阅读说明：本技术 一种基于射频模拟接收系统的测向方法及系统 (Direction finding method and system based on radio frequency analog receiving system ) 是由 左乐 聂剑坤 应钱诚 张浩斌 唐勇 王秀君 胡泽华 范保华 于 2020-06-19 设计创作，主要内容包括：本发明提供了一种基于射频模拟接收系统的测向方法,对于N元均匀圆阵天线,通过鉴相器获得每一路天线与相邻天线的相位差,并记为该路鉴相器的相位差；在来波以仰角为0°入射圆阵天线时,记录每一路鉴相器的相位差为初始相位差；构造每一路鉴相器对应的复数；根据仰角<Image he="90" wi="88" file="DDA0002547934970000013.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>和方位角<Image he="76" wi="88" file="DDA0002547934970000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>,k为迭代次数,计算每路鉴相器的理论相位差；引入向量X和方向向量G,结合构造的复数计算迭代次数k+1的二维入射角的仰角<Image he="83" wi="139" file="DDA0002547934970000014.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>和方位角<Image he="74" wi="141" file="DDA0002547934970000012.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>；计算迭代次数为k+1与迭代次数为k的二维入射角之差,并于门限值比较,小于门限值进入输出仰角和方位角；否则,k的值加1,计算理论相位差。本方法优势在于避免了逻辑判断等运算、相位模糊、鉴相器输入信号幅度不均衡的问题,提高了测向精度。(The invention provides a direction finding method based on a radio frequency analog receiving system, which is characterized in that for N-element uniform circular array antennas, the phase difference between each path of antenna and an adjacent antenna is obtained through a phase discriminator and is recorded as the phase difference of the phase discriminator; when incoming waves enter the circular array antenna with the elevation angle of 0 degree, recording the phase difference of each path of phase discriminator as an initial phase difference; constructing a plurality corresponding to each path of phase discriminator; according to the elevation angle And azimuth angle K is iteration times, and the theoretical phase difference of each path of phase discriminator is calculated; introducing a vector X and a direction vector G, and calculating the elevation angle of the two-dimensional incident angle of the iteration number k +1 by combining the constructed complex number And azimuth angle (ii) a Calculating the difference between the two-dimensional incident angles with the iteration times of k +1 and the iteration times of k, comparing the difference with a threshold value, and outputting an elevation angle and an azimuth angle when the difference is smaller than the threshold value; otherwise, adding 1 to the value of k, and calculating the theoretical phase difference. The method has the advantages of avoiding the problems of arithmetic such as logic judgment, phase ambiguity and unbalanced amplitude of the input signal of the phase discriminator and improving the direction-finding precision.)

1. A direction finding method based on a radio frequency analog receiving system is characterized by comprising the following processes:

step 1, for an N-element uniform circular array antenna, obtaining a voltage phase difference between each path of antenna and an adjacent antenna through a phase discriminator of a radio frequency analog receiving system, and recording the voltage phase difference as a voltage phase difference of the phase discriminator, wherein the voltage phase difference of the last path of phase discriminator is the voltage phase difference of the first path of antenna and the last path of antenna;

step 2, when incoming waves enter the circular array antenna with the elevation angle of 0 degree, recording the voltage phase difference of each phase discriminator as an initial phase difference

Step 3, constructing a plurality number corresponding to each phase discriminator according to the voltage phase difference and the initial phase difference;

step 4,Setting an initial elevation angle of

step 5, when the iteration number is k, according to the elevation angle

step 6, introducing a vector X and a direction vector G, and calculating the elevation angle of the two-dimensional incident angle of the iteration times k +1 by combining the constructed complex number

Step 7, calculating the difference between the two-dimensional incident angles with the iteration times of k +1 and the iteration times of k, comparing the difference result of the two-dimensional incident angles with a threshold value, and entering step 8 if the difference result is smaller than the threshold value; otherwise, adding 1 to the value of the iteration times k, and entering the step 5;

step 8, outputting the two-dimensional incident angleAnd

2. The direction-finding method based on the radio frequency analog receiving system according to claim 1, wherein in the step 1, N in the N-ary uniform circular array antenna is greater than or equal to 3, and the voltage phase difference output of the ith phase detector is as follows:

wherein phi_iIndicating the voltage phase of the ith antenna.

3. The direction-finding method based on the radio frequency analog receiving system according to claim 2, wherein in the step 3, the specific method for constructing the complex number is:

wherein, V_iRepresenting the complex number, Δ Φ, corresponding to the i-th phase detector_iIndicating the voltage phase difference of the ith phase detector,

4. The direction-finding method based on the rf analog receiving system according to claim 3, wherein in the step 5, the specific method for calculating the theoretical phase difference of each phase discriminator is:

wherein the content of the first and second substances,representing the theoretical phase difference of the ith phase discriminator, c is the wave speed in space, rho represents the radius of the circular array antenna, α_iThe angle position of the ith antenna is represented, wherein the angle position of the first antenna is 0; angular separation of two antennas

5. The direction-finding method based on RF analog receiving system according to claim 4, wherein in step 6, the elevation angle of the two-dimensional incident angle is calculatedAnd azimuth angle

step 61, setting vectors

Wherein T represents a matrix transpose;

step 62, calculating a direction vector, G ═ G₁,g₂]^T(ii) a Wherein:

step 63, updating vector X^(k)To obtain the k +1 st vector X^(k+1)A value of (d);

X^(k+1)＝X^(k)+G

wherein the content of the first and second substances,

step 64, according to X^(k+1)Calculating the elevation angle of the k +1 st two-dimensional incident angle

Wherein, | | represents a complex modulus, real represents an operation of taking a real part of a complex number, arg represents an operation of solving a phase of the complex number, and mod (x,2 pi) is a remainder after x is modulo 2 pi.

6. The direction-finding method based on the radio frequency analog receiving system according to claim 5, wherein in the step 7, the specific method for calculating the difference between the two-dimensional incident angle with the iteration number k +1 and the iteration number k is as follows:

7. the direction-finding method based on RF analog receiving system according to claim 1, wherein in step 7, the threshold value is the required direction-finding accuracy.

8. The direction-finding method based on the radio frequency analog receiving system according to claim 1, wherein the radio frequency analog receiving system comprises: the antenna comprises N paths of radio frequency front ends, N paths of one-to-two power dividers and N paths of phase detectors, wherein each path of antenna is sequentially connected with one path of radio frequency front ends and one path of one-to-two power dividers, signals received by the antenna are amplified and filtered by the radio frequency front ends and then enter the one-to-two power dividers to be divided into two paths of signals, the phase detectors respectively receive signals output by the one-to-two power dividers corresponding to two adjacent paths of antennas and output voltage phase differences of two adjacent paths of antennas, and one path of signals of the first one-to-two power divider and the last one path of one-to-two power divider are connected with the same path of phase.

9. A direction-finding system based on a radio frequency analog receiving system is characterized by comprising: the antenna comprises N-element uniform circular array antennas, N paths of one-to-two power dividers, N paths of phase detectors and a signal processing module, wherein each path of antenna is sequentially connected with one path of radio frequency front end and one path of one-to-two power divider; the signal processing module receives the voltage phase difference output by the phase detector, and is used for executing the direction finding method of any one of claims 1-7 and outputting the elevation angle and the azimuth angle of the radiation source.

Technical Field

The invention relates to the technical field of radio monitoring, in particular to a direction finding method and system based on a radio frequency analog receiving system.

Background

The interferometer direction-finding system belongs to a phase direction-finding system, and solves the direction information of incoming waves by utilizing different signal phases received by each antenna unit caused by different antenna spatial positions when the incoming waves reach a direction-finding antenna array. The interferometer direction finding technology has been widely used in the passive direction finding field due to its high precision, clear principle, wide frequency band and other features.

The phase interferometer is a direction-finding method commonly adopted in the current direction-finding system because of high direction-finding precision. The linear least square method is simple in operation, and the two-dimensional incident angle can be obtained by processing the phase information of the circular array with least squares (see the documents: Y.Wu, H.C.so.simple and secure two-dimensional angle estimate for a single source with unified aperture array [ J ]. IEEE extensions Wireless and Provisioning Letters 2008,7(1): 78-80; B.Liao, Y.T.Wu, S.C.Chan.A generation angle estimate for a single source with unified aperture array 2012 [ J ]. IEEE extensions and protection letter, 11(1): 986). However, the phase-based least square method does not consider the phase ambiguity problem and is not suitable for large-aperture circular arrays.

For a large-aperture circular array, the phase discrimination range of the phase discriminator is only 2 pi, when the antenna spacing is large enough to cause the actual phase difference to exceed 2 pi, the phase value output by the phase discriminator can overturn by taking 2 pi as a period, and multi-value ambiguity occurs, so that the real phase and the actual receiving phase are subjected to many-to-one mapping. When the radius of the circular array is large, the phase value range exceeds 2 pi, so that phase ambiguity occurs. The longer the distance between the two antennas is to obtain high angle measurement precision; to achieve a phase not exceeding 2 pi, the distance between the two antennas should be small enough, which is contrary to the condition of improving the direction-finding accuracy.

The reported literature reports adopt a multi-baseline method (see the literature: summer Shao, Yangjingji, one-dimensional search and long and short baseline combined interferometer design method [ J ] fire control radar technology, 2013,42(02): 33-37; quarterly dawn light, high dawn light; an airborne passive positioning method-interferometer positioning [ J ]. firepower and command control, 2008,33(11): 158-, wang Guangsu, Daxu, circular array phase interferometer two-dimensional direction finding ambiguity resolving new method [ J ] remote measuring and controlling, 2007, (05): 53-59; zhao national Wei, high precision airborne single station passive positioning technology research [ D ]. instructor: plum, brave. northwest university of industry, 2007; yuanxiakang phase interferometer direction finding localization study [ J ]. Shanghai Spaceflight, 1999, (03): 3-9), parallel baseline method (see literature: zhang Yi Sail, missile-borne radar direction finding technical research [ D ]. instructor: lyric facing river, university of electronic technology, 2018; cattail, parallel baseline solution fuzzy interferometer direction finding algorithm and realization [ D ]. instructor: koro spring forest, university of electronic technology, 2013; the university of electronic science and technology, a two-dimensional direction-finding method of a circular array phase interferometer based on a parallel baseline, China, CN201110235023.7[ P ]. 2012-04-18; china aerospace science and technology group company, fifth research institute, third research institute, a direction-finding positioning system combining phase difference direction finding and space spectrum direction finding, China, CN201510182536.4[ P ].2015-07-01, an extended baseline method (see literature: china, CN201110226585.5[ P ].2012-04-11), correlation method (see literature: tao, Ling Ming, Rirengang, even odd-even array element number-uniform circular array direction-finding performance research [ J ]. modern radar, 2016,38(11): 24-29; study of two-dimensional direction finding algorithm based on uniform circular array [ D ]. instructor: he, university of electronic technology, 2014; liu Mang surpasses, research on radio direction finding method [ D ]. instructor: yangjianhong, Lanzhou university, 2013; application of correlation operations in phase interferometer disambiguation [ J ] acoustic techniques, 2010,29(05): 538-; china, CN201310116050.1[ P ].2013-08-07), virtual baseline method (see literature: jianlinhong, wideband interferometer signal processing and direction finding algorithm research based on GPU [ D ]. instructor: who, university of electronic technology, 2012; wuvowei micro, Chengting, Jiakexin, He, interferometer direction finding algorithm [ J ] based on virtual array transform modern radar, 2012,34(3): 42-45; li Peng-Fei, broadcasting band direction of arrival base on virtual base evaluation and RBFNN [ J ]. Journal of evaluation, 2012,33(2): 210-. And an optimal baseline method is adopted, wherein different optimal baseline groups are selected according to different azimuth angles, and a two-dimensional incident angle is solved (see the literature: Panyujian, Dingxian, Huangjing, Yangxing, Yuannalchang. the improvement of direction-finding performance of a simulation phase demodulation circular array interferometer and the verification thereof [ J ]. systematic engineering and electronic technology, 37(6),2015), so that the problems of complex calculation and insufficient application of an antenna are solved.

For high accuracy direction finding, the distance between the antennas is required to be large enough, which results in a large ambiguity range of the phase, and one phase difference corresponds to many possible incident angles, which requires adding multiple sets of antennas to remove multiple values of the incident angle. For the ambiguity resolution methods such as the multi-baseline, the parallel baseline, the extended baseline, the virtual baseline and the like, the higher the accuracy is, the more the number of antennas is, the angle measurement only uses part of the antennas, and the rest antennas are only used for eliminating multiple values, so that the hardware resources are not fully utilized, and the angle measurement accuracy cannot be improved through the added antennas.

The analog receiver is widely used in the direction finding of an interferometer, and an analog phase discriminator is adopted to measure the phase difference received by two antennas (see the documents: J.H.Lee, J.M.Wo.interferometer direction-defining system with improved DF acquisition using two-way differential array configurations [ J ]. IEEEextensions and Wireless Propagation Letters,2015,14: 719-722). However, all antennas are used for phase discrimination of a certain antenna, and a power divider with more than one antenna is required to be connected behind the antenna in circuit implementation, so that the problems of small signal intensity of the antenna and unbalanced amplitude of receiving levels of other paths are caused.

In summary, the above method has the following problems:

(a) the steps are complex, and the steps of searching, clustering threshold setting, logic judgment and the like are required;

(b) the calculated amount is large;

(c) the insufficient application of the antenna results in low precision;

(d) the signal strength of the input phase discriminator is unbalanced.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the existing problems, a direction-finding method and a direction-finding system based on a radio frequency analog receiving system are provided, and the purpose of high-precision real-time two-dimensional direction finding is achieved.

The technical scheme adopted by the invention is as follows: a direction finding method based on a radio frequency analog receiving system comprises the following processes:

step 1, for an N-element uniform circular array antenna, obtaining a voltage phase difference between each antenna and an adjacent antenna through a phase discriminator of a radio frequency analog receiving system, and marking the voltage phase difference as a voltage phase difference of the phase discriminator, wherein a voltage difference of a last phase discriminator is a voltage phase difference between a first antenna and a last antenna;

step 2, when incoming waves enter the circular array antenna with the elevation angle of 0 degree, recording the phase difference of each phase discriminator as an initial phase difference;

step 3, constructing a plurality number corresponding to each phase discriminator according to the voltage phase difference and the initial phase difference;

step 4, setting the initial elevation angle asInitial azimuth angle of

The iteration number k is 0;

step 5, when the iteration number is k, according to the elevation angleAnd azimuth angle

Calculating the theoretical phase difference of each path of phase discriminator;

step 6, introducing a complex number calculation iteration number k +1 constructed by combining the vector X and the direction vector G to calculate the elevation angle of the two-dimensional incident angle of the iteration number k +1

And azimuth angle

Step 7, calculating the difference between the two-dimensional incident angles with the iteration times of k +1 and the iteration times of k, comparing the difference result of the two-dimensional incident angles with a threshold value, and entering step 8 if the difference result is smaller than the threshold value; otherwise, adding 1 to the value of the iteration times k, and entering the step 5;

step 8, outputting the two-dimensional incident angle

Andas the elevation and azimuth of the radiation source.

Further, in step 1, N in the N-ary uniform circular array antenna is greater than or equal to 3, and the voltage phase difference output of the ith phase discriminator is as follows:

wherein phi_iIndicating the voltage phase of the ith antenna.

Further, in the step 3, a specific method for constructing a plurality of modules is as follows:

wherein, V_iRepresenting the complex number, Δ Φ, corresponding to the i-th phase detector_iIndicating the voltage phase difference of the ith phase detector,

when an incoming wave enters the circular array antenna with an elevation angle of 0 degree, the phase difference of the voltage output by the ith phase discriminator is shown; i is 1,2,3, …, N.

Further, in step 5, a specific method for calculating the theoretical phase difference of the ith phase discriminator is as follows:

wherein the content of the first and second substances,representing the theoretical phase difference of the ith phase discriminator, c is the wave speed in space, rho represents the radius of the circular array antenna, α_iThe angle position of the ith antenna is represented, wherein the angle position of the first antenna is 0; angular separation of two antennas

Further, in the step 6, the elevation angle of the two-dimensional incident angle is calculated

And azimuth angle

The method comprises the following specific steps:

step 61, setting vectors

Wherein T represents a matrix transpose;

step 62, calculating a direction vector, G ═ G₁,g₂]^T(ii) a Wherein:

step 63, updating vector X^(k)To obtain the k +1 st vector X^(k+1)A value of (d);

X^(k+1)＝X^(k)+G

wherein the content of the first and second substances,

step 64, according to X^(k+1)Calculating the elevation angle of the k +1 st two-dimensional incident angleAnd azimuth angle

Wherein, | | represents a complex modulus, real represents an operation of taking a real part of the complex, and arg represents an operation of solving a complex phase, wherein mod (x,2 pi) is a remainder after x is modulo 2 pi.

Further, in step 7, a specific method for calculating a difference between the iteration number k +1 and the two-dimensional incident angle with the iteration number k is as follows:

further, in step 7, the threshold value is the required direction finding precision.

Further, the radio frequency analog receiving system includes: the antenna comprises N paths of radio frequency front ends, N paths of one-to-two power dividers and N paths of phase detectors, wherein each path of antenna is sequentially connected with one path of radio frequency front ends and one path of one-to-two power dividers, signals received by the antenna are amplified and filtered by the radio frequency front ends and then enter the one-to-two power dividers to be divided into two paths of signals, the phase detectors respectively receive signals output by the one-to-two power dividers corresponding to two adjacent paths of antennas and output voltage phase differences of two adjacent paths of antennas, and one path of signals of the first one-to-two power divider and the last one path of one-to-two power divider are connected with the same path of phase.

The invention also provides a direction-finding system based on the radio frequency analog receiving system, which comprises the following components: the antenna comprises N-element uniform circular array antennas, N paths of one-to-two power dividers, N paths of phase detectors and a signal processing module, wherein each path of antenna is sequentially connected with one path of radio frequency front end and one path of one-to-two power divider; and the signal processing module receives the voltage phase difference output by the phase discriminator, is used for executing the direction finding method and outputting the elevation angle and the azimuth angle of the radiation source.

Compared with the prior art, the beneficial effects of adopting the technical scheme are as follows: complex number operation is adopted, so that the phase ambiguity problem is avoided; the information of all antennas on the circular array is utilized, so that the direction finding precision is improved; an iterative algorithm is adopted, so that operations such as logic judgment and the like are avoided; the phase difference is acquired between the two adjacent antennas, so that the problem of unbalanced amplitude of input signals of the phase discriminator is avoided.

Drawings

FIG. 1 is a direction-finding system architecture diagram of the present invention.

Fig. 2 is a schematic view of a uniform circular array of the present invention.

FIG. 3 is a schematic diagram of an exemplary direction-finding coordinate system array.

FIG. 4 is a plot of the root mean square error in elevation versus the angle of incidence of the present invention.

FIG. 5 is a plot of the root mean square error in azimuth versus angle of incidence for the present invention.

FIG. 6 is a plot of the root mean square error in elevation versus the azimuth angle of incidence for the present invention.

FIG. 7 is a plot of azimuthal root mean square error versus incident azimuthal angle for the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

The invention provides a two-dimensional incident angle measuring method with simple realization and high precision, which adopts a radio frequency analog receiving system as shown in figure 1 and has the main function of converting space electromagnetic waves into phase differences. After receiving signals by the antenna, the signals are amplified and filtered by the radio frequency front end and then enter a one-to-two power divider, phase discrimination is carried out on every two signals after the signals are divided, the phase discrimination is carried out on the 2 nd path antenna and the 1 st path antenna, and the phase difference is recorded as delta phi₁(ii) a Phase discrimination is carried out between the 3 rd path antenna and the 2 nd path antenna, and the phase difference is recorded as delta phi₂(ii) a And analogizing until the Nth antenna and the N-1 th antenna phase are discriminated, and recording the phase difference as delta phi_N-1. Phase discrimination is carried out between the 1 st path antenna and the Nth path antenna, and the phase difference is recorded as delta phi_N. In conjunction with the wiring relationship shown in FIG. 1, the phase difference output is

Φ_iIndicating the voltage phase of the ith antenna. The direction-finding system employed may take the form of, but is not limited to, figure 1. In the figure, N is the number of antennas.

For an N-element uniform circular array, N is more than or equal to 3, the radius is rho, and the angle position of the ith antenna is α_iAs shown in fig. 2, the two-antenna angular spacing Δ α is 2 pi/n, and the angular position of the 1 st antenna is 0, and the antenna array is located on the xoy plane at the elevation angle θ_sIs included angle between the incoming wave direction and the z-axis and has azimuth angle ofThe incoming wave direction makes an angle with the x-axis, as shown in FIG. 3. The specific direction finding method comprises the following steps:

a direction finding method based on a radio frequency analog receiving system comprises the following processes:

step 1, for an N-element uniform circular array antenna, as shown in fig. 2, obtaining a voltage phase difference between each antenna and a next antenna through a phase detector of a radio frequency analog receiving system, and marking the voltage phase difference as a voltage phase difference of the phase detector, wherein a voltage difference of a last phase detector is a voltage phase difference between a first antenna and a last antenna;

step 2, when incoming waves enter the circular array antenna with the elevation angle of 0 degree, recording the phase difference of each phase discriminator as an initial phase difference

Step 3, constructing a plurality number corresponding to each phase discriminator according to the voltage phase difference and the initial phase difference;

step 4, setting the initial elevation angle as

Initial azimuth angle ofThe iteration number k is 0;

step 5, according to the elevation angleAnd azimuth angleCalculating the theoretical phase difference of each path of phase discriminator;

step 6, introducing a complex number calculation iteration number k +1 constructed by combining the vector X and the direction vector G to calculate the elevation angle of the two-dimensional incident angle of the iteration number k +1And azimuth angle

Step 7, calculating the difference between the two-dimensional incident angles with the iteration times of k +1 and the iteration times of k, comparing the difference result of the two-dimensional incident angles with a threshold value, and entering step 8 if the difference result is smaller than the threshold value; otherwise, adding 1 to the value of the iteration times k, and entering the step 5;

step 8, outputting the two-dimensional incident angle

And

as the elevation and azimuth of the radiation source.

In a preferred embodiment, in the step 3, a specific method for constructing the plurality of the modules is as follows:

wherein, V_iRepresenting the complex number, Δ Φ, corresponding to the i-th phase detector_iIndicating the voltage phase difference of the ith phase detector,the phase difference of the phase discriminator of the ith path is shown when incoming waves enter the circular array antenna with the elevation angle of 0 degree; i is 1,2,3, …, N.

In a preferred embodiment, in step 5, a specific method for calculating a theoretical phase difference of each phase detector is as follows:

wherein the content of the first and second substances,representing the theoretical phase difference of the ith phase detector, c is the wave velocity in space, and p represents the radius of the circular array antenna, as shown in fig. 3, α_iThe angle position of the ith antenna is represented, wherein the angle position of the first antenna is 0; angular separation of two antennas

In a preferred embodiment, in step 6, the elevation angle of the two-dimensional incident angle is calculated

And azimuth angleThe method comprises the following specific steps:

step 61, setting vectors

Wherein T represents a matrix transpose;

step 62, calculating a direction vector, G ═ G₁,g₂]^T(ii) a Wherein:

step 63, updating vector X^(k)To obtain the k +1 st vector X^(k+1)A value of (d);

X^(k+1)＝X^(k)+G

wherein the content of the first and second substances,

step 64, according to X^(k+1)Calculating the elevation angle of the k +1 st two-dimensional incident angleAnd azimuth angle

Wherein, | | represents a complex modulus, real represents an operation of taking a real part of the complex, and arg represents an operation of solving a complex phase, wherein mod (x,2 pi) is a remainder after x is modulo 2 pi.

In a preferred embodiment, in step 7, a specific method for calculating a difference between the two-dimensional incident angle with the iteration number k +1 and the two-dimensional incident angle with the iteration number k is as follows:

in a preferred embodiment, in step 7, the threshold value is the required direction-finding accuracy.

In a preferred embodiment, the radio frequency analog receiving system includes: the antenna comprises N paths of radio frequency front ends, N paths of one-to-two power dividers and N paths of phase detectors, wherein each path of antenna is sequentially connected with one path of radio frequency front ends and one path of one-to-two power dividers, signals received by the antenna are amplified and filtered by the radio frequency front ends and then enter the one-to-two power dividers to be divided into two paths of signals, the phase detectors respectively receive signals output by the one-to-two power dividers corresponding to two adjacent paths of antennas and output voltage phase differences of two adjacent paths of antennas, and one path of signals of the first one-to-two power divider and the last one path of one-to-two power divider are connected with the same path of phase.

The invention also provides a direction-finding system based on the radio frequency analog receiving system, which comprises the following components: the antenna comprises N-element uniform circular array antennas, N paths of one-to-two power dividers, N paths of phase detectors and a signal processing module, wherein each path of antenna is sequentially connected with one path of radio frequency front end and one path of one-to-two power divider; and the signal processing module receives the voltage phase difference output by the phase discriminator, is used for executing the direction finding method and outputting the elevation angle and the azimuth angle of the radiation source.

The method has the advantages that complex number operation is adopted, so that the phase ambiguity problem is avoided; the information of all antennas on the circular array is utilized, so that the direction finding precision is improved; an iterative algorithm is adopted, so that operations such as logic judgment and the like are avoided; the phase difference is acquired between the two adjacent antennas, so that the problem of unbalanced amplitude of input signals of the phase discriminator is avoided.

To verify the effect of the present invention, the root mean square of the direction error was calculated by 1000 monte carlo simulations, and the results are shown in fig. 4 to 7. The working frequency is 3GHz, and the signal noise is white Gaussian noise.

Fig. 4 and 5 are plots of the elevation root mean square error and the azimuth root mean square error versus the angle of incidence elevation, respectively, under different phase noise conditions. The simulation conditions are as follows: the array element number N is 11, the array radius r is 360mm, the root mean square of the phase noise respectively takes 5 degrees, 10 degrees, 15 degrees and 20 degrees, and the incidence azimuth angle is 60 degrees.

Fig. 6 and 7 are graphs of the rms error in elevation and the rms error in azimuth versus the azimuth of incidence, respectively, under different phase noise conditions. The simulation conditions are as follows: the array element number N is 7, the array radius r is 400mm, the root mean square of the phase noise respectively takes 5 degrees, 10 degrees, 15 degrees and 20 degrees, and the incident elevation angle is 30 degrees.

The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed. Those skilled in the art to which the invention pertains will appreciate that insubstantial changes or modifications can be made without departing from the spirit of the invention as defined by the appended claims.

All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.

Any feature disclosed in this specification may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.