CN110687497A - Novel DOA estimation method for instantaneous multi-beam paraboloid - Google Patents
Novel DOA estimation method for instantaneous multi-beam paraboloid Download PDFInfo
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- CN110687497A CN110687497A CN201911063410.XA CN201911063410A CN110687497A CN 110687497 A CN110687497 A CN 110687497A CN 201911063410 A CN201911063410 A CN 201911063410A CN 110687497 A CN110687497 A CN 110687497A
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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
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
- G01S3/14—Systems for determining direction or deviation from predetermined direction
Abstract
The invention discloses a novel DOA estimation method aiming at an instantaneous multi-beam paraboloid, which belongs to the technical field of DOA estimation, and is characterized in that a focal plane field of a source signal in a given direction is calculated by utilizing an electromagnetic field theory, an array unit and an angle search range of DOA estimation are determined by utilizing the focal plane field, a received signal data covariance matrix is reconstructed, an improved MUSIC algorithm is designed, and a feed source array is moved to equivalently change an array structure so as to improve the DOA estimation performance; the method combines the reflector antenna theory and the array signal processing, adapts to the characteristics of weak signals received by part of array elements, unfixed and irregular array structure, complex array manifold, high angular resolution, poor DOA estimation stability of part of signals and the like in the DOA estimation of the multi-beam reflector antenna, simplifies the DOA estimation system, and improves the DOA estimation performance.
Description
Technical Field
The invention relates to the technical field of DOA estimation, in particular to a novel DOA estimation method for an instantaneous multi-beam paraboloid.
Background
The large multi-beam reflector antenna realized by the compact focal plane array feed source can enlarge the view field of the reflector antenna and improve the observation efficiency of a radio astronomical telescope, a point-to-multipoint satellite communication antenna, a wide-angle scanning radar antenna and the like. Before the antenna works, the arrival direction of interference signals in an operation visual field is often required to be estimated, and the interference signals are restrained by weighting the exciting voltage of array units. The array feed source is utilized and the DOA estimation algorithm is combined to estimate the incoming wave direction, which becomes an important link in the design of the multi-beam reflector antenna gradually.
The existing DOA estimation of the multi-beam reflector antenna mainly utilizes an array feed source to combine with a focal plane field, and utilizes a classical multi-signal classification method to estimate, but is only limited to DOA estimation of non-correlated signals, and does not consider the beneficial factor that the correlation between signals received by an array unit is reduced after the source signals are gathered on a focal plane through a reflecting plane, so that the DOA estimation is simplified. The characteristics of the reflector antenna are not combined to optimize the array structure and the DOA estimation algorithm, and the angular resolution, the sensitivity and the like are greatly restricted.
Because the focal plane field is uneven, the action of the array units on each source signal is not necessarily the same, the number of the array units possibly acting on weak signals is less, and the incoming wave direction of the weak signals cannot be judged; if the number of array units is increased, the complexity of the system is increased, and some array units cannot act on partial signals, and noise introduced by the array units can weaken the DOA estimation performance of the signals.
Because the angle range of the interference signal does not have any prior information, a wide area needs to be set for DOA estimation, the complexity of DOA estimation by using a conventional intelligent algorithm is increased, and the feasibility of the implementation process and the reliability of the result are reduced.
For non-stationary random signals, the focal plane field is randomly varied; if a plurality of incoherent stationary signals exist, the superposed focal plane fields of the incoherent stationary signals are also randomly changed, and at the moment, the array units can be selected according to the signal amplitude received by each array unit only through long-time observation, but the selected array units are also possibly incorrect, and a reliable DOA estimation result cannot be obtained; when a plurality of source signals exist, the selected array units do not necessarily have the same action on each source signal, the number of array units acting on weak signals is small, the incoming wave direction of the weak signals cannot be judged, and the factors weaken the robust performance of the DOA estimation.
Based on this, the present invention designs a new DOA estimation method for instantaneous multi-beam paraboloids to solve the above problems.
Disclosure of Invention
The present invention aims to provide a new DOA estimation method for instantaneous multi-beam paraboloids to solve the problems mentioned in the background art.
In order to achieve the purpose, the invention provides the following technical scheme: a novel DOA estimation method for instantaneous multi-beam paraboloids comprises a source signal and a feed source array, and specifically comprises the following steps:
s1, calculating the focal plane field of the source signal in the given direction by using an electromagnetic field theory;
s2, determining the array unit and the angle search range of DOA estimation by using the focal plane field;
s3, reconstructing a received signal data covariance matrix and designing an improved MUSIC algorithm;
s4, moving the feed source array to equivalently change the array structure to improve the DOA estimation performance.
Preferably, the strongest point of the electric field of the focal plane field, that is, the central point of the focal plane field is found, and the array unit for DOA estimation is reasonably selected according to the principle that the electric field amplitude difference with the central point is smaller than a certain set value.
Preferably, the direction of the source signal is approximately reversely deduced by combining a Zhulan radiation formula according to the central point of the focal plane field, and the search angle range of the DOA estimation is determined according to the actual working requirement by utilizing the calculated main lobe width.
Preferably, in S3, after the source signal is reflected by the reflection surface, and the correlation between the signals received by the array unit is already reduced, the received data covariance matrix is reconstructed to further reduce the correlation between the signals, and the correlation is subjected to feature decomposition, the feature vectors of the noise subspace and the signal subspace are weighted by using the feature value of the noise and the feature value of the signal, then the signal projection weighted spatial spectrum and the noise projection weighted spatial spectrum are superimposed, and then the DOA is estimated by using the MUSIC algorithm.
Preferably, the feed source array is moved longitudinally, namely the array structure is equivalently changed, and the same signal is measured for multiple times through the array structures in various forms, so that the DOA estimation performance is improved.
Compared with the prior art, the invention has the beneficial effects that:
(1) the reflector antenna theory is combined with the array signal processing, and on the basis that the correlation between signals received by the array unit is reduced after the source signals are reflected by the reflector, the correlation between the signals is further reduced by reconstructing the covariance matrix of the received data, and measures such as dimension reduction and phase resolution interference processing of a space smoothing algorithm and the like or non-dimension reduction and phase resolution interference processing of a Toeplitz matrix and the like are omitted. And a classical multiple signal classification method is improved, so that not only can DOA estimation of related signals be carried out, but also a DOA estimation system can be simplified, the performances of DOA estimation such as angular resolution, sensitivity and the like are improved, and the DOA estimation system is suitable for the characteristics of unfixed and irregular array structure, limited array unit number, complex array manifold, high angular resolution and the like of the DOA estimation system of the array feed source.
(2) Array units are selected by utilizing the focal plane field of the reflecting surface, the array units with too weak signals are removed, a DOA estimation system is simplified, and the receiving noise of the array is reduced.
(3) The DOA estimation search angle range is determined by utilizing the focal plane field, the DOA estimation speed is increased, and the probability of misjudgment caused by factors such as phase ambiguity is reduced.
(4) Based on the principle that different array structures have different DOA estimation performances, the array feed sources of instantaneous multi-beam paraboloids such as FAST can accurately move along the axis of the reflecting surface, when the array feed sources continuously move along the axis of the reflecting surface, the equivalent array structures are changed, the same signal is subjected to DOA estimation for multiple times in the moving process, and the results are compared and analyzed, so that the feasibility of the DOA estimation and the reliability of the estimation results are increased under the conditions that the number of array units is limited and the array structures are irregular.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, the present invention provides a technical solution: a novel DOA estimation method for instantaneous multi-beam paraboloids comprises a source signal and a feed source array, and specifically comprises the following steps:
s1: calculating a focal plane electric field of a source signal in a given direction by using an electromagnetic field theory;
calculating the induced current of a source signal in a given direction on a reflecting surface by using an electromagnetic field theory, and calculating the electric field of any point on a focal plane by using the induced current and combining a Zhulan radiation formula;
s2: determining an array unit and an angle search range of DOA estimation by using a focal plane field;
finding the strongest point of the electric field of the focal plane field, namely the central point of the focal plane field, and reasonably selecting a DOA estimation array unit according to the principle that the electric field amplitude difference with the central point is smaller than a certain set value;
according to the central point of the focal plane field, combining a Zhulan radiation formula to approximately reversely deduce the direction of the source signal, and determining a DOA estimation search angle range according to actual working requirements by utilizing the calculated main lobe width;
s2, array units are selected by utilizing the focal plane field of the reflecting surface, the array units with too weak signals are removed, the DOA estimation system is simplified, and the receiving noise of the array is reduced; the focal plane field is utilized to determine the angle search range, so that the DOA estimation speed is increased, and the probability of misjudgment caused by factors such as phase ambiguity is reduced;
s3: reconstructing a received signal data covariance matrix and designing an improved MUSIC algorithm;
through reflection of the reflecting surface, correlation among signals received by the array units is reduced; therefore, on the basis, correlation among signals is further reduced by reconstructing a covariance matrix of the received signals, and solution intervention measures such as dimension reduction processing and non-dimension reduction processing in conventional array DOA estimation can be omitted;
setting the number of array units as m, the number of source signals as d, the data matrix of the received signal as u, and the reconstructed data matrix of the received signal as uk＝u+P·u*Where P is an inverse angular matrix of order mxm, u*Is a complex conjugate of u;
for u is pairedkPerforming characteristic decomposition to obtain a reconstructed signal characteristic value (lambda)1～λd) And corresponding feature vectors
Eigenvalues (λ) of noised+1～λm) And corresponding feature vectors
Respectively constructing a weighted diagonal identity matrix for the noise eigenvector and the signal eigenvector:
and
establishing spatial spectrum function by applying MUSIC algorithm
DOA estimation is performed where v is the focal plane electric field matrix of the source signal at the center of each array element, vHIs a conjugate transpose matrix;
s3, utilizing the beneficial factor of the correlation reduction after the signal is reflected by the reflecting surface, and reconstructing the array received signal matrix to further reduce the correlation, thereby saving the solution intervention measures such as dimension reduction processing and non-dimension reduction processing in the conventional DOA estimation and simplifying the DOA estimation system; the amplitude of the signal is added into the array manifold, so that the steady performance of DOA estimation is improved; the signal subspace and the noise subspace are weighted, so that the DOA estimation resolution is improved, the noise is suppressed, and the DOA estimation performance under the condition of small snapshot number is improved;
s4: the feed source array is moved to equivalently change the array structure so as to improve the DOA estimation performance;
under the condition that the structure of the array feed source is basically unchanged, when the array feed source deviates from a focal plane along the axis of the reflecting surface but has small deviation distance, the amplitude of signals received by the array unit is basically unchanged, but the relationship between the phases of the received signals is greatly changed and is nonlinearly changed, and the result is equivalent to the change of the array structure; different array structures can obtain different DOA estimation effects, when the array feed source continuously moves along the axis of the reflecting surface, the same signal is measured for multiple times through the array structures in various forms, and the measurement results are compared and analyzed, so that more accurate and reliable results can be obtained;
s4 utilizes the beneficial factor that the array feed source of the instantaneous multi-beam paraboloid can move accurately along the axis of the reflecting surface to change the array structure equivalently, and the DOA estimation is carried out on the same signal for a plurality of times through the array structures in various forms, thereby increasing the feasibility of the DOA estimation and the reliability of the estimation result under the conditions of limited number of array units and irregular array structure.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims (5)
1. A novel DOA estimation method for instantaneous multi-beam paraboloids is characterized by comprising the following specific steps:
s1, calculating the focal plane field of the source signal in the given direction by using an electromagnetic field theory;
s2, determining the array unit and the angle search range of DOA estimation by using the focal plane field;
s3, reconstructing a received signal data covariance matrix and designing an improved MUSIC algorithm;
s4, moving the feed source array to equivalently change the array structure to improve the DOA estimation performance.
2. A new method of DOA estimation for instantaneous multi-beam parabolas according to claim 1, characterized in that: and finding the strongest point of the electric field of the focal plane field, namely the central point of the focal plane field, and reasonably selecting the array unit for DOA estimation according to the principle that the electric field amplitude difference with the central point is smaller than a certain set value.
3. A new method of DOA estimation for instantaneous multi-beam parabolas according to claim 2, characterized in that: and according to the central point of the focal plane field, combining a Zhulan radiation formula to approximately reversely deduce the direction of the source signal, and determining the search angle range of DOA estimation according to the actual working requirement by utilizing the calculated main lobe width.
4. A new method of DOA estimation for instantaneous multi-beam parabolas according to claim 3, characterized in that: in S3, after the source signal is reflected by the reflection surface, and the correlation between the signals received by the array unit has been reduced, the received data covariance matrix is reconstructed to further reduce the correlation between the signals, and the correlation is subjected to feature decomposition, the noise eigenvalues and the signal eigenvalues are used to weight the eigenvectors of the noise subspace and the signal subspace, and then the signal projection weighted spatial spectrum and the noise projection weighted spatial spectrum are superimposed, and then the MUSIC information algorithm is used to perform DOA estimation.
5. A new method of DOA estimation for instantaneous multi-beam parabolas according to claim 4, characterized in that: the feed source array is moved longitudinally, namely the array structure is equivalently changed, and the same signal is measured for multiple times through the array structures in various forms, so that the DOA estimation performance is improved.
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