFID tag 300 is subjected to range compression. Neither azimuth compression nor pulse compression (the S / N ratio does not improve) results in a broad and dark noise state. In addition, by performing the SAR reproduction process considering that the pulse repetition interval of the RFID tag 300 is PRI 'instead of PRI, the radiation pulse from the RFID tag 300 is pulse-compressed (the S / N ratio is improved). This time, the reflected wave from the ground surface becomes a dark noise state having a spread without being pulse-compressed.

  As described above, the image reproduction unit 404 uses the same chirp as that of the synthetic aperture radar 200 for the synthetic aperture radar observation data (received signal) acquired by the signal acquisition unit 402 at the same pulse repetition interval PRI as that of the synthetic aperture radar 200. The first observation signal y (t, s) is generated by performing range compression at a rate k. The image reproducing unit 404 performs azimuth compression on the first observation signal y (t, s), which is the range-compressed received signal, to generate a first compressed signal w (t, s). The image reproduction unit 404 reproduces a ground radar image (an image in which the RFID tag 300 is not reflected) from the generated first compressed signal w (t, s). On the other hand, the image processing unit 405 uses the RFID tag for the synthetic aperture radar observation data (received signal) acquired by the signal acquisition unit 402 for each pulse repetition interval PRI ′ that is the same as the RFID tag 300 but different from the synthetic aperture radar 200. The second observation signal y ′ (t, s) is generated by performing range compression at the same or different chirp rate k ′ as that of the synthetic aperture radar 200 as in 300. The image processing unit 405 generates a second compressed signal w ′ (t, s) by azimuth compressing the second observation signal y ′ (t, s), which is a range-compressed received signal. The image processing unit 405 reproduces an image showing the RFID tag 300 from the generated second compressed signal w ′ (t, s).

  In the present embodiment, the RFID tag 300 does not need to receive the transmission pulse from the synthetic aperture radar 200 and analyze the characteristics thereof, and therefore can be mounted at low cost. In addition, there is an effect of reducing power consumption.

  Step S412 (association with a normal reproduction image) will be described later.

  FIG. 16 is a diagram illustrating an example of a result of SAR reproduction processing for tag information extraction (a reproduced image from which tag information is extracted), that is, a tag information extraction result.

  As shown in FIG. 16, the radiation pulse from the RFID tag 300 appears as a bright spot in the image obtained in step S411 of FIG. In the image shown in FIG. 16, as in the example described above, the RFID tag 300 transmits a radiation pulse not bearing ID information first, and then transmits a radiation pulse bearing 12-bit ID information. Is the case. Therefore, the leftmost bright spot indicates the position of the RFID tag 300 (relative position in the radar image). In step S204 of FIG. 7, the image processing unit 405 of the image processing apparatus 401 displays the image in which the radiation pulse from the RFID tag 300 is reflected as a bright spot in this manner on the ground reproduced by the image reproduction unit 404 in step S203. Overlay (compare) with the radar image (image obtained in step S311 in FIG. 8), which pixel (or pixel group) in the ground radar image is the point where the RFID tag 300 is installed (relative in the radar image) Position). At this time, the image processing unit 405 executes the process of step S412 of FIG. Details of the processing will be described later. Also, the image processing unit 405 reads the ID information of the RFID tag 300 represented on the image as shown in FIG. 16 (for example, the bit value can be determined by the luminance), and the RFID tag 300 identified by the read ID information. Are extracted from the storage device 412. The image processing unit 405 refers to the extracted position information to determine which position in the geographical area the pixel (or pixel group) corresponding to the point where the RFID tag 300 is installed corresponds to the ground radar image. Then, the radar image on the ground is corrected according to the determination result (for example, adding latitude / longitude information to the radar image).

  In step S412 of FIG. 8 (association with a normal reproduction image), the image processing unit 405 starts the point sequence in the image (hereinafter referred to as tag reproduction image) obtained in step S411 in which the RFID tag 300 is shown. However, the following calculation is performed as to where the radar image on the ground (hereinafter referred to as a normal reproduction image) obtained by the image reproduction unit 404 in step S311 corresponds. FIG. 17 shows an example of a tag reproduction image (right side) and a normal reproduction image (left side).

In the tag reproduction image (right side in FIG. 17), the head position (pixel number of the bright spot corresponding to the first received signal) in the point sequence of the radiation pulse of the RFID tag 300 is (i ′, j ′). . Here, 0 ≦ i ′ ≦ N′−1 and 0 ≦ j ′ ≦ M′−1. Assume that the upper left corner of the image is (0, 0) and the lower right corner is (N'-1, M'-1). On the other hand, a corresponding position (pixel number) in a normal reproduction image (left side in FIG. 17) is defined as (i, j). Here, 0 ≦ i ≦ N−1 and 0 ≦ j ≦ M−1. In both images, the signal (radiation pulse) emitted from the RFID tag 300 should have been received by the synthetic aperture radar 200 at the same time. In addition, since both images are based on the same clock signal period _TCLK , the number of pixels counted from the upper left corner (observation head) to the position of the RFID tag 300 is the same in both images. Therefore,
i ′ + j ′ × N ′ = i + j × N
It becomes.

(I ′, j ′) can be read from the tag reproduction image. i is the remainder of dividing the left side of the above equation by N. j is a value obtained by rounding down the value obtained by dividing the left side of the above expression by N. That is, the image processing unit 405
i = mod ((i ′ + j ′ × N ′) / N) (mod (a / b) means a remainder obtained by dividing a by b)
j = [(i ′ + j ′ × N ′) / N] ([x] means the maximum x not exceeding the real number x, that is, truncation)
(I, j) can be obtained as follows.

  As described above, in the present embodiment, the RFID tag 300 performs a radiation pulse generation process. The generated radiation pulse includes ID information (identifier). The chirp rate and pulse width different from those of the synthetic aperture radar 200 are used (or the same chirp rate and pulse width may be used) so that the radiation pulse is not imaged in the normal SAR reproduction process, and the period different from that of the synthetic aperture radar 200. Sent by. The RFID tag 300 emits a radiation pulse toward the synthetic aperture radar 200. Synthetic aperture radar 200 receives the radiation pulse of RFID tag 300. The SAR observation data is transmitted to the synthetic aperture radar image processing facility 400 (ground facility). In addition to the backscattered radio waves from the ground surface, radiation pulses transmitted from the RFID tag 300 are superimposed (added) on the SAR observation data. In the synthetic aperture radar image processing facility 400, (1) normal SAR reproduction processing, and (2) image processing (chirp rate, pulse width, etc.) for restoring the radiation pulse transmitted from the RFID tag 300 (returning to the original bit string) SAR regeneration processing considering that the period of the radiation pulse is different from that of the synthetic aperture radar 200 is performed. In the image generated by the above (1), information of the RFID tag 300 (a bit string identifying each RFID tag 300, that is, ID information, etc.) is not reflected (exactly, a wide range of the image as weak noise). To spread). On the other hand, the information (bit string) of the RFID tag 300 is displayed in the image generated by (2) above, but the image showing the ground surface is not reflected (exactly, it spreads over a wide range as weak noise). ing). By reading the point sequence (corresponding to a bit sequence representing ID information) on the image of (2) above, the RFID tag 300 that is the source of the point sequence can be specified. Thus, according to the present embodiment, it is possible to easily detect a specific position from the reproduced image of the synthetic aperture radar 200 using the RFID tag 300 that actively radiates radio waves. This makes it possible to perform highly accurate geometric correction on the SAR image. Further, since the RFID tag 300 does not need to be synchronized with the synthetic aperture radar 200, a system can be constructed at a low cost.

  Conventional ARC (Active / Radar / Calibrator) was only shown as “one point” on the SAR image. In this embodiment, on the RFID tag 300 side, information (bit string) to be transmitted from the RFID tag 300 is subjected to reverse range compression processing (steps S104 to S107 in FIG. 4) to generate a radiation pulse. Transmit from tag 300. As a result, the radiation pulse from the RFID tag 300 is imaged as a “bit string”, not just as “one point”. That is, according to the present embodiment, meaningful information can be transmitted from the RFID tag 300.

  Further, the conventional ARC appears as a small bright spot on the SAR image. In the present embodiment, the RFID tag 300 transmits a radiation pulse at a different period from the transmission pulse of the synthetic aperture radar 200. Thereby, in the normal SAR reproduction process, the radiation pulse from the RFID tag 300 is not subjected to range compression or azimuth compression. By performing such processing, in this embodiment, the RFID tag 300 can be prevented from being displayed on the SAR image.

Embodiment 2. FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  In the present embodiment, the signal processing unit 304 of the RFID tag 300 reads position information from the memory in addition to the ID information by the CPU, and generates a radiation pulse with the read position information. That is, in the present embodiment, the RFID tag 300 transmits a signal indicating position information of the RFID tag 300 as a radiation pulse. Therefore, the signal processing unit 304 may not transmit the position information stored in the memory to the synthetic aperture radar image processing facility 400 via the network interface unit 306 and the router 322.

  The operation of the image processing apparatus 401 according to this embodiment will be described with reference to FIG.

  Steps S201, S203, and S204 in FIG. 7 are the same as those in the first embodiment. Step S202 is executed after the SAR reproduction process for extracting tag information is executed in step S204.

  In step S <b> 202 (information acquisition process), the information acquisition unit 403 extracts (acquires) position information of the RFID tag 300 from the second compressed signal generated by the image processing unit 405 and stores it in the storage device 412. Specifically, the information acquisition unit 403, like the ID information in the image of FIG. 16, displays the RFID tag 300 represented on the image (image showing the RFID tag 300) obtained in step S411 of FIG. The position information is read (for example, the bit value of the position information can be determined based on the luminance) and stored in the storage device 412. At this time, the information acquisition unit 403 corresponds to the acquired positional information with the ID information of the RFID tag 300 acquired as a result of the tag information extraction by the image processing unit 405 (that is, also extracted from the second compressed signal). In addition, it is stored in the storage device 412.

  As described above, in the present embodiment, the RFID tag 300 includes the GPS receiver 302, and the position information obtained by the GPS receiver 302 along with the ID information is also put on the radiation pulse and transmitted to the synthetic aperture radar 200. To do. That is, the radiation pulse generated by the radiation pulse generation process by the RFID tag 300 includes position information in addition to the ID information. Thereby, the position information of the RFID tag 300 can be specified by the synthetic aperture radar image processing facility 400.

Embodiment 3 FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  In the present embodiment, the RFID tag 300 is attached to the electronic reference point. The electronic reference point observes the position based on the GPS signal (positioning signal) from the GPS satellite group 101. As the electronic reference point, for example, GPS continuous observation points installed at about 1200 locations throughout Japan managed by the Geographical Survey Institute can be used.

  For example, the electronic reference point includes a GPS receiver and a router. The electronic reference point receives a GPS signal from the GPS satellite group 101 by a GPS receiver and observes the position based on the GPS signal. Then, the electronic reference point transmits position information indicating the position observation result to the synthetic aperture radar image processing facility 400 via the electronic reference point network (network) by the router as the position information of the RFID tag 300. Therefore, the RFID tag 300 does not have to include the GPS receiver 302 or the router. The electronic reference point may transmit / receive arbitrary information to / from the RFID tag 300 and transfer the information received from the RFID tag 300 to the synthetic aperture radar image processing facility 400.

  The operation of the image processing apparatus 401 according to this embodiment will be described with reference to FIG.

  Steps S201, S203, and S204 in FIG. 7 are the same as those in the first embodiment. Step S202 is executed after the SAR reproduction process for extracting tag information is executed in step S204.

  In step S202 (information acquisition processing), the information acquisition unit 403 transmits information such as position information transmitted from the electronic reference point to which the RFID tag 300 is attached via the electronic reference point network via the router. Is received (acquired) and stored in the storage device 412. At this time, the information acquisition unit 403 acquires the ID information of the RFID tag 300, for example, by receiving the ID information of the RFID tag 300 together with the position information from the electronic reference point, and the acquired position information is stored in the RFID tag 300. The information is stored in the storage device 412 in association with the ID information.

  As described above, in the present embodiment, the RFID tag 300 is installed in the vicinity of the electronic reference point instead of including the GPS receiver 302. Since the position information of each electronic reference point is published online by the Geospatial Information Authority of Japan, the position information of the RFID tag 300 can be obtained from the synthetic aperture radar image processing equipment by collating the electronic reference point number with the ID information of each RFID tag 300. 400 can be specified.

Embodiment 4 FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  In this embodiment, the RFID tag 300 includes an environmental sensor as the external device 321. The environmental sensor observes, for example, temperature, atmospheric pressure, humidity, and weather as the surrounding environment. For example, observation points of the Japan Meteorological Agency Regional Observation System (AMeDAS: Automated, Meteorological, Data, Acquisition, System) can be used for observing the weather.

  The signal processing unit 304 of the RFID tag 300 acquires an observation value from the environment sensor via the external device interface unit 305, and stores the acquired observation value in a memory as environment information. The signal processing unit 304 reads environmental information from the memory in addition to the ID information by the CPU, and generates a radiation pulse on which the read environmental information is placed. That is, in the present embodiment, the RFID tag 300 transmits a signal indicating the observation result of the environmental sensor as environmental information as a radiation pulse.

  The operation of the image processing apparatus 401 according to this embodiment will be described with reference to FIG.

  Steps S201 to S203 in FIG. 7 are the same as those in the first embodiment.

  In step S <b> 204 (image processing), the image processing unit 405 reads the synthetic aperture radar observation data acquired by the signal acquisition unit 402 from the storage device 412. The image processing unit 405 executes SAR reproduction processing for tag information extraction on the read synthetic aperture radar observation data by the processing device 411 as in the first embodiment, and is reproduced by the image reproduction unit 404. The relative position of the RFID tag 300 in the radar image is specified. At this time, the image processing unit 405 acquires the ID information of the RFID tag 300 as a result of the tag information extraction and also acquires the environment information described above (that is, extracts the ID information and the environment information from the second compressed signal). . The image processing unit 405 reads position information corresponding to the acquired ID information from the storage device 412. The image processing unit 405 corrects the radar image reproduced by the image reproduction unit 404 by the processing device 411 based on the relative position of the identified RFID tag 300 and the geographical position indicated by the read position information. Then, the image processing unit 405 further processes the radar image based on the acquired environment information. For example, if the environment sensor included in the RFID tag 300 observes weather, the image processing unit 405 acquires the weather observation value as the environment information, so that the RFID tag 300 is installed in the ground radar image. It is possible to generate an image in which weather maps around a certain point are superimposed.

  As described above, in the present embodiment, the radiation pulse generated by the radiation pulse generation process by the RFID tag 300 includes the observation values of various attached sensors (external device 321) such as temperature and weather in addition to the ID information. included. Thereby, additional information such as temperature and weather can be mapped to the SAR image by the synthetic aperture radar image processing facility 400.

  As mentioned above, although embodiment of this invention was described, you may implement combining 2 or more embodiment among these. Alternatively, one of these embodiments may be partially implemented. Or you may implement combining two or more embodiment among these partially.

  DESCRIPTION OF SYMBOLS 100 Image processing system, 101 GPS satellite group, 200 Synthetic aperture radar, 201 Synthetic aperture radar antenna, 300 RFID tag, 301 Antenna part, 302 GPS receiver, 303 ID setting part, 304 Signal processing part, 305 External apparatus interface part, 306 Network interface unit, 307 Timer unit, 308 Power supply control unit, 309 Transmission unit, 310 Amplification unit, 311 RF filter unit, 312 Power supply unit, 321 External device, 322 Router, 400 Synthetic aperture radar image processing equipment, 401 Image processing device 402, signal acquisition unit, 403 information acquisition unit, 404 image reproduction unit, 405 image processing unit, 411 processing device, 412 storage device, 413 input device, 414 output device, 901 LCD, 902 keyboard, 903 mouse, 9 04 FDD, 905 CDD, 906 printer, 911 CPU, 912 bus, 913 ROM, 914 RAM, 915 communication board, 920 HDD, 921 operating system, 922 window system, 923 program group, 924 file group.

Claims (16)

A radar mounted on an air vehicle, which generates a chirp-modulated first pulse signal for each predetermined pulse repetition interval PRI and transmits it to the ground, and receives a signal obtained by reflecting the transmitted first pulse signal on the ground as a received signal. A signal acquisition unit that acquires the received signal from a radar that receives as:
A wireless communication apparatus installed on the ground, which generates and transmits a chirp-modulated second pulse signal for each pulse repetition interval PRI ′ different from the pulse repetition interval PRI ′ of the first pulse signal transmitted by the radar. An information acquisition unit that acquires position information indicating a geographical position of a wireless communication device that causes the radar to receive the transmitted second pulse signal as part of the received signal;
The received signal acquired by the signal acquisition unit is range-compressed for each pulse repetition interval PRI, the range-compressed received signal is azimuth-compressed to generate a first compressed signal, and the ground radar image is generated from the generated first compressed signal. An image reproducing unit for reproducing the image by a processing device;
The received signal acquired by the signal acquisition unit is range-compressed at each pulse repetition interval PRI ′, the range-compressed received signal is azimuth-compressed to generate a second compressed signal, and the image is generated from the generated second compressed signal. The relative position of the wireless communication device in the radar image reproduced by the reproduction unit is specified, and the image reproduction unit is based on the specified relative position and the geographical position indicated by the position information acquired by the information acquisition unit An image processing device comprising: an image processing unit that corrects the radar image reproduced by the processing device.   The image processing apparatus according to claim 1, wherein PRI ′> PRI. The radar transmits a signal chirp-modulated at a predetermined chirp rate k (−1 ≦ k <0 or 0 <k ≦ 1) as the first pulse signal,
The wireless communication apparatus performs a chirp modulation on a signal obtained by chirp modulation at a chirp rate k ′ (−1 ≦ k ′ <0 or 0 <k ′ ≦ 1) different from the chirp rate k of the first pulse signal transmitted by the radar. Send it as a two-pulse signal,
The image reproduction unit performs range compression on the reception signal acquired by the signal acquisition unit at a chirp rate k for each pulse repetition interval PRI, and azimuth compresses the range compressed reception signal to generate the first compressed signal,
The image processing unit performs range compression on the reception signal acquired by the signal acquisition unit at a chirp rate k ′ at each pulse repetition interval PRI ′, and azimuth-compresses the range-compressed reception signal to generate the second compressed signal. The image processing apparatus according to claim 1, wherein the image processing apparatus is an image processing apparatus. The wireless communication device transmits a signal indicating an identifier of the wireless communication device as the second pulse signal,
The information acquisition unit stores the acquired position information in a storage device in association with the identifier of the wireless communication device,
The image processing unit further acquires an identifier of the wireless communication device from the generated second compressed signal, reads position information corresponding to the acquired identifier from the storage device, and the specified relative position and the read position information are The image processing apparatus according to claim 1, wherein the radar image reproduced by the image reproduction unit is corrected based on a geographical position to be indicated. The wireless communication device generates the position information based on a positioning signal from a positioning satellite,
The image processing apparatus according to claim 1, wherein the information acquisition unit acquires position information generated by the wireless communication apparatus. The wireless communication device transmits a signal indicating the position information as the second pulse signal,
The image processing apparatus according to claim 1, wherein the information acquisition unit acquires the position information from a second compressed signal generated by the image processing unit. The wireless communication device includes an environmental sensor for observing the surrounding environment, and transmits a signal indicating the observation result of the environmental sensor as environmental information as the second pulse signal,
The image processing unit further acquires the environment information from the generated second compressed signal, and processes the radar image reproduced by the image reproduction unit based on the acquired environment information. Item 7. The image processing apparatus according to any one of Items 1 to 6. In a wireless communication device installed on the ground,
A radar mounted on an air vehicle, which generates a chirp-modulated first pulse signal for each predetermined pulse repetition interval PRI and transmits it to the ground, and receives a signal obtained by reflecting the transmitted first pulse signal on the ground as a received signal. The second pulse signal subjected to chirp modulation is generated and transmitted for each pulse repetition interval PRI ′ different from the pulse repetition interval PRI of the first pulse signal, and the transmitted second pulse signal is transmitted to the radar receiving as A wireless communication apparatus comprising: a transmitter that causes the radar to receive a part of a received signal. The signal acquisition unit of the image processing apparatus is a radar mounted on an air vehicle, and generates a chirp-modulated first pulse signal for each predetermined pulse repetition interval PRI and transmits it to the ground. Obtains the received signal from a radar that receives a signal reflected on the ground as a received signal,
The information acquisition unit of the image processing device is a wireless communication device installed on the ground, and the second pulse signal subjected to chirp modulation is different from the pulse repetition interval PRI of the first pulse signal transmitted by the radar. Generating and transmitting at every interval PRI ′, obtaining position information indicating a geographical position of a wireless communication device that causes the radar to receive the transmitted second pulse signal as a part of the received signal;
The image reproduction unit of the image processing device performs range compression on the reception signal acquired by the signal acquisition unit at each pulse repetition interval PRI, and generates a first compressed signal by azimuth compressing the range compressed reception signal. The ground radar image is reproduced from the first compressed signal by the processing device,
The image processing unit of the image processing device performs range compression on the reception signal acquired by the signal acquisition unit for each pulse repetition interval PRI ′, and azimuth compresses the range compressed reception signal to generate a second compressed signal, The relative position of the wireless communication device in the radar image reproduced by the image reproduction unit is identified from the generated second compressed signal, and the geographical position indicated by the identified relative position and the position information acquired by the information acquisition unit An image processing method comprising: correcting a radar image reproduced by the image reproduction unit by a processing device based on a position. A radar mounted on an air vehicle, which generates a chirp-modulated first pulse signal for each predetermined pulse repetition interval PRI and transmits it to the ground, and receives a signal obtained by reflecting the transmitted first pulse signal on the ground as a received signal. A signal acquisition process for acquiring the received signal from a radar receiving as
A wireless communication apparatus installed on the ground, which generates and transmits a chirp-modulated second pulse signal for each pulse repetition interval PRI ′ different from the pulse repetition interval PRI ′ of the first pulse signal transmitted by the radar. Information acquisition processing for acquiring position information indicating a geographical position of a wireless communication device that causes the radar to receive the transmitted second pulse signal as a part of the received signal;
The received signal acquired by the signal acquisition process is range-compressed at each pulse repetition interval PRI, the range-compressed received signal is azimuth-compressed to generate a first compressed signal, and the ground radar image is generated from the generated first compressed signal. Image reproduction processing for reproducing the image by a processing device;
The reception signal acquired by the signal acquisition process is range-compressed at each pulse repetition interval PRI ′, the range-compressed reception signal is azimuth-compressed to generate a second compressed signal, and the image is generated from the generated second compressed signal. The relative position of the wireless communication device in the radar image reproduced by the reproduction process is specified, and the image reproduction process is performed based on the specified relative position and the geographical position indicated by the position information acquired by the information acquisition process. An image processing program for causing a computer to execute image processing for correcting a radar image reproduced by the processing device using a processing device.   The image processing program according to claim 10, wherein PRI ′> PRI. The radar transmits a signal chirp-modulated at a predetermined chirp rate k (−1 ≦ k <0 or 0 <k ≦ 1) as the first pulse signal,
The wireless communication apparatus performs a chirp modulation on a signal obtained by chirp modulation at a chirp rate k ′ (−1 ≦ k ′ <0 or 0 <k ′ ≦ 1) different from the chirp rate k of the first pulse signal transmitted by the radar. Send it as a two-pulse signal,
In the image reproduction process, the reception signal acquired by the signal acquisition process is range-compressed at a chirp rate k for each pulse repetition interval PRI, the range-compressed reception signal is azimuth-compressed to generate the first compressed signal,
In the image processing, the reception signal acquired by the signal acquisition processing is range-compressed at a chirp rate k ′ at each pulse repetition interval PRI ′, and the range-compressed reception signal is azimuth-compressed to generate the second compressed signal. The image processing program according to claim 10 or 11, characterized in that The wireless communication device transmits a signal indicating an identifier of the wireless communication device as the second pulse signal,
The information acquisition process stores the acquired position information in a storage device in association with the identifier of the wireless communication device,
The image processing further acquires an identifier of the wireless communication device from the generated second compressed signal, reads position information corresponding to the acquired identifier from the storage device, and indicates the specified relative position and the read position information. The image processing program according to any one of claims 10 to 12, wherein the radar image reproduced by the image reproduction process is corrected based on a geographical position. The wireless communication device generates the position information based on a positioning signal from a positioning satellite,
The image processing program according to claim 10, wherein the information acquisition process acquires position information generated by the wireless communication device. The wireless communication device transmits a signal indicating the position information as the second pulse signal,
15. The image processing program according to claim 10, wherein the information acquisition process acquires the position information from a second compressed signal generated by the image processing. The wireless communication device includes an environmental sensor for observing the surrounding environment, and transmits a signal indicating the observation result of the environmental sensor as environmental information as the second pulse signal,
The image processing further includes acquiring the environment information from the generated second compressed signal, and processing a radar image reproduced by the image reproduction processing based on the acquired environment information. The image processing program according to any one of 10 to 15.

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