Two-dimensional angle estimation method based on phase space-variant

Abstract

The invention discloses a two-dimensional angle estimation method based on phase space-variant, and the method comprises the specific steps: obtaining the sampling data of the phase space-variant through the rotation scanning of an antenna space; the relation among the amplitude, phase and frequency information of the target signal is obtained through sampling data sorting; periodically cutting off the sampling data to obtain the phase change of the target signal; performing frequency alignment on phases of signals in each group of data after periodic truncation; carrying out interpolation on the sampling data group after the frequency alignment is completed; constructing a two-dimensional angle compression factor by the interpolated angle resolution and the target signal frequency; and changing the angle interpolation factor and the interpolated signal to azimuth frequency to realize angle compression, and obtaining an azimuth-pitching two-dimensional angle super-resolution result.

Description

Technical Field

[0001] The invention relates to the technical field of passive measurement of radiation source signals, and in particular to a two-dimensional angle estimation method based on phase space variation. Background Art

[0002] In recent years, passive direction finding, as an important direction in the field of array signal processing, has been used more and more widely with the development of science and technology. Whether it is electronic reconnaissance in modern battlefields or communication technology in daily life, passive direction finding plays an important role.

[0003] The development of passive direction finding mainly includes subspace-based super-resolution algorithms, such as MUSIC and ESPRIT. Their main features are multiple channels, high computational complexity, and high resolution. Therefore, the realization of their systems requires large volume, power consumption, and high-performance signal processing capabilities, which are not convenient for miniaturization in engineering. Interferometer-based lateral methods, such as dual-baseline interferometers and rotating interferometers, mainly solve the contradiction between baseline length and direction finding accuracy by constructing multiple baselines, that is, the phase ambiguity problem caused by long baselines, and obtain signal angle information through phase difference.

[0004] At present, the rotating interferometer algorithm can perform phase recovery and angle estimation for continuous waves and pulse waves, but it is still unable to perform direction finding for coherent signals. The phase of coherent signals will produce aliasing, and the interferometer algorithm cannot separate the coherent signals, resulting in induced angle measurement. Subspace-based super-resolution algorithms often resolve coherence through subarray smoothing, which requires more array elements or channels. Therefore, it is urgent to solve the problem of echo coherence affecting direction finding due to multipath effects, coherent signal sources, etc. when passive direction finding is applied in complex environments. Summary of the invention

[0005] The purpose of the present invention is to provide a two-dimensional angle estimation method based on phase space variation, so as to improve the ability to resist coherent signal interference, reduce the influence of multipath interference, and realize accurate measurement of the two-dimensional angle of coherent signals.

[0006] In order to achieve the above object, the present invention provides a two-dimensional angle estimation method based on phase space variation, and the specific steps include:

[0007] Step 1, obtain phase space-varying sampling data by rotating and scanning the antenna space;

[0008] Step 2, by sorting the sampled data, the relationship between the amplitude, phase and frequency information of the target signal is obtained;

[0009] Step 3, periodically truncate the sampled data to obtain the phase change of the target signal;

[0010] Step 4, performing frequency alignment on the phase of the signal in each set of data obtained in step 3;

[0011] Step 5, interpolating the sampling data group that has completed frequency alignment;

[0012] Step 6, constructing a two-dimensional angle compression factor based on the interpolated angle resolution and the target signal frequency;

[0013] Step 7: Change the angle interpolation factor and the interpolated signal to the azimuth frequency to achieve angle compression, and obtain an azimuth-elevation two-dimensional angle super-resolution result.

[0014] Optionally, in step 1, the method for spatial rotation of the antenna is to set a pair of antennas symmetrically fixed on both sides of a rotating table, and traverse and sample the scanning area by rotating the rotating table; when the antennas on both sides capture the target signal at the same time, the sampling data is stored and the rotation angle of the antenna at this time is recorded.

[0015] Optionally, the antenna is an omnidirectional antenna; and the sampling data includes: a target signal, a target elevation angle and a target azimuth angle.

[0016] Optionally, in step 3, the target signal periodic truncation method includes:

[0017] During the first rotation of the antenna, the first data point captured after the scanning angle γ is greater than 0° is used as the starting point of the first group of sampling data. As the scanning angle increases, the last data point captured at the maximum scanning angle within the 360° range of the antenna rotation is used as the ending point of the first group of sampling data. During the second rotation of the antenna, the first data point captured after the scanning angle γ is greater than 360° is used as the starting point of the second group of sampling data, and the last data point captured at the maximum scanning angle within the 720° range of the antenna rotation is used as the ending point of the second group of sampling data; and so on, until the grouping of all sampling data is completed.

[0018] The angle of each set of sampling data is re-marked so that the angle range of each set of sampling data is 0°-360°, that is, the scanning angle in the mth set of sampling data is subtracted by (m-1)×360°.

[0019] Optionally, in step 4, the frequency alignment method includes:

[0020] The center frequency f(γ0) of the phase of the first target signal (i.e., the starting point) in each group of sampled data is taken as the center frequency of the group, and the center frequencies of the phases of other target signals in the group are corrected. For the i+1th data point in the group, the phase compensation coefficient is f(γ0) / f(γ i ), then after the target signal frequency is aligned, the compensation phase of the i+1th target signal for:

[0021]

[0022] Where γ0 is the scanning angle corresponding to the first target signal in the set of sampled data, γ i is the scanning angle corresponding to the i+1th target signal in the set of sampled data.

[0023] Optionally, in step 5, the method for collecting data group interpolation includes:

[0024] For the sampling data group in which the target signal frequency alignment is completed in step 4, the scanning angle γ of the sampling data is set to be spaced at intervals of Δγ, so that the data points in each group are evenly distributed within the range of 0°-360°, and part of the scanning angle is interpolated and extended. The interpolation extension is that for the data points that cannot be captured from the experiment, the phase of the target signal of the data point can be obtained according to the scanning angle corresponding to the data point, so as to obtain the interpolated acquisition data, and each group of acquisition data obtained after interpolation is marked as a space-varying echo s′(γ).

[0025] Optionally, the pitch angle and azimuth angle ranges of the target are divided, and the range of the search pitch angle is 0° to 90°, and the search interval is selected according to the pitch angle resolution; the range of the search azimuth angle is 0° to 360°, and the search azimuth angle interval is the same as the scanning angle interval Δγ.

[0026] Optionally, in step 7, the method of changing the angle interpolation factor and the interpolated signal to the azimuth frequency includes:

[0027] The azimuth angle compression factor is fast Fourier transformed along the azimuth dimension to obtain the azimuth frequency domain angle compression factor H(f); the space-varying echo s′(γ) of each set of collected data is fast Fourier transformed to obtain the azimuth frequency domain space-varying echo phase S(f) of each set of collected data;

[0028] In the azimuth frequency domain, the space-variant echo phase S(f) and the angle compression factor H(f) are multiplied to obtain the azimuth frequency domain angle compression result X(f) of each set of collected data;

[0029] X(f)=S(f)*H(f)

[0030] The azimuth frequency domain angle compression result X(f) of each set of collected data is subjected to azimuth-dimensional inverse fast Fourier transform to obtain the azimuth-dimensional angle super-resolution result x(γ) of each set of collected data;

[0031] All search pitch angles Φ are traversed to obtain the azimuth-pitch two-dimensional angle super-resolution results of each set of collected data, forming a database of target signals and two-dimensional angles.

[0032] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0033] The present invention captures the target signal by the method of antenna rotation scanning, and the required experimental device method is simple and easy to implement. And by periodically truncating and interpolating the collected data, constructing a two-dimensional angle compression factor, and processing the two-dimensional angle compression factor and the signal frequency, the azimuth-elevation two-dimensional angle super-resolution results of the target signal in each azimuth dimension and elevation dimension are obtained, and the azimuth-elevation two-dimensional angle joint estimation of the target signal in the space scan is quickly realized, the anti-coherent signal interference capability is improved, the multipath interference influence is reduced, and the accurate measurement of the coherent signal two-dimensional angle is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of the two-dimensional angle estimation method based on phase space variation of the present invention.

[0035] Figure 2 It is a schematic diagram of the rotation scanning method of the two-dimensional angle estimation method based on phase space variation of the present invention.

[0036] Figure 3 It is a schematic diagram of the space-variant phase of the two-dimensional angle estimation method based on space-variant phase of the present invention.

[0037] Figure 4 It is a schematic diagram of sampling data truncation of the two-dimensional angle estimation method based on phase space variation of the present invention.

[0038] Figure 5 It is a schematic diagram of frequency alignment of the two-dimensional angle estimation method based on phase space variation of the present invention.

[0039] Figure 6 It is a schematic diagram of the azimuth frequency domain bandwidth of the phase space-varying signal of the two-dimensional angle estimation method based on phase space-varying of the present invention.

[0040] Figure 7 It is a two-dimensional schematic diagram of a single target super-resolution result of the two-dimensional angle estimation method based on phase space-variation of the present invention.

[0041] Figure 8 It is a two-dimensional schematic diagram of the coherent target super-resolution result of the two-dimensional angle estimation method based on phase space-variation of the present invention.

[0042] Fig. 9 It is a three-dimensional schematic diagram of the coherent target super-resolution result of the two-dimensional angle estimation method based on phase space-variation of the present invention. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] like Figure 1 As shown, the present invention provides a two-dimensional angle estimation method based on phase space variation, and the specific steps include:

[0047] Step 1: obtain phase space-varying sampling data by rotating the antenna in space.

[0048] The sampling is performed by rotating the antenna in space. Compared with the method of constructing a rotating baseline by circular array traversal sampling, this method can reduce the number of antennas and channel switches and reduce the size of the equipment.

[0049] like Figure 2 As shown, the method of antenna spatial rotation is to set a pair of antennas symmetrically fixed on both sides of the rotating platform, and traverse and sample the scanning area by rotating the rotating platform (driving the antennas to rotate synchronously). When the antennas on both sides capture the target signal at the same time, the sampling data is stored and the angle γ of the antenna rotation at this time is recorded. Among them, the antenna is an omnidirectional antenna; the sampling data includes the target signal, the target pitch angle φ and the target azimuth angle θ.

[0050] Step 2: By sorting the sampled data, the relationship between the amplitude, phase and frequency information of the target signal is obtained.

[0051] Perform signal sorting on the detected target signal and extract the amplitude A(γ) and phase of the target signal And frequency information f(γ), the signal s(γ) reconstructed at the angle γ can be expressed as:

[0052]

[0053] Where R is the scanning radius of the antenna, c is the speed of light, is the phase of the target signal, φ is the target pitch angle, θ is the target azimuth angle, is the initial phase of the target signal, n is the number of target signals, i is the index of the target signal, and j is an imaginary number.

[0054] Step 3: Periodically truncate the sampled data to obtain the phase change of the target signal.

[0055] like Figure 4 As shown, the sampled data captured during one rotation of the antenna is taken as a group of sampled data, and the collected sampled data are truncated to divide the sampled data into multiple groups.

[0056] During the first rotation of the antenna, the first data point captured after the scanning angle γ is greater than 0° is used as the starting point of the first group of sampling data. As the scanning angle increases, the last data point captured at the maximum scanning angle within the 360° range of the antenna rotation is used as the ending point of the first group of sampling data. During the second rotation of the antenna, the first data point captured after the scanning angle γ is greater than 360° is used as the starting point of the second group of sampling data, and the last data point captured at the maximum scanning angle within the 720° range of the antenna rotation is used as the ending point of the second group of sampling data. This process is repeated until all the sampling data are grouped to obtain multiple groups of periodic sampling data groups.

[0057] The angle of each set of sampling data is re-marked so that the angle range of each set of sampling data is 0°-360°, that is, the scanning angle in the mth set of sampling data is subtracted by (m-1)×360°.

[0058] Figure 3 is the phase change of the phase discrimination caused by the rotation of the antenna. According to the multiple sets of sampling data obtained by the above truncation and their corresponding scanning angles γ, the phase φ(γ) change law of the target signal with a scanning angle γ in the range of 0°-360° during the rotation of the antenna is obtained, as shown in Equation 2.

[0059]

[0060] Step 4: perform frequency alignment on the phase of the signal in each set of data obtained in step 3.

[0061] Since there is frame skipping in the target signal during each circle of the spatial scanning, the center frequency of the target signal phase is different, so the phase of the target signal needs to be frequency aligned.

[0062] like Figure 5 As shown in the figure, the center frequency f(γ0) in the phase of the first target signal (i.e., the starting point) in each group of sampled data is used as the center frequency of the group, and the center frequencies of the phases of other target signals in the group are corrected. For the i+1th data point in the group, the phase compensation coefficient is f(γ0) / f(γ i ), then after the target signal frequency is aligned, the compensation phase of the i+1th target signal for:

[0063]

[0064] Where γ0 is the scanning angle corresponding to the first target signal in the set of sampled data, γ i is the scanning angle corresponding to the i+1th target signal in the set of sampled data.

[0065] Step 5, interpolate the sampling data group that has completed frequency alignment, expand the target signal scanning angle, and improve the angular resolution.

[0066] Since there are fewer data points in a set of sampling data, interpolation calculation can be performed according to Formula 2 to improve the resolution of each set of sampling data.

[0067] For the sampling data group in which the target signal frequency alignment is completed in step 4, the scanning angle γ of the sampling data is set to be spaced at intervals of Δγ, so that the data points in each group of sampling data are evenly distributed within the range of 0°-360°, and the scanning angle is interpolated and extended. The interpolation extension is to substitute the scanning angle corresponding to the data point into Formula 2 for the data point that cannot be captured from the experiment to obtain the phase of the target signal of the data point, thereby obtaining the interpolated acquisition data, and each group of acquisition data obtained after interpolation is marked as a space-varying echo s′(γ).

[0068] The scanning angle interval Δγ is the azimuth angle resolution. The smaller the scanning angle interval Δγ is, the higher the azimuth resolution is.

[0069] Step 6: construct a two-dimensional angle compression factor based on the interpolated angle resolution and target signal frequency.

[0070] The target's possible pitch angle and azimuth angle ranges are divided. When capturing target signals in circular scanning, the formula for calculating the target's angle compression factor at different pitch angles and azimuth angles is:

[0071]

[0072] Wherein, Φ is the search elevation angle, which ranges from 0° to 90°, and the search interval ΔΦ is selected according to the pitch angle resolution; γ is the search azimuth angle, which ranges from 0° to 360°, and the search azimuth angle interval Δγ is the same as the scanning angle interval Δγ in step 5.

[0073] Step 7: Change the angle interpolation factor and the interpolated signal to the azimuth frequency to achieve angle compression, and obtain an azimuth-elevation two-dimensional angle super-resolution result.

[0074] The target signal is angle-compressed along the pitch dimension in the azimuth dimension, and the i-th search pitch angle Φ is selected from the search pitch angle Φ in step 6 with a search interval ΔΦ and a range of 0° to 90°. i , and its azimuth angle compression factor is:

[0075]

[0076] Perform FFT (Fast Fourier Transformation) on the azimuth angle compression factor of Formula 5 along the azimuth dimension to obtain the azimuth frequency domain angle compression factor H(f); perform FFT on the space-varying echo s′(γ) of each group of collected data in step 5 to obtain the azimuth frequency domain space-varying echo phase S(f) of each group of collected data.

[0077] In the azimuth frequency domain, the space-variant echo phase S(f) and the angle compression factor H(f) are multiplied to obtain the azimuth frequency domain angle compression result X(f) of each set of collected data, as shown in Equation 6.

[0078] X(f)=S0f)*H(f) (Formula 6)

[0079] The azimuth frequency domain angle compression result X(f) of each set of collected data is subjected to azimuth dimension IFFT (Inverse Fast Fourier Transform) to obtain the azimuth dimension angle super-resolution result x(γ) of each set of collected data.

[0080] All search pitch angles Φ are traversed to obtain the azimuth-pitch two-dimensional angle super-resolution results of each set of collected data, forming a database of target signals and two-dimensional angles.

[0081] The method of the present invention is used to collect the phase space-varying signal azimuth frequency bandwidth, and the collection results are as follows: Figure 6 As shown, the feasibility of the angle compression of the present invention is verified.

[0082] The two-dimensional angle estimation result of the present invention is verified by using a single target to obtain the azimuth-pitch two-dimensional angle super-resolution result of the single target, such as Figure 7 As shown, the effectiveness of the two-dimensional angle estimation of the present invention is verified.

[0083] The two-dimensional angle estimation result of the present invention is verified by using multiple coherent signals to obtain the azimuth-elevation two-dimensional angle super-resolution results of multiple coherent signals, such as Figure 8 , Fig. 9 As shown, the effectiveness of multiple coherent signals for two-dimensional angle estimation.

[0084] In summary, the present invention constructs a two-dimensional angle compression factor through periodic truncation and data interpolation of the collected data, and processes the two-dimensional angle compression factor and the signal frequency to obtain the azimuth-elevation two-dimensional angle super-resolution results of the target signal in each azimuth dimension and elevation dimension, so as to quickly realize the azimuth-elevation two-dimensional angle joint estimation of the target signal in the spatial scan, improve the ability to resist the interference of coherent signals, reduce the influence of multipath interference, and realize the accurate measurement of the two-dimensional angle of the coherent signal.

[0085] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A two-dimensional angle estimation method based on phase space variation, characterized in that: The specific steps include: Step 1, obtain phase space-varying sampling data by rotating and scanning the antenna space; Step 2, by sorting the sampled data, the relationship between the amplitude, phase and frequency information of the target signal is obtained; Step 3, periodically truncate the sampled data to obtain the phase change of the target signal; Step 4, performing frequency alignment on the phase of the signal in each set of data obtained in step 3; Step 5, interpolating the sampling data group that has completed frequency alignment; Step 6, constructing a two-dimensional angle compression factor based on the interpolated angle resolution and the target signal frequency; Step 7: Change the angle interpolation factor and the interpolated signal to the azimuth frequency to achieve angle compression, and obtain an azimuth-elevation two-dimensional angle super-resolution result.

2. The two-dimensional angle estimation method based on phase space variation according to claim 1 is characterized in that: In step 1, the method for spatial rotation of the antenna is to set a pair of antennas symmetrically fixed on both sides of a rotating table, and traverse and sample the scanning area by rotating the rotating table; when the antennas on both sides capture the target signal at the same time, the sampling data is stored and the rotation angle of the antenna at this time is recorded.

3. The two-dimensional angle estimation method based on phase space variation according to claim 2 is characterized in that: The antenna is an omnidirectional antenna; the sampling data includes: a target signal, a target elevation angle and a target azimuth angle.

4. The two-dimensional angle estimation method based on phase space variation according to claim 1, characterized in that: In step 3, the target signal periodic truncation method includes: During the first rotation of the antenna, the first data point captured after the scanning angle γ is greater than 0° is used as the starting point of the first group of sampling data. As the scanning angle increases, the last data point captured at the maximum scanning angle within the 360° range of the antenna rotation is used as the ending point of the first group of sampling data. During the second rotation of the antenna, the first data point captured after the scanning angle γ is greater than 360° is used as the starting point of the second group of sampling data, and the last data point captured at the maximum scanning angle within the 720° range of the antenna rotation is used as the ending point of the second group of sampling data; and so on, until the grouping of all sampling data is completed. The angle of each set of sampling data is re-marked so that the angle range of each set of sampling data is 0°-360°, that is, the scanning angle in the mth set of sampling data is subtracted by (m-1)×360°.

5. The two-dimensional angle estimation method based on phase space variation according to claim 3 is characterized in that: In step 4, the frequency alignment method includes: The center frequency f(γ0) in the phase of the first target signal (i.e., the starting point) in each set of sampled data is taken as the center frequency of the group, and the center frequencies of the phases of other target signals in the group are corrected. For the i+1th data point in the group, the phase compensation coefficient is f(γ0) / f(γ i ), then after the target signal frequency is aligned, the compensation phase of the i+1th target signal for: Where γ0 is the scanning angle corresponding to the first target signal in the set of sampled data, γ i is the scanning angle corresponding to the i+1th target signal in the set of sampled data.

6. The two-dimensional angle estimation method based on phase space variation according to claim 3 is characterized in that: In step 5, the method for collecting data set interpolation includes: For the sampling data group in which the target signal frequency alignment is completed in step 4, the scanning angle γ of the sampling data is set to be spaced at intervals of Δγ, so that the data points in each group are evenly distributed within the range of 0°-360°, and part of the scanning angle is interpolated and extended. The interpolation extension is that for the data points that cannot be captured from the experiment, the phase of the target signal of the data point can be obtained according to the scanning angle corresponding to the data point, so as to obtain the interpolated acquisition data, and each group of acquisition data obtained after interpolation is marked as a space-varying echo s′(γ).

7. The two-dimensional angle estimation method based on phase space variation according to claim 6, characterized in that: The pitch angle and azimuth angle ranges of the target are divided, and the search pitch angle range is 0°~90°, and the search interval is selected according to the pitch angle resolution; the search azimuth angle range is 0°~360°, and the search azimuth angle interval is the same as the scanning angle interval Δγ.

8. The two-dimensional angle estimation method based on phase space variation according to claim 6, characterized in that: In step 7, the method of changing the angle interpolation factor and the interpolated signal to the azimuth frequency includes: The azimuth angle compression factor is fast Fourier transformed along the azimuth dimension to obtain the azimuth frequency domain angle compression factor H(f); the space-varying echo s′(γ) of each set of collected data is fast Fourier transformed to obtain the azimuth frequency domain space-varying echo phase S(f) of each set of collected data; In the azimuth frequency domain, the space-variant echo phase S(f) and the angle compression factor H(f) are multiplied to obtain the azimuth frequency domain angle compression result X(f) of each set of collected data; X(f)=S(f)*H(f) The azimuth frequency domain angle compression result X(f) of each set of collected data is subjected to azimuth-dimensional inverse fast Fourier transform to obtain the azimuth-dimensional angle super-resolution result x(γ) of each set of collected data; All search pitch angles Φ are traversed to obtain the azimuth-pitch two-dimensional angle super-resolution results of each set of collected data, forming a database of target signals and two-dimensional angles.

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