JP6950863B2 - Polarimetric SAR system, program, and polarimetric SAR data correction method - Google Patents

Description

The present invention relates to a polarimetric SAR (Synthetic Aperture Radar) technique having an observation mode using all polarizations.

SAR is a radar that is mounted on platforms such as aircraft and artificial satellites and acquires images of the surface of the earth and sea using radio waves. In recent years, there are a total of four types of polarized waves (generally, two types of linearly polarized waves, horizontal / vertical for transmission and two types of linearly polarized waves, horizontal / vertical for reception, as the polarization directions of radio waves used for transmission and reception. An increasing number of SARs have observation modes that use (called all-polarized light). A SAR having such an observation mode is called a polarimetric SAR, and it is possible to extract and analyze target information that cannot be extracted with a single polarization.

Polarized light is a radio wave in which the vibration direction of the electric field is regular. Horizontally polarized waves refer to polarized waves in which the vibration direction of the electric field is horizontal with respect to the ground surface and the sea surface, and are also called H polarized waves. Vertically polarized wave refers to polarized wave in which the vibration direction of the electric field is perpendicular to horizontal polarized wave, and is also called V-polarized light.

Furthermore, transmission is horizontally polarized, reception is horizontally polarized, HH polarization, transmission is horizontally polarized, reception is vertically polarized, HV polarization, transmission is vertically polarized, and reception is horizontally biased. Waves are called VH polarization, transmission is called vertical polarization, and reception is called vertical polarization.

In the polarimetric SAR technology, which has an observation mode that uses all polarization, when the horizontally polarized data and the vertically polarized data are prepared, the polarization data of an arbitrary inclination is generated by adjusting the amplitude of each. Can be done. In addition, by adjusting the phase difference, it is possible to generate elliptical polarization data having an arbitrary slope and an arbitrary eccentricity. Since this can be applied to both transmission and reception, it is possible to generate observation data transmitted and received with arbitrary polarization from the observation data obtained by the polarimetric SAR.

The applicant discloses such a technique in Patent Documents 1 and 2. Patent Document 1 discloses an image processing method that virtually generates an image in which the inclinations of the polarization planes of the transmitted wave and the received wave are changed by arithmetic processing using the full polarimetric data acquired in the all polarization observation mode. doing. According to this method, by obtaining a plurality of images while changing the inclinations of the polarization planes of the transmitted wave and the received wave, it is possible to obtain an image that clearly reflects the target. Further, Patent Document 2 discloses a correction processing method for improving the range signal-to-virtual image ratio of full polarimetric data acquired in the all-polarization observation mode.

Japanese Patent No. 4973034 Japanese Unexamined Patent Publication No. 2012-32348

There is a synthetic aperture radar that changes the directivity of the radar in order to accurately direct the radio waves to the target. One of the following methods is often used in this type of synthetic aperture radar.

(I) The radio waves are directed to the observation target by scanning the radio waves in the azimuth direction and the elevation direction by the phased array antenna fixed to the platform.

(Ii) The radio wave is directed to the target by mechanically moving the antenna by the two-axis drive mechanism that drives in the yaw direction and the roll direction.

(Iii) A phased array antenna fixed to a platform capable of scanning in the azimuth direction and a uniaxial drive mechanism driven in the roll direction are used to direct radio waves to a target.

(Iv) A phased array antenna fixed to a platform capable of scanning in the elevation direction and a uniaxial drive mechanism driven in the yaw direction are used to direct radio waves to a target.

In the polarimetric SAR, it can be said that the accuracy of the slope of the polarization used in transmission / reception is very important in order to perform the analysis based on the polarization information.

However, when the above method is used when adjusting the directivity in the polarimetric SAR, the radio wave can be directed to the target with some accuracy regardless of the platform attitude, but at that time, an error occurs in the inclination of the polarization. It is possible.

In fact, specifying the direction from the origin in the three-dimensional space has the same value as specifying a point on the two-dimensional sphere, so the direction can be specified with two parameters. Therefore, the direction of the target as seen from the platform can be specified by two parameters. Therefore, by the above method, the radio wave can be accurately directed to the target regardless of the platform posture.

On the other hand, in order to change the slope of the polarized wave used for transmission and reception, it is necessary to physically rotate the antenna surface around the antenna normal. Therefore, the slope of polarization is the third parameter. Therefore, when the radio wave is accurately directed to the target by the above method, an error may occur in the inclination of the polarization depending on the platform attitude.

The slope of polarization can be adjusted by, for example, adopting a 3-axis drive mechanism and determining the directivity. However, from the viewpoint of mass, the directivity adjustment method using the 3-axis drive mechanism is generally heavier than the method using the 2-axis drive mechanism or the phased array antenna.

Further, for example, even in a polarimetric SAR having a three-axis drive mechanism, an error may occur in the directivity adjustment, and a polarization inclination error may occur in the observation data.

The present invention has been made in view of the above problems, and is a polari that accurately corrects the inclination of polarization when directing a radio wave to a target for polarimetric SAR observation having a directivity adjustment function. It is an object of the present invention to provide a remetric SAR system and a polar remetric SAR data correction method.

The polarimetric SAR system according to an embodiment of the present invention accepts a polarimetric SAR unit including an antenna configured so that the directivity can be changed, and at least the directivity of the antenna as a parameter for directing the target. With reference to the angle formed by the target with respect to the platform and the attitude angle obtained by referring to the position and orientation information of the platform, the control angle for directing the directivity of the antenna to the target is calculated, and polarization is performed. Regarding the observation data observed by the control unit that calculates the correction angle of the inclination of the antenna, the antenna control unit that adjusts the directivity of the antenna according to the control angle, and the polarimetric SAR unit according to the control angle. It is characterized by including a SAR observation data processing unit that performs polarization rotation processing using the calculated correction angle.

A program according to an embodiment of the present invention includes an antenna configured so that its directivity can be changed, and includes a polarimetric SAR system that directs the directivity of the antenna to a target according to a derived control angle. Refer to at least the angle formed by the target based on the platform that receives the directivity of the antenna as a parameter for directing the antenna, and the attitude angle obtained by referring to the position / orientation information of the platform. Therefore, the control angle for directing the directivity of the antenna to the target is calculated, and the inclination of the polarization of the observation data is shown as a correction parameter for the polarization rotation processing of the observation data observed according to the control angle. It is characterized in that it operates as a control means for calculating the correction angle.

The polarimetric SAR data correction method according to an embodiment of the present invention includes an antenna configured so that the directivity can be changed, and directs the directivity of the antenna to a target according to a derived control angle. Using the remetric SAR system, at least the angle formed by the target based on the platform received as a parameter for directing the directivity of the antenna to the target, and the attitude angle obtained by referring to the position / orientation information of the platform. With reference to, the control angle for directing the directivity of the antenna toward the target is calculated, the correction angle for the inclination of polarization is calculated, and the directivity of the antenna is adjusted according to the control angle to obtain the directivity. The target is observed by the polarimetric SAR unit with the adjusted antenna, and the observation data observed according to the control angle is subjected to polarization rotation processing according to the correction angle by the SAR observation data processing unit.

According to the present invention, for a polarimetric SAR observation having a directivity adjustment function, a polarimetric SAR system that accurately corrects the inclination of polarized waves when directing a radio wave to a target, and a polarimetric SAR. A data correction method can be provided.

It is a block diagram which shows the polarimetric SAR system 1 of 1st Embodiment. It is a flowchart which shows the flow of the polarimetric SAR data correction method of the polarimetric SAR system 1 of 1st Embodiment. It is a schematic diagram which showed the polarimetric SAR system 1 of the 2nd Embodiment. It is a parameter related to the angle used in the second embodiment. It is a schematic diagram which showed the polarimetric SAR system 1 of the 3rd Embodiment. It is a parameter related to the angle used in the third embodiment. It is a schematic diagram which showed the polarimetric SAR system 1 of the 4th Embodiment. It is a parameter related to the angle used in the fourth embodiment. It is a schematic diagram which showed the polarimetric SAR system 1 of the 5th Embodiment. It is a parameter related to the angle used in the fifth embodiment.

Embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing a polarimetric SAR system 1 of the present embodiment.

As shown in FIG. 1, the polarimetric SAR system 1 includes a polarimetric SAR unit 10, a SAR observation data processing unit 20, an antenna control unit 30, and a control unit 40.

The polarimetric SAR unit 10 includes an antenna configured so that the directivity can be changed. Further, the polarimetric SAR unit 10 adjusts the directivity of the antenna according to the control angle of the antenna notified from the antenna control unit 30.

The SAR observation data processing unit 20 performs polarization rotation processing on the observation data observed by the polarimetric SAR unit 10 using the correction angle calculated by the control unit 40. The observation data for polarization rotation processing is observation data that is polarimetrically observed according to the control angle calculated by the control unit 40.

The antenna control unit 30 adjusts the directivity of the antenna according to the control angle.

The control unit 40 calculates the control angle at which the directivity of the antenna is directed to the target, and also calculates the correction angle for the inclination of the polarization.

As a parameter for directing the directivity of the antenna to the target, the target direction may be accepted from the operator or another information processing system. The control unit 40 derives the control angle (orientation) of the antenna by referring to the parameter for directing the directivity of the antenna to the target and other known parameters (for example, the attitude angle of the platform and the mounting angle of the antenna). do it. The parameter that directs the directivity of the antenna to the target can be exemplified by the off-nadia angle of the target with respect to the platform. Further, the control unit 40 calculates a correction angle which is a correction value for rotating the polarization of the SAR image obtained from the observation data observed at the control angle of the antenna derived using the same parameter. This correction angle is a value for correcting (rotating) the directivity of the antenna directed to the target, is a correction parameter, and is responsible for one axis of directivity adjustment. The attitude angle of the platform mentioned as a known parameter can be used by generating the position / orientation information of the platform based on the satellite positioning signal by using, for example, a GPS (Global Positioning System) receiver and a position / attitude sensor. In this way, the control unit 40 may be configured to acquire the position / orientation information of the platform from the satellite positioning signal.

Next, the polarimetric SAR data correction method performed by the polarimetric SAR system 1 will be described.

FIG. 2 is a flowchart showing the flow of the polarimetric SAR data correction method of the polarimetric SAR system 1 of the present embodiment.

When the observation is started, the polarimetric SAR system 1 (control unit 40) calculates the angle (control angle) at which the directivity of the antenna is directed to the target, and also calculates the correction angle of the inclination of polarization (S101). ). This control angle includes the adjustment angle for two axes of antenna directivity from the platform to the target, excluding the slope of polarization.

Next, the polarimetric SAR system 1 (antenna control unit 30) adjusts the directivity of the antenna according to the control angle (S102).

Next, the polarimetric SAR system 1 (polarimetric SAR unit 10) observes the target (observation area including the target) using an antenna directed at the target at a control angle (S103).

After that, the polarimetric SAR system 1 (SAR observation data processing unit 20) performs polarization rotation processing of the observation data observed according to the control angle according to the correction angle (S104). The corrected observation data is appropriately stored and provided to the operator.

As described above, the polarimetric SAR system 1 can accurately correct the inclination of the polarization of the polarimetric SAR observation having the directivity adjustment function when the radio wave is directed to the target.

[Other Embodiments]
Next, the present invention will be described by explaining some embodiments in which the directivity adjustment function of the antenna in the polarimetric SAR system 1 is divided. In addition, a calculation method according to the divided directivity adjustment function will be described. The following embodiments will explain the differences from the described embodiments, and the description of common parts will be simplified or omitted.

[Second Embodiment]
FIG. 3 is a schematic view showing the polarimetric SAR system 1 of the second embodiment.

The present embodiment is a case where the radio wave is directed to the observation target by scanning the radio wave in the azimuth direction and the elevation direction by the phased array antenna fixed to the platform.

The polarimetric SAR system 1 includes a position / orientation sensor 50 in addition to the polarimetric SAR unit 10, the SAR observation data processing unit 20, the antenna control unit 30, and the control unit 40. The position / attitude sensor 50 outputs the position / attitude information of the platform using GPS.

The polarimetric SAR unit 10 includes a phased array antenna 11 fixed to a platform capable of scanning radio waves in the azimuth direction and the elevation direction. The phased array antenna 11 receives a control angle from the antenna control unit 30, and adjusts the directivity of the antenna according to the angle.

The SAR observation data processing unit 20 includes a polarization rotation processing unit 21. The polarization rotation processing unit 21 corrects the observation data by polarization rotation processing according to the correction angle designated by the control unit 40.

In the polarimetric SAR unit 10 shown in FIG. 3, as a radio observation system network, a vertically polarized light receiving unit, a horizontally polarized light receiving unit, a transmitting unit, a transmission wave changeover switch, and a vertically polarized wave circulator are used. Although the circulator for horizontally polarized waves is shown in the figure, the circuit configuration may be changed as needed.

Similarly, in the SAR observation data processing unit 20 shown in FIG. 3, the vertical polarization separation processing unit, the horizontal polarization separation processing unit, the vertical-vertical polarization image reproduction processing unit, the vertical-horizontal polarization image reproduction processing unit, The horizontally-vertically polarized light image reproduction processing unit, the horizontally-horizontally polarized light image reproduction processing unit, the polarization rotation processing unit, and the storage unit are shown in the figure, but the circuit configuration may be changed as necessary.

For example, the illustrated SAR observation data processing unit 20 acquires the observation data observed by the polarimetric SAR observation and reproduces the image into an image by each image reproduction processing unit. All polarization observation data (vertical-vertical data, For vertical-horizontal data, horizontal-vertical data, horizontal-horizontal data), total polarization observation data with accurate inclination is calculated by polarization rotation processing using the notified correction angle, and each is recorded in the storage unit. .. In this configuration, the corrected observation data, which is the polarization rotation processed observation data, is divided into vertical-vertical data, vertical-horizontal data, horizontal-vertical data, and horizontal-horizontal data, and stored in the storage unit. However, the observation data before the polarization rotation processing may be combined and saved, the corrected observation data may be combined into one image and saved, or the observation data output by each separation processing unit may be saved before imaging. It may be configured to add polarization rotation processing to the observation data.

Next, a calculation method for calculating the control angle at which the directivity of the antenna is directed to the target and the correction angle of the inclination of the polarization in the polarimetric SAR system 1 (control unit 40) of the third embodiment will be described.

FIG. 4 shows parameters related to the angle used in this embodiment. As shown, the input items are α, β, γ, θ, β ₀ , and θ ₀ . The output items are φ _Az , θ _El , Δ H, and Δ V. Also, as variables, R _x (xi), R _y (xi), R _z (xi), and R (α, β, γ) are defined as follows.

The definition of R (α, β, γ) is based on the premise that the position / attitude sensor 50 calculates α, β, and γ according to a general Tate-Bryant sequence (calculated in the order of γ, β, α). There is. If the position / attitude sensors that calculate in a different order are used, R (α), R (β), and R (γ) may be arranged in the reverse order of the calculation.

_{When each parameter is defined as described above, the azimuth directivity angle φ Az} , elevation directivity angle θ El, and _{elevation directivity angle θ El of} the phased array antenna 11 with respect to the input α, β, γ, θ, β ₀ , and θ _0. The correction angles ΔH and ΔV can be calculated as follows.

As described above, the polarimetric SAR system 1 transmits radio waves to the polarimetric SAR observation using the phased array antenna 11 capable of scanning radio waves in two axes in the azimuth direction and the elevation direction as a directivity adjustment function. _{It is possible to calculate φ Az} , θ _El , ΔH, and ΔV that can accurately correct the gradient of polarization after directing to the target.

Today's polarimetric SAR systems are often mounted on satellites and aircraft. For example, in the case of a platform that flies in a stratified area such as an aircraft and it is known in advance that the pitch angle during flight is not 0 degrees, the pitch angle in the azimuth direction of the phased array antenna is set to 0 degrees during flight. Therefore, it may be installed at β _{0 ≠ 0 degrees.} Even in such a case, by setting _{β 0 , φ Az} , θ _El , Δ H, and Δ V can be calculated accurately.

[Third Embodiment]
FIG. 5 is a schematic view showing the polarimetric SAR system 1 of the third embodiment. The description is simplified or omitted for the parts common to the above description.

The present embodiment is a case where the antenna is mechanically operated in the yaw direction and the roll direction by the antenna provided with the two-axis drive mechanism fixed to the platform to direct the radio wave to the observation target.

The polarimetric SAR system 1 includes a position / orientation sensor 50 in addition to the polarimetric SAR unit 10, the SAR observation data processing unit 20, the antenna control unit 30, and the control unit 40. The position / attitude sensor 50 outputs the position / attitude information of the platform using GPS.

The polarimetric SAR unit 10 includes an antenna 12 fixed to a platform on which the antenna can be mechanically operated by a two-axis drive mechanism that drives in the yaw direction and the roll direction. The two-axis drive mechanism of the antenna 12 receives a control angle from the antenna control unit 30, and adjusts the antenna angle according to the control angle.

The SAR observation data processing unit 20 includes a polarization rotation processing unit 21. The polarization rotation processing unit 21 corrects the observation data by polarization rotation processing according to the correction angle designated by the control unit 40.

Next, it is a calculation method for calculating the control angle at which the directivity of the antenna is directed to the target and the correction angle of the inclination of the polarization in the polarimetric SAR system 1 (control unit 40) of the third embodiment.

FIG. 6 is a parameter related to the angle used in this embodiment. As shown, the input items are α, β, γ, θ, and β ₀ . The output items are φ _yaw , θ _roll , ΔH, and ΔV. Also, as variables, R _x (xi), R _y (xi), R _z (xi), and R (α, β, γ) are defined as follows. The definition of the variable is the same as that of the second embodiment. Since the same variables are used in the following embodiments, the description thereof will be omitted in the following embodiments.

_{When each parameter is defined as described above, the yaw angle φ yaw} , roll angle θ _roll , and correction angle ΔH, ΔV of the drive mechanism of the antenna 12 are obtained with respect to the input α, β, γ, θ, and β _0. Can be calculated as follows.

As described above, the polarimetric SAR system 1 receives radio waves for polarimetric SAR observation using an antenna 12 having a biaxial mechanism that can rotate in two axes in the yaw direction and the roll direction as a directivity adjustment function. _{Φ yaw} , θ _roll , ΔH, and ΔV, which can accurately correct the gradient of polarization after directing to the target, can be obtained by calculation.

Further, as in the previous embodiment, in the case of a platform that flies in the stratosphere such as an aircraft and the pitch angle during flight is known in advance to be not 0 degrees, the pitch angle in the azimuth direction of the antenna. May be installed with _{β 0} ≠ 0 degrees in order to make it 0 degrees during flight. Even in such a case, _{by setting β 0} correctly, φ _yaw , θ _roll , ΔH, and ΔV can be calculated accurately.

[Fourth Embodiment]
FIG. 7 is a schematic view showing the polarimetric SAR system 1 of the fourth embodiment. The description is simplified or omitted for the parts common to the above description.

In this embodiment, a phased array antenna provided with a uniaxial drive mechanism fixed to a platform is used to mechanically operate the phased array antenna in the roll direction, and the phased array antenna is used to scan radio waves in the azimuth direction. Is aimed at the observation target.

The polarimetric SAR system 1 includes a position / orientation sensor 50 in addition to the polarimetric SAR unit 10, the SAR observation data processing unit 20, the antenna control unit 30, and the control unit 40. The position / attitude sensor 50 outputs the position / attitude information of the platform using GPS.

The polarimetric SAR unit 10 includes a phased array antenna 13 fixed to a platform on which the antenna can be mechanically operated by a uniaxial drive mechanism driven in the roll direction. The uniaxial drive mechanism of the phased array antenna 13 receives a control angle from the antenna control unit 30, and adjusts the antenna angle according to the control angle. Further, the phased array antenna 13 receives a control angle from the antenna control unit 30, and adjusts the directivity of the antenna according to the angle.

The SAR observation data processing unit 20 includes a polarization rotation processing unit 21. The polarization rotation processing unit 21 corrects the observation data by polarization rotation processing according to the correction angle designated by the control unit 40.

Next, it is a calculation method for calculating the control angle at which the directivity of the antenna is directed to the target and the correction angle of the inclination of the polarization in the polarimetric SAR system 1 (control unit 40) of the fourth embodiment.

FIG. 8 is a parameter related to the angle used in this embodiment. As shown, the input items are α, β, γ, θ, β ₀ , and θ ₀ . The output items are φ _Az , θ _roll , ΔH, and ΔV. The definition of the variable is the same as that of the above-described embodiment.

_{When each parameter is defined as described above, the azimuth directional angle φ Az} of the phased array antenna 13 and _{the roll angle θ roll of the} drive mechanism are obtained with respect to the input α, β, γ, θ, β ₀ , and θ _0. The correction angles ΔH and ΔV can be calculated as follows.

As described above, the polarimetric SAR system 1 is provided with a uniaxial mechanism that can rotate in the roll direction as a directivity adjustment function, and the polarimetric SAR observation using the phased array antenna 13 capable of scanning radio waves in the azimuth direction. _{On the other hand, φ Az} , θ _roll , ΔH, and ΔV that can accurately correct the gradient of polarization after directing the radio wave to the target can be obtained by calculation.

Further, as in the previous embodiment, in the case of a platform that flies in the stratosphere such as an aircraft and the pitch angle during flight is known in advance to be not 0 degrees, the pitch angle in the azimuth direction of the antenna. May be installed with _{β 0} ≠ 0 degrees in order to make it 0 degrees during flight. Even in such a case, φ _Az , θ _roll , ΔH, and ΔV can be calculated accurately by _{setting β 0 correctly.}

[Fifth Embodiment]
FIG. 9 is a schematic view showing the polarimetric SAR system 1 of the fifth embodiment. The description is simplified or omitted for the parts common to the above description.

In this embodiment, a phased array antenna provided with a uniaxial drive mechanism fixed to a platform is used to mechanically operate the phased array antenna in the yaw direction, and the phased array antenna scans radio waves in the elevation direction. This is the case when the radio wave is directed to the observation target.

The polarimetric SAR system 1 includes a position / orientation sensor 50 in addition to the polarimetric SAR unit 10, the SAR observation data processing unit 20, the antenna control unit 30, and the control unit 40. The position / attitude sensor 50 outputs the position / attitude information of the platform using GPS.

The polarimetric SAR unit 10 includes a phased array antenna 14 fixed to a platform on which the antenna can be mechanically operated by a uniaxial drive mechanism driven in the roll direction. The uniaxial drive mechanism of the phased array antenna 14 receives a control angle from the antenna control unit 30, and adjusts the antenna angle according to the control angle. Further, the phased array antenna 14 receives a control angle from the antenna control unit 30, and adjusts the directivity of the antenna according to the angle.

The SAR observation data processing unit 20 includes a polarization rotation processing unit 21. The polarization rotation processing unit 21 corrects the observation data by polarization rotation processing according to the correction angle designated by the control unit 40.

Next, it is a calculation method for calculating the control angle at which the directivity of the antenna is directed to the target and the correction angle of the inclination of the polarization in the polarimetric SAR system 1 (control unit 40) of the fifth embodiment.

FIG. 10 shows parameters related to the angle used in this embodiment. As shown, the input items are α, β, γ, θ, β ₀ , and θ ₀ . The output items are φ _Az , θ _roll , ΔH, and ΔV. The definition of the variable is the same as that of the above-described embodiment.

When each parameter is defined as described above, the elevation directivity angle φ _{El of the} phased array antenna 14 and the yaw angle θ _{ryaw of the} drive mechanism are relative to the input α, β, γ, θ, β ₀ , and θ _0. And the correction angles ΔH and ΔV can be calculated as follows.

As described above, the polarimetric SAR system 1 includes a uniaxial mechanism that can rotate in the yaw direction as a directivity adjustment function, and uses a phased array antenna 14 that can scan radio waves in the elevation direction. _{For observation, φ yow} , θ _El , ΔH, and ΔV, which can accurately correct the gradient of polarization after directing the radio wave to the target, can be obtained by calculation.

Further, as in the previous embodiment, in the case of a platform that flies in the stratosphere such as an aircraft and the pitch angle during flight is known in advance to be not 0 degrees, the pitch angle in the azimuth direction of the antenna. May be installed with _{β 0} ≠ 0 degrees in order to make it 0 degrees during flight. Even in such a case, _{by setting β 0} correctly, φ _yow , θ _El , ΔH, and ΔV can be calculated accurately.

As described above, according to the present invention, for a polarimetric SAR observation having a directivity adjustment function, a polarimetric SAR system that accurately corrects the inclination of polarization when directing a radio wave to a target. , And a polarimetric SAR data correction method can be provided.

The present invention has been described by exemplifying embodiments. However, the specific configuration of the present invention is not limited to the above-described embodiment, and is included in the present invention even if there is a change within a range that does not deviate from the gist of the present invention. For example, changes such as separation and merging of the features of the above-described embodiments, changes in switch positions, and replacement of procedures in the flowchart are free as long as the gist of the present invention and the functions described are satisfied, and the above description limits the present invention. It's not something to do. Further, in the above description, the directivity variable antenna unit has been described using a phased array antenna that can scan on one or two axes and a drive mechanism that can move on one or two axes, but the directivity is provided with a three-axis drive mechanism. The present invention may be used for observation using a drive mechanism for two axes of a three-axis mechanism in a polarimetric SAR system having a variable antenna unit.

In addition, some or all of the above embodiments may also be described as follows. The following notes do not limit the present invention in any way.
[Appendix 1]
A polarimetric SAR unit equipped with an antenna configured to change the directivity,
At least, referring to the angle formed by the target based on the platform received as a parameter for directivity of the antenna toward the target, and the attitude angle obtained by referring to the position / orientation information of the platform, the antenna A control unit that calculates the control angle for directivity toward the target and also calculates the correction angle for the slope of polarization.
An antenna control unit that adjusts the directivity of the antenna according to the control angle,
A SAR observation data processing unit that performs polarization rotation processing using the calculated correction angle for the observation data observed by the polarimetric SAR unit according to the control angle.
Polarimetric SAR system characterized by being equipped with.

[Appendix 2]
The control unit uses the attitude angle obtained by referring to the position / orientation information of the platform according to the angle formed by the target based on the platform that receives the directivity of the antenna as a parameter toward the target, and the antenna with the platform. The polarimetric SAR system according to Appendix 1, wherein the control angle and the correction angle are calculated with reference to the mounting angle assembled in the above.

[Appendix 3]
The polarimetric SAR system according to Appendix 1 or 2, wherein the control unit acquires the position / orientation information of the platform from a satellite positioning signal.

[Appendix 4]
The polarimetric SAR system according to any one of Appendix 1 to 3, wherein the polarimetric SAR unit is configured such that the antenna is configured so that the directivity can be changed without using a three-axis mechanism. ..

[Appendix 5]
The polarimetric SAR system according to any one of Supplementary note 1 to 3, wherein the polarimetric SAR unit is configured such that the antenna is configured so that the directivity can be changed by using a two-axis mechanism.

[Appendix 6]
The polarimetric SAR unit according to any one of Supplementary note 1 to 3, wherein the polarimetric SAR unit is configured such that the antenna is configured so that the directivity can be changed by using a phased array antenna and a uniaxial mechanism. Metric SAR system.

[Appendix 7]
The polarimetric SAR unit is configured to have a directivity that can be changed by using a phased array antenna capable of scanning the antenna in the azimuth direction and the elevation direction. Polarimetric SAR system described in section.

[Appendix 8]
The control unit
The attitude angle, which is the position / orientation information of the platform acquired from the satellite positioning signal, and the antenna on the platform according to the off-nadia angle of the target based on the platform received as a parameter for directing the directivity of the antenna to the target. With reference to the assembled mounting angle, the control angle is calculated and the control angle is calculated.
As a correction parameter for polarization rotation processing of observation data observed by the polarimetric SAR unit, the directionality of the antenna is adjusted by the antenna control unit without using a three-axis mechanism according to the control angle. Any one of Appendix 1 to 7, characterized in that the correction angle indicating the inclination of the polarization of the observation data is calculated based on the off-nadia angle, the attitude angle, and the mounting angle. Polarimetric SAR system described in.

[Appendix 9]
The control unit
The attitude angle, which is the position / orientation information of the platform acquired from the satellite positioning signal, and the antenna on the platform according to the off-nadia angle of the target based on the platform received as a parameter for directing the directivity of the antenna to the target. With reference to the assembled mounting angle, the control angle is calculated and the control angle is calculated.
The directionality of the antenna is adjusted by the antenna control unit using the two axes of the three-axis mechanism according to the control angle, and the correction for polarization rotation processing of the observation data observed by the polarimetric SAR unit is performed. As a parameter, any of Appendix 1 to 3, wherein the correction angle indicating the inclination of the polarization of the observation data is calculated based on the off-nadia angle, the attitude angle, and the mounting angle. Or the polarimetric SAR system described in item 1.

[Appendix 10]
A control unit included in a polarimetric SAR system, which comprises an antenna configured so that its directivity can be changed and directs the directivity of the antenna to a target according to a derived control angle.
At least, referring to the angle formed by the target based on the platform received as a parameter for directing the directivity of the antenna toward the target, and the attitude angle obtained by referring to the position / orientation information of the platform, the antenna The control angle for directing the directivity to the target is calculated, and the correction angle indicating the polarization inclination of the observation data is calculated as a correction parameter for the polarization rotation processing of the observation data observed according to the control angle. A program characterized by operating as a control means.

[Appendix 11]
The posture angle obtained by referring to the position and orientation information of the platform according to the angle formed by the target with respect to the platform that received the control unit as a parameter for directing the directivity of the antenna to the target, and the antenna to the platform. The program according to Appendix 10, wherein the program is operated as a control means for calculating the control angle and the correction angle with reference to the mounting angle assembled in the above.

[Appendix 12]
The program according to Appendix 10 or 11, wherein the control unit is operated as a control means for acquiring position / orientation information of a platform from a satellite positioning signal.

[Appendix 13]
The control unit
The attitude angle, which is the position / orientation information of the platform acquired from the satellite positioning signal, and the antenna on the platform according to the off-nadia angle of the target based on the platform received as a parameter for directing the directivity of the antenna to the target. With reference to the assembled mounting angle, the control angle is calculated and the control angle is calculated.
As a correction parameter for polarization rotation processing of observation data observed by the polarimetric SAR unit, the directionality of the antenna is adjusted by the antenna control unit without using a three-axis mechanism according to the control angle. Addendum 10 to 12 characterized by operating as a control means for calculating the correction angle indicating the inclination of the polarization of the observation data based on the off-nadia angle, the attitude angle, and the mounting angle. The program described in any one of the above.

[Appendix 14]
Using a polarimetric SAR system that comprises an antenna configured so that its directivity can be changed and directs the directivity of the antenna to a target according to a derived control angle.
At least, referring to the angle formed by the target based on the platform received as a parameter for directivity of the antenna toward the target, and the attitude angle obtained by referring to the position / orientation information of the platform, the antenna Calculate the control angle to direct the directivity to the target, and calculate the correction angle of the inclination of the polarization.
Adjust the directivity of the antenna according to the control angle,
The target is observed by the polarimetric SAR unit with the antenna whose directivity is adjusted.
A polarimetric SAR data correction method, characterized in that the observation data observed according to the control angle is subjected to polarization rotation processing according to the correction angle in the SAR observation data processing unit.

[Appendix 15]
Using a polarimetric SAR system that comprises an antenna configured so that its directivity can be changed and directs the directivity of the antenna to a target according to a derived control angle.
At least, referring to the angle formed by the target based on the platform received as a parameter for directivity of the antenna toward the target, and the attitude angle obtained by referring to the position / orientation information of the platform, the antenna Calculate the control angle to direct the directivity to the target, and calculate the correction angle for the inclination of the polarization.
Adjust the directivity of the antenna according to the control angle,
The target is observed by the polarimetric SAR unit with the antenna whose directivity is adjusted.
A polarimetric SAR data correction method, characterized in that the observation data observed according to the control angle is subjected to polarization rotation processing according to the correction angle in the SAR observation data processing unit.

[Appendix 16]
The attitude angle obtained by referring to the position and orientation information of the platform according to the angle formed by the target based on the platform received as the parameter for directing the antenna to the target, and the mounting angle when the antenna is assembled to the platform. The polarimetric SAR data correction method according to Appendix 15, wherein the control angle and the correction angle are calculated with reference to the above.

[Appendix 17]
The polarimetric SAR data correction method according to Appendix 15 or 16, wherein the position / orientation information of the platform is acquired from a satellite positioning signal.

[Appendix 18]
The attitude angle, which is the position / orientation information of the platform acquired from the satellite positioning signal, and the antenna on the platform according to the off-nadia angle of the target based on the platform received as a parameter for directing the directivity of the antenna to the target. With reference to the assembled mounting angle, the control angle is calculated and the control angle is calculated.
The off-nadia angle is used as a correction parameter for polarization rotation processing of the observation data observed by the polarimetric SAR unit by adjusting the directivity of the antenna according to the control angle without using the 3-axis mechanism. The polari according to any one of Appendix 15 to 17, wherein the correction angle indicating the inclination of the polarization of the observation data is calculated based on the attitude angle and the mounting angle. Metric SAR data correction method.

1 Polarimetric SAR system 10 Polarimetric SAR section 11 to 14 Antenna (directional variable antenna section)
20 SAR observation data processing unit 21 Polarization rotation processing unit 30 Antenna control unit 40 Control unit 50 Position / orientation sensor

Claims (10)

A polarimetric SAR unit equipped with an antenna configured to change the directivity,
At least, referring to the angle formed by the target based on the platform received as a parameter for directivity of the antenna toward the target, and the attitude angle obtained by referring to the position / orientation information of the platform, the antenna A control unit that calculates the control angle for directivity toward the target and also calculates the correction angle for the slope of polarization.
An antenna control unit that adjusts the directivity of the antenna according to the control angle,
A SAR observation data processing unit that performs polarization rotation processing using the calculated correction angle for the observation data observed by the polarimetric SAR unit according to the control angle.
Polarimetric SAR system characterized by being equipped with. The control unit uses the attitude angle obtained by referring to the position / orientation information of the platform according to the angle formed by the target based on the platform that receives the directivity of the antenna as a parameter toward the target, and the antenna with the platform. The polarimetric SAR system according to claim 1, wherein the control angle and the correction angle are calculated with reference to the mounting angle assembled in the above. The polarimetric SAR system according to claim 1 or 2, wherein the control unit acquires the position / orientation information of the platform from a satellite positioning signal. The polarimetric SAR unit according to any one of claims 1 to 3, wherein the polarimetric SAR unit is configured so that the directivity of the antenna can be changed without using a three-axis mechanism. system. The polarimetric SAR system according to any one of claims 1 to 3, wherein the polarimetric SAR unit is configured such that the antenna is configured so that the directivity can be changed by using a two-axis mechanism. .. The polarimetric SAR unit according to any one of claims 1 to 3, wherein the polarimetric SAR unit is configured such that the antenna is configured so that the directivity can be changed by using a phased array antenna and a uniaxial mechanism. Remetric SAR system. Any of claims 1 to 3, wherein the polarimetric SAR unit is configured such that the directivity can be changed by using a phased array antenna capable of scanning the antenna in the azimuth direction and the elevation direction. The polarimetric SAR system described in paragraph 1. The control unit
The attitude angle, which is the position / orientation information of the platform acquired from the satellite positioning signal, and the antenna on the platform according to the off-nadia angle of the target based on the platform received as a parameter for directing the directivity of the antenna to the target. With reference to the assembled mounting angle, the control angle is calculated and the control angle is calculated.
As a correction parameter for polarization rotation processing of observation data observed by the polarimetric SAR unit, the directionality of the antenna is adjusted by the antenna control unit without using a three-axis mechanism according to the control angle. Any one of claims 1 to 7, wherein the correction angle indicating the inclination of the polarization of the observation data is calculated based on the off-nadia angle, the attitude angle, and the mounting angle. Polarimetric SAR system described in section. A control unit included in a polarimetric SAR system, which comprises an antenna configured so that its directivity can be changed and directs the directivity of the antenna to a target according to a derived control angle.
At least, referring to the angle formed by the target based on the platform received as a parameter for directing the directivity of the antenna toward the target, and the attitude angle obtained by referring to the position / orientation information of the platform, the antenna The control angle for directing the directivity to the target is calculated, and the correction angle indicating the polarization inclination of the observation data is calculated as a correction parameter for the polarization rotation processing of the observation data observed according to the control angle. A program characterized by operating as a control means. Using a polarimetric SAR system that comprises an antenna configured so that its directivity can be changed and directs the directivity of the antenna to a target according to a derived control angle.
At least, referring to the angle formed by the target based on the platform received as a parameter for directivity of the antenna toward the target, and the attitude angle obtained by referring to the position / orientation information of the platform, the antenna Calculate the control angle to direct the directivity to the target, and calculate the correction angle of the inclination of the polarization.
Adjust the directivity of the antenna according to the control angle,
The target is observed by the polarimetric SAR unit with the antenna whose directivity is adjusted.
A polarimetric SAR data correction method, characterized in that the observation data observed according to the control angle is subjected to polarization rotation processing according to the correction angle in the SAR observation data processing unit.

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