CN109358312B - Method, device, medium and equipment for determining incoming wave direction of incident signal - Google Patents
Method, device, medium and equipment for determining incoming wave direction of incident signal Download PDFInfo
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Abstract
The invention provides a method for determining incoming wave direction of an incident signal, which is based on a plasma sheath environment and comprises the following steps: establishing an antenna array in a plasma sheath environment; decorrelating the antenna array by adopting a space smoothing algorithm to obtain a covariance matrix corrected by the antenna array; adopting a cross coupling calibration algorithm, and processing the spatial spectrum function of the antenna array according to the corrected covariance matrix to obtain a spatial spectrum function without cross coupling coefficients; searching the maximum value of the spatial spectrum function without the mutual coupling coefficient, and determining the incoming wave direction of the incident signal. By combining a space smoothing algorithm and a mutual coupling calibration algorithm, a space spectrum function without mutual coupling coefficients can be obtained, and then the incoming wave direction of an incident signal is determined by the space spectrum function without mutual coupling coefficients, so that the influence of two errors of multipath effect and antenna coupling on the incoming wave direction determination of the incident signal can be weakened, and further the more accurate incoming wave direction can be estimated.
Description
Technical Field
The invention relates to the technical field of satellite navigation, in particular to a method, a device, a medium and equipment for determining incoming wave direction of an incident signal.
Background
The process of the aircraft returning to the atmosphere to the ground is called the reentry process. In the reentry process, the hypersonic aircraft interacts with the atmosphere to form bow-shaped split shock waves in front of the aircraft, the temperature of the gas rises sharply after the shock waves to show high Wen Xiaoying, and air molecules undergo dissociation and ionization reactions; and simultaneously, the heat-resistant ablation material on the surface of the aircraft is ablated under the action of high temperature and high heat flow, and the ablation product is released into the surrounding flow field of the aircraft, so that the complex reentrant flow field with various components is formed. The reentrant bypass flow field is a group of ionized gas, and when the ionization degree of the gas reaches a certain degree, the ionized gas shows the collective behavior of the plasmas to become the plasmas, and at the moment, the reentrant bypass flow field is also called a plasma cladding flow field, reentrant plasmas or a plasma sheath. The formation of the reentrant plasma attenuates the power of the electromagnetic wave propagation and causes the electromagnetic wave to reflect, refract and scatter.
The signal passes through the plasma sheath and then makes multiple reflections between the aircraft surface and the plasma sheath, thereby causing multipath effects. The multipath effect refers to that the GPS receiver can receive satellite signals directly and then reach antenna signals through different propagation paths after receiving plasma sheath emission. Thus, the positioning error formed by the method can reduce the positioning precision of the receiver by multipath effect and lengthen the processing time, and in the WAAS (Wide Area Augmentation System) and DGPS (Difference Global Positioning System) systems, the multipath error can lead to error transmission and seriously reduce the positioning precision of users in the system.
The thickness and electron density of the plasma sheath affect the coupling characteristics between antennas, and the mutual coupling between antennas affects the operation performance of the array antenna, so that the effect of weakening the plasma sheath by using the beam forming technology needs to be considered to correct the coupling error. There is no method for calibrating the mutual coupling of arrays in the existing plasma sheath model, and if the multipath effect and the mutual coupling effect generated by the plasma sheath can be effectively calibrated, the method plays an important role in eliminating the influence of the multipath and the coupling effect.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method, a device, a medium and equipment for determining the incoming wave direction of an incident signal, which can weaken the influence of two errors of multipath effect and antenna coupling on the incoming wave direction determination of the incident signal, and further estimate a more accurate incoming wave direction.
In a first aspect, the present invention provides a method for determining an incoming wave direction of an incident signal, based on a plasma sheath environment, comprising:
establishing an antenna array in a plasma sheath environment;
decorrelating the antenna array by adopting a space smoothing algorithm to obtain a covariance matrix corrected by the antenna array;
adopting a cross coupling calibration algorithm, and processing the spatial spectrum function of the antenna array according to the corrected covariance matrix to obtain a spatial spectrum function without cross coupling coefficients;
searching the maximum value of the spatial spectrum function without the mutual coupling coefficient, and determining the incoming wave direction of the incident signal.
Optionally, the establishing an antenna array in the plasma sheath environment includes:
in the plasma sheath environment, M antenna array elements are uniformly arranged from far field theta k (k=1, 2, … N) of N narrowband sources (wavelength λ) are incident, and an antenna array is built, which is:
X(t)＝A(θ)S(t)+N(t)
where a (θ) refers to an array manifold of direction vectors, S (t) refers to a signal, and N (t) refers to noise.
Optionally, the decorrelating the antenna array by using a spatial smoothing algorithm to obtain a covariance matrix after the antenna array is corrected, including:
correcting the array manifold;
obtaining a covariance matrix of the incident signal according to the corrected array manifold;
adopting a space smoothing algorithm to obtain a forward smoothing covariance matrix and a backward smoothing covariance matrix based on the covariance matrix;
and correcting the covariance matrix according to the forward and backward smooth covariance matrix to obtain the covariance matrix corrected by the antenna array.
Optionally, before the step of using a cross-coupling calibration algorithm to process the spatial spectrum function of the antenna array according to the corrected covariance matrix to obtain the spatial spectrum function without cross-coupling coefficients, the method further includes:
and obtaining a spatial spectrum function of the antenna array by adopting subspace theory.
Optionally, the modifying the array manifold includes:
each direction vector in the array manifold can be modified as:
wherein, C is a mutual coupling matrix of a uniform linear array, which is a banded and symmetrical Toeplitz matrix;
let the spacing between array elements be d=λ/2, the degree of freedom of mutual coupling be p (i.e. the mutual coupling coefficient is 0 when the spacing between two array elements is greater than d (p-1)), where the first row of mutual coupling coefficients satisfies the relationship 0<|c p-1 |<…<c 1 <c 0 ＝1。
Optionally, the processing the spatial spectrum function of the antenna array according to the corrected covariance matrix by adopting a mutual coupling calibration algorithm to obtain a spatial spectrum function without mutual coupling coefficients includes:
obtaining a new mutual coupling matrix according to Toeplitz properties of the mutual coupling matrix;
obtaining a new array manifold according to the new cross coupling matrix;
and obtaining a spatial spectrum function without cross coupling coefficients according to the corrected covariance matrix and the new array manifold.
In a second aspect, the present invention provides an apparatus for determining a direction of an incoming wave of an incident signal, based on a plasma sheath environment, comprising:
the array building module is used for building an antenna array in a plasma sheath environment;
the decorrelation module is used for decorrelating the antenna array by adopting a space smoothing algorithm to obtain a covariance matrix corrected by the antenna array;
the blind calibration module is used for processing the spatial spectrum function of the antenna array according to the corrected covariance matrix by adopting a cross coupling calibration algorithm to obtain a spatial spectrum function without cross coupling coefficients;
and the direction determining module is used for searching the maximum value of the spatial spectrum function without the mutual coupling coefficient and determining the incoming wave direction of the incident signal.
Optionally, the array building module is specifically configured to:
in the plasma sheath environment, M antenna array elements are uniformly arranged from far field theta k (k=1, 2, … N) of N narrowband sources (wavelength λ) are incident, and an antenna array is built, which is:
X(t)＝A(θ)S(t)+N(t)
where a (θ) refers to an array manifold of direction vectors, S (t) refers to a signal, and N (t) refers to noise.
In a third aspect, the present invention provides a computer readable storage medium having stored thereon a computer program which when executed by a processor implements a method of determining the direction of an incoming signal.
In a fourth aspect, the present invention provides a processing device for determining a direction of an incoming wave of an incident signal, based on a plasma sheath environment, comprising: the system comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor realizes the method for determining the incoming wave direction of the incident signal when executing the program.
According to the invention, by combining the spatial smoothing algorithm and the mutual coupling calibration algorithm, the spatial spectrum function without the mutual coupling coefficient can be obtained, and then the incoming wave direction of the incident signal is determined by the spatial spectrum function without the mutual coupling coefficient, so that the influence of two errors of multipath effect and antenna coupling on the incoming wave direction determination of the incident signal can be weakened, and further, the more accurate incoming wave direction can be estimated.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Like elements or portions are generally identified by like reference numerals throughout the several figures. In the drawings, elements or portions thereof are not necessarily drawn to scale.
FIG. 1 is a flow chart of a method for determining incoming wave direction of an incident signal according to the present invention;
FIG. 2 is a graph comparing spatial spectrum curves calculated by three methods provided by the present invention;
FIG. 3 is a three-dimensional pattern of an uncalibrated array antenna provided by the present invention;
FIG. 4 is a two-dimensional pattern of an uncalibrated array antenna provided by the present invention;
FIG. 5 is a three-dimensional pattern of a calibrated array antenna provided by the present invention;
FIG. 6 is a two-dimensional pattern of a calibrated array antenna provided by the present invention;
fig. 7 is a schematic diagram of an apparatus for determining an incoming wave direction of an incident signal according to the present invention.
Detailed Description
Embodiments of the technical scheme of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present invention, and thus are merely examples, which should not be construed as limiting the scope of the present invention.
It is noted that unless otherwise indicated, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.
The invention provides a method, a device, a medium and equipment for determining the incoming wave direction of an incident signal. Embodiments of the present invention will be described below with reference to the accompanying drawings.
Referring to fig. 1, fig. 1 is a flowchart of a method for determining an incoming wave direction of an incident signal according to an embodiment of the present invention, where the method for determining an incoming wave direction of an incident signal according to the embodiment includes:
step S101: an antenna array in a plasma sheath environment is established.
Step S102: and performing decorrelation on the antenna array by adopting a space smoothing algorithm to obtain a covariance matrix corrected by the antenna array.
Step S103: and processing the spatial spectrum function of the antenna array according to the corrected covariance matrix by adopting a cross coupling calibration algorithm to obtain the spatial spectrum function without cross coupling coefficients.
Step S104: searching the maximum value of the spatial spectrum function without the mutual coupling coefficient, and determining the incoming wave direction of the incident signal.
By combining a space smoothing algorithm and a mutual coupling calibration algorithm, a space spectrum function without mutual coupling coefficients can be obtained, and then the incoming wave direction of an incident signal is determined by the space spectrum function without mutual coupling coefficients, so that the influence of two errors of multipath effect and antenna coupling on the incoming wave direction determination of the incident signal can be weakened, and further the more accurate incoming wave direction can be estimated.
In one embodiment of the present invention, the method for establishing an antenna array in a plasma sheath environment includes: in the plasma sheath environment, M antenna array elements are uniformly arranged from far field theta k (k=1, 2, … N) of N narrowband sources (wavelength λ) are incident, and an antenna array is built, which is:
X(t)＝A(θ)S(t)+N(t) (1)
where a (θ) refers to an array manifold of direction vectors, S (t) refers to a signal, and N (t) refers to noise.
When the antenna array is established, the antenna array in the plasma sheath environment can be simulated through the HFSS.
In a specific embodiment of the present invention, the decorrelating the antenna array by using a spatial smoothing algorithm to obtain a covariance matrix after the antenna array is corrected includes: correcting the array manifold; obtaining a covariance matrix of the incident signal according to the corrected array manifold; adopting a space smoothing algorithm to obtain a forward smoothing covariance matrix and a backward smoothing covariance matrix based on the covariance matrix; and correcting the covariance matrix according to the forward and backward smooth covariance matrix to obtain the covariance matrix corrected by the antenna array.
Correction of array manifold:
when there is a mutual coupling error, each direction vector in the array manifold can be modified as:
wherein C is a mutual coupling matrix of a uniform linear array, which is a ribbon-shaped, symmetrical Toeplitz matrix.
The direction vector after correction is represented, and a (θ) represents the direction vector before correction.
Let the spacing between array elements be d=λ/2. The degree of freedom of mutual coupling is p (i.e., when the distance between two array elements is greater than d (p-1)), the mutual coupling coefficient is 0. Wherein the first row mutual coupling coefficient satisfies the relationship 0<|c p-1 |<…<c 1 <c 0 ＝1。
Obtaining a covariance matrix of the incident signal according to the corrected array manifold:
according to formula (2), a covariance matrix of the array output can be obtained, specifically:
R XX ＝E[X(t)X(t) H ]＝CAR S A H C H +σ 2 I (4)
wherein R is s A covariance matrix representing the incident signal; sigma represents noise power; i represents an identity matrix.
Adopting a space smoothing algorithm, and obtaining a forward and backward smoothing covariance matrix based on the covariance matrix, wherein the specific process is as follows:
an M-ary equidistant antenna matrix is divided into L sub-arrays in a sliding manner, each sub-array having K elements, where k=m-l+ 1. Then the output of the first forward subarray is:
wherein, the liquid crystal display device comprises a liquid crystal display device,
A M a direction vector array manifold representing subarrays; s (t) represents the input signal of the subarray; n is n l And (t) represents noise of the subarray.
Therefore, the covariance matrix of the first forward subarray is:
defining a forward spatial smoothing covariance matrix as:
similarly, the backward spatial smoothing covariance matrix can be obtained as:
thus, the forward and backward smoothing covariance matrix is defined as:
correcting the covariance matrix according to the forward and backward smooth covariance matrix to obtain the covariance matrix corrected by the antenna array, wherein the method comprises the following specific steps of:
in general, R fb Only the Hermite matrix, not the Toeplitz matrix. By utilizing Toeplitz property, R fb Correction is carried out, R fbX Is R fb Thus, the spatial smoothing of equation (4) yields:
wherein, the liquid crystal display device comprises a liquid crystal display device,
in a specific embodiment of the present invention, before the step of processing the spatial spectrum function of the antenna array according to the corrected covariance matrix by using a cross-coupling calibration algorithm to obtain a spatial spectrum function without cross-coupling coefficients, the method further includes: and obtaining a spatial spectrum function of the antenna array by adopting subspace theory.
According to subspace theory:
obtaining an array space spectrum function P MUSIC (θ) is
Wherein U is N Is a noise subspace.
The angle in equation (13) is changed, and the incoming wave direction of the incident signal is determined by finding the peak.
In a specific embodiment of the present invention, the processing, by using a cross-coupling calibration algorithm, the spatial spectrum function of the antenna array according to the corrected covariance matrix to obtain a spatial spectrum function without cross-coupling coefficients includes: obtaining a new mutual coupling matrix according to Toeplitz properties of the mutual coupling matrix; obtaining a new array manifold according to the new cross coupling matrix; and obtaining a spatial spectrum function without cross coupling coefficients according to the corrected covariance matrix and the new array manifold.
According to Toeplitz property of the mutual coupling matrix, a new mutual coupling matrix is obtained, and the specific process is as follows:
since C is a symmetric Toeplitz matrix, starting from each of the mutual coupling coefficients that make up the mutual coupling matrix, C is expressed as:
obtaining a new cross-coupling matrix, wherein c q For mutual coupling coefficients, the array manifold can be represented as a new array manifold, which is:
wherein c= [ c ] 0 ,c 1 ,c 2 ,…,c p-1 ] T Are mutually connected withThe coefficient matrix is coupled, and W (theta) is M multiplied by p to form a transformation matrix consisting of steering vectors.
According to the corrected covariance matrix and the new array manifold, a spatial spectrum function without cross coupling coefficients is obtained, and the specific process is as follows:
decomposing the characteristic value of the formula (10) to obtain a noise subspace U N Substituting formula (13) to obtain:
P MUSIC (θ)＝1/||(Ca(θ)) H U N || 2 (16)
substituting formula (15) into formula (16) to obtain:
P MUSIC (θ)＝1/||(W(θ)c) H U N || 2
＝1/(c H W(θ) H U N U N H W(θ)c)
＝1/(c H Φ(θ)c) (17)
wherein Φ (θ) =w (θ) H U N U N H W (θ) is uncorrelated with the cross-coupling coefficient.
P-solving MUSIC The maximum problem of (θ) can be translated into a quadratic programming problem under linear constraints. I.e.
minc H Φ(θ)c
s.t.ε T c＝1 (18)
Wherein cε=1, ε= [1,0, …,0] T 。
The method is obtained by a Lagrangian solution method,
substituting the obtained product into a space spectrum function formula (17),
P MUSIC (θ)＝ε T Φ -1 (θ)ε (20)
a spatial spectral function is obtained that does not contain cross-coupling coefficients. And searching the maximum position of the spatial spectrum function which is formed and does not contain the mutual coupling coefficient, and determining the incoming wave direction of the incident signal.
In using the present invention, MA can be usedTLAB simulates the method of the invention, verifying the accuracy of the method. The specific process is as follows: using an array model in an HFSS simulation plasma sheath environment, the array element number m=8, the plasma collision frequency v=2.1e10hz, and the electron density ne=1.6e12cm -3 Thickness δ=0.2 cm. The added source is GPS signal center frequency 1.57542GHz, and array element spacing is half wavelength of the incident signal. When MATLAB is used for simulating the invention, the degree of freedom of mutual coupling is selected to be 3, and the mutual coupling coefficient is selected to be the mutual coupling parameter of HFSS simulation of [1, -0.2232-0.3432i, -0.1143+0.1456i ]]T. The noise is zero-mean Gaussian white noise, the azimuth angles of 2 coherent signal sources are 0 and 65 respectively, the experiment times are 100 times, the snapshot number is 200, and the signal-to-noise ratio is 10dB.
The result shows that when the array mutual coupling exists, the conventional space smoothing algorithm cannot obtain the correct spectrum peak to fail, and the method can accurately distinguish the wave directions from 0 to 65. As shown in fig. 2.
The invention determines the calibration information of array coupling, namely the amplitude and the phase of each array element to be regulated. And loading the calibration information on an array model of the HFSS to obtain a calibration result.
The array antenna after coupling calibration is significantly improved as shown in fig. 3-6.
The method is based on a space smoothing decorrelation processing technology, corrects the coupling influence of the array by a blind calibration method and estimates the accurate direction of arrival. The method is suitable for eliminating the multipath effect and the coupling effect generated by the plasma sheath in a satellite navigation system, and improves the positioning accuracy of satellites.
The method for determining the incoming wave direction of the incident signal is provided by the invention.
Based on the same inventive concept as the method for determining the incoming wave direction of the incident signal, the embodiment of the invention also provides a device for determining the incoming wave direction of the incident signal, as shown in fig. 2. Since the apparatus embodiments are substantially similar to the method embodiments, the description is relatively simple, and reference should be made to the description of the method embodiments for relevant points.
The invention provides a device for determining the incoming wave direction of an incident signal, which is based on a plasma sheath environment and comprises the following components:
an array building module 101, configured to build an antenna array in a plasma sheath environment;
a decorrelation module 102, configured to decorrelate the antenna array by using a spatial smoothing algorithm, so as to obtain a covariance matrix corrected by the antenna array;
the blind calibration module 103 is configured to process the spatial spectrum function of the antenna array according to the corrected covariance matrix by using a mutual coupling calibration algorithm, so as to obtain a spatial spectrum function without a mutual coupling coefficient;
the direction determining module 104 is configured to search the maximum value of the spatial spectrum function without mutual coupling coefficient, and determine the incoming wave direction of the incident signal.
In one embodiment provided by the present invention, the array building module 101 is specifically configured to:
in the plasma sheath environment, M antenna array elements are uniformly arranged from far field theta k (k=1, 2, … N) of N narrowband sources (wavelength λ) are incident, and an antenna array is built, which is:
X(t)＝A(θ)S(t)+N(t)
where a (θ) refers to an array manifold of direction vectors, S (t) refers to a signal, and N (t) refers to noise.
In one embodiment provided by the present invention, the decorrelation module 102 includes:
an array manifold correction unit for correcting the array manifold;
a covariance matrix obtaining unit, configured to obtain a covariance matrix of the incident signal according to the modified array manifold;
the smoothing calculation unit is used for obtaining a forward and backward smoothing covariance matrix based on the covariance matrix by adopting a spatial smoothing algorithm;
and the correction matrix unit is used for correcting the covariance matrix according to the forward and backward smooth covariance matrix to obtain the covariance matrix corrected by the antenna array.
In a specific embodiment provided by the present invention, the apparatus further includes:
and the spectrum function calculation module is used for obtaining the space spectrum function of the antenna array by adopting subspace theory.
In one embodiment of the present invention, the array manifold correction unit is specifically configured to:
each direction vector in the array manifold can be modified as:
wherein, C is a mutual coupling matrix of a uniform linear array, which is a banded and symmetrical Toeplitz matrix;
let the spacing between array elements be d=λ/2, the degree of freedom of mutual coupling be p (i.e. the mutual coupling coefficient is 0 when the spacing between two array elements is greater than d (p-1)), where the first row of mutual coupling coefficients satisfies the relationship 0<|c p-1 |<…<c 1 <c 0 ＝1。
In one embodiment provided by the present invention, the blind calibration module 103 includes:
the property analysis unit is used for obtaining a new mutual coupling matrix according to the Toeplitz property of the mutual coupling matrix;
a new array manifold obtaining unit, configured to obtain a new array manifold according to the new mutual coupling matrix;
and the spectrum function calculation unit is used for obtaining a spatial spectrum function without mutual coupling coefficients according to the corrected covariance matrix and the new array manifold.
The device for determining the incoming wave direction of the incident signal is provided by the invention.
Based on the same inventive concept as the method for determining the incoming wave direction of the incident signal, correspondingly, the embodiment of the invention also provides a computer readable storage medium, on which a computer program is stored, which when being executed by a processor, implements the method for determining the incoming wave direction of the incident signal.
As can be seen from the above technical solution, the computer readable storage medium provided in this embodiment stores a computer program thereon, and when the program is executed by a processor, the program can obtain a spatial spectrum function without mutual coupling coefficients by combining a spatial smoothing algorithm and a mutual coupling calibration algorithm, and then determine an incoming wave direction of an incident signal by the spatial spectrum function without mutual coupling coefficients, so as to weaken the influence of two errors of multipath effect and antenna coupling on the incoming wave direction determination of the incident signal, and further estimate a more accurate incoming wave direction.
Based on the same inventive concept as the method for determining the incoming wave direction of the incident signal, corresponding to the method, the embodiment of the invention further provides a processing device for determining the incoming wave direction of the incident signal, which comprises: the system comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor realizes the method for determining the incoming wave direction of the incident signal when executing the program.
As can be seen from the above technical solution, the processing device for determining the incoming wave direction of the incident signal provided in this embodiment can obtain a spatial spectrum function without mutual coupling coefficient by combining a spatial smoothing algorithm and a mutual coupling calibration algorithm, and determine the incoming wave direction of the incident signal by the spatial spectrum function without mutual coupling coefficient, so as to weaken the influence of two errors of multipath effect and antenna coupling on the incoming wave direction determination of the incident signal, and further estimate a more accurate incoming wave direction.
In the description of the present invention, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means 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 present invention. In this specification, schematic representations of the above terms are not necessarily directed 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. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention, and are intended to be included within the scope of the appended claims and description.
Claims (6)
1. A method for determining the direction of an incoming wave of an incident signal based on a plasma sheath environment, comprising:
establishing an antenna array in a plasma sheath environment;
decorrelating the antenna array by adopting a space smoothing algorithm to obtain a covariance matrix corrected by the antenna array;
adopting a cross coupling calibration algorithm, and processing the spatial spectrum function of the antenna array according to the corrected covariance matrix to obtain a spatial spectrum function without cross coupling coefficients;
searching the maximum value of the spatial spectrum function without the mutual coupling coefficient, and determining the incoming wave direction of an incident signal;
the method further comprises the following steps of:
adopting subspace theory to obtain a space spectrum function of the antenna array;
the method for obtaining the covariance matrix of the antenna array after correction comprises the following steps of:
correcting the array manifold;
obtaining a covariance matrix of the incident signal according to the corrected array manifold;
adopting a space smoothing algorithm to obtain a forward smoothing covariance matrix and a backward smoothing covariance matrix based on the covariance matrix;
correcting the covariance matrix according to the forward and backward smooth covariance matrix to obtain a covariance matrix corrected by the antenna array;
the method for processing the spatial spectrum function of the antenna array by adopting a cross coupling calibration algorithm according to the corrected covariance matrix to obtain the spatial spectrum function without cross coupling coefficients comprises the following steps:
obtaining a new mutual coupling matrix according to Toeplitz properties of the mutual coupling matrix;
obtaining a new array manifold according to the new cross coupling matrix;
and obtaining a spatial spectrum function without cross coupling coefficients according to the corrected covariance matrix and the new array manifold.
2. The method of claim 1, wherein modifying the array manifold comprises:
each direction vector in the array manifold can be modified as:
wherein, C is a mutual coupling matrix of a uniform linear array, which is a banded and symmetrical Toeplitz matrix;
let the interval between array elements be d=λ/2, the degree of freedom of mutual coupling be p, i.e. when the interval between two array elements is greater than d (p-1), the mutual coupling coefficient is 0, wherein the first row of mutual coupling coefficient satisfies the relation 0 < |c p-1 |＜…＜c 1 ＜c 0 ＝1。
3. An apparatus for determining the direction of an incoming wave of an incident signal based on a plasma sheath environment, comprising:
the array building module is used for building an antenna array in a plasma sheath environment;
the decorrelation module is used for decorrelating the antenna array by adopting a space smoothing algorithm to obtain a covariance matrix corrected by the antenna array;
the blind calibration module is used for processing the spatial spectrum function of the antenna array according to the corrected covariance matrix by adopting a cross coupling calibration algorithm to obtain a spatial spectrum function without cross coupling coefficients;
the direction determining module is used for searching the maximum value of the spatial spectrum function without the mutual coupling coefficient and determining the incoming wave direction of the incident signal;
wherein, still include: the pre-acquisition module is used for acquiring a space spectrum function of the antenna array by adopting subspace theory;
wherein the antenna array comprises an array manifold, and the decorrelation module is specifically configured to:
correcting the array manifold;
obtaining a covariance matrix of the incident signal according to the corrected array manifold;
adopting a space smoothing algorithm to obtain a forward smoothing covariance matrix and a backward smoothing covariance matrix based on the covariance matrix;
correcting the covariance matrix according to the forward and backward smooth covariance matrix to obtain a covariance matrix corrected by the antenna array;
wherein, the blind calibration module is specifically used for:
obtaining a new mutual coupling matrix according to Toeplitz properties of the mutual coupling matrix;
obtaining a new array manifold according to the new cross coupling matrix;
and obtaining a spatial spectrum function without cross coupling coefficients according to the corrected covariance matrix and the new array manifold.
4. The apparatus of claim 3, wherein the array building module is specifically configured to:
in the plasma sheath environment, M antenna array elements are uniformly arranged from far field theta k k=1, 2, … N of incident N narrowband sources, wavelength λ, and an antenna array is established, which is:
X(t)＝A(θ)S(t)+N(t)
where a (θ) refers to an array manifold of direction vectors, S (t) refers to a signal, and N (t) refers to noise.
5. A computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the method of one of claims 1-2.
6. A processing device for determining the direction of an incoming wave of an incident signal, based on a plasma sheath environment, comprising: memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method according to one of claims 1-2 when executing the program.
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