Array Phase Error Correction Method and System

Abstract

The present invention relates to the technical field of signal processing, and discloses an array phase error correction method and system, aiming at solving the problem that the existing array error correction method will cause the degradation of DOA estimation performance, including the following steps: determining a plurality of positions to be corrected in the field of view of the array antenna; sequentially performing correction on each position to be corrected, and the method for performing correction on each position to be corrected includes: placing an auxiliary point source at the corresponding position to be corrected, and receiving, by the array, the electromagnetic wave signal reflected by the auxiliary point source; respectively extracting the signal components corresponding to the auxiliary point source from the electromagnetic wave signals received by each array element in the array; and correcting the direction vector within the corresponding defined range based on the signal components. The present invention improves the correction effect, will not cause the degradation of DOA estimation performance, and has a relatively low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of signal processing, and more particularly to an array phase error correction method and system. Background Art

[0002] One of the important functions of devices such as radars, mobile communication base stations, and sonars is to detect the azimuth of a target, which often requires the use of DOA estimation technology in array signal processing. Many high-resolution DOA estimation algorithms are sensitive to array errors, and array errors often cause the performance of these algorithms to deteriorate or even fail. Therefore, array error correction is of great significance. In engineering applications, due to factors such as component differences and manufacturing processes, array errors always exist. Array errors usually include element channel amplitude-phase errors, element position errors, and element mutual coupling errors.

[0003] In some applications with low requirements for direction finding accuracy, such as using a radar for short-distance target tracking and positioning, the zero-degree angle correction method is usually used to correct the linear receiving array error. The processing flow of this method is as follows: First, place an auxiliary point source (such as a corner reflector) in the line-of-sight direction of the array antenna. Second, the array receives the signal reflected from the auxiliary point source and extracts the signal components corresponding to the point source in the received signals of each element. Then, calculate the ratio of the ideal zero-degree angle direction vector of each element to the previously extracted signal component, and regard these values as array errors. Finally, use these array errors to correct the ideal direction vectors of all angles. Although this method is simple, in direction finding applications with a large array beam width, if the target is at a large angle, this correction method will cause the performance of DOA estimation to decline. Summary of the Invention

[0004] The present invention aims to solve the problem that the existing array error correction method will cause the performance of DOA estimation to decline, and proposes an array phase error correction method and system.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0006] In a first aspect, an array phase error correction method is provided, including the following steps:

[0007] Step 1: Determine a plurality of positions to be corrected in the field of view of the array antenna;

[0008] Step 2: Perform correction on each position to be corrected in turn. The method for performing correction on each position to be corrected includes:

[0009] Step 21: Place an auxiliary point source at the corresponding position to be corrected, and receive the electromagnetic wave signal reflected by the auxiliary point source through the array;

[0010] Step 22: Extract the signal components corresponding to the auxiliary point source from the electromagnetic wave signals received by each element in the array;

[0011] Step 23: Correct the direction vector within the corresponding defined range based on the signal components.

[0012] As a further optimization, the field of view of the array antenna is defined by the azimuth angle (θ min , θ max ) and the elevation angle . Determining multiple positions in the field of view of the array antenna specifically includes:

[0013] The field of view of the array antenna is sliced into M regions along the azimuth angle dimension, and then sliced into N regions along the elevation angle dimension. Further, the field of view of the array antenna is sliced into K regions, and each region in the K regions is used as a position to be calibrated, where K = M * N, and M and N are positive integers.

[0014] As a further optimization, in step 21, placing an auxiliary point source at the corresponding position to be calibrated specifically includes:

[0015] Placing an auxiliary point source at the spherical coordinates (R ij , θ i , ), where the direction of placing the auxiliary point source is the direction of the symmetry center of the position to be calibrated. Here, R ij represents the distance from the corresponding position in the spherical coordinates to the origin, θ i represents the azimuth angle of the corresponding position in the spherical coordinates, represents the elevation angle of the corresponding position in the spherical coordinates, i = 1, 2,..., M, j = 1, 2,..., N.

[0016] As a further optimization, in step 22, extracting the signal components corresponding to the auxiliary point source from the electromagnetic wave signals received by each element in the array specifically includes:

[0017] Assume the array includes P elements, then the signal component S ij corresponding to the auxiliary point source extracted from the electromagnetic wave signals received by each element is:

[0018]

[0019] Among them, the signal component corresponding to the auxiliary point source extracted from the electromagnetic wave signal received by element p is:

[0020]

[0021] In the formula, p = 1, 2,..., P, A represents the amplitude of the electromagnetic wave signal, ω represents the phase of the electromagnetic wave signal, and e represents the natural exponent.

[0022] As a further optimization, in step 23, the direction vectors within the corresponding defined range are corrected based on the signal components, specifically including:

[0023] Calculate the phase error of the array in the direction of (θ x , ) according to the signal components corresponding to each array element, where θ x ∈Φ x , Φ x represents the azimuth angle defined range corresponding to the position to be corrected, and Ψ x represents the elevation angle defined range corresponding to the position to be corrected;

[0024] Correct the direction vector of the array in the direction of (θ x , ) according to the phase error.

[0025] As a further optimization,

[0026] When i = 1 corresponding to the position to be corrected, the azimuth angle defined range Φ x of the signal component is:

[0027]

[0028] When 1 < i < M corresponding to the position to be corrected, the azimuth angle defined range Φ x of the signal component is:

[0029]

[0030] When i = M corresponding to the position to be corrected, the azimuth angle defined range Φ x of the signal component is:

[0031]

[0032] As a further optimization,

[0033] When j = 1 corresponding to the position to be corrected, the elevation angle defined range Ψ x of the signal component is:

[0034]

[0035] When 1 < j < N corresponding to the position to be corrected, the elevation angle defined range Ψ x of the signal component is:

[0036]

[0037] When j = N corresponding to the position to be corrected, the defined range Ψ of the elevation angle corresponding to the signal component x is as follows:

[0038]

[0039] As a further optimization, the formula for calculating the phase error Δ x , ) of the array in the (θ x ) direction according to the signal components corresponding to each array element is as follows:

[0040] Δ x = t x . / |t x |;

[0041] wherein, t x = a x . / S ij , a x represents the ideal direction vector corresponding to the array in the (θ x , ) direction,. / represents the dot division between vectors, and | | represents taking the modulus of each element in the vector.

[0042] As a further optimization, the formula for correcting the direction vector of the array in the (θ x , x , ) direction according to the phase error Δ

[0043]

[0044] In the formula, represents the corrected direction vector,.* represents the dot multiplication between vectors, and conj( ) represents taking the conjugate of each element in the vector.

[0045] In a second aspect, there is provided an array phase error correction system, including: a determination unit and a correction unit;

[0046] The determination unit is configured to determine a plurality of positions to be corrected in the field of view of the array antenna;

[0047] The correction unit is configured to perform corrections on each position to be corrected in sequence;

[0048] The correction unit specifically includes: an auxiliary point source, an extraction unit, and a correction unit;

[0049] The auxiliary point source is configured to be placed at the corresponding position to be corrected;

[0050] The array is configured to receive the electromagnetic wave signal reflected by the auxiliary point source and send it to the extraction unit;

[0051] The extraction unit extracts the signal components corresponding to the auxiliary point sources from the electromagnetic wave signals received by each array element in the array.

[0052] The correction unit is used to correct the direction vector within the corresponding defined range based on the signal components.

[0053] The beneficial effects of the present invention are as follows: The array phase error correction method and system of the present invention solve the problem of the decline in the direction finding accuracy of target positioning devices such as radars caused by array phase errors. Moreover, the auxiliary point source information at multiple positions is used to correct the array phase error, improving the correction effect. Even in the direction finding applications with a relatively large array beam width, when the target is at a large angle, it will not cause a decline in the DOA estimation performance. In addition, the implementation method of the present invention is simple and the cost is low, fully considering the balance between the correction effect and the engineering implementation cost. Description of the Drawings

[0054] Figure 1 It is a schematic flow chart of the array phase error correction method described in the embodiment of the present invention;

[0055] Figure 2 It is a schematic flow chart of performing correction on each position to be corrected described in the embodiment of the present invention;

[0056] Figure 3 It is a schematic diagram of the spatial relationship between the array and the auxiliary point sources described in the embodiment of the present invention. Detailed Embodiments

[0057] The following will describe the embodiments of the present invention in detail with reference to the drawings.

[0058] The array phase error correction method provided by the present invention includes the following steps: Step 1, determine multiple positions to be corrected in the field of view of the array antenna; Step 2, perform correction on each position to be corrected in sequence. The method for performing correction on each position to be corrected includes: Step 21, place an auxiliary point source at the corresponding position to be corrected, and receive the electromagnetic wave signals reflected by the auxiliary point source through the array; Step 22, extract the signal components corresponding to the auxiliary point sources from the electromagnetic wave signals received by each array element in the array; Step 23, correct the direction vector within the corresponding defined range based on the signal components.

[0059] Specifically, the present invention improves the calibration effect by performing calibration at multiple positions to be calibrated in the field of view of the array antenna. For each position to be calibrated, the calibration method mainly includes: First, an auxiliary point source is set at the position to be calibrated. The auxiliary point source is used to reflect electromagnetic wave signals. When each element in the array receives the electromagnetic wave signals, the signal components corresponding to the auxiliary point source are respectively extracted from the electromagnetic wave signals received by each element. Finally, the direction vectors within the corresponding defined range are corrected according to the signal components corresponding to each element.

[0060] Embodiment

[0061] In this embodiment, a linear array antenna of a frequency-modulated continuous-wave radar is taken as an example. The array includes 4 elements, the element spacing is half a wavelength, the signal frequency band is from 60 GHz to 64 GHz, and the main beam width of the antenna is: azimuth angle from -60° to +60°, elevation angle from -5° to +5°. This radar is used to detect the distance and azimuth angle of the target. The array phase error calibration method described in this embodiment, as Figure 1 shown, includes the following steps:

[0062] Step 1, determine multiple positions to be calibrated in the field of view of the array antenna;

[0063] In this embodiment, the field of view of the array antenna is defined by the azimuth angle (θ min , θ max ) and the elevation angle . The determination of multiple positions in the field of view of the array antenna specifically includes:

[0064] The field of view of the array antenna is divided into M regions along the azimuth angle dimension, and then divided into N regions along the elevation angle dimension. Further, the field of view of the array antenna is divided into K regions, and each region in the K regions is used as a position to be calibrated, where K = M * N, and M and N are positive integers.

[0065] The main beam of the array antenna determines the field of view of the array. Therefore, θ min = -60°, θ max = +60°, The larger the values of M and N, the better the calibration effect, but the higher the implementation cost. Therefore, the values of M and N can be reasonably set according to application requirements. Since this linear array is used to obtain the azimuth angle, M = 4 and N = 1 can be taken, and then K is 4.

[0066] Step 2, perform calibration on each position to be calibrated in turn, as Figure 2 shown. The calibration method for each position to be calibrated includes:

[0067] Step 21, place an auxiliary point source at the corresponding position to be calibrated, and receive the electromagnetic wave signals reflected by the auxiliary point source through this array;

[0068] Placing an auxiliary point source at the corresponding position to be calibrated specifically includes:

[0069] Placing an auxiliary point source at the spherical coordinates (R ij , θ i , ), where the direction of placing the auxiliary point source is the direction where the symmetry center of the position to be calibrated is located. Among them, R ij represents the distance from the corresponding position in spherical coordinates to the origin, θ i represents the azimuth angle of the corresponding position in spherical coordinates, represents the elevation angle of the corresponding position in spherical coordinates, i = 1, 2,..., M, j = 1, 2,..., N. At the same time, it should be ensured that there are no strong interference targets near the auxiliary point source. Preferably, it is in an anechoic chamber environment. The spatial relationship between the auxiliary point source and the array is as Figure 3 shown.

[0070] In this embodiment, the positions of 4 auxiliary point sources are set as: (3, -45°, 0°), (3, -15°, 0°), (3, 15°, 0°), (3, 45°, 0°). That is, θ1 = -45°, θ2 = -15°, θ3 = 15°, θ4 = 45°; R 11 = R 21 = R 31 = R 41 = 3.

[0071] The radar is placed in an open space. The radar antenna plane is perpendicular to the ground, and the height of the antenna center from the ground is 1.5 meters. Place an auxiliary point source at one of the positions, such as (3, -45°, 0°); here, the auxiliary point source is served by a triangular reflector with an isosceles side length of about 0.05 meters, and the reflector opening faces the radar antenna. The radar emits a frequency-modulated continuous wave pulse. By setting appropriate pulse frequency modulation slope, pulse duration, and ADC sampling time, the distance resolution of the radar can be made as small as possible while the maximum detectable distance exceeds the distance between the reflector and the radar. Use this receiving array to receive the electromagnetic wave reflected from the auxiliary point source; here, the received intermediate frequency signal is taken as the input for the next step.

[0072] Step 22: Extract the signal components corresponding to the auxiliary point source from the electromagnetic wave signals received by each element in the array;

[0073] The extracting the signal components corresponding to the auxiliary point source from the electromagnetic wave signals received by each element in the array specifically includes:

[0074] Suppose the array includes P elements, then the signal components S ij corresponding to the auxiliary point source extracted from the electromagnetic wave signals received by each element are:

[0075]

[0076] Among them, the signal component corresponding to the auxiliary point source extracted from the electromagnetic wave signal received by the array element p is:

[0077]

[0078] In the formula, p = 1, 2,..., P, A represents the amplitude of the electromagnetic wave signal, ω represents the phase of the electromagnetic wave signal, and e represents the natural exponential.

[0079] Specifically, in this embodiment, the intermediate frequency signals received by each array element are subjected to Fourier transform to obtain the target distance spectrum, the frequency point closest to 3 meters is found in the distance spectrum, and the first peak near this frequency point is searched. The spectral component where this peak is located is the signal component corresponding to the auxiliary point source. The above components extracted from the signals received by the 4 array elements constitute

[0080] Step 23. Correct the direction vector within the corresponding defined range based on the signal component.

[0081] Correcting the direction vector within the corresponding defined range based on the signal component specifically includes:

[0082] Step 231. Calculate the phase error of the array in the direction of (θ x , ) according to the signal component corresponding to each array element, where θ x ∈Φ x , Φ x represents the azimuth angle defined range corresponding to the position to be corrected, and Ψ x represents the elevation angle defined range corresponding to the position to be corrected;

[0083] The formula for calculating the phase error Δ x , ) of the array in the direction of (θ x ) according to the signal component corresponding to each array element is as follows:

[0084] Δ x = t x . / |t x |;

[0085] Among them, t x = a x . / S ij , a x represents the calculated array in the direction of (θ x , The ideal direction vector corresponding to the direction, and. / represents the dot division between vectors, and || represents taking the modulus of each element in the vector.

[0086] Among them, when i = 1 corresponding to the position to be corrected, the defined range Φ of the azimuth angle corresponding to the signal component x is:

[0087]

[0088] When 1 < i < M corresponding to the position to be corrected, the defined range Φ of the azimuth angle corresponding to the signal component x is:

[0089]

[0090] When i = M corresponding to the position to be corrected, the defined range Φ of the azimuth angle corresponding to the signal component x is:

[0091]

[0092] When j = 1 corresponding to the position to be corrected, the defined range Ψ of the elevation angle corresponding to the signal component x is:

[0093]

[0094] When 1 < j < N corresponding to the position to be corrected, the defined range Ψ of the elevation angle corresponding to the signal component x is:

[0095]

[0096] When j = N corresponding to the position to be corrected, the defined range Ψ of the elevation angle corresponding to the signal component x is:

[0097]

[0098] Taking i = 2, j = 1 as an example, then Φ2 = [-30°, 0°], Ψ1 = [-5°, 5°].

[0099] Step 232, correct the direction vector of the array in the (θ x , ) direction according to the phase error.

[0100] The formula for correcting the direction vector of the array in the (θ x , x , ) direction according to the phase error Δ

[0101]

[0102] In the formula, represents the corrected direction vector,.* represents the dot product between vectors, and conj( ) represents taking the conjugate of each element in the vector.

[0103] In this embodiment, the corrected direction vector

[0104] Repeat steps S21 - S23 to complete the calibration of all positions to be calibrated.

[0105] Based on the above technical solution, this embodiment also proposes an array phase error correction system, including: a determination unit and a correction unit;

[0106] The determination unit is used to determine a plurality of positions to be calibrated in the field of view of the array antenna;

[0107] The correction unit is used to perform calibration on each position to be calibrated in sequence;

[0108] The correction unit specifically includes: an auxiliary point source, an extraction unit, and a correction unit;

[0109] The auxiliary point source is used to be placed at the corresponding position to be calibrated;

[0110] The array is used to receive the electromagnetic wave signal reflected by the auxiliary point source and send it to the extraction unit;

[0111] The extraction unit extracts the signal component corresponding to the auxiliary point source from the electromagnetic wave signals received by each element in the array respectively;

[0112] The correction unit is used to correct the direction vector within the corresponding defined range based on the signal component.

[0113] It can be understood that since the array phase error correction system described in the embodiment of the present invention is a system for implementing the array phase error correction method described in the embodiment, for the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method.

Claims

1. Array phase error correction method, characterized in that, It includes the following steps: Step 1: Determine multiple positions to be corrected in the field of view of the array antenna; Step 2: Perform correction on each position to be corrected in sequence. The method for performing correction on each position to be corrected includes: Step 21: Place an auxiliary point source at the corresponding position to be corrected, and receive the electromagnetic wave signal reflected by the auxiliary point source through this array; Step 22: Extract the signal components corresponding to the auxiliary point source from the electromagnetic wave signals received by each array element in this array respectively; Step 23: Correct the direction vector within the corresponding defined range based on the signal components, specifically including: Calculate the phase error of the array in the direction of ( , ) according to the signal components corresponding to each array element, where , , represents the azimuth angle definition range corresponding to the position to be corrected, and represents the elevation angle definition range corresponding to the position to be corrected; According to the phase error, the direction vector of the array in the ( , ) direction is corrected, and the formula is as follows: ； In the formula, represents the corrected direction vector, represents the dot product between vectors, represents taking the conjugate of each element in the vector, represents the array at ( , ) corresponding ideal direction vector in the direction, represents the phase error of the array at ( , ) in the direction.

2. The array phase error correction method according to claim 1, wherein The field of view of the array antenna is defined by the azimuth angle ( , ), and the elevation angle ( , ). Multiple positions are determined in the field of view of the array antenna, specifically including: The field of view of the array antenna is divided along the azimuth dimension into regions, and then divided along the elevation dimension into regions. Furthermore, the field of view of the array antenna is divided into regions. Each region in the regions is used as a position to be calibrated. Among them, , and are positive integers.

3. The array phase error correction method according to claim 2, wherein In Step 21, the operation of placing an auxiliary point source at the corresponding position to be corrected specifically includes: At the spherical coordinates ( , , ) with the array antenna as the origin, an auxiliary point source is placed in the direction of the symmetry center of the position to be calibrated. Among them, represents the distance from the corresponding position in the spherical coordinates to the origin, represents the azimuth angle of the corresponding position in the spherical coordinates, represents the elevation angle of the corresponding position in the spherical coordinates, = 1, 2, …, , = 1, 2, …, .

4. The array phase error correction method according to claim 3, wherein In Step 22, the operation of extracting the signal components corresponding to the auxiliary point source from the electromagnetic wave signals received by each array element in this array respectively specifically includes: Assume that the array includes array elements, and the signal components corresponding to the auxiliary point source are extracted from the electromagnetic wave signals received by each array element as follows: ； Among them, the signal component corresponding to the auxiliary point source extracted from the electromagnetic wave signal received by the array element is: ； wherein, = 1, 2, …, , represents the amplitude of the electromagnetic wave signal, represents the phase of the electromagnetic wave signal, represents the natural exponent.

5. The array phase error correction method according to claim 3, characterized in that When = 1 for the position to be calibrated, the azimuth definition range corresponding to the signal component is as follows: ； When corresponding to the position to be calibrated then the defined range of the azimuth angle corresponding to the signal component is as follows: ； When the one corresponding to the position to be corrected = then the defined range of the azimuth angle corresponding to the signal component is: 。 6. The array phase error correction method according to claim 3, characterized in that When = 1 for the position to be corrected, the defined range of the elevation angle corresponding to the signal component is as follows: ； When corresponding to the position to be corrected then the defined range of the elevation angle corresponding to the signal component is: ； When the one corresponding to the position to be calibrated = , the defined range of the elevation angle corresponding to the signal component is as follows: 。 7. The array phase error correction method according to claim 4, characterized in that, The formula for calculating the phase error of the array in the direction of ( , ) according to the signal components corresponding to each array element is as follows: ； Among them, , represents the ideal direction vector corresponding to the array in the ( , ) direction, represents element-wise division between vectors, represents taking the modulus of each element in the vector.

8. Array phase error correction system, characterized in that, It includes: A determination unit and a correction unit; The determination unit is used to determine multiple positions to be corrected in the field of view of the array antenna; The correction unit is used to perform correction on each position to be corrected in sequence; The correction unit specifically includes: an auxiliary point source, an extraction unit, and a correction unit; The auxiliary point source is used to be placed at the corresponding position to be corrected; The array is used to receive the electromagnetic wave signal reflected by the auxiliary point source and send it to the extraction unit; The extraction unit extracts the signal components corresponding to the auxiliary point source from the electromagnetic wave signals received by each array element in this array respectively; The correction unit is used to correct the direction vector within the corresponding defined range based on the signal components, specifically including: Calculate the phase error of the array in the direction of ( , ) according to the signal components corresponding to each array element, where , , represents the azimuth angle definition range corresponding to the position to be corrected, and represents the elevation angle definition range corresponding to the position to be corrected; According to the phase error, the direction vector of the array in the ( , ) direction is corrected, and the formula is as follows: ； In the formula, represents the corrected direction vector, represents the dot product between vectors, represents taking the conjugate of each element in the vector, represents the array at ( , ) corresponding ideal direction vector in the direction, represents the phase error of the array at ( , ) in the direction.

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