JP4902868B2 - Information processing apparatus and program - Google Patents

Description

  The present invention relates to an interferometric synthetic aperture radar technique for obtaining an image (synthetic aperture radar image and digital altitude model) including altitude information by observing the ground surface and mounted on a flying body such as an aircraft or a satellite. Is.

Synthetic Aperture Radar is mounted on a mobile platform such as an aircraft or satellite, and performs observation by transmitting and receiving radio waves to the side while moving, and processing the obtained data to obtain a two-dimensional high-resolution image of the observation area. This is a radar capable of obtaining a synthetic aperture radar image.
Interferometric synthetic aperture radar is a radar that can obtain altitude information (numerical altitude model) of an observation area using two synthetic aperture radar images obtained by observing the same point from different positions (for example, a digital elevation model). Patent Document 1).
This process for obtaining altitude information is called an interferometry process.
JP 2004-191053 A

The interferometric synthetic aperture radar obtains the difference in phase information from two synthetic aperture radar images and converts the difference in phase information into altitude information to obtain altitude information in the observation region.
Conversion from this phase information difference to altitude information requires the value of the incident angle to the observation region (observation target), and the altitude information of the own aircraft is required to obtain the value of the incident angle.
For this reason, in a general interference type synthetic aperture radar, the altitude information of its own device is measured by mounting a GPS (Global Positioning System) antenna on the airframe.
However, since GPS has high position accuracy but low altitude accuracy and an error, there is a problem that an error occurs in the obtained altitude information of the observation area.

  One of the main objects of the present invention is to solve such a problem, and is characterized by suppressing an error included in altitude information of an observation region and performing highly accurate altitude measurement.

An information processing apparatus according to the present invention includes:
An information processing device mounted on a flying object,
A pulse signal transmitted from any one of the three or more antennas arranged on the flying object, reflected by the observation target and received by the three or more antennas is acquired, Information on the motion status, position and altitude of the flying object is obtained from a sensor that measures the motion status, position and altitude, and three information are obtained using the pulse signal and information on the motion status, position and altitude of the flying object. An image generation unit for generating the above two-dimensional image;
A first altitude information generating unit that generates two or more altitude information indicating the altitude of the observation target using the three or more two-dimensional images generated by the image generating unit;
An error estimator that estimates an error included in altitude information using the two or more altitude information generated by the first altitude information generator and the positional relationship of the three or more antennas;
And a second altitude information generation unit that generates altitude information indicating the altitude of the observation target after error correction using the error estimated by the error estimation unit.

  According to the present invention, the error included in the altitude information is estimated using two or more altitude information about the observation target and the positional relationship of three or more antennas, and the error is corrected using the estimated error. Thus, since the altitude of the observation target is measured, an error included in the altitude information can be suppressed and highly accurate altitude measurement can be performed.

Embodiment 1 FIG.
In this embodiment, an interferometric synthetic aperture radar device that is mounted on a flying body such as an aircraft or an artificial satellite and obtains a high-resolution image and altitude information of the ground surface, the altitude information of the ground surface due to the measurement error of its own altitude. An interference-type synthetic aperture radar apparatus that can estimate and compensate for errors will be described.

FIG. 1 is a configuration diagram showing a configuration example of an interference synthetic aperture radar apparatus 100 according to Embodiment 1 of the present invention.
The interferometric synthetic aperture radar apparatus 100 is mounted on a flying object such as an aircraft or an artificial satellite.
Moreover, the range enclosed with the broken line among the components of the interference type synthetic aperture radar apparatus 100 is an example of the information processing apparatus 200 according to the present invention.

In FIG. 1, reference numerals 1 to 3 denote antennas A, B, and C, which are parts mounted on a mobile platform such as an aircraft or an artificial satellite, and these require the positional relationship shown in FIG.
In FIG. 2, the moving platform moves in a direction perpendicular to the paper surface, and the antennas A to C are arranged in a straight line within a plane parallel to the paper surface.
In the conventional interferometric synthetic aperture radar, there are only two antennas, and this configuration is one of the features of this apparatus.
In the interferometric synthetic aperture radar, a straight line connecting two antennas that perform interferometry processing is referred to as a baseline. However, in the configuration of the present apparatus, baselines having the same inclination from the horizontal plane and different lengths are required.
Specifically, as shown in FIG. 2, the area between the antenna A and the antenna B is called a baseline 1, and the area between the antenna A and the antenna C is called a baseline 2.
Further, the distance between antennas, that is, the length of the baseline is referred to as a baseline distance.

The antenna A is a part that radiates the high-frequency pulse signal generated by the signal transmission / reception unit 2 to the space, and the antennas A to C are reflected by the reflected signal of the high-frequency pulse signal, that is, the observation region (observation target). This is the part that receives the high-frequency pulse signal.
The sway sensor 4 includes an inertial sensor that measures the movement status (speed, acceleration, posture, etc.) of the mobile platform and a GPS (Global Positioning System) antenna that measures the position and altitude of the mobile platform.
The signal transmission / reception unit 5 generates a high-frequency pulse signal and sends it to the antenna A, and constitutes transmission / reception means for amplifying signals received by the antennas A to C.
From the signal received from the signal transmission / reception unit 5 and the information on the motion state and position of the platform and the altitude measured by the motion sensor 4, the image reproduction processing unit 6 is a synthetic aperture radar image (two-dimensional high-resolution image). Image).
The synthetic aperture radar image 7 is image data generated by the image reproduction processing unit 6 and is generated for each of the data of the antennas A to C.
That is, the image reproduction processing unit 6 transmits a pulse signal transmitted from one of the three antennas arranged on the mobile platform (flying object) and reflected by the observation target and received by the three antennas. Acquire the movement status, position and altitude information of the mobile platform from the sensors that acquire and measure the movement status, position and altitude of the mobile platform, and use the pulse signal and the motion status, position and altitude information of the mobile platform A synthetic aperture radar image 7 that is three two-dimensional images is generated.
The image reproduction processing unit 6 is an example of an image generation unit.

The interferometry processing unit 8 generates altitude information of the observation area from the two synthetic aperture radar images.
The observation area altitude information 9 is altitude information indicating the altitude of the observation area (observation target). Two pieces of altitude information can be obtained by combining two of the three synthetic aperture radar images.
That is, the interferometry processing unit 8 generates two pieces of altitude information indicating the altitude of the observation region using the three synthetic aperture radar images generated by the image reproduction processing unit 6.
The interferometry processing unit 8 is an example of a first altitude information generation unit.
Note that the observation area altitude information 9 generated by the interferometry processing unit 8 generally includes an error, as will be described in detail later.

The two-baseline error estimation unit 10 estimates an error included in altitude information from two altitude information obtained under the conditions of two baselines having the same inclination from the horizontal plane and different lengths.
That is, the 2-baseline error estimation unit 10 estimates the error included in the altitude information using the two altitude information generated by the interferometry processing unit 8 and the positional relationship between the three antennas.
Specifically, the error estimation unit 10 using two baselines uses two baseline distances having different lengths, which are the distances between the three antennas, and uses the incident angle ( Estimate the error of off-nadir angle.
The error in the incidence angle (off-nadir angle) of the high-frequency pulse signal to the observation area is the actual incidence angle (off-nadir angle) in the observation area of the high-frequency pulse signal transmitted from the antenna A and the self-measured by GPS. This means the difference from the incident angle (off-nadir angle) of the calculated high-frequency pulse signal calculated using the machine altitude.
The 2-baseline error estimation unit 10 is an example of an error estimation unit.

The interferometry reprocessing unit 11 performs the interferometry processing again using the corrected incident angle to the observation region.
By performing this processing, it is possible to obtain the altitude information 12 of the observation region in which the error is suppressed.
That is, the interferometry reprocessing unit 11 generates altitude information indicating the altitude after error correction of the observation region, using the error (incident angle error) estimated by the error estimation unit 10 based on two baselines.
The interferometry reprocessing unit 11 is an example of a second altitude information generation unit.

  In the present apparatus, at least two baseline error estimation unit 10 and interferometry reprocessing unit 11 are not included in the conventional configuration, and are newly added parts in the present apparatus.

In addition, in this apparatus, the observation conditions are limited, and it is desirable that the difference between the incident angle (off-nadir angle) to the observation region and the baseline inclination is 10 degrees or less.
The above conditions are often used for interferometric synthetic aperture radar because its performance is highest when the incident angle (off-nadir angle) to the observation region is equal to the slope of the baseline.
Also in this apparatus, it is desirable that the difference between the incident angle (off-nadir angle) to the observation region and the inclination of the baseline is small. For example, it is more desirable that the difference between the two is about 0 to 5 degrees.

  Next, the principle by which the error of altitude information in the observation area can be suppressed by the configuration of this apparatus will be described.

First, consider the geometric conditions of observation shown in FIG.
In the radar, the phase information of the signal is proportional to the distance (slant range) between the antenna and the observation area.
Therefore, when the phase difference φ of the signals observed at the same point with the antennas S1 and S2 is obtained, the following equation is obtained from the geometric relationship.

  Here, λ is the radar wavelength, B is the length of the baseline, θ is the incident angle, α is the slope of the baseline, h is the altitude of the observation region, H is the altitude of the aircraft, and r is the slant range.

  With respect to these equations 1 and 2, the following equation is obtained as a phase change with respect to an altitude change by differentiating θ as a parameter.

  By integrating this with respect to φ, the following equation is obtained.

  In the conventional interferometry processing, the phase information is converted into altitude information in the observation region using this equation.

  Here, θ is considered. As shown in FIG. 5, θ is obtained from the aircraft altitude H and the slant range r by the following equation.

For this reason, if there is an error in its own altitude H, an error occurs in θ. If there is an error in θ, an error occurs in the altitude information h in the observation region from Equation 4 (see FIG. 5C)).
Here, when the error of θ is dθ and the altitude information of the observation region where the error occurs is h ′, the following equation is obtained.

  In the radar, since the slant range is at least several kilometers and the error of H by the GPS antenna is about several meters to several tens of meters, dθ << 1. Therefore, Equation 6 is approximated under the condition of dθ << 1, and the following equation is obtained.

Further, the following equation is obtained by approximating Equation 7 from | θ−α | << 1, which is the limitation of the observation condition described above.

In contrast, the lengths of the two baselines are B ₁ and B _2, and the height information of the observation region at that time is h ₁ ′ and h ₂ ′. When this difference dh ′ is obtained, the following equation is obtained.

From this, it can be seen that dh ′ is proportional to dθ, and therefore it is possible to obtain dθ from dh ′. Therefore, by performing the interferometry process again using the obtained dθ, it is possible to obtain altitude information of the observation region in which the error is suppressed.

When dθ is obtained from dh ′ using Equation 9, θ in the parentheses on the right side of Equation 9 is θ in which an error is suppressed in the equation, but an actually known value has an error. θ. For this reason, an error remains in calculating dh ′.
Since this error is a minute term, it can be ignored in an approximate manner. However, by performing a convergence operation in which the processes of the interferometry processing unit 8 to the interferometry reprocessing unit 11 are repeatedly performed, the error can be further reduced. It is also possible to suppress it.

Hereinafter, an example of the operation of the interferometric synthetic aperture radar apparatus 100 according to the present embodiment will be described based on the above-described observational geometric conditions. First, the above equations 1 to 9 were used as the premise of the description. The coefficient will be described.
λ (radar wavelength) is information stored in advance in a storage device (not shown) of the interference type synthetic aperture radar device 100.
B (baseline distance) is information stored in advance in the storage device of the interferometric synthetic aperture radar apparatus 100.
θ (incidence angle (off-nadir angle)) is information obtained by the interferometry processing unit 8 using Equation 5 during the interferometry processing.
α (baseline inclination) is information stored in advance in the storage device of the interferometric synthetic aperture radar apparatus 100.
h (the altitude of the observation region) is information that the interferometry processing unit 8 obtains from the synthetic aperture radar image 7 by interferometry processing.
H (own device altitude) is information measured by the motion sensor 4.
r (slant range) is information stored in advance in the storage device of the interferometric synthetic aperture radar apparatus 100.

  Next, an operation example of the interference-type synthetic aperture radar apparatus 100 according to the present embodiment will be described using the flowchart of FIG.

First, the antenna A radiates the high-frequency pulse signal generated by the signal transmission / reception unit 5 into space. The antennas A to C receive reflected signals that are radiated into space and reflected from the ground surface.
Further, the signal transmission / reception unit 2 amplifies signals received by the antennas A to C. At that time, the motion sensor 4 measures the movement and position information of the mobile platform (step S1).

The image reproduction processing unit 6 acquires the pulse signals received by the antennas A to C from the signal transmission / reception unit 5, acquires the platform motion status and position, and altitude information measured by the motion sensor 4. From the signal, platform motion status and position, and altitude information, the image reproduction processing unit 6 performs image reproduction processing to reproduce a synthetic aperture radar image that is a two-dimensional high resolution image.
At this time, the image reproduction process is performed for each of the data of the antennas A to C, and three synthetic aperture radar images 7 are obtained (step S2) (image generation step).

Next, the interferometry processing unit 8 performs interferometry processing.
Among the processes of the interferometry processing unit 8, S3 to S8 are realized by an existing method, and can be realized by, for example, the method disclosed in Patent Document 1. However, it is not necessarily limited to the method described in Patent Document 1, and other methods may be used.
The difference from the prior art is that two combinations for selecting two of the three synthetic aperture radar images 7 are picked up, and interferometry processing is performed for each combination to obtain altitude information 9 for two observation regions. In the past, two synthetic aperture radar images were processed once to obtain one altitude information of the observation area.
In the phase advanced conversion step (S7), interferometry processing unit 8, using Equation 4 above, two highly information altitude information h ₂ about altitude information h ₁ and baseline 2 for baseline 1 Is calculated.
Specifically, the altitude information h ₁ for the baseline ₁ is calculated by substituting the baseline distance of the baseline 1 into the coefficient B of the equation 4, and the baseline distance of the baseline 2 is substituted into the coefficient B of the equation 4. Then, altitude information h2 for the baseline ₂ is calculated.
Note that the coefficient θ included in Equation 4 may be calculated using Equation 5 before the phase height conversion step (S7), or may be calculated during the phase height conversion step (S7). .
In addition, the altitude information h ₁ and h ₂ calculated by the interferometry processing unit 8 using Equation 4 is influenced by the own altitude H measured by the GPS, which is not highly accurate (see Equation 5). The altitude information h ₁ and h ₂ actually includes an error as shown in Equation 8, and it is necessary to remove this error.

Therefore, the error estimation unit 10 based on two baselines obtains an error of the incident angle (off nadir angle) to the observation region from the height information h ₁ and h _{2 of the two} observation regions.
As described above, the altitude information h ₁ and h ₂ of the two observation regions includes an error as shown in Expression 8, and thus the altitude information h ₁ and h ₂ are represented by h1 ′ and h2 in Expression 9. Equivalent to '. Further, the error of the incident angle to the observation region corresponds to dθ in Equation 9.
Therefore, the 2-baseline error estimation unit 10 obtains dθ from h1 ′ and h2 ′ using Equation 9 (step S9) (error estimation step).

Next, the interferometry reprocessing unit 11 corrects θ with dθ obtained by the error estimation unit 10 based on two baselines, and the interferometry reprocessing unit 11 performs interferometry processing again, and after error suppression The altitude information 12 of the observation area is obtained (steps S10 to S15).
Specifically, the interferometry reprocessing unit 11 performs the calculation of Expression 4 by adding dθ to θ of Expression 4 in the phase height conversion step (second height information generation step) of S14.
That is, by performing the calculation shown in the following Expression 10, h (the height of the observation region) from which the error has been removed can be obtained.

Of the processes of the interferometry reprocessing unit 11, S10 to S15 are the same as S3 to S8 of the interferometry processing unit 8 and can be realized by existing technology, and thus description thereof is omitted.
As shown in FIG. 7, the interferometry reprocessing unit 11 may omit the processes of S10 to S13, directly perform the phase height conversion step of S14, and perform the calculation of Equation 10 above. Good.

In the above description, there are three antennas. For this reason, there are three synthetic aperture radar images and two height information in the observation area. However, four or more antennas may be used. is there.
For example, if there are four antennas, there will be four synthetic aperture radar images and three observation area altitude information. When the altitude information of the observation area is h ₁ ′, h ₂ ′, h ₃ ′, two errors dθ are obtained as dθ ₁ = h ₁ ′ −h ₂ ′ and dθ ₂ = h ₁ ′ −h ₃ ′. Derived. The average of the two error d [theta] ₁ and d [theta] _2, by substituting the equation 10, when four and the antenna can be obtained even h the error is eliminated (high observation area).
Similarly, when the number of antennas is five or more, h (the height of the observation region) from which errors are removed can be obtained using the average value of a plurality of errors dθ.

As described above, according to the present embodiment, in the interference-type synthetic aperture radar device that is mounted on a mobile platform such as an aircraft or an artificial satellite and obtains a high-resolution image and altitude information of the ground surface, It is possible to estimate and compensate for errors in altitude information on the ground surface.
In other words, three or more antennas are arranged linearly in a plane perpendicular to the aircraft axis, and two pieces of altitude information of the interferometric synthetic aperture radar image are obtained, and an error is estimated from the difference in the obtained height information. Thus, the altitude error on the ground surface can be suppressed by performing the compensation type synthetic aperture radar processing again. As a result, highly accurate three-dimensional information about the terrain can be acquired.

As described above, in the present embodiment, the interference type synthetic aperture radar apparatus having the following configuration has been described.
(A) Three or more antennas mounted on a mobile platform such as an aircraft or a satellite and arranged linearly in a plane perpendicular to the aircraft axis;
(B) a vibration sensor composed of an inertial sensor for measuring the movement of the mobile platform and a GPS antenna for measuring the position and altitude of the mobile platform;
(C) A signal transmission / reception unit constituting a transmission / reception means for amplifying a signal received by the antenna while generating a high-frequency pulse signal and sending it to the antenna;
(D) an image reproduction processing unit that reproduces a synthetic aperture radar image, which is a two-dimensional high-resolution image, from the signal received from the signal transmission / reception unit and the platform motion and position information measured by the motion sensor;
(E) an interferometry processing unit that generates altitude information of an observation area from two synthetic aperture radar images;
(F) a two-baseline error estimator that calculates an error in the incident angle to the observation region from two height information obtained under the conditions of two baselines having the same inclination from the horizontal plane and different lengths;
(G) an interferometry reprocessing unit for performing interferometry processing again using the corrected incident angle to the observation region;
(H) An observation condition in which the difference between the incident angle to the observation region and the inclination of the baseline from the horizontal plane is several degrees or less.

Embodiment 2. FIG.
FIG. 3 is a block diagram showing a configuration example of an interference-type synthetic aperture radar apparatus 100 that is a high-resolution radar apparatus according to Embodiment 2 of the present invention. Compared to Embodiment 1, an error estimation unit based on a different baseline inclination is shown. 13 and the arrangement method of the antennas A to C are different.

  As shown in FIG. 4, the antennas A to C are arranged such that the base lines formed by the antennas A, B, and C have the same length, and the inclinations of the respective base lines with respect to the horizontal plane are different.

  The error estimation unit 13 based on different baseline inclinations is a part for obtaining an error in incident angle to the observation region from two altitude information obtained under the conditions of two baselines having the same length and different inclinations from the horizontal plane. is there.

  The equation by which the error estimation unit 13 based on different baseline inclinations calculates the error of the incident angle to the observation region from the two altitude information can be obtained in the same manner as in the first embodiment, and is the following equation.

Here, α ₁ indicates the inclination of the baseline 1 (baseline between the antenna A and the antenna B) with respect to the horizontal plane, and α ₂ indicates the inclination of the baseline 2 (baseline between the antenna A and the antenna C) with respect to the horizontal plane. Indicates.
The difference from Equation 9 is that, in Equation 9, baseline distances B ₁ and B _{2 of} different lengths were included, but in Equation 11, inclinations α ₁ and α ₂ with respect to the horizontal plane for each baseline were included. It is a point.

In the present embodiment, in the flowchart of FIG. 6 or FIG. 7, an error estimation step based on the slopes of different baselines is performed instead of the error estimation step based on two baselines (S9). The same processing as the processing shown in FIG. 6 or FIG. 7 is performed except for the error estimation step due to different baseline inclinations.
In the error estimation step based on different baseline inclinations, the angle of incidence on the observation region is calculated using Expression 11 instead of Expression 9 for the _two altitude information h ₁ and h ₂ derived in the interferometry process. An error dθ is obtained.
Then, in the interferometry reprocessing, the error dθ obtained by the error estimation processing based on the different slopes of the baselines is substituted into Equation 10 to obtain altitude information in which the error is suppressed.

As described above, in the present embodiment, the interference type synthetic aperture radar apparatus having the following configuration has been described.
(A) Three or more antennas mounted on a mobile platform such as an aircraft or a satellite and arranged linearly in a plane perpendicular to the aircraft axis;
(B) a vibration sensor composed of an inertial sensor for measuring the movement of the mobile platform and a GPS antenna for measuring the position and altitude of the mobile platform;
(C) A signal transmission / reception unit constituting a transmission / reception means for amplifying a signal received by the antenna while generating a high-frequency pulse signal and sending it to the antenna;
(D) an image reproduction processing unit that reproduces a synthetic aperture radar image, which is a two-dimensional high-resolution image, from the signal received from the signal transmission / reception unit and the platform motion and position information measured by the motion sensor;
(E) an interferometry processing unit that generates altitude information of an observation area from two synthetic aperture radar images;
(F) an error estimator based on different baseline inclinations for obtaining an error in incident angle to the observation region from two height information obtained under the conditions of two baselines having the same length and different inclinations from the horizontal plane;
(G) an interferometry reprocessing unit for performing interferometry processing again using the corrected incident angle to the observation region;
(H) An observation condition in which the difference between the incident angle to the observation region and the inclination of the baseline from the horizontal plane is several degrees or less.

Finally, a hardware configuration example of the information processing apparatus 200 shown in the first and second embodiments will be described.
The information processing apparatus 200 includes a CPU (Central Processing Unit, a central processing unit, a processing unit, a processing unit, a microprocessor, a microcomputer, and a processor) that executes a program. The CPU is connected to, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), a magnetic disk device, and the like via the bus, and controls these hardware devices.
For example, an operating system (OS), a program group, and a file group are stored in the magnetic disk device. The programs in the program group are executed by the CPU and operating system.

In the program group, programs for executing the functions described as “˜units” in the description of the first and second embodiments are stored. The program is read and executed by the CPU.
In the description of the first and second embodiments, the file group includes “determination of”, “calculation of”, “comparison of”, “measurement of”, “estimation of”, and “conversion of”. , Information, data, signal values, variable values, and parameters indicating the results of the processing described as “to create” are stored as items of “to file” and “to database”. The “˜file” and “˜database” are stored in a recording medium such as a disk or a memory. Information, data, signal values, variable values, and parameters stored in a storage medium such as a disk or memory are read out to the main memory or cache memory by a CPU via a read / write circuit, and extracted, searched, referenced, compared, Used for CPU operations such as calculation, calculation, processing, editing, and output. Information, data, signal values, variable values, and parameters are stored in the main memory, registers, cache memory, buffer memory, etc. during CPU operations such as extraction, search, reference, comparison, calculation, calculation, processing, editing, and output. Temporarily stored.
The arrows in the flowcharts described in the first and second embodiments mainly indicate input / output of data and signals, and the data and signal values are RAM memory, magnetic disk of magnetic disk device, and other recording media. To be recorded.

  In addition, what is described as “˜unit” in the description of the first and second embodiments may be “˜circuit”, “˜device”, “˜device”, and “˜step”. , “˜procedure”, and “˜processing”. That is, what is described as “˜unit” may be realized by firmware stored in the ROM. Alternatively, it may be implemented only by software, or only by hardware such as elements, devices, substrates, and wirings, by a combination of software and hardware, or by a combination of firmware. Firmware and software can be recorded as a program on a recording medium such as a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD. The program is read by the CPU and executed by the CPU. That is, the program causes the computer to function as the “˜unit” in the first and second embodiments. Alternatively, the computer executes the procedure and method of “to unit” in the first and second embodiments.

It is a figure which shows the structural example of the interference type synthetic aperture radar apparatus by Embodiment 1 of this invention. It is a figure which shows the example of arrangement | positioning of the antenna of the interference type synthetic aperture radar apparatus by Embodiment 1 of this invention. It is a figure which shows the structural example of the interference type synthetic aperture radar apparatus by Embodiment 2 of this invention. It is a figure which shows the example of arrangement | positioning of the antenna of the interference type synthetic aperture radar apparatus by Embodiment 2 of this invention. It is a figure which shows the geometric condition of observation for demonstrating the subject which this invention solves. It is a flowchart figure which shows the operation example of the interference type synthetic aperture radar apparatus by Embodiment 1 of this invention. It is a flowchart figure which shows the operation example of the interference type synthetic aperture radar apparatus by Embodiment 1 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Antenna A, 2 Antenna B, 3 Antenna C, 4 Motion sensor, 5 Signal transmission / reception part, 6 Image reproduction process part, 7 Synthetic aperture radar image, 8 Interferometry process part, 9 Altitude information of observation area, 10 2 base Error estimation unit by line, 11 Interferometry reprocessing unit, 12 Height information of observation area after error suppression, 13 Error estimation unit by different baseline inclination, 100 Interferometric synthetic aperture radar device, 200 Information processing device.

Claims (9)

An information processing device mounted on a flying object,
A pulse signal transmitted from one of the three antennas arranged on the flying object, reflected by the observation target and received by the three antennas is obtained, and the movement state and position of the flying object And information on the movement state, position and altitude of the flying object from a sensor for measuring altitude, and using the pulse signal and information on the movement state, position and altitude of the flying object, three two- dimensional images are obtained. An image generator to generate;
Using the three two-dimensional image generated by the image generating unit, the first altitude information generation for two generate an observation target altitude information indicating an altitude observation target altitude of the observed object that contains errors And
Using the two observation target altitude information generated by the first altitude information generation unit and the positional relationship between the three antennas , the actual incident angle of the pulse signal transmitted from the antenna to the observation target And the difference between the calculated incident angle of the pulse signal calculated using the altitude of the flying object acquired from the sensor and the incident angle of the pulse signal to the observed object as an error. An error estimator to estimate;
Using the error estimated by the error estimator, it possesses a second altitude information generating unit for generating altitude information indicating altitude after error correction of the observed object,
The error estimator is
Using the difference between the two observation target altitudes indicated in the two observation target altitude information and the baseline distance that is the distance between the antennas of the three antennas, the incident angle of the pulse signal to the observation target is determined. An information processing apparatus characterized by estimating an error . The image generation unit
Obtaining pulse signals received by three antennas arranged linearly on the aircraft,
The error estimator is
Using the difference between the two observation object altitudes and the two baseline distances of the three antennas having different lengths to estimate the error in the incident angle of the pulse signal to the observation object ; The information processing apparatus according to claim 1 . The error estimator is
The information processing apparatus according to claim 2, wherein an error of an incident angle of the pulse signal to the observation target is estimated by the following equation.

Where dh 'is the difference between the two observation altitudes, h ₁ 'And h ₂ ′ Is the two observation object altitudes, dθ is the error of the incident angle of the pulse signal to the observation object, and B ₁ And B ₂ Is the two baseline distances, θ is the calculated incident angle of the pulse signal to the observation object, λ is the wavelength of the pulse signal, r is the strange range to the observation object, α is the baseline Is the inclination relative to the horizontal plane, π is the pi, and φ is the phase difference of signals observed at the same point with two antennas. The information processing apparatus includes:
4. The information processing apparatus according to claim 2 , wherein the information processing apparatus is mounted on a flying body in which a difference between an inclination of a baseline connecting the three antennas with respect to a horizontal plane and an off-nadir angle is 10 degrees or less. The image generation unit
Acquire pulse signals received by three antennas arranged so that the baselines connecting the antennas with respect to the horizontal plane have different inclinations for each baseline and the baseline distances are equal to each other,
The error estimator is
Using the difference between the two observation object altitudes, the baseline distance, and the inclination of each baseline with respect to the horizontal plane to estimate the error of the incident angle of the pulse signal to the observation object, The information processing apparatus according to claim 1. The error estimator is
6. The information processing apparatus according to claim 5, wherein an error in an incident angle of the pulse signal to the observation target is estimated by the following equation.

Where dh 'is the difference between the two observation altitudes, h ₁ 'And h ₂ 'Is the two observation object altitudes, dθ is the error of the incident angle of the pulse signal to the observation object, B is the baseline distance, and θ is the calculated incident angle of the pulse signal to the observation object , Λ is the wavelength of the pulse signal, r is the strange range to the observation object, α ₁ And α ₂ Is the inclination of the two baselines with respect to the horizontal plane, π is the pi, and φ is the phase difference of the signals observed at the same point with the two antennas. The image generation unit
Examples 3 two-dimensional images, three raw form a synthetic aperture radar image is a two-dimensional high-resolution image,
The first altitude information generation unit
Wherein performing interferometry process using three synthetic aperture radar image generated by the image generation unit, in any one of claims 1 to 6, characterized in that two generate the observation target altitude information The information processing apparatus described. An information processing device mounted on a flying object,
A pulse signal transmitted from any one of the four or more antennas arranged on the flying object, reflected by the observation target and received by the four or more antennas is acquired, Information on the movement status, position, and altitude of the flying object is acquired from a sensor that measures the movement status, position, and altitude. Using the pulse signal and information on the movement status, position, and altitude of the flying object, four information are obtained. An image generation unit for generating the above two-dimensional image;
A first altitude that generates three or more observation target altitude information indicating an observation target altitude that is an altitude of the observation target including an error, using the four or more two-dimensional images generated by the image generation unit. An information generator,
Using the three or more observation target altitude information generated by the first altitude information generation unit and the positional relationship of the four or more antennas, a pulse signal transmitted from an antenna is transmitted to the observation target. The difference between the actual incident angle and the calculated incident angle of the pulse signal calculated by using the altitude of the flying object acquired from the sensor to the observation target is the incidence of the pulse signal on the observation target. An error estimator for estimating the angle error;
A second altitude information generating unit that generates altitude information indicating the altitude after error correction of the observation target, using the error estimated by the error estimating unit;
The error estimator is
The difference between the two observation target altitudes indicated in the two observation target altitude information of the three or more observation target altitude information and the pulse signal that is the basis for generating the two observation target altitude information are received. An information processing apparatus that estimates an error of an incident angle of a pulse signal to the observation target using a baseline distance that is an inter-antenna distance among the three antennas. On the computer mounted on the aircraft,
A pulse signal transmitted from one of the three antennas arranged on the flying object, reflected by the observation target and received by the three antennas is obtained, and the movement state and position of the flying object And information on the movement state, position and altitude of the flying object from a sensor for measuring altitude, and using the pulse signal and information on the movement state, position and altitude of the flying object, three two- dimensional images are obtained. Image generation processing to generate,
Using the three two-dimensional image generated by the image generation processing, first altitude information generation for two generate an observation target altitude information indicating an altitude observation target altitude of the observed object that contains errors Processing,
Using the two observation target altitude information generated by the first altitude information generation process and the positional relationship between the three antennas , an actual incident angle of the pulse signal transmitted from the antenna to the observation target And the difference between the calculated incident angle of the pulse signal calculated using the altitude of the flying object acquired from the sensor and the incident angle of the pulse signal to the observed object as an error. An error estimation process to be estimated;
Using the error estimated by the error estimation process, a second altitude information generation process for generating altitude information indicating the altitude after error correction of the observation target is executed,
In the error estimation process,
In the computer,
Using the difference between the two observation target altitudes indicated in the two observation target altitude information and the baseline distance that is the distance between the antennas of the three antennas, the incident angle of the pulse signal to the observation target is determined. A program characterized by estimating an error .

Images