JP5777400B2 - Image radar signal processor - Google Patents

Description

  The present invention relates to an image radar signal processing apparatus that is mounted on a platform such as an aircraft or an artificial satellite and captures a high-resolution image of the ground surface or the sea surface.

  2. Description of the Related Art Conventionally, an image radar signal processing device mounted on a platform such as an aircraft or an artificial satellite includes a SAR (Synthetic Aperture Radar) sensor having an antenna. In this SAR sensor, observation is performed by transmitting and receiving radio signals to and from a predetermined area such as the ground surface and the sea surface while the platform on which the image radar signal processing device is mounted is moving, and the obtained radio signals are A two-dimensional high-resolution image is obtained by signal processing (see, for example, Patent Document 1).

  In the conventional apparatus disclosed in Patent Document 1, a certain point in the observation area is two-dimensionally spread on the radio signal received by the SAR sensor. Therefore, by applying signal processing called image reproduction processing to the two-dimensional data, the one-dimensionally spread one point can be compressed to one point. As an image reproduction process used at this time, there are various methods such as a polar format method, a range Doppler method, and a chirp scaling method.

  In these image reproduction processes, FFT (Fast Fourier Transform) calculation processing is performed on two-dimensional data in the range direction (radiation direction of radio waves) or the azimuth direction (direction orthogonal to the radio wave irradiation direction). An IFFT (Inverse Fast Fourier Transform) calculation process, a coefficient multiplication process, and the like are performed.

JP 2004-198275 A

The image reproduction process described above is a process with a high calculation load, but an image radar signal processing apparatus mounted on an artificial satellite or the like is limited by the scale, weight, power, etc. of the calculation apparatus. In addition, in the case of an artificial satellite, orbiting the earth, communication is difficult when the artificial satellite is behind the earth as seen from the ground station, and the time during which data transmission to the ground station is possible Is limited. For this reason, when performing image reproduction / transmission processing on the image radar signal processing device, within the time limit for data transmission (between the image radar signal processing device and the ground station) under the constraints of the arithmetic device as described above. The process needs to be completed (within a time that allows communication between them).
Here, in the case of an artificial satellite or the like, the predetermined area is observed from the platform and the predetermined area is observed, and after the radio signal is acquired, the image reproduction process is performed. It is necessary to make some simple calculation. Specifically, it is conceivable to reduce the processing size by thinning out the pixels of the acquired radio signal image, or to process only a specific area. Alternatively, when the arithmetic device is configured with a dedicated circuit or the like, it is conceivable to perform the operation by fixed-point arithmetic and reduce the arithmetic accuracy by limiting the data bit width. As described above, when image reproduction processing is performed on the image radar signal processing apparatus, it is necessary to simplify the image reproduction processing within the limited time, and thus it is difficult to obtain a highly accurate SAR image at the ground station. was there.

  In addition, due to restrictions on image reproduction processing on the image radar signal processing device as described above, conventionally, radio signals observed and acquired by the image radar signal processing device are transmitted to the ground station as they are and installed on the ground. It has been common to perform image reproduction processing using a computer or the like. However, the radio signal is complex number data including phase information, and there is a problem that the amount of data is generally larger than the data after image reproduction processing. In addition, there is a restriction on the data transfer performance between the image radar signal processing device and the ground station. Therefore, there is a problem that the amount of data (number of observation data) that can be transmitted to the ground station is limited.

  The present invention has been made to solve the above-described problems. Conventionally, a high-precision SAR image is obtained at the ground station under the restriction of data transfer performance between the image radar signal processing apparatus and the ground station. An object of the present invention is to provide an image radar signal processing apparatus that can be acquired with the number of observation data described above.

An image radar signal processing apparatus according to the present invention is an image radar signal processing apparatus that is mounted on a flying object and has a communication unavailable time zone between communication available time zones with a ground station. Command receiving means for receiving a command, target observing means for radiating a signal to a predetermined area according to the command received by the command receiving means, and receiving a reflected signal from the predetermined area with respect to the signal, And based on the received signal and the movement data acquired by the target observation means and the flying object observation means according to the command received by the observation means having the flying object observation means for acquiring the movement data of the flying object and the command receiving means Simple image processing means for performing image reproduction processing within a communicable time zone observed by the observation means and reproducing simple SAR images; Based on the received signals and motion data acquired by the target observing means and the flying object observing means according to the command received by the command receiving means, the image reproduction processing is more accurate than the simple image processing means using the communication unavailable time zone. In accordance with the command received by the command receiving means and the high precision image processing means for reproducing the high precision SAR image , the simple SAR image reproduced by the simple image processing means is transmitted to the ground station in the communicable time zone, Alternatively, the image processing apparatus includes a transmission processing unit that transmits a high-accuracy SAR image reproduced by the high-accuracy image processing unit in a communication disabled time zone to a ground station in a communication enabled time zone after the communication disabled time zone .

  According to the present invention, since it is configured as described above, a high-precision SAR image can be obtained from the ground station with a higher number of observation data than the conventional one under the restriction of the data transfer performance between the image radar signal processing device and the ground station. Can be obtained at.

It is a block diagram which shows the structure of the image radar signal processing apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the program content of the image radar signal processing apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows the processing timing of the image radar signal processing apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the image radar signal processing apparatus which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structure of the image radar signal processing apparatus which concerns on Embodiment 5 of this invention. It is a block diagram which shows the structure of the image radar signal processing apparatus concerning Embodiment 6 of this invention. It is a flowchart which shows the program content of the image radar signal processing apparatus which concerns on Embodiment 6 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
1 is a block diagram showing a configuration of an image radar signal processing apparatus according to Embodiment 1 of the present invention.
The image radar signal processing apparatus is mounted on a movable platform (flying object) such as an aircraft or an artificial satellite, and captures a high-resolution image (SAR image) of a predetermined area such as the ground surface or the sea surface, and a ground station (not shown). To send to. In the following, description will be made on the assumption that there are a time zone in which communication is possible and a time zone in which communication is not possible between the image radar signal processing device and the ground station.

As shown in FIG. 1, the image radar signal processing apparatus includes an observation unit 1, a data holding unit 2, a high-speed image processing unit (simple image processing unit) 3, a small image processing unit (high-precision image processing unit) 4, and a transmission. It comprises processing means 5.
Although not shown in FIG. 1, the image radar signal processing apparatus actually includes a control unit that performs overall control. This control means is connected to each means 1-5 in the image radar signal processing apparatus via a system bus or a control signal line, and controls each means 1-5 based on a command from the ground station. However, in the following description, for the sake of brevity, each means 1 to 5 will be described as executing data processing by itself.

The observation means 1 is a general term for sensor devices having an antenna, a transmitter, a receiver, a motion sensor, etc. (all not shown). This observation means 1 is composed of a command reception means 11, a target observation means 12 and a flying object observation means 13.
The command receiving means 11 is a receiver for receiving a command from the ground station via an antenna. The command received by the command receiving means 11 is distributed to each means 1-5 in the image radar signal processing apparatus.

  The target observation unit 12 performs observation by transmitting and receiving a high-frequency panel signal to and from a predetermined area in accordance with the command distributed from the command reception unit 11, and acquires a reception signal necessary for reproducing the SAR image. is there. Specifically, the target observation means 12 first generates a high-frequency pulse signal at the transmitter and radiates it from the antenna to a predetermined area, and receives an echo signal reflected at the predetermined area at the receiver via the antenna. To do. Then, the received echo signal is amplified and converted into an intermediate frequency, and then converted into a digital signal to obtain a final received signal. The reception signal acquired by the target observation unit 12 is output to the data holding unit 2.

  The flying object observing means 13 measures the motion of the platform on which the image radar signal processing device is mounted by a motion sensor, and acquires motion data including the instantaneous position of the platform when transmitting and receiving a high-frequency pulse signal. is there. The movement data acquired by the flying object observation means 13 is output to the data holding means 2.

  The data holding means 2 holds received signals and motion data acquired by the observation means 1 (target observation means 12 and flying object observation means 13) as data, and reproduces them by the high-speed image processing means 3 and the small image processing means 4. The obtained SAR image (simple SAR image, high-accuracy SAR image) is held.

  The high-speed image processing means 3 calculates various coefficients based on the exercise data held in the data holding means 2 in accordance with the command distributed from the command receiving means 11, and performs the processing on the received signal held in the data holding means 2. Thus, a simple SAR image is reproduced by performing high-speed image reproduction processing. The image reproduction processing by the high-speed image processing means 3 is performed within a communicable time zone when the observation means 1 observes a predetermined area. For this reason, processing time is limited, and fixed-point arithmetic is performed using dedicated computers and dedicated circuits such as FFT / IFFT circuits, multiplication circuits, coefficient calculation circuits, etc., and the bit width of data is limited to reduce calculation accuracy. Perform high-speed computation with. Further, this image reproduction process may be executed by thinning out the number of pixels to be processed, or may be executed only for a partial area of the received signal. The simple SAR image reproduced by the high-speed image processing means 3 is output to the data holding means 2.

  The small image processing means 4 calculates various coefficients based on the motion data held in the data holding means 2 in accordance with the command delivered from the command receiving means 11, and for the received signal held in the data holding means 2. Thus, high-precision SAR images are reproduced by performing image reproduction processing that is smaller and more accurate than the high-speed image processing means 3. The image reproduction processing by the small image processing means 4 is performed using a communication unavailable time zone with the ground station. For this reason, there is no restriction on the processing time, and a general-purpose computer or the like that performs a floating-point operation that is small and has sufficient accuracy at a low speed is used. The high-accuracy SAR image reproduced by the small image processing unit 4 is output to the data holding unit 2.

  In accordance with the command distributed from the command receiving unit 11, the transmission processing unit 5 transmits the reception signal held in the data holding unit 2, the simple SAR image, and the high-precision SAR image to the ground station in consideration of the communicable time ( Downlink).

Next, the operation of the image radar signal processing apparatus according to the first embodiment configured as described above will be described. FIG. 2 is a flowchart showing the program contents of the image radar signal processing apparatus according to the first embodiment of the present invention, and FIG. 3 is a timing chart showing the processing timing of each means 1-5 at that time.
In the following description, it is assumed that the platform is an artificial satellite. That is, a case where a time zone in which communication with the ground station can be performed and a time zone in which communication with the ground station cannot be performed in one round due to the platform orbiting the earth will be described. This communication situation is actually affected by various factors, but for the sake of simplicity, FIG. 3 shows that communication is possible when the platform is on the horizon when viewed from the ground station, and communication is otherwise impossible. .

  In the operation of the image radar signal processing apparatus, as shown in FIG. 2, first, the command receiving means 11 receives a command indicating an observation instruction from the ground station (step ST1). By receiving this command, the ground station instructs the observation area, direction, high-frequency pulse signal transmission timing, observation mode, number of observations, transmission area to the ground station and the number of images to be transmitted. The The start timing of the command reception process at step ST1 is any timing within the communicable time zone, but FIG. 3 shows a case where the command reception process at step ST1 is started at the same time communication is enabled. The command received by the command receiving means 11 is distributed to each means 1-5 in the image radar signal processing apparatus.

  Next, the target observation means 12 generates a high-frequency pulse signal and radiates it to a predetermined area, and receives an echo signal reflected from the predetermined area (step ST2). The start timing of the pulse signal transmission / reception processing in step ST2 is determined by the observation area indicated by the command. Therefore, as shown in FIG. 3, there may be a pause period after the command reception process at step ST1 is completed and before the pulse signal transmission / reception process at step ST2 is started.

  Next, the target observing means 12 amplifies the received echo signal, converts it to an intermediate frequency, and then converts it to a digital signal to obtain a received signal (step ST3). The received signal acquired by the target observation unit 12 is output to the data holding unit 2 and held as data.

  The flying object observing means 13 measures the motion of the platform on which the image radar signal processing device is mounted, and acquires motion data including the instantaneous position of the platform at the time of transmission / reception of a high-frequency pulse signal (step ST4). The movement data acquired by the flying object observation means 13 is output to the data holding means 2 and held as data.

  Next, the high-speed image processing means 3 calculates various coefficients based on the exercise data held in the data holding means 2 in accordance with the command distributed from the command receiving means 11, and receives the received data held in the data holding means 2. A simple SAR image is reproduced by performing high-speed image reproduction processing on the signal (step ST5). At this time, as shown in FIG. 3, the image radar signal processing apparatus needs to complete the simple SAR image reproduction / transmission processing of steps ST5 and ST6 within the communicable time zone. Therefore, there is a time restriction on the simple SAR image reproduction process, and high-speed computation is performed by reducing the computation accuracy by performing fixed-point computation using a dedicated computer or a dedicated circuit. The simple SAR image reproduced by the high-speed image processing means 3 is output to the data holding means 2 and held.

  Next, the transmission processing means 5 reads the simple SAR image held in the data holding means 2 according to the command distributed from the command receiving means 11, and transmits it to the ground station within the communicable time zone (step ST6). Thereby, in the ground station, a simple SAR image can be acquired within a communicable time zone in the lap when the image radar signal processing apparatus observes the predetermined area.

  On the other hand, the small image processing means 4 calculates various coefficients based on the exercise data held in the data holding means 2 in accordance with the command distributed from the command receiving means 11, and also receives the received signal held in the data holding means 2. A high-precision SAR image is reproduced by performing a small and high-precision image reproduction process (step ST7). The start timing of the high-accuracy SAR image reproduction process in step ST7 is after the simple SAR image reproduction process in step ST5 is completed, as shown in FIG. Further, the high-accuracy SAR image reproduction process is performed using a communication unavailable time zone with the ground station. For this reason, there is no restriction on the processing time, and a floating point calculation that can obtain sufficient accuracy at a small size and at a low speed is performed using a general-purpose computer. The high-accuracy SAR image reproduced by the small image processing unit 4 is output to the data holding unit 2 and held.

Next, after the time period during which communication with the ground station is disabled has elapsed, the command receiving means 11 receives a command indicating a high-accuracy SAR image transmission instruction from the ground station at the beginning of the time during which communication is possible in the next round (step ST8). By receiving this command, transmission of a high-accuracy SAR image to the ground station, selection of an image area, and the like are instructed. The command received by the command receiving unit 11 is distributed to the transmission processing unit 5 in the image radar signal processing apparatus. Note that the command reception indicating the high-accuracy SAR image transmission instruction in step ST8 may be executed simultaneously with the command reception indicating the observation instruction in step ST1 in this round.
In FIG. 3, the command reception process of step ST1 is performed simultaneously with the command reception process of step ST8, and the observation process of steps ST2 to 4 and the simplified SAR of step ST5 are performed in parallel with the high-accuracy SAR image transmission process of step ST9 described later. The case where image reproduction processing is performed is shown.

Next, the transmission processing means 5 reads out the high-accuracy SAR image held in the data holding means 2 according to the command distributed from the command receiving means 11, and transmits it to the ground station (step ST9). At this time, as shown in FIG. 3, the transmission processing means 5 takes into consideration the transmission time so as not to disturb the simple SAR image transmission process of step ST6 in this round, and the high-precision SAR image transmission process of step ST9. Execute.
Specifically, when it is instructed to transmit a plurality of high-accuracy SAR images from the ground station, and when it is determined that all the high-accuracy SAR images cannot be transmitted within the transmission time (constraint time). Only the number of high-accuracy SAR images that can be transmitted within the restricted time is transmitted. Further, when the transmission of one high-accuracy SAR image is instructed from the ground station and it is determined that the transmission cannot be completed within the restricted time, the high-accuracy SAR image is divided and communication in a plurality of rounds is performed. You may make it transmit in the idle time etc. before performing the simple SAR image transmission process of a possible time slot | zone.

  In the above example, the processes in steps ST2 to ST6 are described as being sequentially processed in FIG. 3, but the processes in steps ST2 to ST6 are processed in a pipeline manner to observe a plurality of SAR images. -You may make it transmit.

  As described above, according to the first embodiment, a high-precision SAR image is reproduced by performing a small and high-accuracy image reproduction process using a communication unavailable time zone with the ground station, and observation in the next round Since this high-accuracy SAR image is transmitted to the ground station using the time zone of the processing and the simple SAR image reproduction processing, data transfer from the image radar signal processing device to the ground station can be used effectively. In addition, a large amount of high-accuracy SAR images can be transmitted to the ground station.

Embodiment 2. FIG.
In the first embodiment, the high-accuracy SAR image transmission process (step ST9 in FIG. 2) by the transmission processing unit 5 has been described for transmitting a high-accuracy SAR image as much as possible within the limited time. When the ground station determines that transmission of all high-accuracy SAR images reproduced by the small image processing means 4 cannot be completed within the restricted time, a desired image (from a plurality of high-accuracy SAR images is selected). A command specifying a desired high-accuracy SAR image, a desired area on the high-accuracy SAR image, etc.) is transmitted, and only the image is transmitted to the ground station by the transmission processing means 5.
The image radar signal processing apparatus according to the second embodiment has the same configuration as that of the image radar signal processing apparatus according to the first embodiment shown in FIG.

  Next, the operation of the image radar signal processing apparatus according to the second embodiment will be described with reference to the flowchart of FIG. The operation of the image radar signal processing apparatus according to the second embodiment is the same as that of the image radar signal processing apparatus according to the first embodiment except for steps ST8 and ST9 in FIG. . Hereinafter, a case will be described in which the ground station transmits a command specifying only a specific area on the high-accuracy SAR image.

In the ground station, before transmitting a command indicating a high-accuracy SAR image transmission instruction to the image radar signal processing device, the high-accuracy SAR in the previous round is determined based on the trajectory of the platform, the observation schedule of the SAR image in the next round, and the like. The time required for image transmission and the transmission start time of the simple SAR image in the next round are estimated. If it is determined that the transmission of the high-accuracy SAR image cannot be completed within the limited time, the high-accuracy SAR is within a range in which the transmission can be completed within the limited time based on the acquired simple SAR image in the previous round. A desired area on the image is designated, and a command including this information is transmitted.
In step ST8, the command receiving means 11 receives a command including this area designation information. The command received by the command receiving unit 11 is distributed to the transmission processing unit 5.

  Next, in step ST9, the transmission processing means 5 cuts out only the designated area on the high-accuracy SAR image held in the data holding means 2 in accordance with the command (area designation information) distributed from the command receiving means 11. To the ground station.

  In the above example, the case where a part of the region on the high-accuracy SAR image is specified is shown. However, when a plurality of high-accuracy SAR images are reproduced by the small image processing unit 4, the ground station Based on the acquired simple SAR image, a desired image may be specified from the plurality of high-precision SAR images, and a command including this information may be transmitted. Then, according to this command (image designation information), the transmission processing means 5 reads only the designated high precision SAR image from the high precision SAR images held in the data holding means 2 and transmits it to the ground station.

  Alternatively, the ground station may designate priorities for a plurality of areas on the high-accuracy SAR image, and transmit a command including this information in advance. When the transmission processing unit 5 determines that the transmission of the high-accuracy SAR image cannot be completed within the restricted time, the priority on the high-accuracy SAR image held in the data holding unit 2 according to the command (priority information) is determined. Are cut out in order from the higher area and transmitted to the ground station. In addition, the ground station may transmit a command instructing SAR image transmission divided into a plurality of laps.

  As described above, according to the second embodiment, when the ground station determines that the transmission of the high-accuracy SAR image cannot be completed within the restricted time, the high-accuracy SAR image reproduced by the small image processing unit 4 Since the configuration is such that a desired image (a desired high-accuracy SAR image, a desired area of the high-accuracy SAR image, etc. from a plurality of high-accuracy SAR images) is designated by a command, the effect of the first embodiment In addition, even if the transmission time of the high-accuracy SAR image is limited, the desired high-accuracy SAR image can be acquired at the ground station.

Embodiment 3 FIG.
In the first embodiment, the simple SAR image is reproduced by the high-speed image processing means 3 and the high-precision SAR image is reproduced by the small image processing means 4 based on the received signal. However, in the third embodiment, A case where a high-precision SAR image is also reproduced by the high-speed image processing means 3 will be described.
The image radar signal processing apparatus according to the third embodiment shown in FIG. 4 deletes the small image processing means 4 of the image radar signal processing apparatus according to the first embodiment shown in FIG. The processing means 3b is changed. The other configurations are the same, and the same reference numerals are given and description thereof is omitted.

The high-speed image processing means 3b, in accordance with the command distributed from the command receiving means 11, in addition to the reproduction of the simple SAR image by the high-speed image reproduction processing based on the received signal and the motion data held in the data holding means 2, A high-accuracy SAR image is reproduced by a small-sized and high-accuracy image reproduction process equivalent to the small-size image processing means 4. The high-speed image processing means 3b includes a control means 31 for controlling the means 32 to 34 in the high-speed image processing means 3b, and various coefficients for image reproduction processing based on the motion data held in the data holding means 2. Coefficient calculation means 32 for calculating, FFT / IFFT processing means 33 for performing FFT processing and IFFT processing on each pixel data of the received signal held in the data holding means 2, and complex multiplication of each pixel data and coefficient. Multiplication means 34. Here, the FFT / IFFT processing means 33 and the multiplication means 34 are assumed to be dedicated circuits that perform fixed-point arithmetic at high speed. The coefficient calculation means 32 is assumed to be a floating point arithmetic unit (high precision image processing unit) that performs floating point arithmetic and calculates coefficients with high precision.
Note that these configurations assume image reproduction processing using the chirp scaling method, but when other image reproduction processing is used, a configuration in which other calculation means is added may be used. .

  Next, the operation of the image radar signal processing apparatus according to the third embodiment will be described with reference to the flowchart of FIG. The operation of the image radar signal processing apparatus according to the third embodiment is the same as the operation of the image radar signal processing apparatus according to the first embodiment except for steps ST5 and ST7 in FIG. .

  In step ST5, the control means 31 of the high-speed image processing means 3b controls the coefficient calculation means 32, the FFT / IFFT processing means 33 and the multiplication means 34 according to the command distributed from the command receiving means 11, and the data holding means 2 On the basis of the received signal and motion data held in, a high-speed image reproduction process is performed within the communicable time zone observed by the observation means 1 to reproduce a simple SAR image. Specifically, first, the coefficient calculation means 32 calculates various coefficients based on the exercise data. Then, the FFT / IFFT processing means 33 and the multiplication means 34 perform FFT / IFFT processing in the range direction or azimuth direction on the received signal and coefficient multiplication using the coefficient calculated by the coefficient calculation means 32 a plurality of times. Thus, the simple SAR image is reproduced.

  In step ST7, the control means 31 of the high-speed image processing means 3b controls the coefficient calculation means 32 according to the command distributed from the command receiving means 11, and receives the received signal and the motion data held in the data holding means 2. Based on the above, a small and highly accurate image reproduction process is performed using the communication unavailable time period, and a highly accurate SAR image is reproduced. Specifically, a high-precision SAR image is reproduced by performing FFT / IFFT or coefficient multiplication at a low speed using the floating point arithmetic unit of the coefficient calculating means 32.

  As described above, according to the third embodiment, the high-speed image processing unit 3b is configured to perform the high-accuracy SAR image processing in addition to the simple SAR image reproduction processing, and thus the small image processing unit 4 is eliminated. Therefore, the apparatus can be reduced in size and cost can be reduced.

Embodiment 4 FIG.
In the first embodiment, the case where a high-accuracy SAR image is transmitted in the high-accuracy SAR image transmission process (step ST9 in FIG. 2) by the transmission processing unit 5 has been described. In the fourth embodiment, a command from the ground station is shown. Thus, a case where the reception signal itself before the image reproduction processing is transmitted will be described.
The image radar signal processing apparatus according to the fourth embodiment has the same configuration as that of the image radar signal processing apparatus according to the first embodiment shown in FIG.

  Next, the operation of the image radar signal processing apparatus according to the fourth embodiment will be described with reference to the flowchart of FIG. The operation of the image radar signal processing apparatus according to the fourth embodiment is the same as the operation of the image radar signal processing apparatus according to the first embodiment, except for steps ST8 and ST9 in FIG. .

In the ground station, when a command indicating a high-accuracy SAR image transmission instruction is transmitted to the image radar signal processing apparatus, a command including information for instructing transmission (downlink) of the received signal is transmitted.
In step ST8, the command receiving means 11 receives a command including this received signal transmission instruction information. The command received by the command receiving unit 11 is distributed to the transmission processing unit 5.

  Next, in step ST9, the transmission processing means 5 reads the received signal held in the data holding means 2 according to the command (received signal transmission instruction information) distributed from the command receiving means 11, and transmits it to the ground station.

In the above example, it is assumed that the entire received signal is transmitted, but the ground station specifies a desired area of the received signal based on the acquired simple SAR image and includes this information. A command may be transmitted. Then, the transmission processing means 5 cuts out only the designated area on the received signal held in the data holding means 2 according to this command (area designation information) and transmits it to the ground station.
Further, when a plurality of received signals are acquired by the target observation means 12, the ground station designates a desired signal from the plurality of received signals based on the acquired simple SAR image, and this information You may make it transmit the command containing. Then, according to this command (signal designation information), the transmission processing means 5 reads only the designated reception signal from the reception signals held in the data holding means 2 and transmits it to the ground station.

  As described above, according to the fourth embodiment, the reception signal is transmitted to the ground station using a time other than the transmission time of the simple SAR image. The received signal can be acquired without disturbing the acquisition. In addition, since it is possible to select a received signal after confirming a simple SAR image, transmission of unnecessary information can be reduced and data can be transmitted efficiently.

Embodiment 5 FIG.
In the second embodiment, the case where a desired image is designated from the high-accuracy SAR images reproduced by the small image processing means 4 at the ground station has been described. On the other hand, the simple SAR image reproduction process by the high-speed image processing means 3 is a process for performing high-speed calculation by limiting the bit width of data and lowering the calculation accuracy. However, depending on the received signal, within the limited bit width. There is a case where the calculation is settled and, as a result, data equivalent to the high-precision SAR image can be obtained. Therefore, in the fifth embodiment, in consideration of the above points, it is determined whether or not to execute the high-accuracy SAR image reproduction process according to the calculation result by the high-speed image processing means 3c, and the high-accuracy SAR to be transmitted is transmitted. A case where an image is selected will be described.
The image radar signal processing apparatus according to the fifth embodiment shown in FIG. 5 is obtained by changing the high-speed image processing means 3 of the image radar signal processing apparatus according to the first embodiment shown in FIG. 1 to a high-speed image processing means 3c. . The other configurations are the same, and the same reference numerals are given and description thereof is omitted.

  The high-speed image processing unit 3c reproduces a simple SAR image by high-speed image reproduction processing based on the received signal and motion data held in the data holding unit 2 in accordance with the command distributed from the command receiving unit 11. This high-speed image processing means 3c includes overflow (digit loss) in processing by the FFT / IFFT processing means 33 and multiplication means 34 in addition to the means 31 to 34 of the high-speed image processing means 3b in the third embodiment shown in FIG. ) And its peak value are monitored, and a digit loss judging means 35 for counting the number of occurrences of overflow is provided. Information indicating the number of overflow occurrences counted by the digit loss determining means 35 is output to the data holding means 2 and held therein.

  Next, the operation of the image radar signal processing apparatus according to the fifth embodiment will be described with reference to the flowchart of FIG. The operation of the image radar signal processing apparatus according to the fifth embodiment is the same as the operation of the image radar signal processing apparatus according to the first embodiment except for steps ST5, 7, and 9 in FIG. Omitted.

In step ST5, as in the high-speed image processing unit 3b in the third embodiment, the high-speed image processing unit 3c controls the coefficient calculation unit 32, the FFT / IFFT processing unit 33, and the multiplication unit 34 so that the high-speed image processing unit 3c operates at high speed. An image reproduction process is performed to calculate a simple SAR image.
At this time, the digit loss determining means 35 monitors the occurrence of overflow and the peak value in the processing by the FFT / IFFT processing means 33 and the multiplication means 34, and counts the number of occurrences of overflow. Information indicating the number of occurrences of overflow counted by the digit loss judging unit 35 is output to the data holding unit 2 and held together with the simple SAR image reproduced by the high-speed image processing unit 3c.

  In step ST7, the small image processing means 4 calculates various coefficients based on the exercise data held in the data holding means 2 in accordance with the command distributed from the command receiving means 11 as in the first embodiment. At the same time, a high-accuracy SAR image is reproduced by performing a small and highly accurate image reproduction process on the received signal held in the data holding unit 2. However, the small image processing unit 4 confirms information indicating the number of overflow occurrences held in the data holding unit 2 before starting the high-accuracy SAR image reproduction processing. Here, when it was confirmed that the overflow did not occur, the small image processing means 4 could obtain data equivalent to the high-precision SAR image by the simple SAR image reproduction process of the high-speed image processing means 3c. It is determined that the reproduced simple SAR image matches the high-precision SAR image, and the high-precision SAR image reproduction process is not executed.

  In step ST9, the transmission processing means 5 reads out the high-accuracy SAR image held in the data holding means 2 based on the command distributed from the command receiving means 11, as in the first embodiment, Send to the station. However, the transmission processing means 5 confirms information indicating the number of overflow occurrences held in the data holding means 2 before starting the high-accuracy SAR image transmission processing. Here, when it is confirmed that the overflow has not occurred, the transmission processing means 5 does not execute the high-accuracy SAR image transmission process, and transmits only information indicating that no overflow has occurred to the ground station. To do.

  In the above example, the processing is reduced on the assumption that the simple SAR image and the high-accuracy SAR image coincide with each other only when no overflow occurs. It is also possible to determine whether or not to execute high-accuracy SAR image reproduction / transmission processing by providing a threshold value for. Also, pre-designate an area that appears to be important on the received signal or on the simple SAR image, weight the area, count the overflow, and determine whether to execute high-precision SAR image playback / transmission processing. You may make it do.

  As described above, according to the fifth embodiment, by counting the overflow that has occurred in the simple SAR image reproduction process by the high-speed image processing means 3c, data equivalent to the high-precision SAR image is obtained in the simple SAR image reproduction process. Since the digit loss determining means 35 for determining whether or not it has been obtained, unnecessary high-precision SAR image reproduction / transmission processing can be reduced. Moreover, since unnecessary high-precision SAR image reproduction processing can be reduced, the calculation load of the image radar signal processing apparatus can be reduced, and power consumption can be reduced.

Embodiment 6 FIG.
In the fifth embodiment, the case where it is determined whether or not to execute the high-accuracy SAR image reproduction / transmission process according to the calculation result in the high-speed image processing means 3c has been described. On the other hand, a case will be described where a plurality of simple SAR images are reproduced, and minute changes in these simple SAR images are extracted to determine whether or not to execute high-accuracy SAR image reproduction / transmission processing.
The image radar signal processing apparatus according to the sixth embodiment shown in FIG. 6 is obtained by adding change extracting means 6 to the configuration of the image radar signal processing apparatus according to the first embodiment shown in FIG. The other configurations are the same, and the same reference numerals are given and description thereof is omitted.

  The change extraction unit 6 superimposes a plurality of simple SAR images on a predetermined area held in the data holding unit 2 to perform a minute change extraction process, and extracts a minute change in these simple SAR images. With regard to the minute change extraction process for the SAR image by the change extraction unit 6, a conventionally known technique (see, for example, Patent Document 2) can be applied, and detailed description thereof is omitted.

[Patent Document 2]
JP 2010-281484 A

  Next, the operation of the image radar signal processing device according to the sixth embodiment configured as described above will be described. FIG. 7 is a flowchart showing the program contents of the image radar signal processing apparatus according to Embodiment 6 of the present invention. In the operation of the image radar signal processing apparatus according to the sixth embodiment shown in FIG. 7, the same operation as that of the image radar signal processing apparatus according to the first embodiment shown in FIG.

When transmitting a command indicating an observation instruction to the image radar signal processing apparatus, the ground station designates a predetermined area from which a minute change is extracted, and transmits a command including this information.
Then, the command receiving means 11 receives a command including this area designation information (step ST1). The command received by the command receiving means 11 is distributed to each means 1-5.

Next, the observation means 1 and the high-speed image processing means 3 observe the designated predetermined area twice in accordance with the command (minute change area designation information) distributed from the command reception means 11, and obtain two simple SAR images. Playback is performed (steps ST2 to ST5). The two simple SAR images are held in the data holding unit 2.
Next, the transmission processing means 5 transmits the simple SAR image held in the data holding means 2 to the ground station according to the command distributed from the command receiving means 11 (step ST6).

Next, the change extracting unit 6 performs a minute change extraction process by superimposing two simple SAR images held in the data holding unit 2, and counts minute change points in these simple SAR images (step ST11). .
Next, the change extracting unit 6 determines whether or not there is a change in the predetermined region by determining whether the counted number of minute change points has exceeded a predetermined threshold (step ST12). In step ST12, when the change extraction unit 6 determines that there is no change in the predetermined area, the small image processing unit 4 is not instructed to perform the high-accuracy SAR image reproduction process, and skips the process of step ST7.

  On the other hand, if it is determined that there is a change in the predetermined area, the change extracting unit 6 instructs the small image processing unit 4 to perform high-accuracy SAR image reproduction processing, and the small image processing unit 4 holds the data in the data holding unit 2. A high-accuracy SAR image is reproduced by performing a small-size and high-accuracy image reproduction process on the latest received signal (step ST7). This high-accuracy SAR image is output to the data holding unit 2 and held.

Next, after the time period in which communication with the ground station is disabled has elapsed, the command receiving means 11 receives a command from the ground station at the beginning of the communication possible time in the next round (step ST8). The command received by the command receiving unit 11 is distributed to the transmission processing unit 5.
Next, the transmission processing means 5 follows the command distributed from the command receiving means 11, and when the change extraction means 6 determines that there is a change in the predetermined area in step ST12, the transmission processing means 5 The accuracy SAR image is extracted and transmitted to the ground station. Otherwise, the transmission processing means 5 transmits only information indicating that there is no change to the ground station (step ST9).

  In the above example, a high-accuracy SAR image is transmitted to the ground station in accordance with the command reception process in step ST8. However, in step ST7, the change extraction unit 6 determines that there is a change in the predetermined area. In this case, the image radar signal processing apparatus may actively notify the ground station that there is a change in the predetermined area via the transmission processing means 5. Further, in the above example, change extraction processing is performed for only one area. However, when a plurality of areas are specified and there is a change in any of the areas, a high-accuracy SAR image is transmitted. Also good. Furthermore, only an area near the change point in one image may be cut out and transmitted to the ground station. In the above example, the change extraction means 6 performs the determination by counting the number of change points. However, the correlation between the images is taken, and it is determined that there is a change when the correlation is low (the change is large). You may make it do.

  In the above example, a series of processing is completed by observing one region twice in the same lap and performing change extraction processing on the simple SAR image based on these received signals. Processing may be continuously performed in a round, and a high-accuracy SAR image may be transmitted to the ground station whenever there is a change. In the above example, a predetermined area is specified by the ground station, and the image radar signal processing apparatus performs observation a plurality of times for the predetermined area. The same area may be searched from the past data held in 2 and called to perform change extraction processing.

  As described above, according to the sixth embodiment, the change extraction unit 6 performs change extraction processing on a plurality of simple SAR images, and determines whether or not there is a change in the simple SAR images. Therefore, it is possible to selectively transmit a high-accuracy SAR image of the changed area to the ground station and reduce unnecessary information transmission, thereby efficiently transmitting data.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  1 observation means, 2 data holding means, 3, 3b, 3c high-speed image processing means (simple image processing means), 4 small image processing means (high-precision image processing means), 5 transmission processing means, 6 change extraction means, 11 command Reception means, 12 Target observation means, 13 Aircraft observation means, 31 Control means, 32 Coefficient calculation means, 33 FFT / IFFT processing means, 34 Multiplication means, 35 Digit loss judgment means

Claims (10)

In an image radar signal processing apparatus that is mounted on a flying object and has a non-communication time zone between communication time zones with a ground station,
Command receiving means for receiving a command from the ground station, radiating a signal to a predetermined area in accordance with the command received by the command receiving means, and receiving a reflected signal from the predetermined area with respect to the signal Target observation means for acquiring, and observation means having a flying object observation means for acquiring movement data of the flying object,
According to the command received by the command receiving means, based on the received signal and the motion data acquired by the target observing means and the flying object observing means, the image reproduction is performed within the communicable time zone in which the observing means performs the observation. Simple image processing means for performing processing and reproducing a simple SAR image;
According to the command received by the command receiving means, based on the received signal and motion data acquired by the target observing means and the flying object observing means, the communication disabled time zone is used and the higher than the simple image processing means. High-accuracy image processing means for performing accurate image reproduction processing and reproducing a high-accuracy SAR image;
According to the command received by the command receiving means, the simple SAR image reproduced by the simple image processing means is transmitted to the ground station in the communicable time zone, or the non-communication time zone by the high-precision image processing means. in the image radar signal processing apparatus characterized by comprising a transmission processing means for transmitting a high-precision SAR image reproduced in the ground station to said communication time zone after zone the incommunicable time. The transmission processing means transmits an image designated by the ground station from the high-precision SAR images reproduced by the high-precision image processing means to the ground station according to the command received by the command receiving means. The image radar signal processing apparatus according to claim 1. The transmission processing means transmits a high-accuracy SAR image reproduced by the high-accuracy image processing means or a reception signal acquired by the target observation means to the ground station according to the command received by the command receiving means. The image radar signal processing apparatus according to claim 1 or 2, wherein The simple image processing means includes a digit loss judging means for detecting a digit loss in the image reproduction process,
The high-accuracy image processing means, when the number of digits detected by the digit-loss determining means is within a threshold, is highly accurate based on the received signal and the motion data corresponding to the simple SAR image in which the digit-loss is detected. The image radar signal processing apparatus according to claim 1, wherein the image reproduction process is not executed. The target observing means executes a received signal acquisition process for the predetermined area a plurality of times in accordance with the command received by the command receiving means,
The image radar signal processing apparatus includes a change extraction unit that performs change extraction on each simple SAR image reproduced by the simple image processing unit based on a plurality of reception signals acquired by the target observation unit,
When a change is extracted by the change extraction unit, the high-accuracy image processing unit executes a high-accuracy image reproduction process based on the latest received signal and motion data corresponding to the simple SAR image from which the change is extracted. The image radar signal processing apparatus according to any one of claims 1 to 3, wherein the image radar signal processing apparatus comprises: In an image radar signal processing apparatus that is mounted on a flying object and has a non-communication time zone between communication time zones with a ground station,
Command receiving means for receiving a command from the ground station, radiating a signal to a predetermined area in accordance with the command received by the command receiving means, and receiving a reflected signal from the predetermined area with respect to the signal Target observation means for acquiring, and observation means having a flying object observation means for acquiring movement data of the flying object,
According to the command received by the command receiving means, based on the received signal and the motion data acquired by the target observing means and the flying object observing means, the image reproduction is performed within the communicable time zone in which the observing means performs the observation. Processing, reproducing a simple SAR image, and in accordance with the command received by the command receiving means, based on the received signal and motion data acquired by the target observing means and the flying object observing means, Simple image processing means for performing high-precision image reproduction processing using the image reproduction processing and reproducing high-precision SAR images;
In accordance with the command received by the command receiving means, the simple SAR image reproduced by the simple image processing means is transmitted to the ground station in the communicable time zone, or in the non-communication time zone by the simple image processing means. An image radar signal processing apparatus comprising: a transmission processing unit configured to transmit the reproduced high-accuracy SAR image to the ground station in the communicable time zone after the communication unavailable time zone . The transmission processing means transmits an image designated by the ground station from the high-accuracy SAR images reproduced by the simple image processing means to the ground station according to the command received by the command receiving means. The image radar signal processing apparatus according to claim 6, wherein: The transmission processing unit transmits a high-accuracy SAR image reproduced by the simple image processing unit or a reception signal acquired by the target observation unit to the ground station according to the command received by the command receiving unit. 8. The image radar signal processing apparatus according to claim 6, wherein the image radar signal processing apparatus is characterized in that: The simple image processing means includes a digit loss judging means for detecting a digit loss in the image reproduction process,
The simple image processing means is a high-accuracy image based on the received signal and the motion data corresponding to the simple SAR image in which the digit loss is detected when the number of digits detected by the digit loss determination means is within a threshold value. The image radar signal processing apparatus according to claim 6, wherein the reproduction process is not executed. The target observing means executes a received signal acquisition process for the predetermined area a plurality of times in accordance with the command received by the command receiving means,
The image radar signal processing apparatus includes a change extraction unit that performs change extraction on each simple SAR image reproduced by the simple image processing unit based on a plurality of reception signals acquired by the target observation unit,
When a change is extracted by the change extraction unit, the simple image processing unit executes a highly accurate image reproduction process based on the latest received signal and motion data corresponding to the simple SAR image from which the change is extracted. The image radar signal processing apparatus according to claim 6, wherein the image radar signal processing apparatus is one of the following.

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