CN108549079A - Triantennary interference delay Doppler radar altimeter landform spy shows independent positioning method - Google Patents
Triantennary interference delay Doppler radar altimeter landform spy shows independent positioning method Download PDFInfo
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- CN108549079A CN108549079A CN201810331357.6A CN201810331357A CN108549079A CN 108549079 A CN108549079 A CN 108549079A CN 201810331357 A CN201810331357 A CN 201810331357A CN 108549079 A CN108549079 A CN 108549079A
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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
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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
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
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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
- 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 kind of triantennaries, and delay doppler altimeter landform spy to be interfered to show independent positioning method, mainly solves the problems, such as that existing method altimetry precision and ground resolution are relatively low.Implementation step is：Establish the echo signal model of triantennary interference delay Doppler radar altimeter；Calculate echo-signal noise power estimation and detection threshold；Interference window delimited, the surface units that all range values are higher than detection threshold are obtained；Special aobvious point is chosen, the surface units of not aliasing are selected；Interferometric phase is extracted, angle of the surface units relative to aerial array normal is obtained；According to the angle of special aobvious corresponding distance, the aobvious point of spy relative to the center and course in aobvious place of the angle of aerial array normal and spy Doppler channel in interference window, special aobvious three-dimensional coordinate is estimated.The present invention improves the resolution ratio on the altimetry precision and vertical course direction of radar altimeter, can choose more special aobvious points and provide three-dimensional coordinate information, positioning when can use terrain match to target.
Description
Technical field
The present invention relates to Radar Technology field, more particularly to a kind of delay Doppler radar altimeter landform spy shows point location
Method, positioning when can use terrain match to target.
Background technology
Existing inertial guidance system is corrected since the error of its accumulation can be increased with the flight time, and without itself
Function, typically by means of other correctives.So it is current grind to correct inertial navigation system using Terrain Contour Matching navigation system
Study carefully hot spot, and the core of Terrain Contour Matching navigation system is exactly altimeter, then to the Measurement Resolution of altimeter and measurement accuracy
It is proposed higher requirement.The altimetry precision and ground resolution of conventional radar altimeter are all relatively low, and use at delay Doppler
After reason, the resolution ratio along course direction is improved, but the resolution ratio in vertical course is still relatively low, and then influences elevation carrection
Precision.
The airborne dual-antenna interference delay Doppler radar altimeter system of American R ＆ D, is equipped with two vertical course lines point
The antenna of cloth also adds interference angle measurement ability except the ability of delay doppler processing.Since interferometric phase and ground dissipate
The angle that wave is emitted back towards relative to beauty's battle array is related, will be to improve the Height Estimation based on echo frontier using interferometric phase information
Precision provides additional supplementary means.But the interference of American R ＆ D delay Doppler radar altimeter system is only double antenna
System, since the echo-signal of the equidistant surface units at left and right sides of course line will overlap in a range cell, this
Kind dual-antenna system is difficult to effectively extract the angle information of surface units, and the equidistant ground that cannot be distinguished at left and right sides of course line is single
The location information of member, and then influence radar altimeter and improved in the resolution ratio on the direction of course, cause matching to position
Precision is low, cannot meet the matched demand of landform.
Invention content
It is an object of the invention in view of the above shortcomings of the prior art, propose a kind of triantennary interference delay Doppler's thunder
Independent positioning method is shown up to altimeter landform spy, to improve the spatial resolution of the altimetry precision and vertical course of radar altimeter,
Positioning accuracy when terrain match is improved, the matched demand of landform is met.
To achieve the above object, technical scheme of the present invention includes as follows：
(1) signal model for establishing triantennary interference delay Doppler radar altimeter, i.e., by three perpendicular to flight path side
To antenna equidistantly arrange, the spacing between antenna be d, d>0, the height on antenna distance ground is H meters, H>100；
(2) signal, three antennas while receives echo-signal are emitted by intermediate antenna；
(3) to the noise power in echo-signalEstimated, and according to noise powerWith detection probability PfaIt calculates
Detection threshold UT；
(4) search is higher than detection threshold U in echo-signalTPeak point, since the range cell of peak point position,
It is searched for echo frontier and rear edge, is less than detection threshold U when there is signal amplitudeTRange cell when stop search, then draw
Surely interfere window, which includes that all signal amplitude values are higher than detection threshold UTRange cell；
(5) selection that special aobvious point is carried out in interference window, that is, select the surface units of not aliasing；
(6) corresponding n-th of the range cell of center Doppler frequency for calculating m Doppler channel is handled by interfering
Angle theta (m, n) of the corresponding surface units relative to aerial array normal；
(7) according to the aobvious point of landform spy in interference window between intermediate antenna distance R and its relative to aerial array normal
Angle theta (m, n), estimate the three-dimensional coordinate parameter H of the aobvious point of landform spym,n, Xm,n, Ym,n：
Wherein, Hm,nIt is corresponding for center Doppler frequency corresponding n-th of range cell in m Doppler channel
Difference in height of the face unit relative to carrier aircraft platform, Xm,nCenter Doppler frequency for m Doppler channel is n-th corresponding
The corresponding surface units of range cell are upwardly deviated from the vertical course coordinate in carrier aircraft ground course line, Y in vertical course sidem,nFor
Carrier aircraft uniform rectilinear is flat fly under conditions of, corresponding n-th of the range cell of center Doppler frequency in m Doppler channel
Corresponding surface units in the case where being upwardly deviated from radar altimeter along course side special aobvious point along course coordinate, θ (m, n) is No. m
The corresponding surface units of corresponding n-th of the range cell of center Doppler frequency in Doppler channel are relative to aerial array method
The angle of line, B are signal bandwidth, and λ is transmitting signal wavelength, and N is the umber of pulse for postponing doppler processing, and v is carrier aircraft speed
Degree,For the corresponding special aobvious angle with carrier aircraft velocity vector of center Doppler frequency in m Doppler channel：Fr is pulse recurrence frequency.
The present invention has the following advantages that compared with prior art：
1, lateral angles measurement capability of the present invention since triantennary array is utilized, it is opposite can to measure surface units
In the angle corresponding to path in elevation direction, and then obtain the three-dimensional coordinate of the aobvious point of landform spy；
2, the present invention interferes delay Doppler radar altimeter landform spy to show independent positioning method, solution as a result of triantennary
Conventional radar altimeter measurement accuracy of having determined and the low problem of resolution ratio, improve the resolution ratio in the vertical course of altimeter；
3, using in a Doppler channel, there may be multiple special aobvious points in the present invention, while it is aobvious to measure multiple landform spies
The three-dimensional coordinate of point helps to improve positioning accuracy when terrain match, reduces number of flights when measuring.
Description of the drawings
Fig. 1 is the implementation flow chart of the present invention；
Fig. 2 is the schematic diagram of a scenario that present invention emulation uses；
Fig. 3 is triantennary interference delay Doppler radar altimeter geometrical relationship figure in the present invention；
Fig. 4 is that triantennary interference delay Doppler radar altimeter landform spy shows point location schematic diagram in the present invention；
Fig. 5 is that the interference window in the present invention delimit schematic diagram；
Fig. 6 is terrain simulation result figure under the conditions of hypsography is larger with the present invention；
Fig. 7 is terrain simulation result figure under the conditions of hypsography is smaller with the present invention.
Specific implementation mode
Referring to Fig.1, steps are as follows for specific implementation of the invention：
Step 1, the echo signal model for establishing triantennary interference delay Doppler radar altimeter.
With reference to Fig. 3, the identical antenna in three intervals is disposed along vertical course direction, by the spacing between antenna, i.e. baseline
Length is denoted as d, d>0, the height on antenna distance ground is H meters, H>100, A points are any one surface units on ground, the
The distance of one antenna 1 to A points is R1, the distance of second antenna 2 to A points is R2, the distance of third antenna 3 to A points is
R3, the angle of aerial array normal and A points is θ, and coordinate origin is ρ with A points at a distance from, and the angle of vector and A points is
Φ sends pulse signal by first antenna 1, is received jointly by first antenna, 1, second antenna 2 and third antenna 3
Ground echo signal.
The signal model that three antennas receive the interference delay Doppler radar altimeter of ground echo signal indicates respectively
It is as follows：
Wherein, s1(t) it is the output signal of first antenna 1, λ is wavelength, LPFor propagation attenuation, H is carrier aircraft height, h
For the height of surface units, x, y are respectively the transverse and longitudinal coordinate for the surface units that coordinate is (x, y), TPFor echo-signal pulsewidth, G
(x, y) is the antenna gain of the corresponding surface units of coordinate (x, y), and σ (x, y) is the corresponding surface units unit plane of coordinate x, y
Product scattering coefficient, s2(t) it is the output signal of second antenna 2, d is baseline length, and θ (x, y) is that coordinate (x, y) is corresponding
Angle of the surface units relative to aerial array normal, s3(t) it is the output signal of third antenna 3.
From echo signal model as can be seen that for the same scattering unit on ground, the output of the second antenna 2
Signal has more an interferometric phase item e compared to first antenna 1-j2πdsinθ(x,y)/λ, the output signal of third antenna 3 is compared to first
Antenna 1 has more an interferometric phase item：ej2πdsinθ(x,y)/λ。
With reference to Fig. 4, it is assumed that the corresponding oblique distance of i-th of range cell after echo-signal discrete sampling is Ri=ic/2FS,
If can calculate some range cell in echo-signal can calculate the range cell in the interferometric phase of three antennas
Angle theta (x, y) of the corresponding surface units relative to aerial array, pass through the oblique distance by first antenna 1 to the surface units
RiWith aerial array relative to the angle theta (x, y) of the surface units and the angle of the surface units and courseCalculate this
The three-dimensional coordinate H, X, Y of surface units, wherein H is difference in height of the surface units relative to carrier aircraft platform, and X is the ground
Unit is upwardly deviated from the vertical course coordinate in carrier aircraft ground course line in vertical course side, and Y is that winged item is put down in carrier aircraft uniform rectilinear
Under part, the surface units in the case where being upwardly deviated from radar altimeter along course side special aobvious point along course coordinate.
Step 2 handles echo-signal.
For coordinate estimation, optimal selection is that the signal of N/2 Doppler channel output is selected to handle, more
General Le channel is the resolution cell formed after postponing doppler processing, but in order to without loss of generality and convenient for analysis, sheet
Example assumes ground scatter by taking the signal that the m Doppler channel adjacent with N/2 Doppler channel exports as an example
Unit is distributed only on the equal Doppler curves corresponding to m Doppler channel, is realized as follows：
(2a) noise powerEstimation：
It is needed before carrying out Height Estimation processing first in the place windowing estimating noise power far from echo frontierThis is made an uproar
Acoustical powerIt is calculated as follows：
Wherein, N1It is interference window window starting distance unit number, M is the length of noise estimation window；
(2b) calculates detection threshold UT：
Wherein, PfaIt is the detection probability being arranged according to specific application scenarios；
(2c) delimit interference window：
With reference to Fig. 5, the specific implementation of this step is：First, peak point of the search higher than detection threshold in echo-signal
Position, it is assumed that range cell serial number K where peak point, i.e., since K range cells, respectively to echo frontier and rear edge
Search is less than detection threshold U when there is signal amplitudeTRange cell when stop search；Then interference window, the interference delimited
Window includes that all signal amplitude values are higher than detection threshold UTRange cell, it is assumed here that P is that peak point is arrived in interference window forward position
Range cell number, Q arrive the range cell number of peak point for edge after interference window；
(2d) chooses landform spy from interference window and shows point：
The condition that the echo-signal of the aobvious point of (2d1) structure landform spy should meet
Assuming that σAIt is the echo-signal amplitude of A points,It is the phase of the echo-signal of A points, w1It is connect for first antenna
The noise signal received, w2For the noise signal that second antenna receives, w3For the noise signal that third antenna receives,
The output of first antenna 1, the second antenna 2 and third antenna 3 is reduced to：
Wherein,That is w1,w2,w3Gaussian distributed, N are the symbols of Gaussian Profile,It is
Noise power；
According to echo model, exist in consideration noise, the echo-signal of the aobvious point of landform spy should meet the following conditions：
1) Amplitude Ratio criterion：
Define the amplitude output signal of the second antenna 2 and third antenna 3 than average statisticalAnd root-mean-square deviationIt is expressed as：
Wherein, SNR is signal-to-noise ratio, and SNR is unknown in practice, needs to be estimated according to echo-signal；
In view of the presence of the system non-ideal factor of various complexity in practice, it is assumed that the second antenna 2 and third antenna 3
The average statistical of the Amplitude Ratio of output signalApproximate Gaussian distributed, in this way | s3|/|s2| value just have
95.4% probability is fallenWithin this section, accordingly, it is possible to be sentenced using Signal to Noise Ratio (SNR)
Whether the echo of the range cell is the aobvious thresholding put of landform spy calmly；
By the Amplitude Ratio of signalReleasing amplitude criterion with the relationship of the section upper limit is：
2) interference phase difference criterion：
By the Interference phase angle of 2 output signal of the second antennaWith the interference phase of 3 output signal of third antenna
Parallactic angleApproximate representation is：
Wherein,Due to
And w2Multiple Gauss distribution is obeyed, so the w12 being made of it, w13 also Gaussian distributed, i.e.,
Therefore the Interference phase angle of 2 output signal of the second antennaWith the Interference phase angle of 3 output signal of third antennaThe sum of be：
angle(s2·s1 *)+angle(s3·s1 *)=imag (w12+w13)/σA,
Due toSo the sum of two interferometric phases Gaussian distributed and its
Variance is：Therefore under noise conditions, the value of the sum of two interferometric phases has 95.4% probability
It falls within this section [- 4/SNR, 4/SNR], thus can judge returning for the range cell using Signal to Noise Ratio (SNR) to calculate
Whether wave is the aobvious thresholding put of landform spy；
By the Interference phase angle of 2 output signal of the second antennaWith the interference phase of 3 output signal of third antenna
Parallactic angleThe sum of relationship with the section upper limit, releasing interference phase difference criterion is：
(2d2) derives criterion when practical application
The aobvious point condition of spy derived by (2d1) obtains the center Doppler frequency correspondence for m Doppler channel
Two criterions of echo-signal of n-th of range cell be：
1) Amplitude Ratio criterion：
2) interference phase difference criterion：
Wherein, s1(m, n) is that the center Doppler frequency in the m Doppler channel that first antenna 1 receives is corresponding
The echo-signal of n-th range cell, s2(m, n) is that how general the center in the m Doppler channel that the second antenna 2 receives is
Strangle the echo-signal of corresponding n-th of the range cell of frequency, s3(m, n) is that the m Doppler that third antenna 3 receives is logical
The echo-signal of corresponding n-th of the range cell of center Doppler frequency in road, SNR (m) are the dry of m Doppler channel
The average signal-to-noise ratio of all range cells in window is related to, SNR (m) can be calculate by the following formula：
(2d3) chooses landform spy and shows point：
According to the center Doppler frequency in the two condition pair m Doppler channels obtained (2d2) it is corresponding n-th away from
Echo-signal from unit is judged, if the echo-signal meets the Amplitude Ratio condition and interference phase difference item of (2d2) simultaneously
Part, then the echo-signal is referred to as that landform spy shows point, if not satisfied, then the echo-signal is referred to as that non-landform spy shows point；
(2e) calculates the corresponding ground of corresponding n-th of the range cell of center Doppler frequency in m Doppler channel
Angle theta (m, n) of the unit relative to aerial array normal：
θ (m, n)=arcsin { λ [angle (s3(m,n)·s1(m,n)*)-angle(s2(m,n)·s1(m,n)*)]/4π
D },
Wherein, n ∈ [K-P, K+Q] indicate the position of the range cell of the aobvious point of all landform spies in m Doppler channel
Serial number, P are the range cell numbers for interfering window forward position to arrive peak point, and Q is a along the range cell to peak point after interference window
Number, K are range cell serial numbers where peak point；
The estimation of (2f) three-dimensional coordinate：
Estimated according to the oblique distance R of the aobvious point of the landform spy in interference window and its angle theta (m, n) relative to aerial array normal
The three-dimensional coordinate parameter H of the aobvious point of landform spym,n,Xm,n,Ym,n, complete the positioning of point aobvious to landform spy：
Wherein, Hm,nIt is corresponding for center Doppler frequency corresponding n-th of range cell in m Doppler channel
Difference in height of the face unit relative to carrier aircraft platform；Xm,nCenter Doppler frequency for m Doppler channel is n-th corresponding
The corresponding surface units of range cell are upwardly deviated from the vertical course coordinate in carrier aircraft ground course line in vertical course side；Ym,nFor
Carrier aircraft uniform rectilinear is flat fly under conditions of, corresponding n-th of the range cell of center Doppler frequency in m Doppler channel
Corresponding surface units in the case where being upwardly deviated from radar altimeter along course side special aobvious point along course coordinate；It is No. m
Angle of the corresponding special aobvious point of center Doppler frequency in Doppler channel with carrier aircraft velocity vector, calculation formula are：
Fr is pulse recurrence frequency.
The effect of the present invention can pass through following emulation further verification.
1, experiment condition
Simulating scenes of the present invention are as shown in Figure 2 comprising：3 antennas；
Radar simulation parameter：Speed 250m/s, power 2w, antenna gain 26dB, frequency 6GHz, pulsewidth 50MHz, DBS arteries and veins
Rush number 128, baseline length 0.08m, carrier aircraft height 3000m.
2, experiment content and result：
Experiment 1 carries out surveying high emulation under big rise and fall orographic condition.
This example has selected the output in N/2 Doppler channel, makes respectively to N/2 Doppler multi-channel output signal
It is how general with conventional half power points Height Estimation method, least mean-square error fitting Height Estimation method and triantennary interference delay
It strangles the aobvious independent positioning method of radar altimeter landform spy to handle, obtained simulation estimate result such as Fig. 6, wherein：
Fig. 6 (a) is the measurement simulation result using conventional half power points Height Estimation method；
Fig. 6 (b) is the measurement simulation result that Height Estimation method is fitted using least mean-square error；
Fig. 6 (c) is the Dan Duopu for interfering the aobvious independent positioning method of delay Doppler radar altimeter landform spy using triantennary
The Terrain Elevation for strangling the interference of channel-Dan Texian points measures simulation result；
Fig. 6 (d) is the distribution situation of the ground scatter unit obtained using traditional Height-measuring algorithm；
Fig. 6 (e) is to interfere delay Doppler radar altimeter landform spy to show the ground that independent positioning method obtains using triantennary
The distribution situation of area scattering unit；
Fig. 6 (f) is the Dan Duopu for interfering the aobvious independent positioning method of delay Doppler radar altimeter landform spy using triantennary
The Terrain Elevation for strangling the more special aobvious point interference in channel-measures simulation result；
Estimate that root-mean-square error can more above-mentioned existing two methods and measurement of the invention essence by computed altitude
Degree, the results are shown in Table 1；
Table 1
| Algorithm | Half power points | Least mean-square error is fitted | Interferometry |
| Height Estimation root-mean-square error [m] | 46.6302 | 35.2037 | 1.3772 |
It can be obtained by Fig. 6 and table 1：Under big rise and fall orographic condition, triantennary interference delay Doppler radar altimeter
The altimetry precision that landform spy shows independent positioning method has great raising relative to conventional method, and has calculated vertical course
The coordinate of special aobvious point, improves the resolution ratio on vertical course direction on direction.In addition, due in a Doppler channel
There may be multiple special aobvious points, so being capable of providing more special aobvious points is used for terrain match, are conducive to improve terrain match
Precision.
Experiment 2 carries out surveying high emulation under the conditions of rising and falling shape smaller.
This example has selected the output in N/2 Doppler channel, makes respectively to N/2 Doppler multi-channel output signal
It is how general with conventional half power points Height Estimation method, least mean-square error fitting Height Estimation method and triantennary interference delay
It strangles the aobvious independent positioning method of radar altimeter landform spy to handle, obtained simulation estimate result such as Fig. 7, wherein：
Fig. 7 (a) is the measurement simulation result using conventional half power points Height Estimation method；
Fig. 7 (b) is the measurement simulation result that Height Estimation method is fitted using least mean-square error；
Fig. 7 (c) is the Dan Duopu for interfering the aobvious independent positioning method of delay Doppler radar altimeter landform spy using triantennary
The Terrain Elevation for strangling the interference of channel-Dan Texian points measures simulation result；
Fig. 7 (d) is the distribution situation of the ground scatter unit obtained using traditional Height-measuring algorithm；
Fig. 7 (e) is to interfere delay Doppler radar altimeter landform spy to show the ground that independent positioning method obtains using triantennary
The distribution situation of area scattering unit；
Fig. 7 (f) is the Dan Duopu for interfering the aobvious independent positioning method of delay Doppler radar altimeter landform spy using triantennary
Strangle the interference landform elevation carrection simulation result of the more special aobvious points in channel-；
Estimate that root-mean-square error can more above-mentioned existing two methods and measurement of the invention essence by computed altitude
Degree, the results are shown in Table 2；
Table 2
It can be obtained by Fig. 7 and table 2：Under the conditions of rising and falling shape smaller, with the reduction of hypsography degree, carrier aircraft line two
The phenomenon that surface units of side mutual aliasing, aggravates, therefore the aobvious point quantity of the spy that can be extracted will decline, and lead to triantennary
Although the altimetry precision that interference delay Doppler radar altimeter landform spy shows independent positioning method is declined, relative to biography
System algorithm, the present invention have calculated the coordinate of special aobvious point on vertical course direction, have improved the resolution ratio on vertical course direction.
Claims (6)
1. a kind of triantennary interference delay doppler altimeter landform spy shows independent positioning method, including：
(1) signal model for establishing triantennary interference delay Doppler radar altimeter, i.e., by three perpendicular to flight path direction
Antenna equidistantly arranges, and the spacing between antenna is d, d>0, the height on antenna distance ground is H meters, H>100；
(2) signal, three antennas while receives echo-signal are emitted by intermediate antenna；
(3) to the noise power in echo-signalEstimated, and according to noise powerWith detection probability PfaCalculate detection
Thresholding UT；
(4) search is higher than detection threshold U in echo-signalTPeak point, since the range cell of peak point position, to return
Wavefront and rear edge are searched for, and are less than detection threshold U when there is signal amplitudeTRange cell when stop search, then delimit dry
Window is related to, which includes that all signal amplitude values are higher than detection threshold UTRange cell；
(5) selection that special aobvious point is carried out in interference window, that is, select the surface units of not aliasing；
(6) corresponding n-th of range cell correspondence of center Doppler frequency for calculating m Doppler channel is handled by interfering
Angle theta (m, n) of the surface units relative to aerial array normal；
(7) it is shown according to the landform spy in interference window and puts distance R and its folder relative to aerial array normal between intermediate antenna
Angle θ (m, n) estimates the three-dimensional coordinate parameter H of the aobvious point of landform spym,n, Xm,n, Ym,n：
Wherein, Hm,nIt is single for the corresponding ground of corresponding n-th of the range cell of center Doppler frequency in m Doppler channel
Difference in height of the member relative to carrier aircraft platform, Xm,nFor corresponding n-th of the distance of center Doppler frequency in m Doppler channel
The corresponding surface units of unit are upwardly deviated from the vertical course coordinate in carrier aircraft ground course line, Y in vertical course sidem,nFor in carrier aircraft
Uniform rectilinear is flat fly under conditions of, corresponding n-th of the range cell of center Doppler frequency in m Doppler channel is corresponding
Surface units in the case where being upwardly deviated from radar altimeter along course side special aobvious point along course coordinate, θ (m, n) is m Doppler
Folder of the corresponding surface units of corresponding n-th of the range cell of center Doppler frequency in channel relative to aerial array normal
Angle, B are signal bandwidth, and λ is transmitting signal wavelength, and N is the umber of pulse for postponing doppler processing, and v is carrier aircraft speed,For the corresponding special aobvious angle with carrier aircraft velocity vector of center Doppler frequency in m Doppler channel：Fr is pulse recurrence frequency.
2. according to the method described in claim 1, triantennary interference postpones the letter of Doppler radar altimeter wherein in step (1)
Number model indicates as follows：
Wherein, s1(t) it is the output signal of first antenna, λ is wavelength, LPFor propagation attenuation, H is carrier aircraft height, and h is ground
The height of unit, x, y are respectively the transverse and longitudinal coordinate for the surface units that coordinate is (x, y), TPFor echo-signal pulsewidth, G (x, y) is
The antenna gain of the corresponding surface units of coordinate (x, y), σ (x, y) are coordinate x, y corresponding surface units unit area scattering system
Number, s2(t) it is the output signal of second antenna, d is baseline length, and θ (x, y) is the corresponding surface units phase of coordinate (x, y)
For the angle of aerial array normal, s3(t) it is the output signal of third antenna.
3. according to the method described in claim 1, noise power in the wherein described step (3)Estimation and detection threshold UT's
It calculates, carries out as follows：
Wherein, N1It is interference window window starting distance unit number, M is the length of noise estimation window, PfaIt is according to specific
The detection probability of application scenarios setting.
4. according to the method described in claim 1, selecting the ground of not aliasing single in interference window in the wherein described step (5)
Member carries out as follows：
(5a) assumes σAIt is the echo-signal amplitude of A points,It is the phase of the echo-signal of A points, w1It is received for first antenna
The noise signal arrived, w2For the noise signal that second antenna receives, w3It, will for the noise signal that third antenna receives
The signal model established in step (1) is reduced to：
Wherein, s1For the echo-signal that first antenna after simplification receives, s2It is received for second antenna after simplification
Echo-signal, s3The echo-signal that third antenna after simplification receives,That is w1,w2,w3It obeys
Gaussian Profile, N are the symbols of Gaussian Profile,It is noise power；
(5b) according to echo model, in the presence of considering noise, the echo signal amplitude ratio of the aobvious point of setting landform spy is sentenced
Other condition and interference phase difference criterion：
Amplitude Ratio criterion：K-P≤n≤K+Q,
Interference phase difference criterion：
Wherein, s1(m, n) is that the center Doppler frequency in the m Doppler channel that first antenna receives is n-th corresponding
The echo-signal of range cell, s2(m, n) is the center Doppler frequency in the m Doppler channel that second antenna receives
The echo-signal of corresponding n-th of range cell, s3(m, n) is in the m Doppler channel that third antenna receives
The echo-signal of corresponding n-th of the range cell of heart Doppler frequency,For s1The conjugated signal of (m, n), SNR (m) are
The average signal-to-noise ratio of all range cells in the interference window in m Doppler channel, P be interference window forward position to peak point away from
From unit number, Q is along the range cell number for arriving peak point after interference window, and K is range cell serial number where peak point；
(5c) judge three antennas in each range cell output signal whether and meanwhile meet two conditions in (3b2), if
Meet, then the surface units are that landform spy shows point, and otherwise, which cannot be chosen for landform spy and show point.
5. according to the method described in claim 4, wherein in the interference window in m Doppler channel all range cells it is flat
Equal Signal to Noise Ratio (SNR) (m), is calculate by the following formula：
Wherein, P is the range cell number for interfering window forward position to arrive peak point, and Q is after interference window along the distance list to peak point
First number, K are range cell serial number where peak point, s1(m, n) is the m Doppler channel that first antenna receives
The echo-signal of corresponding n-th of the range cell of center Doppler frequency, s2(m, n) is No. m that second antenna receives
The echo-signal of corresponding n-th of the range cell of center Doppler frequency in Doppler channel, s3(m, n) is that third antenna connects
The echo-signal of corresponding n-th of the range cell of center Doppler frequency in the m Doppler channel received,It is noise
Power.
6. according to the method described in claim 1, how general the center for calculating m Doppler channel in the wherein described step (6) is
Angle theta (m, n) of the corresponding surface units of corresponding n-th of the range cell of frequency relative to aerial array normal is strangled, by such as
Lower formula carries out：
Wherein, n ∈ [K-P, K+Q] indicate the position number of the range cell of the aobvious point of all landform spies in m Doppler channel,
P is the range cell number for interfering window forward position to arrive peak point, and Q is after interference window is along the range cell number to peak point, K
Range cell serial number where peak point.
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