KR20180115489A - Apparatus and method for 3 dimension altitude estimation using interferometric synthetic aperture radar altimeter - Google Patents

Abstract

The present invention relates to an apparatus and a method for measuring a three-dimensional altitude using an interferometric altimeter. The apparatus for measuring a three-dimensional altitude according to one embodiment of the present invention comprises: a reception portion for receiving data from at least two antennas; an altitude compensation portion for compensating and summing the altitude relative to a bust of signals received after the altitude relative to the bust is compensated and summed; a matching pursuit portion for performing matching pursuit based on the summed compensation; an altitude information extraction portion for extracting altitude information of N cross-tracks relative to the matching-pursued signal; and an image data generating portion for generating image data by reflecting the extracted altitude information.

Description

[0001] APPARATUS AND METHOD FOR 3 DIMENSION ALTITUDE ESTIMATION USING INTERFEROMETRIC SYNTHETIC APERTURE RADAR ALTIMETER [0002]

The present invention relates to an apparatus and method for measuring three-dimensional altitude using an interference altimeter. More particularly, the present invention relates to an apparatus and method for measuring three-dimensional altitude using an interference altimeter, This paper deals with the technical idea of obtaining information about a wider area without topographical level by taking phase compensation according to ambiguity in another form.

Numerical studies have been conducted on radar - based altimetry methods in direct flight (Nadir) directions. The satellite is being used to acquire terrain accuracy, and it is aimed at precise altitude measurement with two or more antennas (Cryosat, SWOT to be launched in 2020). It is used to prevent collision in aviation, receives more than two antennas, obtains precise terrain information, and is working to serve as a navigation system in case GPS is not working. Honeywell sells a product called PTAN and is being developed by ratheon and Thales.

The altimeter calculates the altitude nearest the radar by measuring the closest point of the signal received at the radar. The Delay Doppler Radar Altimeter can increase the resolution of the along track using the SAR's along track compression technique in the altimeter. Estimate the nearest point to reflect the largest signal, extract the peak point of the received signal, and perform azimuth compression. This technique is used in cyrosat and sentinel-3 as SAR modes.

Interference altimeters use more than one receiver. By using the SAR technique, it is possible to find a peak point in two pieces of received data, determine a phase difference of each received peak point, and determine at which point the signal is received.

There are two major problems with two or more interferometric altimeters in a sudden change of terrain.

The first is the case where the peak point found by the SAR technique reflects a larger signal at a point other than the nearest point. It usually occurs in coastal areas or large rivers. In reality, if the direct downward direction is the coast or the river, this is the nearest point, but it reflects the larger signal on the land and the peak point is judged as a point other than the direct downward direction.

The second is that the phase difference of the peak point can be measured from 0 to 2 pi (pi).

The phase difference can be determined by the length of the wavelength and the baseline of the two antennas. Therefore, phase unwrapping should be performed but can not be used if other information is missing or changes significantly. For this purpose, three or more aerial altimeters are used.

Korean Patent Application No. 10-2013-0032083 "Radio altimeter performance analyzer and its operation algorithm" Korean Patent No. 10-2011-0117370 "Apparatus and method for altitude estimation using pneumatic altimeter and satellite navigation system"

The present invention aims at extracting and calculating two or more points at the same time as extracting one peak point along the track and calculating altitude.

The object of the present invention is to solve the problem that the phase difference exceeds 2 pi by acquiring the value at the point where the phase value coincides most with the azimuth direction.

The present invention aims at making the phase compensation different according to ambiguity and calculating the altitude of the region of 2pi or more.

An object of the present invention is to solve the problem by outputting a plurality of points to be measured for a part difficult to measure an angle of arrival (AOA).

A three-dimensional altimeter according to an exemplary embodiment of the present invention includes a receiver for receiving data from at least two antennas, a phase compensator for compensating a phase of the burst and summing the phases of the bursts of the signals received by summing, A matched tracking unit for performing matching based on the compensated compensation information, an altitude information extracting unit for extracting altitude information of N cross-tracks for the matched tracked signal, And an image data generating unit for generating image data by reflecting the image data.

The phase compensation unit according to an embodiment may reflect at least one of the attitude and position information of the flying object to compensate for the phase and add the phase.

The matching tracking unit according to an exemplary embodiment may perform matching tracking using a dictionary of the cross-track and the altitude by reflecting at least one of the attitude and position information of the air vehicle .

The three-dimensional altimeter apparatus according to an embodiment may further include a correction processing unit for performing a phase correction on the received signals.

The correction processing unit may perform the phase correction considering the positions of the altitude and the cross-track of the received signals.

The matching tracer according to an embodiment extracts a value having a maximum value of a value after a matched filter process for the summed compensation or extracts a largest value with a maximum matching with a dictionary , Subtracts the extracted value from the received signals, and repeatedly performs the subtraction until the subtraction result is less than or equal to a threshold value.

A three-dimensional altitude measurement apparatus according to an exemplary embodiment of the present invention includes a receiver for receiving data from at least two antennas, a phase correction unit for performing phase correction on all bursts of the received signals, and azimuth compressing the phase- An altitude information extracting unit for extracting altitude information of N cross-tracks for the matched tracked signal, and an altitude information extracting unit for extracting altitude information of the cross- And an image data generation unit for generating image data by reflecting the extracted altitude information.

The azimuth compression processing unit according to an embodiment can perform the phase correction and the azimuth compression using a distance function with respect to the ground surface derived from the precision speed, position, and attitude information of the air vehicle.

A method of operating a three-dimensional altimeter according to an embodiment includes receiving data from at least two antennas at a receiving unit, compensating a phase of the burst by a phase compensation unit, And performing a matching traversal on the basis of the summed compensation in the matching tracker, wherein in the altitude information extracting unit, N cross-tracks for the matched track- And generating the image data by reflecting the extracted altitude information in the image data generating unit.

The step of compensating and summing the phases according to an embodiment may include a step of compensating and summing the phases by reflecting at least one of the attitude and position information of the air vehicle.

The step of performing matching tracing according to an exemplary embodiment may include at least one of a posture and a position information of a flying object and may be used as a matching track by using a dictionary for the cross- (Matching Pursuit).

According to an embodiment of the present invention, there is provided a method of operating a three-dimensional altimeter, comprising: receiving data from at least two antennas at a receiving unit; performing azimuthal compression processing on all bursts of the received signals; A step of performing preliminary processing by azimuth compressing the corrected result; a step of matching tracing the pre-processed signals in a matching trace section; and a step of performing, in an altitude information extracting section, - extracting altitude information of a track (cross-track), and generating image data in the image data generating unit by reflecting the extracted altitude information.

The step of performing the phase correction and the azimuth compression according to an embodiment may include performing the phase correction and the azimuth compression using a distance function with respect to the ground surface derived from the precision speed, . ≪ / RTI >

According to one embodiment, it is possible to extract two points or more at the same time, as opposed to extracting one peak point along the track and calculating altitude.

According to the present invention, it is possible to solve the problem that the phase difference exceeds 2 pi by acquiring the value at the point where the phase value coincides most with the azimuth direction.

According to the present invention, it is possible to solve this problem by outputting a plurality of points to be measured, for a part difficult to measure the angle of arrival (AOA).

1 is a view for explaining an image radar that receives signals in a downward direction in two or more antennas.
2 is a view for explaining a three-dimensional altitude measurement apparatus to which a partial coherent algorithm is applied.
3 is a diagram for explaining a three-dimensional altitude measurement apparatus to which an overall coherent algorithm is applied.
FIGS. 4 to 6 illustrate a method for compensating for a range cell of a first antenna and a range antenna of a second antenna.
7 is a view for explaining a data processing method of one burst in a Synthetic Aperture Radar (SAR) mode.
8 is a diagram for explaining an algorithm for data processing of a burst.
9 is a diagram for explaining an algorithm for data processing of a SARin mode burst.
FIG. 10 is a view for explaining a three-dimensional altitude measurement method to which a partial coherent algorithm is applied.
11 is a view for explaining a three-dimensional altitude measurement method to which an overall coherent algorithm is applied.

It is to be understood that the specific structural or functional descriptions of embodiments of the present invention disclosed herein are presented for the purpose of describing embodiments only in accordance with the concepts of the present invention, May be embodied in various forms and are not limited to the embodiments described herein.

Embodiments in accordance with the concepts of the present invention are capable of various modifications and may take various forms, so that the embodiments are illustrated in the drawings and described in detail herein. However, it is not intended to limit the embodiments according to the concepts of the present invention to the specific disclosure forms, but includes changes, equivalents, or alternatives falling within the spirit and scope of the present invention.

The terms first, second, or the like may be used to describe various elements, but the elements should not be limited by the terms. The terms may be named for the purpose of distinguishing one element from another, for example without departing from the scope of the right according to the concept of the present invention, the first element being referred to as the second element, Similarly, the second component may also be referred to as the first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Expressions that describe the relationship between components, for example, "between" and "immediately" or "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises ", or" having ", and the like, are used to specify one or more of the features, numbers, steps, operations, elements, But do not preclude the presence or addition of steps, operations, elements, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning of the context in the relevant art and, unless explicitly defined herein, are to be interpreted as ideal or overly formal Do not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the patent application is not limited or limited by these embodiments. Like reference symbols in the drawings denote like elements.

1 is a diagram 110 illustrating an image radar 111 receiving signals in a downward direction from two or more antennas.

The image radar 111 can observe the image of the observation point while moving in the v direction. The image radar 111 is capable of observing images of viewpoints using two different antennas that are spaced apart from each other by a certain distance in the left-right direction or the up-down direction. At this time, two different antennas can receive images of the ground observed by signals transmitted from one or more antennas.

), 영상 레이다(111)의 고도(H), 관측점의 고도(h), 영상 레이다(111)가 지면에 프로젝션된 위치에서 관측점까지의 직선 거리(x), 서로 다른 두 개의 안테나 거리(B)의 항목들이 산출될 수 있다.At this time, according to each of the two different antennas, the directions a1 and a2 projected on the ground as the downward direction, the directions b1 and b2 toward the observation point, and the angle formed by a1 and b1

The altitude H of the image radar 111, the altitude h of the observation point, the straight line distance x from the position where the image radar 111 is projected on the ground to the observation point, Can be calculated.

In this case, the distances from the two different antennas to the observation point may vary depending on the difference between the two different antennas. That is, the difference between the distance from the first antenna to the observation point and the distance from the second antenna to the observation point can be calculated by Equation (1) below.

[Equation 1]

는 영상 레이다(111)의 지면에 프로젝션된 방향과 관측점을 향하는 방향의 각도,

는 B에서

의 차이로 해석될 수 있다. 또한,

및

는 각각 모호성을 해결하기 위해서 사용될 수 있는 두 개의 주파수이다. 이때, 두 주파수는 모든 안테나에서 사용되어야 한다.At 120, B in Equation (1) is the distance between different antennas,

The angle of the direction projected on the ground surface of the image radar 111 and the direction toward the observation point,

In B

As shown in Fig. Also,

And

Are two frequencies that can be used to solve ambiguity, respectively. At this time, both frequencies should be used in all antennas.

및

는 각각의 안테나 및 주파수에서 측정되는 위상 값이다. 1번 주파수에서 i번째 안테나에서 측정되는 위상은 phi(1,i)와 같이 나타낸다면 두 개의 안테나가 있다면 모두 4개의 위상을 측정해야 된다. 이는 모호성 n, m을 계산하기 위함이다. 첫 번째 안테나와 두 번째에 대해 최소 공배수로 확장이 가능하도록 하기 위한 수치로 해석될 수 있다. 또한, 거리 차에 대한 두 개의 주파수에 대한 위상차를 얻게 되는데, n과 m은 정수로 위상차에 대한 오차가 가장 적은 값을 선택하면 된다.In Equation (1)

And

Is the phase value measured at each antenna and frequency. If the phase measured at the i-th antenna at frequency 1 is represented as phi (1, i), then all four antennas should be measured. This is to calculate ambiguity n, m. Can be interpreted as a numerical value to enable expansion to the least common multiple for the first antenna and the second antenna. Also, a phase difference with respect to two frequencies with respect to the distance difference is obtained, where n and m are integers, and a value with the smallest error with respect to the phase difference is selected.

Each antenna is located at a certain distance in the left or right direction or up and down direction. If you have more than three antennas, you can solve the 2pi ambiguity by having the proper baseline, respectively.

Equation (1) can be used to expand the ambiguity of 2 pi to ambiguity of the least common multiple of the wavelengths corresponding to two frequencies using more than one frequency.

In the present invention, it is possible to increase the exposure time for observation through beam steering, thereby acquiring a high resolution image.

That is, in the present invention, the beam can be steered such that the antenna is continuously directed to the ground target by rotating the pitch axis using an antenna facing in the downward direction. Accordingly, in the present invention, the exposure time is increased and images can be collected by observing a long time from a farther distance. At this time, the resolution in the azimuth direction is proportional to the bandwidth of the Doppler frequency of the target and platform, which is proportional to L / 2. L can be interpreted as the distance the platform moves while observing, and beam steering is possible in the direction of rotating the platform to increase the variation of the rate of change of distance between the target and platform.

A partially coherent algorithm in the present invention is a technique for processing processing using only data observed during a short period of time, such as a suddenly changing wave or sea, which will be described in detail with reference to FIG.

2 is a view for explaining a three-dimensional altitude measurement apparatus to which a partial coherent algorithm is applied.

In the case of a rapid change of terrain in a short time such as an ocean area, it is impossible to coherently combine several signals, so that only one burst period or a certain number of signals can be used have.

The three-dimensional altimeter 200 includes a receiving unit 210, a phase compensating unit 220, a matching tracking unit 230, an altitude information extracting unit 240, and an image data generating unit 250 ).

The receiving unit 210 according to an exemplary embodiment may receive data from at least two antennas. For example, the three-dimensional altimeter 200 may transmit pulsed radar signals, FMCW, burst pulses, and may be dechirped or deramed in response thereto. Signal can be received. The three-dimensional altimeter 200 may mechanically or electrically steer the beam direction to increase the exposure time for a specific point at which the altitude suddenly changes during reception.

The phase compensation unit 220 according to an embodiment can compensate for the phase of the received burst and add the sum. For example, the phase compensating unit 220 can compensate for at least one of the posture and the position information of the air vehicle, and compensate for the phase.

The matching tracking unit 230 according to an exemplary embodiment may perform matching tracking based on the summed compensation. For example, the matching tracking unit 230 may perform at least one of the posture and the positional information of the flying object and perform matching tracking using the dictionary of the cross-track and altitude .

For example, the matching tracker 230 may perform matching pursuit based on the model. Such a dictionary model may vary as the ambiguity (integer n) increases (occurs) or as the range increases.

In other words, ambiguity does not occur under any range, but this ambiguity may arise for observing a wider area. By creating different dictionaries as the ambiguity varies in modeling, a wider area can be utilized.

The phase of the received signal can be compensated using the precise orbit and attitude data. To this end, a correction processor (not shown) may perform phase correction on the received signals. In particular, the correction processing unit (not shown) may perform the phase correction on the basis of the positions of the altitude and the cross-track of the received signals.

The matching tracking unit 230 may match and track the execution result, calculate a value for the maximum point, extract and store a value for the maximum point according to the matching tracking algorithm, and remove the component of the value from the data. This process can be performed until a value beyond a reference value can not be extracted, and a 3D image can be produced using the extracted data. For example, the matching tracking unit 230 extracts a maximum value of the value after the matched filter processing for the summed compensation, extracts the largest value in agreement with the dictionary, The extracted value may be subtracted from the received signals and repeatedly performed until the subtraction result is less than or equal to a threshold value.

For this, the altitude information extracting unit 240 may extract N cross-track altitude information for the matched tracked signal.

As a result, the image data generator 250 according to an exemplary embodiment may generate image data by reflecting the extracted altitude information.

A fully coherent algorithm according to the present invention is a technique required to widely use a maximum number of signals that do not greatly vary even after a few seconds, such as land, and will be described in detail with reference to FIG.

3 is a view for explaining a three-dimensional altitude measurement apparatus 300 to which an overall coherent algorithm is applied.

Unlike marine areas, where the land area is unchanged for a relatively long time, all signals exposed using one or more bursts can be used coherently for an overall coherent algorithm.

For this, the three-dimensional altimeter 300 to which the entire coherent algorithm is applied includes a receiving unit 310, an azimuth compressing unit 320, an azimuth compressing unit 320, an altitude information extracting unit 330, (340). ≪ / RTI >

The receiving unit 310 according to an exemplary embodiment may receive data from at least two antennas. For example, the receiving unit 310 may receive data from at least two antennas. In particular, the three-dimensional altimeter 200 transmits a pulsed radar signal, FMCW, and burst pulses, and outputs a dechirp or deramped signal in response thereto . The three-dimensional altimeter 200 may mechanically or electrically steer the beam direction to increase the exposure time for a specific point at which the altitude suddenly changes during reception.

The azimuth compression processing unit 320 according to an exemplary embodiment may perform phase correction for all bursts of received signals and azimuth compressing the phase-corrected result.

For example, it is possible to use the incoming signal even at a look angle that is greater than the bandwidth (Beamwidth). Therefore, a situation arises in which the range cell of the first antenna rx1 and the range cell of the second antenna rx2 do not coincide with each other, rather than obtaining the phase difference of the same range. And the azimuth compression processing unit 320 can compensate for this.

The azimuth compression processing unit 320 according to an embodiment can perform phase correction and azimuth compression using a distance function with respect to the ground surface derived from precise speed, position, and attitude information of a flying object. The configuration for performing compensation in the azimuth compression processing unit 320 will be described in detail with reference to FIGS. 4 to 6. FIG.

In addition, the azimuth compression processing unit 320 according to an exemplary embodiment may perform matching tracking based on the summed compensation. For example, the azimuth compression processor 320 reflects at least one of the posture and the positional information of the airplane and performs matching tracking using the dictionary of the cross-track and altitude .

The phase of the received signal can be compensated using the precise orbit and attitude data. To this end, a correction processor (not shown) may perform phase correction on the received signals. In particular, the correction processing unit (not shown) may perform the phase correction on the basis of the positions of the altitude and the cross-track of the received signals.

The correction processing unit (not shown) may perform phase compensation.

For example, when altitude measurement at the Nadir point is not possible, it can be squinted from the Nadir to the proceeding direction and steered forward or backward to steadily observe for a certain period of time .

For mechanical or electrical steering, a radiometric calibration according to the antenna beam pattern must be performed. That is, the correction processing unit (not shown) can compensate the antenna gain according to the azimuth look angle.

To this end, the correction processor (not shown) can perform the phase compensation of the signals received by the two antennas according to altitude and the position and altitude of the cross-track.

The signals received at each antenna may be located at different positions depending on the altitude, altitude, cross-track position, altitude, baseline, and the received signal. At this time, the azimuth compression processing unit 320 can generate such a received signal model based on the trajectory and attitude of a given satellite. The azimuth compression processing unit 320 may input a model after range compression or a model before range compression into a dictionanry.

Also, the azimuth compression processing unit 320 can extract two or more maximum points having a large backward magnitude using a matched filter. That is, the azimuth compression processing unit 320 extracts the maximum value of the value after the matched filter processing for the summed compensation, or extracts the largest value with the greatest match with the dictionary, And subtracts the received signal from the received signals and repeatedly performs the subtraction until the subtraction result is less than or equal to a threshold value.

That is, the azimuth compression processing unit 320 obtains the largest value while subtracting the largest value from the received signal, and obtains the largest value while matching the next with the dictionary, and subtracts the value from the received signal, Can be repeatedly performed until the calculated value becomes equal to or less than the calculated threshold value.

Dictionaries can perform matching tracking using models before azimuth compression and can use matching tracking using models after azimuth compression. In addition, range compression can be modeled before and after matching.

The azimuth compression processing unit 320 may reduce the noise by fitting the intensity to the n-th order polynomial for each azimuth when tracking the matching using the azimuth value of each azimuth.

The azimuth compression processing unit 320 may perform matching tracking of the execution result, calculate a value for the maximum point, extract a value for the maximum point according to the matching tracking algorithm, and store the extracted value in the data to remove the component for the value. This process can be performed until a value beyond a reference value can not be extracted, and a 3D image can be produced using the extracted data. For example, the azimuth compression processing unit 320 extracts a maximum value of the value after the matched filter processing for the summed compensation, or extracts the largest value in agreement with the dictionary, The extracted value may be subtracted from the received signals and repeatedly performed until the subtraction result is less than or equal to a threshold value.

To this end, the altitude information extractor 330 may extract N cross-track altitude information for the matched tracked signal. In addition, the image data generation unit 340 may generate image data by reflecting the extracted altitude information.

For example, when the terrain changes frequently and bursts are used, only the signals in one burst are used, so that altitude information can be obtained at intervals as long as interval intervals of bursts of along tracks are projected on the ground have. Also, in the entire coherent algorithm, the altitude information according to the observed signal interval can be obtained.

FIGS. 4 to 6 illustrate a method for compensating for a range cell of the first antenna rx1 and a range cell of the second antenna rx2, which do not coincide with each other.

The present invention can utilize the incoming signal even at a look angle that is greater than the bandwidth (Beamwidth). Therefore, the present invention does not find a phase difference in the same range but a situation where the range cells of the first antenna rx1 and the second antenna rx2 do not coincide may occur.

First, the transmission signal can be expressed by the following equation (2).

&Quot; (2) "

In Equation (2), f ₀ is the center frequency of the transmission signal, k is the frequency modulation rate (or chirp rate), and t is a time-dependent variable.

)이 딜레이 되는 형태가 될 수 있다.On the other hand, a signal to be received for a point target having a reflection cross-sectional area of 1 can be expressed by the following equation (3)

) May be delayed.

&Quot; (3) "

In addition, the point to be delayed can be modeled as shown in Equation (4) below.

&Quot; (4) "

In Equation (4), H is the distance in the downward direction of the image radar, h is the height of the observation point, and c is the speed of light.

Further, in order to obtain a signal of a wide bandwidth with a low-end analog-to-digital converter, dechirp or deramping is used, which can be expressed as Equation (5).

&Quot; (5) "

는 딜레이되는 일정 시간으로 해석될 수 있다.In Equation (5), f ₀ is the center frequency of the transmitted signal, k is a natural number, and t can be interpreted as a time-dependent variable. Also,

Can be interpreted as a certain time delayed.

Further, when a low pass filter is applied to Equation (5), it can be expressed by Equation (6).

&Quot; (6) "

는 딜레이되는 일정 시간으로 해석될 수 있다.In Equation (6), f ₀ is the center frequency of the transmitted signal, k is a natural number, and t can be interpreted as a time-dependent variable. Also,

Can be interpreted as a certain time delayed.

Further, if a fast Fourier transform (FFT) is performed on Equation (6), Equation (7) is obtained and range compression can be performed.

&Quot; (7) "

는 딜레이되는 일정 시간으로 해석될 수 있다.In the formula 7], f may be interpreted as the frequency, f ₀ is the center frequency, k is a natural number, t is variable according to the time of the transmission signal of the transmission signal. Also,

Can be interpreted as a certain time delayed.

6 is an embodiment 600 for explaining the phase difference according to the time delay of the propagation.

Referring to FIG. 6, a signal received from an antenna spaced by a base line (B) on a payload can be expressed by Equation (8) with a difference in distance according to a time delay of propagation .

&Quot; (8) "

In Equation (8), R1 is the distance from the antenna 1 to the observation point, R2 is the distance from the antenna 2 to the observation point, H is the distance in the downward direction of the image radar, and h is the height of the observation point.

Equation (8) can be expressed by the following equation (9) where the phase is delayed by the received signal.

&Quot; (9) "

FIG. 7 is a diagram 700 illustrating a data processing method of one burst in a Synthetic Aperture Radar (SAR) mode.

If the phase difference exceeds 2 pi, the position can not be identified. To compensate for this, you can use more than one frequency as shown below.

&Quot; (10) "

는 신호의 파장, h는 관측점의 고도, v는 영상 레이다의 속도로 해석될 수 있다.In Equation (10), k is a natural number, f is a frequency of a signal,

Is the wavelength of the signal, h is the altitude of the observation point, and v is the velocity of the image radar.

Referring to reference numeral 700, a signal that has passed through the delay-phase FFT 730 after the data store 720 together with the delay phase coefficient 710 is input to the delay FFT 740 through a multiplier. The signal outputting the delay FFT 740 may then be Doppler / position mapping and look-up integration 750. For example, the signal outputting the delay FFT 740 may be subjected to look-up integration 750 to 140 per thousand.

The signal that has been subjected to the lookup integration 750 may be transferred to the multiplier in the form of a range de-ramp through the range-gate tracker 760 and transferred to the data store 720.

8 is a diagram 800 illustrating an algorithm for data processing of a burst.

According to the data processing method of one burst in the SAR mode, it is possible to generate a received signal through a delay IFFT after phase-correcting the demodulated signal by FFT along the direction of the demodulation.

&Quot; (11) "

&Quot; (12) "

는 위성 속도 방향의 벡터,

는 k번째 scatterer의 방향 벡터,

는 베이스라인의 방향 벡터,

는 시야각(look angle),

는 얼롱 트랙 샘플링 인터벌(along track sampling interval), k는 자연수로서 파형의 번호로 해석될 수 있다. 또한, [수학식 12]에서

는 버스트 인터벌로 해석될 수 있다.In equations (11) and (12)

Is the vector of the satellite velocity direction,

Is the direction vector of the kth scatterer,

Is the direction vector of the baseline,

A look angle,

Is the along track sampling interval, k can be interpreted as the number of the waveform as a natural number. In Equation 12,

Can be interpreted as a burst interval.

The approximate algorithm is as follows. The phase of the received signal is compensated using the precise orbit and attitude data, and the value for the maximum point is calculated by matching tracking. The value for the maximum point is extracted and stored according to the algorithm of matching tracking, The component can be removed. This process is performed until a value beyond a reference value can not be extracted, and a 3D image is produced using the extracted data.

More specifically, the algorithm will be described in more detail with reference to FIG.

9 is a diagram illustrating an algorithm 900 for data processing of SARin mode bursts.

According to the algorithm 900, the signal at antenna 1 901 and the signal at antenna 2 904 are de-ramped (902, 905), respectively.

On the other hand, the demodulated signals may be phase-compensated through steps 903 and 906, respectively. A number phase difference operation 908 can be performed that detects 907 the phase compensated signals through steps 903 and 906. [ According to the algorithm 900, the computed phase difference can be input to the phase dictionary 909 and used in the search 910 of the Angle of Arrival (AOA). The present invention is capable of outputting a plurality of points to be measured, for a portion where it is difficult to measure the angle of arrival (AOA).

Meanwhile, the algorithm 900 may increase the accuracy by removing the maximum value from the retrieved arrival angle (911) and feeding back the removed signal to the peak detection process.

On the other hand, after the process of removing the maximum value from the arrival angle 912, the signal may be input as feedback for phase compensation. Further, the dictionary value of the attitude and the trajectory target position can be input to the phase compensation 903 to improve the accuracy of the system.

Meanwhile, the algorithm 900 may check the result of peak detection (907) and determine whether to continue or terminate the three-dimensional mapping. To do this, the algorithm 900 determines whether the signal is above a threshold value (914), and if the signal is greater than or equal to the threshold value, it continues the three-dimensional mapping, and if the signal is below the threshold, .

FIG. 10 is a view for explaining a three-dimensional altitude measurement method to which a partial coherent algorithm is applied.

A three-dimensional altitude measurement method employing a partial coherent algorithm may receive data from at least two antennas (step 1010).

In addition, the three-dimensional altitude measurement method may add up the phase for the received bursts (step 1020). The three-dimensional altitude measurement method may perform Matching Pursuit based on the summed compensation (step 1030) and may extract altitude information of N cross-tracks for the matched tracked signal (step < RTI ID = 0.0 & 1040). For example, the three-dimensional altitude measurement method can compensate for at least one of the attitude and position information of the flight vehicle to compensate for the phase.

The three-dimensional altitude measurement method uses at least one of the attitude and position information of the aviation body for matching tracing and performs matching tracking using a dictionary for the cross-track and altitude Matching Pursuit.

The three-dimensional altitude measurement method calculates the value for the maximum point by matching the execution result, extracts the value for the maximum point according to the matching tracking algorithm, and removes the component for the value from the data. This process can be performed until a value beyond a reference value can not be extracted, and a 3D image can be produced using the extracted data. For example, the three-dimensional altitude measurement method can extract the maximum value of the value after the matched filter processing for the summed compensation, extract the largest value with the greatest agreement with the dictionary, Subtracted from the received signals, and repeatedly performed until the subtraction result is less than or equal to a threshold value.

As a result, the three-dimensional altitude measurement method may generate the image data by reflecting the extracted altitude information (step 1050).

11 is a view for explaining a three-dimensional altitude measurement method to which an overall coherent algorithm is applied.

A three-dimensional altitude measurement method using an overall coherent algorithm may receive data from at least two antennas (step 1110). In addition, the three-dimensional altimetry method may perform phase correction for all bursts of received signals and azimuth compressing the phase corrected result (step 1120).

For example, it is possible to use the incoming signal even at a look angle greater than the beamwidth. Therefore, a situation arises in which the range cells of the first antenna rx1 and the range rx2 of the second antenna rx2 do not coincide with each other, rather than obtaining the phase difference of the same range. The measurement method can compensate.

For example, in order to perform the phase correction and the azimuth compression, the three-dimensional elevation measurement method performs the phase correction and the azimuth compression using a distance function to the ground surface derived from the precision speed, position, and attitude information of the air vehicle can do.

In addition, the three-dimensional altitude measurement method may perform matching tracking by azimuth compressing the phase-corrected result (step 1120). In addition, the three-dimensional altitude measurement method may extract N cross-track altitude information for the matched tracked signal (step 1130). Meanwhile, the three-dimensional altitude measurement method may generate the image data by reflecting the extracted altitude information (Step 1140).

As a result, according to the present invention, it is possible to extract two points or more at the same time, as opposed to extracting one peak point along the track and calculating the altitude. Further, according to the present invention, it is possible to solve the problem that the phase difference exceeds 2 pi by solving the problem of obtaining the value at the point where the phase value coincides most with the azimuth direction, and it is difficult to measure the angle of arrival (AOA) For a part, it can be solved by outputting a plurality of points to be measured.

Also, by using the present invention, it is possible to simultaneously extract altitude information for various points on an area where electromagnetic wave reflection scattering is large on the ground from the payload, and when the phase compensation is over 2 pi, You can get information about the terrain without altitude.

In addition, it can be used to acquire the current position based on 3D terrain map without the help of GNSS like GPS like PTAN technology. Until now, only one point has been extracted, but it is easier to match the existing terrain elevation map by extracting more than two points and obtaining additional information about altitude information. In addition, in the case of altitude measurement, it is possible to extract the terrain in a wide space even if there is no DEM. Especially, it is possible to compensate the fact that the altitude can not be extracted in the direct downward direction near the coast where the altitude changes rapidly. In addition, by acquiring altitude information of various points, it is possible to acquire information close to a three-dimensional image to create an altitude map.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

200: Three-dimensional altimeter 210: Receiver
220: phase compensation unit 230: matching tracking unit
240: altitude information extracting unit 250:

Claims (14)

A receiver for receiving data from at least two or more antennas;
A phase compensator for compensating a phase of the burst to compensate for a phase of a burst of the summed-up signals;
A matching tracking unit for performing matching based on the summed compensation;
An altitude information extractor for extracting altitude information of N cross-tracks for the matched track; And
An image data generation unit for generating image data by reflecting the extracted altitude information,
Dimensional altitude measurement device. The method according to claim 1,
Wherein the phase compensation unit reflects at least one of the attitude and position information of the flying object and compensates for the phase. The method according to claim 1,
Wherein the matching tracking unit reflects at least one of the attitude and position information of the flying object and performs matching tracking using a dictionary of the cross-track and altitude. The method according to claim 1,
A correction processing unit for performing phase correction on the received signals;
Dimensional altitude measurement device. 5. The method of claim 4,
Wherein,
And performs the phase correction considering the positions of the altitude and the cross-track of the received signals. The method according to claim 1,
The matching-
Extracts a maximum value of the value after the matched filter processing for the summed compensation, or extracts the largest value in agreement with the dictionary and outputs the extracted value to the received signals And repeatedly performs the subtraction until the subtraction result is less than or equal to a threshold value. The method according to claim 1,
The receiver may further comprise:
Wherein the at least two antennas receive different data having different transmission frequencies and different phases from at least two antennas. A receiver for receiving data from at least two or more antennas;
An azimuth compression processor for performing phase correction on all bursts of the received signals and azimuth compressing the phase corrected result to perform matching tracking;
An altitude information extractor for extracting altitude information of N cross-tracks for the matched track; And
An image data generation unit for generating image data by reflecting the extracted altitude information,
Dimensional altitude measurement device. 9. The method of claim 8,
The azimuth compression processing unit includes:
A three-dimensional altitude measurement apparatus for performing the phase correction and the azimuth compression using a distance function for an earth surface derived from precise velocity, position, and attitude information of a flying object. A method of operating a three-dimensional elevation measuring device,
Receiving, at a receiving unit, data from at least two or more antennas;
Compensating the phase for the burst to compensate for the phase of the burst of the summed received signals and summing;
In a matching tracing section, matching tracing based on the summed compensation;
Extracting altitude information of N cross-tracks for the matched tracked signal in an altitude information extracting unit; And
The image data generation unit generates image data by reflecting the extracted altitude information
Dimensional altitude measurement device. 11. The method of claim 10,
The step of compensating and summing the phases comprises:
A step of compensating and summing the phase by reflecting at least one of the posture and the position information of the flight body
Dimensional altitude measurement device. 11. The method of claim 10,
The matching step may include:
A step of performing matching tracing using at least one of the posture and the position information of the vehicle using a dictionary of the cross-track and altitude
Dimensional altitude measurement device. A method of operating a three-dimensional elevation measuring device,
Receiving, at a receiving unit, data from at least two or more antennas;
Performing azimuth compressing on the phase-corrected result to perform a matching pulse in an azimuth compression processing unit, performing phase correction on all bursts of the received signals, and azimuth compressing the phase-corrected result;
Extracting altitude information of N cross-tracks for the matched tracked signal in an altitude information extracting unit; And
The image data generation unit generates image data by reflecting the extracted altitude information
Dimensional altitude measurement device. 9. The method of claim 8,
Wherein performing phase correction and azimuth compression comprises:
Performing the phase correction and the azimuth compression using a distance function with respect to the ground surface derived from the precision speed, position, and attitude information of the flying object;
Dimensional altitude measurement device.

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