CN111505626A - Method for measuring two-dimensional terrain gradient by using bottom view differential interference - Google Patents

Method for measuring two-dimensional terrain gradient by using bottom view differential interference Download PDF

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CN111505626A
CN111505626A CN202010337998.XA CN202010337998A CN111505626A CN 111505626 A CN111505626 A CN 111505626A CN 202010337998 A CN202010337998 A CN 202010337998A CN 111505626 A CN111505626 A CN 111505626A
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antenna
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CN111505626B (en
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杨双宝
康雪艳
翟振和
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National Space Science Center of CAS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/0218—Very long range radars, e.g. surface wave radar, over-the-horizon or ionospheric propagation systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/288—Coherent receivers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section

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Abstract

The invention discloses a method for measuring two-dimensional terrain gradient by using bottom view differential interference, which comprises the following steps: to left antenna A of satellite-borne radarLIntermediate antenna AOAnd a right antenna ARCarrying out azimuth-range compression processing on the received echoes to obtain pulse echoes after the compression processing of the three antennas; performing interference processing on the compressed pulse echoes to obtain two interference echoes; performing azimuth-distance two-dimensional smoothing on the two interference echoes respectively; extracting A from the smoothed interference echoLARInterference phase; based on a plurality of ALARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm; benefit toCalculating the grade angle along the rail direction on the ground grid unit by using the ratio of the terrain tracking elevation output by the echo to the corresponding ground grid unit distance; the down-track slope angle can also be obtained by the same method as the cross-track slope angle. The method of the invention can be carried out in<And realizing the accuracy of measuring the terrain slope with the urad magnitude on a 5-kilometer spatial scale.

Description

Method for measuring two-dimensional terrain gradient by using bottom view differential interference
Technical Field
The invention relates to the technical field of space-based radars, in particular to a high-precision small terrain slope measurement (the measurement precision is superior to 0.0001 degree) of a satellite-borne microwave radar, such as a method for measuring the terrain slope (<3 degrees) of a south-north pole ice frame and the terrain slope (<0.1 degrees) of an ocean, and particularly relates to a method for measuring the two-dimensional terrain slope by using bottom view differential interference.
Background
Since 2004, the scientific community is striving towards mapping high-resolution, high-precision (1mGal) global gravitational fields; meanwhile, the high measurement accuracy of the ice surface of the north pole and the south pole is required to be further improved. Both of which require high accuracy terrain grade information.
The radar which can be used for surveying and mapping the ocean slope at present is mainly a satellite-borne microwave altimeter, such as a real-aperture radar altimeter existing in China and 3 novel radar altimeters developed in recent years, namely a bottom-view synthetic aperture radar altimeter, a bottom-view interferometric synthetic aperture radar altimeter and a wide-swath small-incidence-angle interferometric imaging radar altimeter.
(1) A spaceborne base view synthetic aperture radar altimeter. On the basis of the traditional real-aperture radar altimeter, a bottom view synthetic aperture altimeter is proposed and developed abroad, such as a European and air Bureau on-orbit radar altimeter Sentinel-3 (translated and called as Sentinel 3 in China). The device is used for observing the average height, the effective wave height and the backscattering coefficient of the sea surface under the satellite, and further generating global sea surface elevation, sea surface wave height, sea surface wind speed, sea surface gradient and ocean gravity field products.
The spaceborne base view synthetic aperture radar altimeter can measure the ocean gradient along the direction, but cannot measure the two-dimensional sea surface terrain gradient along the direction of the track and the direction of the cross track.
(2) A satellite-borne base view synthetic aperture interferometric radar altimeter, such as the on-orbit radar altimeter Cryosat-2 of the European Bureau. The working modes of the system are divided into a bottom-view real aperture mode, a bottom-view synthetic aperture mode and a bottom-view interference synthetic aperture mode. The bottom view interference synthetic aperture mode is mainly used for measuring the terrain gradient of the south and north pole ice racks.
Theoretically speaking, the instrument can be used for surveying and mapping the gradient of the two-dimensional terrain. However, since the coupling of the terrain slope and the base line roll angle affects the interference phase together, the method can only depend on the star sensor on the star and can only be used for calibrating the star sensor, and the precision of the calibrated star sensor is only 100urad magnitude (1s average). Therefore, the instrument can only meet the requirement of measuring the gradient of the ice rack, but cannot realize high-precision (1urad) two-dimensional marine terrain gradient measurement.
(3) Space-based (space-borne) interferometric imaging radar altimeter. The small-incidence-angle interference imaging altimeter (such as a domestic Tiangong-2 three-dimensional imaging altimeter and a foreign SWOT altimeter) has the main advantages that due to the adoption of a small-incidence-angle observation mode, compared with the bottom view radar altimeter, the observation swath of the bottom view radar altimeter can be improved by about 8 times at the same track height, so that two-dimensional sea surface high imaging is realized, and the small-incidence-angle interference imaging altimeter has important significance for ocean dynamics. The cost is that the height measurement precision is reduced compared with that of a bottom view radar altimeter (such as a traditional real aperture radar altimeter and a bottom view synthetic aperture altimeter).
Since the marine terrain slope is very small and the height measurement accuracy of the imaging height meter is deteriorated as the imaging height meter is far away from the nadir point, high-accuracy (urad magnitude) two-dimensional sea surface terrain slope measurement cannot be realized.
Disclosure of Invention
The invention aims to solve the problem that the existing radar altimeter technology cannot realize high-precision two-dimensional terrain slope surveying and mapping, in particular to ocean slope surveying and mapping; a method for measuring the gradient of a two-dimensional terrain by using bottom view differential interferometry is provided.
To achieve the above object, embodiment 1 of the present invention proposes a method of measuring a two-dimensional terrain slope using bottom-view differential interferometry, the method including:
to left antenna A of satellite-borne radarLIntermediate antenna AOAnd a right antenna ARCarrying out azimuth-range compression processing on the received echoes to obtain pulse echoes after the compression processing of the three antennas;
performing interference processing on the compressed pulse echoes to obtain two interference echoes;
performing azimuth-distance two-dimensional smoothing on the two interference echoes respectively;
extracting A from the smoothed interference echoLARInterference phase;
based on a plurality of ALARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm;
and calculating the slope angle along the rail direction on the ground grid unit by utilizing the ratio of the terrain tracking elevation output by the echo waves to the corresponding ground grid unit distance.
As an improvement of the above method, the pulse echo after compression processing is subjected to interference processing to obtain two interference echoes; the method specifically comprises the following steps:
Figure BDA0002467424050000021
Figure BDA0002467424050000022
wherein,
Figure BDA0002467424050000023
is an antenna AOAn echo of a jth range gate of the received ith echo pulse;
Figure BDA0002467424050000024
is an antenna ALAn echo of a jth range gate of the received ith echo pulse;
Figure BDA0002467424050000025
is ARReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000026
is an antenna AOAnd an antenna ALInterference echo of j distance gate between ith interference echo pulseThe wave is generated by the wave generator,
Figure BDA0002467424050000027
is an antenna AOAnd an antenna ARThe interference echo of the jth range gate of the ith interference echo pulse.
As an improvement of the above method, the extracting A from the smoothed interference echoLARInterference phase; the method specifically comprises the following steps:
from interfering echoes
Figure BDA0002467424050000031
The interference phase extracted from
Figure BDA0002467424050000032
Comprises the following steps:
Figure BDA0002467424050000033
from interfering echoes
Figure BDA0002467424050000034
The interference phase extracted from
Figure BDA0002467424050000035
Comprises the following steps:
Figure BDA0002467424050000036
wherein,
Figure BDA00024674240500000311
() Is a phase function; n1, n2 respectively represent the number of azimuth direction pulses and the number of range gates participating in the sum average; m isijThe jth range gate for the ith echo pulse, tracking gate labeled j 0;
ALARinterference phase
Figure BDA0002467424050000037
Comprises the following steps:
Figure BDA0002467424050000038
wherein k is the electromagnetic wave number, and B is the base length, i.e. the left antenna ALPhase center and right antenna ARDistance of phase centers.
As an improvement of the above method, said base is based on a plurality of ALARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm; the method specifically comprises the following steps:
ALARinterference phase
Figure BDA0002467424050000039
The relationship with the transverse rail direction slope angle β is:
Figure BDA00024674240500000310
wherein d, e, f are radar system and platform parameters, sigmahIs the root mean square height of the earth surface;
the cross-track direction slope angle β is estimated using a plurality of interference phases and a least squares method.
Embodiment 2 of the present invention provides a method for measuring a two-dimensional terrain slope using bottom view differential interferometry, the method including:
to left antenna A of satellite-borne radarLIntermediate antenna AORight radar antenna aRBackward antenna AAAnd a forward antenna AFCarrying out azimuth-range compression processing on the received echoes to obtain pulse echoes after the five antennas are compressed;
interference processing is carried out on the pulse echoes after the compression processing, and four interference echoes are obtained;
performing azimuth-distance two-dimensional smoothing on the four interference echoes respectively;
extracting A from the smoothed interference echoLARInterference phase and AAAFInterference phase;
based on a plurality of ALARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm;
based on a plurality of AAAFAnd (5) interfering the phase, and estimating the slope angle in the direction along the rail by using a least square algorithm.
As an improvement of the above method, the pulse echo after compression processing is subjected to interference processing to obtain four interference echoes; the method specifically comprises the following steps:
Figure BDA0002467424050000041
Figure BDA0002467424050000042
Figure BDA0002467424050000043
Figure BDA0002467424050000044
wherein,
Figure BDA0002467424050000045
is AOReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000046
is ALReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000047
is ARReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000048
is AAReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000049
is AFReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA00024674240500000410
is AOAntenna and ALThe echo of the jth range gate of the ith interference echo pulse between the antennas;
Figure BDA00024674240500000411
is AOAntenna and ARAn echo of a jth range gate of an ith interference echo pulse between the antennas;
Figure BDA00024674240500000412
is AOAntenna and AAAn echo of a jth range gate of an ith interference echo pulse between the antennas;
Figure BDA00024674240500000413
is AOAntenna and AFThe echo of the jth range gate of the ith interfering echo pulse between the antennas.
As an improvement of the above method, said extracting a from the smoothed interference echo is characterized byLARInterference phase and AAAFInterference phase; the method specifically comprises the following steps:
from interfering echoes
Figure BDA00024674240500000414
The interference phase extracted from
Figure BDA00024674240500000415
Comprises the following steps:
Figure BDA00024674240500000416
from interfering echoes
Figure BDA00024674240500000417
The interference phase extracted from
Figure BDA00024674240500000418
Comprises the following steps:
Figure BDA0002467424050000051
from interfering echoes
Figure BDA0002467424050000052
Medium extracted interference phase psiOA(mij0) Comprises the following steps:
Figure BDA0002467424050000053
from interfering echoes
Figure BDA0002467424050000054
Medium extracted interference phase psiOF(mij0) Comprises the following steps:
Figure BDA0002467424050000055
wherein,
Figure BDA00024674240500000514
() Is a phase function; n1, n2 respectively represent the number of azimuth direction pulses and the number of range gates participating in the sum average; m isijThe jth range gate for the ith echo pulse, tracking gate labeled j 0;
ALARinterference phase
Figure BDA0002467424050000056
Comprises the following steps:
Figure BDA0002467424050000057
AAAFinterference phase
Figure BDA0002467424050000058
Comprises the following steps:
Figure BDA0002467424050000059
wherein k is the electromagnetic wave number, and B is the base length, i.e. the left antenna ALPhase center and right antenna ARDistance of phase centers.
As an improvement of the above method, said base is based on a plurality of ALARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm; based on a plurality of AAAFInterference phase, estimating the slope angle along the rail direction by using a least square algorithm; the method specifically comprises the following steps:
ALARinterference phase
Figure BDA00024674240500000510
The relationship with the transverse rail direction slope angle β is:
Figure BDA00024674240500000511
wherein d, e, f are radar system and platform parameters, sigmahIs the root mean square height of the earth surface;
using a plurality of ALAREstimating a transverse rail direction slope angle β by an interference phase and a least square method;
AAAFinterference phase
Figure BDA00024674240500000512
Form slope angle with the direction of the rail
Figure BDA00024674240500000515
The relationship of (1) is:
Figure BDA00024674240500000513
wherein r, s, t are radar system and platform parameters, sigmahIs the root mean square height of the earth surface;
using a plurality of AAAFEstimating the grade angle of the terrain along the track direction by using interference phase and least square method
Figure BDA00024674240500000613
Embodiment 3 of the present invention provides a method for measuring a two-dimensional terrain slope using bottom view differential interferometry, the method comprising:
to left antenna A of satellite-borne radarLIntermediate antenna AORight antenna ARBackward antenna AAAnd a forward antenna AFCarrying out azimuth-range compression processing on the received echoes to obtain pulse echoes after the five antennas are compressed;
interference processing is carried out on the pulse echoes after the compression processing, and four interference echoes are obtained;
performing azimuth-distance two-dimensional smoothing on the four interference echoes respectively;
extracting A from the smoothed interference echoLARInterference phase and AAAFInterference phase;
based on a plurality of ALARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm;
based on a plurality of AAAFAnd (5) interfering the phase, and estimating a first down-track direction slope angle by using a least square algorithm.
Calculating a second down-track direction slope angle on the ground grid unit by utilizing the ratio of the terrain tracking elevation output by the echo to the corresponding ground grid unit distance;
and carrying out weighted average on the first along-rail direction slope angle and the second along-rail direction slope angle to obtain a final along-rail direction slope angle.
As an improvement of the above method, the weighted average of the first along-rail direction slope angle and the second along-rail direction slope angle to obtain a final along-rail direction slope angle specifically includes:
the first along the rail directionSlope angle
Figure BDA0002467424050000061
And a second down-track slope angle
Figure BDA0002467424050000062
Carrying out weighted average:
Figure BDA0002467424050000063
wherein,
Figure BDA0002467424050000064
the final grade angle along the rail direction is obtained;
Figure BDA0002467424050000065
Figure BDA0002467424050000066
wherein,
Figure BDA0002467424050000067
and
Figure BDA0002467424050000068
respectively a first down-track slope angle
Figure BDA0002467424050000069
The standard deviation and variance corresponding to the measurement method of (2);
Figure BDA00024674240500000610
and
Figure BDA00024674240500000611
is the second along-the-track direction slope angle
Figure BDA00024674240500000612
The corresponding standard deviation and variance of the measurement method (2).
The invention has the advantages that:
1. the method establishes a rigorous mathematical model which is closer to the measurement geometric relation and the physical measurement process, completes system design based on the mathematical characteristics of the model and realizes error cancellation;
2. the method can realize two-dimensional sea surface (/ ice frame) terrain gradient measurement with the accuracy of the terrain gradient of the urad magnitude on the spatial scale of less than 5 kilometers, which cannot be realized by other measurement means at present;
3. when the marine terrain gradient and the south and north pole ice rack terrain gradient are measured, under the relatively loose engineering realization condition, the method can eliminate the influence of the baseline mechanical deformation, the roll angle and the pitch angle on the measurement of the terrain gradient through error compensation, and obviously improve the measurement precision of the terrain gradient compared with other existing methods;
4. different from radar altimeter equipment for realizing the drawing of the ocean terrain gradient based on height measurement, the method of the invention directly measures the two-dimensional sea surface gradient in the satellite-borne realization process, so that a laser reflection array, a Doris system, a correction radiometer system and the like which are necessary for realizing high-precision distance measurement are not needed; the rigorous requirements on a base line and a special calibration field of a wide swath small incidence angle interferometric altimeter and the like are not required; the cost of engineering realization is obviously lower than that of a method for inverting the terrain slope by using an altimeter through elevation measurement.
Drawings
FIG. 1 is a schematic diagram of two-dimensional sea surface terrain slope measurement;
FIG. 2 is a schematic view of a geometric observation model;
FIG. 3 is AOThe echo and the tracking point of the echo received by the antenna are shown schematically;
FIG. 4 is a schematic phase diagram corresponding to roll angle;
FIG. 5 is a phase diagram of terrain slope;
FIG. 6 is a diagram illustrating simulated cross-track terrain slope estimation results;
fig. 7 is a schematic diagram of a scheme employing differential interference techniques in both the down-track and cross-track directions.
Detailed Description
The technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.
Example 1
The geometric relationship between the slope of the observed terrain and the baseline vector is depicted in fig. 1 (for clarity of illustration, the proportional relationship between angle and height in the figure is distorted, but does not affect the nature of the problem and the description of the problem). The radar flies inwards perpendicular to the paper, antenna AL,AO,ARAnd receiving the electromagnetic wave reflected by the ground. From the theory of interferometry, antenna A can be knownLARInterference angle phi (x, β, sigma) corresponding to phase psi of interference echoh) (phi ═ psi/(k · B), where k is the electromagnetic wave number and B is the baseline length) are the antenna baseline roll angle χ, the terrain slope angle β (parameters defined later) and the local root mean square height σhAs a function of (c). Therefore, the antenna roll angle and the slope angle in the cross track direction can be solved by establishing the mathematical relation between the echo phase and the antenna roll angle and the terrain slope.
The theoretical basis of the invention is the established echo model and the echo phase model. Terrain slope measurement accuracy on the order of a urad in the cross-track direction can be achieved based on the bottom view interferometric radar altimeter system shown in fig. 1 (demonstrated below). Therefore, a high-precision two-dimensional sea (/ ice) grade measurement can be realized based on the bottom view interferometric radar system shown in fig. 1.
The theoretical basis of the present invention is described below. Based on the geometric observation model shown in fig. 2 and the geometric relationship described in fig. 1, a desired mathematical model can be established.
In fig. 2, the antenna base length B. Radar antenna AOLocated at the center of the base line, with nadir N, and radar antenna AOThe height relative to the nadir N is H, and the local earth radius of the nadir N is Re. Baseline direction self-radar antenna ALDirectional radar antenna ARAnd the direction is the same as the X-axis direction. The radar flies along the Y-axis direction with the roll angle chi being positive counterclockwise (i.e. when chi is viewed against the flying direction)>At 0, the left antenna A looks against the direction of flightLHigher than the right antenna AR). The antenna pitch angle mu, viewed against the X-axis, is positive counterclockwise (i.e. when mu is>0, the radar visual axis is forward looking). The baseline yaw angle is ζ, and counterclockwise when viewed against the Z axis (i.e., in the down-view direction) (i.e., when ζ is positive)>0, left antenna ALRear, right antenna ARPrior). The spherical coordinates of the point target T are
Figure BDA0002467424050000081
Wherein
Figure BDA0002467424050000082
Figure BDA0002467424050000083
Indicating the height of the point target T above the reference sphere. The plane of the point target is the passing point
Figure BDA0002467424050000084
Figure BDA0002467424050000085
Tangent plane of, and passing point of
Figure BDA0002467424050000086
The included angle of the tangent plane in the transverse rail direction (in the X-axis direction) is defined as the direction definition of the slope angle β in the transverse rail direction and the rolling angle X, and the slope angle in the along (along) rail direction is
Figure BDA0002467424050000087
Is defined the same as the pitch angle mu.
The base line is perpendicular to the plane formed by the connecting line from the satellite to the nadir and the flying speed. The phase centers of the 3 antennas are respectively positioned at A in figure 1O,AL,ARIn a position, and AOALSub-base line and AOARThe baseline is symmetrical (the symmetry means geometric symmetry, and the mechanical and thermal deformation parameters are the same, although the length of the two baseline can be corrected by calculation, the length of the two baseline is equal, so that the calculation is convenient, therefore, the length of the two baseline is assumed to be equal). The visual axes of the 3 antennas are in the same plane and are parallel to each other. Intermediate antenna AOThe boresight is in the plane formed by the satellite-to-nadir point connecting line and the flight speed and is parallel to the satellite-to-nadir point connecting line. Antenna AOEmitting an electromagnetic pulse, AO,AL,ARAnd 3 antennas simultaneously receive radar echoes reflected by the ground. Where the antenna feed should be separated from the baseline to minimize the effect of baseline distortion on the baseline length.
For the geometric observation model and the physical model, the phase of the interference echo can be obtained:
Figure BDA0002467424050000091
wherein,
Figure BDA0002467424050000092
indicating radar antenna AOAnd a radar antenna ALThe phase of the interference echo between;
Figure BDA0002467424050000093
indicating radar antenna AOAnd a radar antenna ARη ═ 1+ H/ReFor local earth curvature, σhIs the local root mean square height. τ is the echo delay corresponding to the radar echo detection range gate. At an echo delay τ of 0, a differential interference can be obtained according to equation (1):
Figure BDA0002467424050000094
and
Figure BDA0002467424050000095
the formulae (2-1) and (3-1) can be further written as
Figure BDA0002467424050000096
Figure BDA0002467424050000097
Wherein a, b and c are parameters related to the radar system; d. e, f are radar system and platform parameters.
The roll angle χ can be obtained by using the formula (2-2), and then the gradient angle β in the cross rail direction can be calculated by using the formula (3-2). under the condition of large sample, the measurement accuracy of the gradient angle β in the cross rail direction of the system is,
Figure BDA0002467424050000098
η thereincThe coherence factor for interfering echoes is typically over 0.95 for oceans. N is the independent observation pulse number, and 9000 independent sample numbers can be obtained on the scale of 2km for a radar system adopting bottom view synthetic aperture processing. Therefore, the measurement precision of the two-dimensional terrain slope angle can reach the urad magnitude.
In the direction along the track, calculating the gradient of the terrain along the track according to the elevations h (x) of all the points under the satellite measured by the radar altimeter and the distance delta x between all the points under the satellite
Figure BDA0002467424050000099
By adopting the bottom view synthetic aperture radar altimeter technology, the ground elevation measurement of centimeter magnitude can be realized on the spatial scale of kilometer magnitude, so that the measurement precision of the terrain slope of urad magnitude in the direction along the rail can be realized.
For the measurement scheme described above, with the system parameters 800km track height, Ka band, base length 2m (base length is defined as a)L,ARThe distance between the phase centers of the two antennas), the pulse repetition frequency is 9KHz, the signal bandwidth is 320MHz as an example, and the specific technical implementation is described.
The high-precision topographic gradient measurement of a two-dimensional sea surface (ice surface) can be realized by implementing the bottom view differential interferometry in the following way. In the presence of AOFor transmitting antennas and by designing the pulse repetition frequencyThe rate PRF transmits electromagnetic pulses towards the surface. Receiving the ground reflection echo by 3 antennas simultaneously, and recording as psi0,ΨL,ΨR(ii) a To psi0(may also be Ψ)LOr ΨR) And (3) carrying out azimuth-range compression processing (or only carrying out range compression processing) on the echo, carrying out on-orbit tracking on the processed echo, and keeping a locked target echo signal. The treatment process is as follows:
1. for the received echo Ψ0,ΨL,ΨRAll carry out azimuth-distance compression processing and carry out AOThe received echoes (which may be from either of the other two antennas) are processed for high accuracy re-tracking. The jth range gate of the ith echo pulse is recorded as mijThe tracking gate is labeled j 0. Simultaneously outputting the corresponding root mean square height sigma of the earth surfaceh. See tracking distance gate shown in figure 3.
2. And performing interference processing on the pulse echo after the compression processing to obtain:
Figure BDA0002467424050000101
Figure BDA0002467424050000102
wherein,
Figure BDA0002467424050000103
is AOReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000104
is ALReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000105
is ARReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000106
is AOAntenna and ALThe echo of the jth range gate of the ith interference echo pulse between the antennas,
Figure BDA0002467424050000107
is AOAntenna and ARThe echo of the jth range gate of the ith interfering echo pulse between the antennas.
3. To pair
Figure BDA0002467424050000108
And
Figure BDA0002467424050000109
and performing azimuth-distance two-dimensional smoothing.
4. Extracting an interference phase:
Figure BDA00024674240500001010
Figure BDA00024674240500001011
wherein,
Figure BDA00024674240500001012
() Is a phase function; n1, n2 represent the number of azimuth pulses and the number of range gates, respectively, participating in the sum-average.
5. For the ith group of echoes (A) according to equation (2)O,AL,ARThe ith echo received by 3 antennas is a group) to obtain differential interference phase
Figure BDA0002467424050000111
Figure BDA0002467424050000112
Figure BDA0002467424050000113
See the phase given in figure 4 of the accompanying drawings.
6. For multiple differential interference phases
Figure BDA0002467424050000114
And estimating the roll angle x and system parameters a, b and c by using a least square algorithm.
7. Calculating A for each group of echoesLARInterference phase
Figure BDA0002467424050000115
Figure BDA0002467424050000116
Figure BDA0002467424050000117
See the phase given in fig. 5.
8. To a plurality of
Figure BDA0002467424050000118
The terrain slope angle β and radar system and platform parameters d, e, f are estimated using least squares, see the terrain slope angle estimate given in fig. 6.
9. In the along-track direction, the grade along the along-track direction on the ground grid unit is given by utilizing the terrain tracking elevation output by measuring the echo and the corresponding distance ratio of the ground grid unit
Figure BDA0002467424050000119
Figure BDA00024674240500001110
Wherein, h (x)1) Is a coordinate x in the direction of the orbit1Elevation of the earth's surface, h (x)2) Is a coordinate x in the direction of the orbit2The elevation of the earth's surface at. Measuring earth surface elevation h (x) by using radar altimeter1)，h(x2) Is aAnd (4) mature technology.
In view of the fact that no satellite-borne base view differential interference observation radar system exists at present, simulation experiments can be designed for verification. In the simulation, 7 terrain slopes were set in the cross-rail direction. The simulation parameters are shown in table 1 below.
TABLE 1 simulation parameters
Figure BDA00024674240500001111
Figure BDA0002467424050000121
The simulation is performed according to the parameters, and the simulation result is shown in fig. 3-6. FIG. 3 is AOThe echo received by the antenna and the tracking point thereof. Fig. 4 shows the differential interference phase corresponding to the roll angle. Fig. 5 shows interference phases corresponding to terrain slope angles. FIG. 6 is an estimate of a simulated lateral rail terrain slope angle estimate.
Example 2
The differential interference technique described above is also employed in the down-track direction, so that the overall scheme is shown in FIG. 7, with baseline AFAAAnd the aforementioned base line ALARIn the same plane and perpendicular to each other; a. theFAABase length and ALARThe base lengths are the same. The embodiment of the differential interference technique in the down-track direction is the same as that in the first embodiment.
For the geometric observation model and the physical model, the phase of the interference echo can be obtained:
Figure BDA0002467424050000122
wherein,
Figure BDA0002467424050000123
indicating radar antenna AOAnd a radar antenna AAThe phase of the interference echo between;
Figure BDA0002467424050000124
indicating radar antenna AOAnd a radar antenna AFη ═ 1+ H/ReFor local earth curvature, σhIs the local root mean square height. τ is the echo delay corresponding to the radar echo detection range gate. At an echo delay τ of 0, the differential interference can be obtained according to equation (4):
Figure BDA0002467424050000125
and
Figure BDA0002467424050000126
the formulae (5-1) and (6-1) can be further written as
Figure BDA0002467424050000127
Figure BDA0002467424050000128
Wherein l, m, n are radar system related parameters; r, s, t are radar system and platform related parameters.
For the measurement scheme described above, with the system parameters 800km track height, Ka band, base length 2m (base length is defined as a)L,ARThe distance between the phase centers of the two antennas), the pulse repetition frequency is 9KHz, the signal bandwidth is 320MHz as an example, and the specific technical implementation is described.
The high-precision topographic gradient measurement of a two-dimensional sea surface (ice surface) can be realized by implementing the bottom view differential interferometry in the following way. In the presence of AOTo transmit the antenna and transmit electromagnetic pulses toward the surface at a designed pulse repetition frequency PRF. Receiving the ground reflection echo by 5 antennae simultaneously, and recording as psio，ΨL，ΨR，ΨA，ΨF(ii) a To psio(may also be Ψ)L，ΨR，ΨA，ΨFAny one of the two) echoes are subjected to azimuth-range compression processing (or only range compression processing), and the processed echoes are subjected to on-orbit tracking to keep a target echo signal locked. Then the following treatment processes are carried out:
1. to psio，ΨL，ΨR，ΨA,ΨFThe echo is compressed in azimuth-range direction and A is processedOThe antenna (any one of the other four antennas) receives the echo to perform high-precision re-tracking processing. The jth range gate of the ith echo pulse is recorded as mijThe tracking gate is labeled j 0. Simultaneously outputting the corresponding root mean square height sigma of the earth surfaceh. See tracking distance gate in fig. 4.
2. And performing interference processing on the pulse echo after the compression processing to obtain:
Figure BDA0002467424050000131
Figure BDA0002467424050000132
Figure BDA0002467424050000133
Figure BDA0002467424050000134
wherein,
Figure BDA0002467424050000135
is AOReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000136
is ALReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000137
is ARReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000138
is AAReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000139
is AFReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA00024674240500001310
is AOAntenna and ALThe echo of the jth range gate of the ith interference echo pulse between the antennas;
Figure BDA00024674240500001311
is AOAntenna and ARAn echo of a jth range gate of an ith interference echo pulse between the antennas;
Figure BDA00024674240500001312
is AOAntenna and AAThe echo of the jth range gate of the ith interfering echo pulse between the antennas.
Figure BDA00024674240500001313
Is AOAntenna and AFThe echo of the jth range gate of the ith interfering echo pulse between the antennas.
3. To pair
Figure BDA00024674240500001314
And
Figure BDA00024674240500001315
and performing azimuth-distance two-dimensional smoothing.
4. Extracting an interference phase:
Figure BDA0002467424050000141
Figure BDA0002467424050000142
Figure BDA0002467424050000143
Figure BDA0002467424050000144
wherein,
Figure BDA00024674240500001413
() Is a phase function; n1, n2 represent the number of azimuth pulses and the number of range gates, respectively, participating in the sum-average.
5. For the ith group of echoes (A) according to equation (2)O,AL,AR,AF,AAThe ith echo received by 5 antennae is a group) to obtain ALARInterference phase
Figure BDA0002467424050000145
And AAAFInterference phase
Figure BDA0002467424050000146
Figure BDA0002467424050000147
Figure BDA0002467424050000148
Figure BDA0002467424050000149
Figure BDA00024674240500001410
6. To a plurality of
Figure BDA00024674240500001411
The cross-track direction terrain slope angle β and system parameters d, e, f are estimated using least squares.
7. To a plurality of
Figure BDA00024674240500001412
Estimating out the terrain slope angle along the rail direction by using least square
Figure BDA00024674240500001414
And system parameters r, s, t.
Example 3
And adopting the differential interference technology along the direction of the track, and simultaneously carrying out the height measurement of nadir points. The overall scheme is thus shown in FIG. 7, baseline AFAAAnd the aforementioned base line ALARIn the same plane and perpendicular to each other. This has the advantage that the accuracy of the grade of the terrain in the direction of the rail can be further improved. The reasons are two reasons: firstly, the phase information and the elevation information are mutually independent; and secondly, gradient errors caused by elevation errors caused by the fact that the target sea surface gradient is not considered when the elevation is measured in the direction along the track in the first scheme can be avoided. According to the existing sea surface height observation data, the elevation measurement error caused by the sea surface gradient of most sea areas is only mm magnitude, but in some sea areas, the error can reach cm magnitude, so that the gradient error exceeds 1 urad. The cost of this approach is higher system complexity and economic cost.
The high-precision topographic gradient measurement of a two-dimensional sea surface (ice surface) can be realized by implementing the bottom view differential interferometry in the following way. In the presence of AOTo transmit the antenna and transmit electromagnetic pulses toward the surface at a designed pulse repetition frequency PRF. Receiving the ground reflection echo by 5 antennae simultaneously, and recording as psio，ΨL，ΨR，ΨA，ΨF(ii) a To psio(may also be Ψ)L，ΨR，ΨA，ΨFAny one of) intoAnd (3) carrying out line direction-distance direction compression processing (or only carrying out distance direction compression processing), carrying out on-orbit tracking on the processed echo, and keeping a locked target echo signal. Then the following treatment processes are carried out:
1. to psio，ΨL，ΨR，ΨA，ΨFThe echo is compressed in azimuth-range direction and A is processedOThe antenna (or any one of other four antennas) receives the echo and carries out high-precision re-tracking processing. The jth range gate of the ith echo pulse is recorded as mijThe tracking gate is labeled j 0. Simultaneously outputting the corresponding root mean square height sigma of the earth surfaceh。
2. And performing interference processing on the pulse echo after the compression processing to obtain:
Figure BDA0002467424050000151
Figure BDA0002467424050000152
Figure BDA0002467424050000153
Figure BDA0002467424050000154
wherein,
Figure BDA0002467424050000155
is AOReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000156
is ALReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000157
is AROf the jth range gate of the ith echo pulse received by the antennaEcho waves;
Figure BDA0002467424050000158
is AAReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA0002467424050000159
is AFReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure BDA00024674240500001510
is AOAntenna and ALThe echo of the jth range gate of the ith interference echo pulse between the antennas;
Figure BDA00024674240500001511
is AOAntenna and ARAn echo of a jth range gate of an ith interference echo pulse between the antennas;
Figure BDA00024674240500001512
is AOAntenna and AAThe echo of the jth range gate of the ith interfering echo pulse between the antennas.
Figure BDA00024674240500001513
Is AOAntenna and AFThe echo of the jth range gate of the ith interfering echo pulse between the antennas.
3. To pair
Figure BDA00024674240500001514
And
Figure BDA00024674240500001515
and performing azimuth-distance two-dimensional smoothing.
4. Extracting an interference phase:
Figure BDA0002467424050000161
Figure BDA0002467424050000162
Figure BDA0002467424050000163
Figure BDA0002467424050000164
wherein,
Figure BDA00024674240500001622
() Is a phase function; n1, n2 represent the number of azimuth pulses and the number of range gates, respectively, participating in the sum-average.
5. For the ith group of echoes (A) according to equation (2)O,AL,AR,AF,AA1 group of ith echoes received by 5 antennas) to obtain ALARInterference phase
Figure BDA0002467424050000165
And AAAFInterference phase
Figure BDA0002467424050000166
Figure BDA0002467424050000167
Figure BDA0002467424050000168
Figure BDA0002467424050000169
Figure BDA00024674240500001610
6. To a plurality of
Figure BDA00024674240500001611
The cross-rail direction slope angle β and system parameters d, e, f are estimated using least squares.
7. A plurality of
Figure BDA00024674240500001612
Estimating a first down-track slope angle by using least squares
Figure BDA00024674240500001623
And system parameters r, s, t.
8. Using the output of the measured echo to track the elevation of the terrain and the distance ratio of the corresponding ground grid unit to give a second down-track slope angle on the ground grid unit
Figure BDA00024674240500001613
Figure BDA00024674240500001614
9. The first along-rail direction slope angle
Figure BDA00024674240500001615
And a second down-track slope angle
Figure BDA00024674240500001616
Carrying out weighted average:
Figure BDA00024674240500001617
wherein
Figure BDA00024674240500001618
Figure BDA00024674240500001619
Figure BDA00024674240500001620
And
Figure BDA00024674240500001621
the standard deviation and variance are respectively corresponding to the two measurement methods.
The innovation points of the invention are as follows:
1. and modeling the echoes received by the radar antennas participating in the ground-view differential interference processing on each antenna echo under the same reference system, thereby obtaining a ground-view interference radar echo model and a ground-view differential interference phase model. The method is an innovative point of the invention and a theoretical basis of the invention.
2. According to the symmetry of the base view interference phase, a differential interference equation set is constructed by adopting symmetrical double baselines, and the gradient and the roll angle of the target terrain are separated (/ decoupled) from the interference phase, so that the method is theoretical innovation and technical innovation.
3. Measuring two-dimensional terrain slope in the cross-track and down-track directions using a bottom view symmetrical baseline 3 receiving channel (as shown in fig. 7) is a technical innovation of the present invention. The advantage of using the symmetrical base line is that the base line deformation error compensation, the satellite platform roll angle compensation and the satellite platform pitch angle compensation can be realized when the terrain gradient is observed, and the measurement error is reduced.
4. The processing step (flow) of inverting the high-precision terrain slope through the bottom-view differential interference echo is the 4 th innovation point of the invention.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (10)

1. A method of measuring two-dimensional terrain grade using bottom view differential interferometry, the method comprising:
to left antenna A of satellite-borne radarLIntermediate antenna AOAnd a right antenna ARAzimuth-range compression of received echoesProcessing to obtain pulse echoes after the three antennas are compressed;
performing interference processing on the compressed pulse echoes to obtain two interference echoes;
performing azimuth-distance two-dimensional smoothing on the two interference echoes respectively;
extracting A from the smoothed interference echoLARInterference phase;
based on a plurality of ALARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm;
and calculating the slope angle along the rail direction on the ground grid unit by utilizing the ratio of the terrain tracking elevation output by the echo waves to the corresponding ground grid unit distance.
2. The method for measuring the gradient of the two-dimensional terrain by using bottom-view differential interferometry according to claim 1, wherein the compressed pulse echo is subjected to interference processing to obtain two interference echoes; the method specifically comprises the following steps:
Figure FDA0002467424040000011
Figure FDA0002467424040000012
wherein,
Figure FDA0002467424040000013
is an antenna AOAn echo of a jth range gate of the received ith echo pulse;
Figure FDA0002467424040000014
is an antenna ALAn echo of a jth range gate of the received ith echo pulse;
Figure FDA0002467424040000015
is ARJ of the ith echo pulse received by the antennaEcho of the range gate;
Figure FDA0002467424040000016
is an antenna AOAnd an antenna ALThe interference echo of the jth range gate between the ith interference echo pulse,
Figure FDA0002467424040000017
is an antenna AOAnd an antenna ARThe interference echo of the jth range gate of the ith interference echo pulse.
3. A method of measuring two dimensional terrain grade using undersight differential interferometry according to claim 2, characterized in that said extracting a from smoothed interference echoesLARInterference phase; the method specifically comprises the following steps:
from interfering echoes
Figure FDA0002467424040000018
The interference phase extracted from
Figure FDA0002467424040000019
Comprises the following steps:
Figure FDA00024674240400000110
from interfering echoes
Figure FDA00024674240400000111
The interference phase extracted from
Figure FDA00024674240400000112
Comprises the following steps:
Figure FDA0002467424040000021
wherein,
Figure FDA0002467424040000022
() Is a phase function; n1, n2 respectively represent the number of azimuth direction pulses and the number of range gates participating in the sum average; m isijThe jth range gate for the ith echo pulse, tracking gate labeled j 0;
ALARinterference phase
Figure FDA0002467424040000023
Comprises the following steps:
Figure FDA0002467424040000024
wherein k is the electromagnetic wave number, and B is the base length, i.e. the left antenna ALPhase center and right antenna ARDistance of phase centers.
4. A method of measuring two dimensional terrain slopes using undersight differential interferometry according to claim 3, wherein said determining is based on a plurality aLARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm; the method specifically comprises the following steps:
ALARinterference phase
Figure FDA0002467424040000025
The relationship with the transverse rail direction slope angle β is:
Figure FDA0002467424040000026
wherein d, e, f are radar system and platform parameters, sigmahIs the root mean square height of the earth surface;
the cross-track direction slope angle β is estimated using a plurality of interference phases and a least squares method.
5. A method of measuring two-dimensional terrain grade using bottom view differential interferometry, the method comprising:
to satellite carrierLeft antenna A of radarLIntermediate antenna AORight radar antenna aRBackward antenna AAAnd a forward antenna AFCarrying out azimuth-range compression processing on the received echoes to obtain pulse echoes after the five antennas are compressed;
interference processing is carried out on the pulse echoes after the compression processing, and four interference echoes are obtained;
performing azimuth-distance two-dimensional smoothing on the four interference echoes respectively;
extracting A from the smoothed interference echoLARInterference phase and AAAFInterference phase;
based on a plurality of ALARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm;
based on a plurality of AAAFAnd (5) interfering the phase, and estimating the slope angle in the direction along the rail by using a least square algorithm.
6. The method for measuring the gradient of the two-dimensional terrain by using bottom-view differential interferometry according to claim 5, wherein the compressed pulse echoes are subjected to interference processing to obtain four interference echoes; the method specifically comprises the following steps:
Figure FDA0002467424040000031
Figure FDA0002467424040000032
Figure FDA0002467424040000033
Figure FDA0002467424040000034
wherein,
Figure FDA0002467424040000035
is AOReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure FDA0002467424040000036
is ALReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure FDA0002467424040000037
is ARReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure FDA0002467424040000038
is AAReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure FDA0002467424040000039
is AFReceiving an echo of a jth range gate of an ith echo pulse by an antenna;
Figure FDA00024674240400000310
is AOAntenna and ALThe echo of the jth range gate of the ith interference echo pulse between the antennas;
Figure FDA00024674240400000311
is AOAntenna and ARAn echo of a jth range gate of an ith interference echo pulse between the antennas;
Figure FDA00024674240400000312
is AOAntenna and AAAn echo of a jth range gate of an ith interference echo pulse between the antennas;
Figure FDA00024674240400000313
is AOAntenna and AFThe echo of the jth range gate of the ith interfering echo pulse between the antennas.
7. A method of measuring two-dimensional terrain slopes using undersight differential interferometry according to claim 6, wherein said extracting A from smoothed interference echoesLARInterference phase and AAAFInterference phase; the method specifically comprises the following steps:
from interfering echoes
Figure FDA00024674240400000314
The interference phase extracted from
Figure FDA00024674240400000315
Comprises the following steps:
Figure FDA00024674240400000316
from interfering echoes
Figure FDA00024674240400000317
The interference phase extracted from
Figure FDA00024674240400000318
Comprises the following steps:
Figure FDA00024674240400000319
from interfering echoes
Figure FDA00024674240400000320
Medium extracted interference phase psiOA(mij0) Comprises the following steps:
Figure FDA0002467424040000041
from interfering echoes
Figure FDA0002467424040000042
Medium extracted interference phase psiOF(mij0) Comprises the following steps:
Figure FDA0002467424040000043
wherein,
Figure FDA0002467424040000044
is a phase function; n1, n2 respectively represent the number of azimuth direction pulses and the number of range gates participating in the sum average; m isijThe jth range gate for the ith echo pulse, tracking gate labeled j 0;
ALARinterference phase
Figure FDA0002467424040000045
Comprises the following steps:
Figure FDA0002467424040000046
AAAFinterference phase
Figure FDA0002467424040000047
Comprises the following steps:
Figure FDA0002467424040000048
wherein k is the electromagnetic wave number, and B is the base length, i.e. the left antenna ALPhase center and right antenna ARDistance of phase centers.
8. The method of claim 7 for measuring two dimensional terrain grade using undersight differential interferometry, wherein the base is based on a plurality ALARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm; based on a plurality of AAAFInterference phase, estimating the slope angle along the rail direction by using a least square algorithm; specifically comprises：
ALARInterference phase
Figure FDA0002467424040000049
The relationship with the transverse rail direction slope angle β is:
Figure FDA00024674240400000410
wherein d, e, f are radar system and platform parameters, sigmahIs the root mean square height of the earth surface;
using a plurality of ALAREstimating a transverse rail direction slope angle β by an interference phase and a least square method;
AAAFinterference phase
Figure FDA00024674240400000411
Form slope angle with the direction of the rail
Figure FDA00024674240400000412
The relationship of (1) is:
Figure FDA00024674240400000413
wherein r, s, t are radar system and platform parameters, sigmahIs the root mean square height of the earth surface;
using a plurality of AAAFEstimating the grade angle of the terrain along the track direction by using interference phase and least square method
Figure FDA00024674240400000414
9. A method of measuring two-dimensional terrain grade using bottom view differential interferometry, the method comprising:
to left antenna A of satellite-borne radarLIntermediate antenna AORight antenna ARBackward antenna AAAnd forward directionAntenna AFCarrying out azimuth-range compression processing on the received echoes to obtain pulse echoes after the five antennas are compressed;
interference processing is carried out on the pulse echoes after the compression processing, and four interference echoes are obtained;
performing azimuth-distance two-dimensional smoothing on the four interference echoes respectively;
extracting A from the smoothed interference echoLARInterference phase and AAAFInterference phase;
based on a plurality of ALARInterference phase, estimating the slope angle in the transverse rail direction by using a least square algorithm;
based on a plurality of AAAFInterference phase, estimating a first down-track direction slope angle by using a least square algorithm;
calculating a second down-track direction slope angle on the ground grid unit by utilizing the ratio of the terrain tracking elevation output by the echo to the corresponding ground grid unit distance;
and carrying out weighted average on the first along-rail direction slope angle and the second along-rail direction slope angle to obtain a final along-rail direction slope angle.
10. The method according to claim 9, wherein the weighted average of the first and second off-track slope angles to obtain a final off-track slope angle comprises:
the first along-rail direction slope angle
Figure FDA0002467424040000051
And a second down-track slope angle
Figure FDA0002467424040000052
Carrying out weighted average:
Figure FDA0002467424040000053
wherein,
Figure FDA0002467424040000054
the final grade angle along the rail direction is obtained;
Figure FDA0002467424040000055
Figure FDA0002467424040000056
wherein,
Figure FDA0002467424040000057
and
Figure FDA0002467424040000058
respectively a first down-track slope angle
Figure FDA0002467424040000059
The standard deviation and variance corresponding to the measurement method of (2);
Figure FDA00024674240400000510
and
Figure FDA00024674240400000511
is the second along-the-track direction slope angle
Figure FDA00024674240400000512
The corresponding standard deviation and variance of the measurement method (2).
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112799056A (en) * 2020-12-28 2021-05-14 上海卫星工程研究所 Spaceborne radar altimeter system and method

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5552787A (en) * 1995-10-10 1996-09-03 The United States Of America As Represented By The Secretary Of The Navy Measurement of topography using polarimetric synthetic aperture radar (SAR)
CN101046510A (en) * 2006-03-31 2007-10-03 中国科学院空间科学与应用研究中心 Subaperture radar altimeter
CN103675790A (en) * 2013-12-23 2014-03-26 中国国土资源航空物探遥感中心 Method for improving earth surface shape change monitoring precision of InSAR (Interferometric Synthetic Aperture Radar) technology based on high-precision DEM (Digital Elevation Model)
CN104316920A (en) * 2014-11-11 2015-01-28 上海无线电设备研究所 High-precision sea surface height extracting method of radar altimeter through small incidence angle interference
CN106569211A (en) * 2016-11-09 2017-04-19 上海卫星工程研究所 Space-borne double-star formation SAR (synthetic aperture radar) three-pass differential interferometry-based baseline design method
CN110058230A (en) * 2019-04-01 2019-07-26 中国科学院国家空间科学中心 The estimation method and system of the mountain terrain angle of orientation based on full-polarization SAR
CN110823191A (en) * 2019-10-08 2020-02-21 北京空间飞行器总体设计部 Method and system for determining ocean current measurement performance of mixed baseline dual-antenna squint interference SAR
CN110850382A (en) * 2019-12-18 2020-02-28 中国人民解放军61540部队 Method and system for evaluating measurement accuracy of interferometric radar altimeter

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5552787A (en) * 1995-10-10 1996-09-03 The United States Of America As Represented By The Secretary Of The Navy Measurement of topography using polarimetric synthetic aperture radar (SAR)
CN101046510A (en) * 2006-03-31 2007-10-03 中国科学院空间科学与应用研究中心 Subaperture radar altimeter
CN103675790A (en) * 2013-12-23 2014-03-26 中国国土资源航空物探遥感中心 Method for improving earth surface shape change monitoring precision of InSAR (Interferometric Synthetic Aperture Radar) technology based on high-precision DEM (Digital Elevation Model)
CN104316920A (en) * 2014-11-11 2015-01-28 上海无线电设备研究所 High-precision sea surface height extracting method of radar altimeter through small incidence angle interference
CN106569211A (en) * 2016-11-09 2017-04-19 上海卫星工程研究所 Space-borne double-star formation SAR (synthetic aperture radar) three-pass differential interferometry-based baseline design method
CN110058230A (en) * 2019-04-01 2019-07-26 中国科学院国家空间科学中心 The estimation method and system of the mountain terrain angle of orientation based on full-polarization SAR
CN110823191A (en) * 2019-10-08 2020-02-21 北京空间飞行器总体设计部 Method and system for determining ocean current measurement performance of mixed baseline dual-antenna squint interference SAR
CN110850382A (en) * 2019-12-18 2020-02-28 中国人民解放军61540部队 Method and system for evaluating measurement accuracy of interferometric radar altimeter

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
XIANGWEI YU 等: "Extraction of DEM and Error Analysis in Mountainous Area by Using Spaceborne SAR Data", 《2019 6TH ASIA-PACIFIC CONFERENCE ON SYNTHETIC APERTURE RADAR (APSAR)》 *
周春霞: "星载SAR干涉测量技术及其在南极冰貌地形研究中的应用", 《中国优秀博硕士学位论文全文数据库(博士)基础科学辑》 *
杨双宝: "基于合成孔径技术的高精度雷达高度计技术研究", 《中国优秀博硕士学位论文全文数据库(博士)信息科技辑》 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112799056A (en) * 2020-12-28 2021-05-14 上海卫星工程研究所 Spaceborne radar altimeter system and method
CN112799056B (en) * 2020-12-28 2022-12-13 上海卫星工程研究所 Spaceborne radar altimeter system and method

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