CN106707280A - Synthetic aperture radar effective baseline estimation method based on registration and curve fitting - Google Patents
Synthetic aperture radar effective baseline estimation method based on registration and curve fitting Download PDFInfo
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- CN106707280A CN106707280A CN201510787599.2A CN201510787599A CN106707280A CN 106707280 A CN106707280 A CN 106707280A CN 201510787599 A CN201510787599 A CN 201510787599A CN 106707280 A CN106707280 A CN 106707280A
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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
- G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
- G01S13/9021—SAR image post-processing techniques
- G01S13/9023—SAR image post-processing techniques combined with interferometric techniques
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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
- G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
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Abstract
The invention discloses a synthetic aperture radar effective baseline estimation method based on registration and curve fitting. The synthetic aperture radar effective baseline estimation method comprises steps that 1, a baseline searching set is determined; 2, rough registration of input multi-channel synthetic aperture radar data is carried out by using the baseline values of the searching set; 3, relevancy values between channels after the rough registration are acquired; 4, high-order fitting is carried out by using the sample points of the relevancy values to acquire a curve used for describing the relation between the relevancy values and the baseline values; 5, the maximum value of the acquired curve after the fitting is searched, and the baseline value corresponding to the maximum value is the effective baseline. The method of reliably estimating the synthetic aperture radar effective baseline is provided.
Description
Technical field
The invention belongs to physical field, and in particular to by rough registration, simultaneously binding curve is fitted the method that accurate baseline is estimated that obtains in synthetic aperture radar field.
Background technology
In synthetic aperture radar field, velocity to moving target is estimated and reorientation is both needed to using the information of baseline.In practice, the value of the baseline is frequently with by the equivalent equivalent baseline value for obtaining of geometrical relationship.However, being moved error, the error of antenna radiation pattern, the difference and miscellaneous noise ratio of interchannel system function of off-course by platform（CNR）Deng influence, equivalent baseline value will be generally offset from virtual base of the necessary being in system, and these errors can be propagated in the velocity estimation and reorientation result of moving target.Therefore, the estimation problem of virtual base of the necessary being in system need to be solved.
At present, the virtual base estimation technique in polarization sensitive synthetic aperture radar system is mainly by estimating Along-track interferometry（ATI）The slope on phase inclined-plane is completed.Gierull is in document " C.H. Gierull, ' Digital channel balancing of
along-track interferometric SAR data,’ DRDC, Ottawa,
Propose that a kind of feature based value is decomposed in ON, Canada, Tech. Rep. TM 2003-024, Mar. 2003. "（EDB）Method.Its basic thought is to obtain the estimation on linear interference phase inclined-plane by carrying out Eigenvalues Decomposition to sample covariance matrix in range-Dopler domain, then the slop estimation virtual base according to the phase inclined-plane.In the method, to reduce the variance of baseline estimations, the estimation of sample covariance matrix need to be carried out in whole range gates, and the number of range gate easily reaches the magnitude of thousands of in data of synthetic aperture radar, therefore the method comparison is time-consuming.Additionally, Chen et al. document " Z.-Y. Chen, T. Wang, and N. Ma,
‘Accurate baseline estimation for synthetic aperture radar-ground moving target
indication systems based on co-registration and median filtering,’ IET Radar
Complete the estimation on phase inclined-plane in Sonar Navig., vol. 8, no. 6, pp. 607-615, Jul. 2014. " using essence registration from a new angle, recycle medium filtering further to improve the estimated accuracy on phase inclined-plane.The method obtains accurate baseline estimations again by the slope on evaluation phase inclined-plane.
Above two is based on the baseline estimations technology of evaluation phase inclined-plane slope, although can accurately estimate virtual base, but these methods are both needed to select the phase sample in antenna main beam, so just depend on the precision of Estimation of Doppler central frequency.However, the evaluated error of doppler centroid can obtain different center frequency values generally in the magnitude of 1 percent pulse recurrence frequencies using different Estimation of Doppler central frequency algorithms.Therefore, above-mentioned baseline estimations technology is unstable.
The content of the invention
The problem that the present invention is solved is that the estimated accuracy of existing virtual base method of estimation depends on the estimated accuracy of doppler centroid, namely the unstable problem of baseline estimations technology；To solve described problem, the present invention provides the polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching.
The polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching that the present invention is provided includes：
Step one, determine baseline search collection；
Step 2, the Multichannel SAR data to being input into carry out rough registration；
Step 3, the relevance degree for obtaining the interchannel after rough registration；
Step 4, the sample point using the relevance degree for obtaining, the curve of relation between the fitting description degree of correlation and baseline value；
Step 5, the maximum for finding fitting curve obtained, the corresponding baseline value of the maximum are virtual base.
Further, the baseline search collection is initialized as
, wherein,,,It is by the equivalent equivalent baseline value for obtaining of geometrical relationship.It is assumed herein that the total deviation of baseline estimationsNo more than。
Further, the baseline search collection is：
Wherein,
,
,
,
Represent and carry out floor operation to nearest integer.
Further, the step 2 includes：
Step 2.1, the data of synthetic aperture radar of input is converted into range-Dopler domain,WithThe 1st passage and the 2nd range-Dopler domain signal of passage are represented respectively, wherein,The expression distance dimension time,Expression Doppler frequency,Expression virtual base,Represent synthetic aperture radar platform along course flying speed；
Step 2.2, on the basis of passage 1, using baseline search collectionInterior value carries out rough registration to passage 2, and rough registration operation can be described as：
Wherein,Represent and utilizeIt is rightThe output signal that rough registration is obtained is carried out,。
Further, the expression formula of the relevance degree of the interchannel after rough registration is：
Wherein,It is a constant, and：
。
Further, the step 4 includes：Carried out curve fitting using the degree of correlation sample for obtaining so that functional valueRelevance degree can be fitted in least mean-square error meaning, the fitting functionIt is expressed as：
,。
Further, the step 5 includes：
Step 5.1, six rank multinomials tried to achieve using the step 4CoefficientConstruction function of the relevance degree on baseline value：
,
Step 5.2, degree of correlation functionMaximum corresponding to baseline value be virtual base：
。
Compared with prior art, the present invention has advantages below：
First, the present invention makes full use of the cross correlation information of interchannel, in the absence of the problem unstable to Estimation of Doppler central frequency, thus can obtain sane virtual base estimate；
Second, the present invention obtains sample point of the degree of correlation at different baseline values by the way of baseline search rough registration, and method flow design is simple；
3rd, the present invention has the advantages that speed is fast, high precision due to completing the estimation of function of the degree of correlation on baseline value using the mode of curve matching.
Brief description of the drawings
Fig. 1 is the operational flowchart of the polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching provided in an embodiment of the present invention.
Fig. 2 is the compares figure of the matched curve that the polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching provided in an embodiment of the present invention is obtained and original sample point.
Fig. 3 is the polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching provided in an embodiment of the present invention and EDB methods（The method that feature based value is decomposed）With CMB methods（Method based on registration and medium filtering）Performance comparision figure.
Specific embodiment
Hereinafter, the present invention is further elaborated in conjunction with the accompanying drawings and embodiments.For the baseline estimations of multi-channel system, without loss of generality, as a example by estimating the virtual base between passage 1 and passage 2, embodiments of the invention are made schematically to illustrate, the virtual base of other interchannels can be estimated with identical method.
Reference picture 1, is input into the multi-channel data of synthetic aperture radar, and the data are converted into range-Dopler domain first.Note passage 1 and the range-Dopler domain signal of passage 2 areWith, then its available following formula be associated：
Wherein,Represent the distance dimension time；
Represent azimuth dimension frequency, namely Doppler frequency；
Represent virtual base；
Represent synthetic aperture radar platform along course flying speed.
Influenceed by various error sources, virtual baseCan deviate by the equivalent equivalent baseline for obtaining of geometrical relationship, but total deviationNot more than, so the baseline search interval that rough registration is used can be initialized as, wherein, minimum possible baseline value, the baseline value of maximum possible。
To estimate virtual base, following |input paramete need to be initialized：
1) equivalent baseline.Equivalent baseline is obtained by geometrical relationship is equivalent.For example, for using the transmitting of antenna it is multiple along course at intervals ofAntenna simultaneously receive situation,。
2) scale that the baseline value at initial sample point is accurate to.If for example,, then baseline value is accurate at initial sample pointM namely 1cm.
3) baseline estimations need the scale being accurate to.If for example,, then baseline estimations need to be accurate tom。
Polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching provided in an embodiment of the present invention, including：
Step 1 、Produce baseline search collection.Baseline search collection
Wherein,
,
,
,
Represent and carry out floor operation to nearest integer.
Step 2, rough registration.Passage 1 is reference channel, and baseline search collection is utilized on the basis of passage 1Interior value carries out rough registration to passage 2, and rough registration operation can be described as：
Wherein,Represent and utilizeIt is rightThe output signal that rough registration is obtained is carried out,。
Step 3, obtain relevance degree.The correlation between passage 2 after reference channel 1 and rough registration is characterized by the degree of correlation.The expression formula for calculating the degree of correlation is as follows：
Wherein,It is a constant, and：
Step 4, curve matching.Six rank curve matchings are carried out as the following formula using the sample value on the degree of correlation for obtaining, can be in the hope of six rank multinomialsCoefficient, the coefficient causes functional valueCan be in least mean-square error meaning to relevance degreeIt is fitted：
,
Step 5, estimate virtual base.Usage factorComplete degree of correlation functionEstimation：
,
Virtual base corresponding to maximal correlation angle value is virtual base of the necessary being in system：
Effect of the invention can further be verified by following experiment.Experiment actual measurement data of synthetic aperture radar used derives from certain airborne experiment.In order to detect ground moving object, the antenna of experimental system is used and is arranged along course.Radar parameter is as follows：The GHz of carrier frequency 9, the Hz of pulse recurrence frequency 840, doppler bandwidth 530 Hz, the Hz of doppler centroid -90, the m/s of platform speed 106, antenna sub-aperture are spaced 0.4 m.
Fig. 2 is curve-fitting results of the invention.Star point in figure is the sample value that the degree of correlation obtained after baseline search collection is traveled through in step 3, and black solid line is then the result after being carried out curve fitting using these sample values.The corresponding baseline value of maximum of the relevance degree curve after the fitting is 0.1652 m.Using the baseline value and carry out the relevance degree that rough registration obtained using the baseline value that EDB methods and CMB methods are obtained and be shown in Table 1.As can be seen that the inventive method better performances compared with EDB methods and CMB methods.
Table 1
| Baseline value（ m ） | Relevance degree | |
| Nominal value（Equivalent baseline value） | 0.2000 | 0.9477 |
| EDB methods | 0.1639 | 0.9681 |
| CMB methods | 0.1645 | 0.9682 |
| The inventive method | 0.1652 | 0.9682 |
Fig. 3 is the inventive method and EDB methods and the comparing figure of the baseline estimations performance of CMB methods.Doppler centroid value in this experiment is estimated by classical relevant Doppler（CDE）Algorithm is obtained.However, the estimated accuracy of current Estimation of Doppler central frequency algorithm is about 1 the percent of pulse recurrence frequency, therefore the real doppler centroid of this experiment interval range that may be present is [- 100 Hz, -80 Hz].It can be seen that existing EDB methods and CMB methods change with the change of Estimation of Doppler central frequency value, thus the robustness of both approaches can not be guaranteed.And the method for the present invention is then unrelated with Estimation of Doppler central frequency value, sane baseline estimations value can be obtained.
Although the present invention is disclosed as above with preferred embodiment; but it is not for limiting the present invention; any those skilled in the art are without departing from the spirit and scope of the present invention; the methods and techniques content that may be by the disclosure above makes possible variation and modification to technical solution of the present invention; therefore; every content without departing from technical solution of the present invention; any simple modification, equivalent variation and modification made to above example according to technical spirit of the invention, belong to the protection domain of technical solution of the present invention.
Claims (7)
1. based on the registering polarization sensitive synthetic aperture radar system virtual base method of estimation with curve matching, it is characterised in that including：
Step one, determine baseline search collection；
Step 2, the Multichannel SAR data to being input into carry out rough registration；
Step 3, the relevance degree for obtaining the interchannel after rough registration；
Step 4, the sample point using the relevance degree for obtaining, the curve of relation between the fitting description degree of correlation and baseline value；
Step 5, the maximum for finding fitting curve obtained, the corresponding baseline value of the maximum are virtual base.
2. according to the polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching described in claim 1, it is characterised in that the initialisation range of the baseline search collection is
, wherein,,It is equivalent baseline.
3. according to the polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching described in claim 1, it is characterised in that the baseline search collection is, wherein,,,,Represent and carry out floor operation to nearest integer.
4. according to the polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching described in claim 1, it is characterised in that the step 2 includes：
Step 2.1, the data of synthetic aperture radar of input is converted into range-Dopler domain,WithThe 1st passage and the 2nd range-Dopler domain signal of passage are represented respectively, wherein,The expression distance dimension time,Expression Doppler frequency,Expression virtual base,Represent synthetic aperture radar platform along course flying speed；
Step 2.2, on the basis of passage 1, using baseline search collectionInterior value carries out rough registration to passage 2, and rough registration operation can be described as：
Wherein,Represent and utilizeIt is rightThe output signal that rough registration is obtained is carried out,。
5. according to the polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching described in claim 1, it is characterised in that the expression formula of the relevance degree of the interchannel after rough registration is：
Wherein,It is a constant, and：
。
6. according to the polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching described in claim 1, it is characterised in that the step 4 includes：Carried out curve fitting using the degree of correlation sample for obtaining so that functional valueRelevance degree can be fitted in least mean-square error meaning, the fitting functionIt is expressed as：
,。
7. according to the polarization sensitive synthetic aperture radar system virtual base method of estimation based on registration and curve matching described in claim 1, it is characterised in that the step 5 includes：
Step 5.1, six rank multinomials tried to achieve using the step 4CoefficientConstruction function of the relevance degree on baseline value：
,
Step 5.2, degree of correlation functionMaximum corresponding to baseline value be virtual base：
。
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Cited By (4)
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| CN109242872A (en) * | 2018-08-27 | 2019-01-18 | 西安电子科技大学 | Interference baseline estimation method based on SRTM DEM |
| CN111220979A (en) * | 2020-01-16 | 2020-06-02 | 电子科技大学 | Imaging method for curved synthetic aperture radar |
| CN112068138A (en) * | 2019-06-10 | 2020-12-11 | 通用汽车环球科技运作有限责任公司 | Ultra-short range radar sensor system and method |
| CN113064168A (en) * | 2021-03-17 | 2021-07-02 | 电子科技大学 | Imaging method for curved synthetic aperture radar |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109242872A (en) * | 2018-08-27 | 2019-01-18 | 西安电子科技大学 | Interference baseline estimation method based on SRTM DEM |
| CN112068138A (en) * | 2019-06-10 | 2020-12-11 | 通用汽车环球科技运作有限责任公司 | Ultra-short range radar sensor system and method |
| CN112068138B (en) * | 2019-06-10 | 2024-05-28 | 通用汽车环球科技运作有限责任公司 | Ultra short range radar sensor system and method |
| CN111220979A (en) * | 2020-01-16 | 2020-06-02 | 电子科技大学 | Imaging method for curved synthetic aperture radar |
| CN111220979B (en) * | 2020-01-16 | 2022-05-13 | 电子科技大学 | Imaging method for curved synthetic aperture radar |
| CN113064168A (en) * | 2021-03-17 | 2021-07-02 | 电子科技大学 | Imaging method for curved synthetic aperture radar |
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