A uniform sampling method for obtaining hole-free difference array based on array movement

Abstract

The present invention discloses a uniform sampling method for obtaining a hole-free difference array based on array movement, comprising: obtaining a set of element positions in the array difference matrix and recording the length h of the maximum interval between elements; sampling at the current time t, and recording the array output data at that time; sampling at times t+d / v, t+2d / v, ..., as the array moves; synthesizing the sampled data to obtain the output of a synthesized array; and processing the output of the synthesized array using a spatial smoothing subspace method to obtain a more accurate DOA estimate than the original array. The present invention can fully utilize the array's movement characteristics and, combined with the array output obtained by sampling at specific points, obtain a synthesized array with a completely continuous difference matrix, a higher degree of freedom, and better estimation results.

Description

Technical Field

[0001] The present invention relates to the technical field of sparse array antenna direction finding, and in particular to a uniform sampling method for obtaining a non-aperture difference array based on array movement. Background Art

[0002] Spatial spectrum estimation, also known as Direction of Arrival (DOA) estimation, is an important branch in the field of array signal processing and is widely used in radar, sonar, navigation, and autonomous driving.

[0003] Traditional arrays for DOA estimation generally use uniform linear arrays. To avoid ambiguity in the estimated angle, the element spacing of a uniform linear array is limited to less than or equal to half a wavelength. The limited element spacing makes it more susceptible to mutual coupling and, when the number of elements is fixed, limits the array aperture, which in turn affects the array's estimation performance. Sparse arrays, on the other hand, can break through the half-wavelength limitation, thereby reducing the mutual coupling between elements while achieving a larger array aperture. However, most of the difference co-arrays of existing sparse arrays contain missing elements, that is, holes. The hole problem reduces the degrees of freedom of the sparse array, thereby reducing the number of targets that can be identified.

[0004] Therefore, studying how to fill the holes in the sparse array differential matrix to increase the degree of freedom is a technical problem that needs to be solved. Summary of the Invention

[0005] In light of this, the present invention aims to provide a uniform sampling method for obtaining a hole-free difference matrix based on array movement, addressing the technical problems mentioned in the background art. This invention addresses the problem of holes in the difference matrix of existing sparse arrays and proposes an effective array sampling method to fill these holes, taking into account the scenario of array movement. This method selects several specific time points during the array movement process, collects array sampling data at these corresponding time points, and stacks and reconstructs the sampled data to obtain the final synthesized array output.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A uniform sampling method for obtaining a hole-free difference array based on array movement, the uniform sampling method comprising:

[0008] Step S1: for a physical array, determine its array element position set Wherein, the physical array is used for performing DOA estimation;

[0009] Step S2: Calculate the element position set of the difference array for the physical array in step S1.

[0010] Step S3: for the array element position set obtained in step S2 Calculate the length h of its largest continuous hole;

[0011] Step S4: Take time t as the initial sampling time of the array, and sequentially Sampling is performed to obtain the output value at the corresponding moment, where d is equal to the value of half the wavelength of the incident signal and v is the array movement speed;

[0012] Step S5, performing phase compensation on the output values ​​at different times obtained in step S4, and then synthesizing them to obtain the output of the synthesized array;

[0013] Step S6: virtualizing the synthesized array obtained in step S5 to obtain the output of its difference matrix;

[0014] Step S7: Apply a spatial smoothing subspace method to the difference matrix obtained in step S6 to obtain a final DOA estimate.

[0015] Furthermore, in step S1, assuming that the physical array has N array elements, the position set of the array elements is

[0016] Furthermore, in step S2, the element position set of the difference array

[0017] Furthermore, in step S4, at the initial sampling time t, the array output vector is:

[0018]

[0019] In formula (1), K represents the number of signal sources incident on the array, v represents the speed of the array movement, and a(θ k ) is the array steering vector, s k is the signal amplitude, w0 is the frequency of the incident signal, c is the propagation speed of the incident signal, and λ is the wavelength of the incident signal; A=[a(θ1),a(θ2),...,a(θ K )] is the direction matrix of the array, s(t)=[s1(t)exp(-j2πvtsin(θ1) / λ,...,s K (t)exp(-j2πvtsin(θ K ) / λ] represents the incident signal vector, and n(t) is the noise vector.

[0020] Furthermore, in step S4, at time When sampling, the corresponding output value is:

[0021]

[0022] In formula (2) and formula (3), Q is expressed as

[0023]

[0024] Furthermore, in step S5, phase compensation is performed, and its specific expression is:

[0025]

[0026] In formula (4) and formula (5), Q is expressed as ,

[0027] Furthermore, in step S5, the synthesis is performed, and the expression is:

[0028]

[0029] In formula (6), Among them, the expression of the synthetic array corresponding to y(t) is q∈[1,2,...,Q].

[0030] Furthermore, in step S6, a virtualization method is used for the output of the synthesized array to obtain a corresponding differential matrix, which is specifically expressed as:

[0031]

[0032] Furthermore, in step S7, the spatial smoothing subspace method includes the SS-ESPRIT method.

[0033] The beneficial effects of the present invention are:

[0034] The difference matrix of the synthesized array obtained by this invention is completely continuous and hole-free, thus enabling sparse arrays to achieve greater degrees of freedom. This invention can improve the degrees of freedom, number of identifiable signals, and estimation accuracy of sparse arrays without increasing the number of physical array elements, thereby reducing hardware overhead and cost, and can be applied to mobile platforms such as vehicles and ships. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of a flow chart of a uniform sampling method for obtaining a hole-free difference array based on array movement provided in Example 1;

[0036] Figure 2A schematic diagram of sampling the mobile array provided in Example 1;

[0037] Figure 3 This is a graph showing the angle estimation performance of the uniform sampling method provided in Example 1 as the signal-to-noise ratio changes;

[0038] Figure 4 This is a graph showing the performance of angle estimation when the uniform sampling method provided in Example 1 changes with snapshots;

[0039] Figure 5 Schematic diagram of the resolution of the uniform sampling method provided in Example 1. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. 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 making creative efforts shall fall within the scope of protection of the present invention.

[0041] Example 1

[0042] See also Figure 1-Figure 5 This embodiment provides a uniform sampling method for obtaining a hole-free difference array based on array movement, including:

[0043] For a physical array, determine its array element position set Wherein, the physical array is used for performing DOA estimation;

[0044] For the physical array, calculate the element position set of its difference array

[0045] For the obtained array element position set Calculate the length h of its largest continuous hole;

[0046] Take time t as the initial sampling time of the array, and sequentially at time Sampling is performed to obtain the output value at the corresponding moment, where d is equal to the value of half the wavelength of the incident signal and v is the array movement speed;

[0047] After phase compensation is performed on the output values ​​obtained at different times, they are synthesized to obtain the output of the synthesized array;

[0048] The obtained synthetic array is subjected to a virtualization method to obtain the output of its difference array;

[0049] The spatial smoothing subspace method is used on the obtained difference matrix to obtain the final DOA estimation value.

[0050] Specifically, in this embodiment, in order to more clearly illustrate the method provided in this embodiment, a more specific example is provided for illustration, specifically including:

[0051] Step 1: Assume that the original antenna array is as follows Figure 2 As shown in the first row, the physical array element positions are {0,6,7,12,14,18,21,24,28,30,35,36}d.

[0052] Step 2: The difference matrix of the original antenna array is as follows Figure 2 As shown in the second to last row, there are many holes in the difference matrix, among which the largest continuous hole length is h=4.

[0053] Step 3: To fill the holes in the difference matrix, determine the sampling start time as t, and sample at time t, t+d / v, and t+2d / v in sequence to obtain the output values ​​of the array at different times. The expression is:

[0054]

[0055]

[0056] In the formula, K represents the number of signal sources incident on the array, v represents the speed of the array movement, and a(θ k ) is the array steering vector, a(θ k )=[exp(-j2πd1sinθ k / λ),...,exp(-j2πd L sinθ k / λ)] T , s k is the signal amplitude, w0 is the frequency of the incident signal, c is the propagation speed of the incident signal, A=[a(θ1),a(θ2),...,a(θ K )] is the direction matrix of the array, n(t) is the noise vector;

[0057]

[0058] Step 4: Multiply the array output obtained by the above sampling by the corresponding phase correction factor to perform phase compensation. The expression is:

[0059]

[0060] In the formula,

[0061]

[0062] Step 5: Synthesize the sampled data at different times. The expression is:

[0063]

[0064] In the formula,

[0065] The expression for the resultant array corresponding to y(t) is:

[0066]

[0067] Step 6: Apply the virtualization method to the output of the above synthetic array to obtain the corresponding differential matrix, which is expressed as:

[0068]

[0069] Step 7: Apply spatial smoothing subspace methods, such as the SS-ESPRIT method, to the difference matrix to obtain the corresponding DOA estimation value.

[0070] In order to verify the correctness and advancement of the method of this embodiment, this embodiment conducts simulation experiments, and the specific experimental results are as follows: Figure 3-Figure 5 As shown, specifically:

[0071] Figure 3 The following graph shows the performance of the θ angle estimation method of this embodiment as the signal-to-noise ratio (SNR) changes. It can be seen that the performance of the array angle estimation is significantly improved after using the method of this embodiment. The performance of the method of this embodiment also improves as the SNR increases.

[0072] Figure 4 This figure shows the performance of the θ angle estimation method of this embodiment as the snapshot ratio changes. It can be seen that the performance of the array angle estimation is significantly improved after using the method of this embodiment. The performance of this embodiment method also improves as the number of snapshots increases.

[0073] Figure 5 : is the resolution performance diagram of the method of this embodiment. It can be seen that after using the method of this embodiment, the angular resolution of the array is greatly improved. After using the method of this embodiment, the array can distinguish signal sources with smaller angular intervals.

[0074] In summary, the present invention can fully utilize the mobility characteristics of the array and combine the array output obtained by sampling at specific points to obtain a synthetic array with a completely continuous difference matrix, higher degree of freedom and better estimation effect.

[0075] Anything not described in detail in the present invention is well known to those skilled in the art.

[0076] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A uniform sampling method for obtaining a hole-free difference array based on array movement, characterized in that: The uniform sampling method includes: Step S1: for a physical array, determine its array element position set The physical array is used for DOA estimation; the physical array has N array elements, and the position set of its array elements is Step S2: Calculate the element position set of the difference array for the physical array in step S1. Step S3: for the array element position set obtained in step S2 Calculate the length h of its largest continuous hole; Step S4: Take time t as the initial sampling time of the array, and sequentially Sampling is performed to obtain the output value at the corresponding moment, where d is equal to the value of half the wavelength of the incident signal and v is the array movement speed; Step S5, performing phase compensation on the output values ​​at different times obtained in step S4, and then synthesizing them to obtain the output of the synthesized array; Step S6: virtualizing the synthesized array obtained in step S5 to obtain the output of its difference matrix; Step S7: applying a spatial smoothing subspace method to the difference matrix obtained in step S6 to obtain a final DOA estimate; In step S4, at the initial sampling time t, the array output vector is: In formula (1), K represents the number of signal sources incident on the array, v represents the speed of the array movement, and a(θ k ) is the array steering vector, a(θ k )=[exp(-j2πd1sinθ k / λ),...,exp(-j2πd L sinθ k / λ)] T (k∈[1,2,...,K]), s k is the signal amplitude, w0 is the frequency of the incident signal, c is the propagation speed of the incident signal, and λ is the wavelength of the incident signal; A=[a(θ1),a(θ2),...,a(θ K )] is the direction matrix of the array, s(t)=[s1(t)exp(-j2πvtsin(θ1) / λ,...,s K (t)exp(-j2πvtsin(θ K ) / λ] represents the incident signal vector, and n(t) is the noise vector; In step S4, at time When sampling, the corresponding output value is: In formula (2) and formula (3), Q is expressed as In step S5, phase compensation is performed, and its specific expression is: In formula (4) and formula (5), Q is expressed as In the step S5, the synthesis is performed, and the expression is: In formula (6), Among them, the expression of the synthetic array corresponding to y(t) is In step S6, a virtualization method is used on the output of the synthetic array to obtain the corresponding differential matrix, which is specifically expressed as:

2. The uniform sampling method for obtaining a hole-free difference array based on array movement according to claim 1, characterized in that: In step S7, the spatial smoothing subspace method includes the SS-ESPRIT method.

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