Single-channel spatial spectrum direction finding method based on phased array
阅读说明：本技术 一种基于相控阵的单通道空间谱测向方法 (Single-channel spatial spectrum direction finding method based on phased array ) 是由 刘寅生 段洪涛 李景春 唱亮 孙浩 李蓉 范振雄 于 2020-04-27 设计创作，主要内容包括：本发明实施例提供了一种基于相控阵的单通道空间谱测向方法,包括若干个测向天线,以及与天线数量相同的模拟移相器,每根测向天线与一个模拟移相器相连,经每个模拟移相器输出的模拟信号,经过合路器合并后送入到ADC进行采样,采样后的结果送入到测向接收机中,具体包括以下步骤：S1、通过对多个预定方位角方向的扫描估计出空域协方差矩阵；S2、对空域协方差矩阵进行特征值分解,获取噪声空间基向量；S3、基于噪声空间基向量通过谱峰搜索,获得来波信号估计。本发明实施例提供了一种基于相控阵的单通道空间谱测向方法,进一步降低了系统的成本和设计复杂度,具有更广泛的应用范围。(The embodiment of the invention provides a single-channel spatial spectrum direction finding method based on a phased array, which comprises a plurality of direction finding antennas and analog phase shifters with the same number as the antennas, wherein each direction finding antenna is connected with one analog phase shifter, analog signals output by each analog phase shifter are combined by a combiner and then sent to an ADC for sampling, and the result after sampling is sent to a direction finding receiver, and the method specifically comprises the following steps: s1, estimating a spatial covariance matrix through scanning a plurality of preset azimuth directions; s2, performing eigenvalue decomposition on the space domain covariance matrix to obtain a noise space basis vector; and S3, obtaining an incoming wave signal estimation through spectrum peak searching based on the noise space basis vector. The embodiment of the invention provides a single-channel spatial spectrum direction finding method based on a phased array, further reduces the cost and the design complexity of a system, and has a wider application range.)
1. A single-channel spatial spectrum direction-finding method based on a phased array is characterized by comprising a plurality of direction-finding antennas and analog phase shifters with the same number as the antennas, wherein each direction-finding antenna is connected with one analog phase shifter, analog signals output by each analog phase shifter are combined by a combiner and then sent to an ADC for sampling, and a result after sampling is sent to a direction-finding receiver, and the method specifically comprises the following steps:
s1, estimating a spatial covariance matrix through scanning a plurality of preset azimuth directions;
s2, performing eigenvalue decomposition on the space domain covariance matrix to obtain a noise space basis vector;
and S3, obtaining an incoming wave signal estimation through spectrum peak searching based on the noise space basis vector.
2. The method according to claim 1, wherein the S1 includes:
suppose that the Q known azimuths are uniformly distributed over a range of (-90 deg., 90 deg.), noted asBeam-forming unit composed of analog phase shifter for regulating its beam-alternate direction
If the current azimuth angle is theta(q)The steering vector is a (theta)(q)) The received signal obtained by the direction-finding receiver is:
cq[n]＝aH(θ(q))y[n](1)
wherein H is a conjugate transpose;
acquiring N sampling points, where N is 0,1, …, and N-1, and calculating the current average power as:
wherein R represents an unknown spatial covariance matrix;
with the matrix transformation relationship, equation (2) can be rewritten as:
wherein the content of the first and second substances,r ═ vec (r), T is a matrix transpose, and given Q known azimuth angles, equation (3) is extended to a system of Q equations, i.e. Q equations
Ar＝p (4)
Wherein A ═ A1，A2，…，AQ)T，p＝(P1，P2，…，PQ)TThe matrix A is a non-full rank matrix, and an unknown vector r in the formula (4) is solved by adopting a diagonal loading method, namely
Wherein I represents M2×M2Identity matrix of σ2Represents the diagonal loading coefficient, is obtainedThen, reconstructing a spatial covariance matrix by the following formula:
3. the method according to claim 2, wherein the S2 includes:
obtaining a noise space basis vector through eigenvalue decomposition:
where V represents the noise spatial basis vector.
4. The method according to claim 3, wherein the S3 includes:
obtaining an azimuth estimate of the incoming wave signal by searching for peaks of the cost function:
where a (θ) is the array steering vector of M × 1, its mth element can be expressed as:
in the formula (x)m，ym) Indicating the position coordinates of the mth direction-finding antenna.
Technical Field
The invention relates to the technical field of electronic information, in particular to a single-channel spatial spectrum direction finding method based on a phased array.
Background
The radio direction finding system is an important component of a radio monitoring system and has very important application in the military and civil fields. As a novel radio direction finding system, the space spectrum direction finding system is a novel radio signal direction finding system, has high direction finding resolution and sensitivity, can also carry out direction finding on a plurality of signals on the same frequency, and is the future development direction of a radio monitoring system. The spatial spectrum direction-finding system mainly depends on a subspace signal processing technology to realize high-resolution direction finding. In terms of system hardware, this requires that the direction-finding receiver must be equipped with the same number of radio frequency receiving channels as the number of antennas, and that each radio frequency receiving channel can perform coherent sampling on the received signal. The hardware requirement not only brings challenges to the development of the space spectrum direction-finding system, but also greatly increases the cost of the space spectrum direction-finding system, and is not beneficial to the popularization and application of the advanced technology.
At present, a spatial spectrum direction finding system mainly has two schemes, wherein the first scheme is a multi-channel method, and the second scheme is a single-channel method based on disturbance vectors.
The multi-channel scheme requires that each channel on hardware is provided with a receiving channel, and received signals on all direction-finding antennas can be fed into the direction-finding receiving interior. The space spectrum direction finding scheme puts high requirements on system hardware: firstly, the number of receiving channels is consistent with the number of antennas, and when the number of antennas is large, a large number of receiving channels must be arranged in a direction-finding system, so that the cost of the system is greatly increased; secondly, in order to obtain the phase difference on different antennas, the sampling clocks of each receiving channel must adopt a coherent clock source, and the sampling clocks of each channel are ensured to be aligned in time, so that a special clock signal system needs to be equipped, the system cost is further increased, and the complexity of hardware design is also increased; finally, when the received signals on each direction-finding antenna are sampled and converged to a direction-finding receiver, massive data streams are formed in the direction-finding receiver, and great challenges are brought to data processing software and hardware inside the direction-finding receiver.
Although the single-channel scheme based on the perturbation vector can effectively avoid the disadvantages of the multi-channel scheme, because the array weight coefficient needs to adjust the amplitude of each antenna branch, each direction-finding antenna needs to be provided with a variable gain amplifier in addition to an analog phase shifter for adjusting the weight coefficient amplitude of the branch. The introduction of a plurality of variable gain amplifiers not only increases the cost of the system, but also further improves the difficulty of system development; meanwhile, for some phased array systems without a variable gain amplifier, since each branch only has an analog phase shifter and cannot adjust the weight coefficient amplitude of each branch, the method based on the disturbance vector cannot be applied to such phased array systems.
Disclosure of Invention
The embodiment of the invention provides a single-channel spatial spectrum direction finding method based on a phased array, which is used for overcoming the defects in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme.
A single-channel spatial spectrum direction-finding method based on a phased array comprises a plurality of direction-finding antennas and analog phase shifters with the same number as the antennas, wherein each direction-finding antenna is connected with one analog phase shifter, analog signals output by each analog phase shifter are combined by a combiner and then are sent to an ADC for sampling, and a result after sampling is sent to a direction-finding receiver, and the method specifically comprises the following steps:
s1, estimating a spatial covariance matrix through scanning a plurality of preset azimuth directions;
s2, performing eigenvalue decomposition on the space domain covariance matrix to obtain a noise space basis vector;
and S3, obtaining an incoming wave signal estimation through spectrum peak searching based on the noise space basis vector.
Preferably, the S1 includes:
suppose that the Q known azimuths are uniformly distributed over a range of (-90 deg., 90 deg.), noted asBeam-forming unit composed of analog phase shifter for regulating its beam-alternate direction
If the current azimuth angle is theta(q)The steering vector is a (theta)(q)) The received signal obtained by the direction-finding receiver is:
cq[n]＝aH(θ(q))y[n](1)
wherein H is a conjugate transpose;
acquiring N sampling points, where N is 0,1, …, and N-1, and calculating the current average power as:
wherein R represents an unknown spatial covariance matrix;
with the matrix transformation relationship, equation (2) can be rewritten as:
wherein the content of the first and second substances,r ═ vec (r), T is a matrix transpose, and given Q known azimuth angles, equation (3) is extended to a system of Q equations, i.e. Q equations
Ar＝p (4)
Wherein A ═ A1，A2，…，AQ)T，p＝(P1，P2，…，PQ)TThe matrix A is a non-full rank matrix, and an unknown vector r in the formula (4) is solved by adopting a diagonal loading method, namely
Wherein I represents M2×M2Identity matrix of σ2Represents the diagonal loading coefficient, is obtainedThen, reconstructing a spatial covariance matrix by the following formula:
preferably, the S2 includes:
obtaining a noise space basis vector through eigenvalue decomposition:
where V represents the noise spatial basis vector.
Preferably, the S3 includes:
obtaining an azimuth estimate of the incoming wave signal by searching for peaks of the cost function:
where a (θ) is the array steering vector of M × 1, its mth element can be expressed as:
in the formula (x)m，ym) Indicating the position coordinates of the mth direction-finding antenna.
According to the technical scheme provided by the embodiment of the invention, the single-channel spatial spectrum direction finding method based on the phased array can recover the spatial domain covariance matrix only by adjusting the phase of the weight coefficient of each branch. Therefore, each direction-finding antenna branch only needs to be provided with an analog phase shifter, and a variable gain amplifier does not need to be arranged. Compared with a single-channel direction finding system based on disturbance vectors, in the single-channel direction finding scheme based on the phased array, each direction finding antenna branch only needs to be provided with an analog phase shifter, and the cost and the design complexity of the system are further reduced; meanwhile, whether each antenna branch is provided with a variable gain amplifier or not, the method provided by the invention can be applied to obtain the space-domain covariance matrix estimation, so that the method provided by the invention has a wider application range.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are 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 to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a flowchart of a single-channel spatial spectrum direction finding method based on a phased array according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a single-channel spatial spectrum direction finding system based on a phased array according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
For the convenience of understanding the embodiments of the present invention, the following description will be further explained by taking several specific embodiments as examples in conjunction with the drawings, and the embodiments are not to be construed as limiting the embodiments of the present invention.
The implementation of the invention provides a single-channel spatial spectrum direction finding method based on a phased array, which is shown in figures 1-2: including a plurality of direction finding antenna to and the simulation phase shifter the same with antenna quantity, every direction finding antenna links to each other with a simulation phase shifter, and the analog signal of moving the output of phase shifter through every simulation sends into ADC after the combiner merges and samples, and the result after the sampling sends into the direction finding receiver, specifically includes following step:
s1, estimating a spatial covariance matrix by scanning a plurality of predetermined azimuth directions, comprising:
suppose that the Q known azimuths are uniformly distributed over a range of (-90 deg., 90 deg.), noted asBeam-forming unit composed of analog phase shifter for regulating its beam-alternate direction
If the current azimuth angle is theta(q)Then the steering vector is a (θ)(q)) The received signal obtained at this time can be expressed as
cq[n]＝aH(θ(q))y[n](1)
Wherein H is a conjugate transpose.
Obtaining N sampling points, where N is 0,1, …, and N-1, the current average power can be calculated as
Where R represents an unknown spatial covariance matrix.
Using the matrix transformation relationship, equation (2) can be rewritten as
WhereinAnd r ═ vec (r), and T is a matrix transpose. Given that there are Q known azimuths, equation (3) can be extended to a system of Q equations, i.e.
Ar＝p (4)
Wherein A ═ A1，A2，…，AQ)T，p＝(P1，P2，…，PQ)T. Since the matrix A is a non-full-rank matrix, the unknown vector r in the formula (17) can be solved by adopting a diagonal loading method, namely
Wherein I represents M2×M2Identity matrix of σ2Representing the diagonal loading factor. Is obtained byThen, the spatial covariance matrix can be reconstructed by the following formula
S2, performing eigenvalue decomposition on the space-domain covariance matrix to obtain a noise space basis vector, including: obtaining noise space basis vectors by eigenvalue decomposition
Where v represents the noise spatial basis vector.
S3, obtaining an incoming wave signal estimation through spectrum peak search based on the noise space basis vector, wherein the method comprises the following steps: obtaining an estimate of the azimuth of an incoming wave signal by searching for peaks of a cost function
Where a (θ) is the array steering vector of M × 1, its mth element can be expressed as
Here, (x)m，ym) Indicating the position coordinates of the mth direction-finding antenna.
In summary, according to the single-channel spatial spectrum direction finding method based on the phased array provided by the embodiment of the present invention, in the single-channel phased array system, the spatial covariance matrix is estimated by scanning a plurality of predetermined directions, so that the spatial spectrum direction finding method is implemented in the single-channel phased array system.
Those of ordinary skill in the art will understand that: the figures are merely schematic representations of one embodiment, and the blocks or flow diagrams in the figures are not necessarily required to practice the present invention.
From the above description of the embodiments, it is clear to those skilled in the art that the present invention can be implemented by software plus necessary general hardware platform. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which may be stored in a storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method according to the embodiments or some parts of the embodiments.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for apparatus or system embodiments, since they are substantially similar to method embodiments, they are described in relative terms, as long as they are described in partial descriptions of method embodiments. The above-described embodiments of the apparatus and system are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.