A method for extracting direction finding correction parameters for multi-antenna base station

Abstract

The present invention discloses a method for extracting direction-finding correction parameters for a multi-antenna base station, wherein the extracted parameters include: phase difference zero bias parameters of each pair of antennas, which are used to correct the influence of fixed delay phase difference caused by non-signal transmission of a pair of antennas on direction-finding; and internal angle parameters of a unit group of three antennas, which are used to correct the influence of the geometric layout structure of a group of antennas on direction-finding. The obtained direction-finding correction parameters are written into the base station firmware as system fixed parameters, which can reduce the influence of several major error sources during real-time direction-finding and effectively improve the direction-finding accuracy; in addition, the process of this method is basically fully automatic, without manual intervention in the middle, simple and easy to use, and has a self-checking function for evaluating parameter availability, and the extracted direction-finding correction parameters are highly reliable.

Description

Technical Field

[0001] The invention relates to the field of multi-antenna direction finding, and in particular to a multi-antenna direction finding parameter extraction and correction method. Background Art

[0002] The direction finding method based on the phase difference of arrival (PDOA) is to convert the phase difference of the two received signals into the distance difference of the wireless signal on the spatial propagation path, and then form a triangular relationship with the distance between the two antennas to obtain the direction angle. Assume that the antenna distance is d, the wavelength of the wireless signal is λ, the angle between the incoming wave direction and the antenna normal vector is θ, and the phase difference of arrival between the two antennas is satisfy:

[0003]

[0004] Since two antennas can only measure half a circle and cannot distinguish between forward and backward directions, to achieve 360-degree full-circle direction finding, it is necessary to obtain the phase difference between at least three antennas.

[0005] But in fact, the arrival phase difference obtained by subtracting the received phase obtained by each signal receiving unit cannot be used directly because it also contains multiple error sources, mainly including:

[0006] (1) Fixed delay phase difference caused by non-signal transmission, mainly including: the difference in counter reference caused by the delay difference of the internal clock of the receiver reaching each signal demodulation unit, and the delay difference caused by the different lengths of the antenna feed lines on the receiver. The impact of these errors on direction finding is independent of the direction itself and is collectively referred to as phase difference zero bias;

[0007] (2) Antenna phase geometric distortion error refers to the absolute difference between the phase measured by the antenna and the theoretical phase. This error is mainly caused by the geometric structure of the antenna. In addition, the shape and size of the floor and the shape of the vibrator will also have a certain impact. Due to the actual manufacturing process, the performance parameters of each antenna cannot be guaranteed to be completely consistent, resulting in a certain difference between the phase difference curve between the antennas and the theoretical curve, that is, it is not a regular sine curve. This makes the angle calculated in each direction deviate from the actual angle to varying degrees.

[0008] Therefore, for multi-antenna direction-finding base stations based on PDOA, direction-finding correction parameters need to be extracted before leaving the factory and written into the base station firmware as system fixed parameters, so that the impact of the above error sources can be effectively reduced during real-time direction finding and the direction-finding accuracy can be improved. Summary of the invention

[0009] The present invention discloses a method for extracting direction finding correction parameters of a multi-antenna base station. The obtained direction finding correction parameters can effectively reduce the influence of the main error sources of the corresponding direction finding accuracy and improve the direction finding accuracy. The present invention comprises the following steps:

[0010] Collecting the received phase difference data of each pair of antennas of the multi-antenna base station at multiple angle positions of the whole circumference of the direction finding plane at equal angle intervals; calculating the phase difference zero bias parameters of each pair of antennas according to the received phase difference data at the multiple angle positions, wherein the phase difference zero bias parameters are used to correct the influence of the fixed delay phase difference caused by the non-signal transmission of a pair of antennas on the direction finding;

[0011] Obtain zero-bias corrected phase difference data at multiple angle positions after each pair of antennas eliminates the phase difference zero bias, and calculate the internal angle parameters of each group of antennas with three antennas as a unit group, wherein the internal angle parameters are used to correct the influence of the geometric layout structure of a group of antennas on direction finding;

[0012] Each group of antennas calculates the directional angle data corresponding to the multiple angular positions according to the zero bias corrected phase difference data at the multiple angular positions and the internal angle parameters;

[0013] It is determined whether the direction angles of the multiple angle positions meet the monotonicity condition. If so, it is considered that the extraction of the direction finding correction parameter is successful; otherwise, it is considered that the estimation of the direction finding correction parameter fails.

[0014] Optionally, the step of collecting receiving antenna phase difference data of each pair of antennas of a multi-antenna base station at multiple angle positions throughout a direction finding plane at equal angle intervals is characterized in that the specific steps include:

[0015] The multi-antenna base station is placed at the center of the turntable, and the direction-finding plane is parallel to the rotation plane of the turntable. The transmitting tag is placed at a certain distance from the base station antenna as the LOS diameter, and sends a wireless signal to the multi-antenna base station at a certain frequency;

[0016] Record the initial position as 0 degrees, and collect multiple continuous reception phase data from the transmitting tag to each antenna of the multi-antenna base station at the current angle position;

[0017] Taking two antennas as a unit pair, determining whether the plurality of continuously received phase data collected by each pair of antennas at a current angle position meets a phase stability condition;

[0018] If the phase stability condition is met, the cumulative rotation angle value of the turntable at the current angle position is recorded as the reference direction angle, and the receiving phase difference data of each pair of antennas corresponding to the reference direction angle value is calculated; then, the turntable is started to rotate in one direction at a certain angle interval, and enters the next angle position, and the receiving phase difference data of each pair of antennas is collected according to the steps of the previous angle position until the turntable completes a 360-degree rotation of the direction-finding plane; if the phase stability condition is not met, the receiving phase data of each antenna at this angle position is continued to be collected;

[0019] If multiple consecutive received phase data of at least one pair of antennas do not meet the phase stability condition within a certain time threshold of the current angle position, it is considered that the extraction of the direction finding correction parameters has failed, and the transmitting tag position is adjusted to start again.

[0020] The determining whether the plurality of continuously received phase data collected by each pair of antennas at the current angle position meets the phase stability condition specifically includes:

[0021] Calculate multiple continuous receiving phase difference data of each pair of antennas, normalize to (-π,π], and then perform continuity correction;

[0022] Calculate the receiving phase difference variance of each pair of antennas according to the multiple continuous receiving phase difference data after continuity correction;

[0023] If the received phase difference variance of each pair of antennas is less than a certain threshold, it is considered that the phase stability condition is met; otherwise, it is considered that the phase stability condition is not met;

[0024] Or, specifically include:

[0025] Calculate a plurality of continuous received phase difference data of each pair of antennas;

[0026] Calculating sine values ​​and cosine values ​​of the plurality of received phase difference data;

[0027] Calculate the square sum parameter of the mean of the sine value and the mean of the cosine value of the plurality of received phase difference data;

[0028] If the square sum parameter of each pair of antennas is greater than a certain threshold, it is considered that the phase stability condition is met; otherwise, it is considered that the phase stability condition is not met.

[0029] Correspondingly, the calculating of the received phase difference data of each pair of antennas corresponding to the reference direction angle includes:

[0030] Calculate the mean of the multiple receiving phase differences after continuity correction for each pair of antennas as the phase difference data corresponding to the reference direction angle; or, obtain the phase difference data corresponding to the reference direction angle through the inverse tangent function based on the mean of the sine values ​​and the mean of the cosine values ​​of the multiple receiving phase difference data.

[0031] Optionally, the phase difference zero bias parameter of each pair of antennas is calculated according to the received phase difference data at the multiple angular positions, characterized in that the specific steps include:

[0032] Continuously correcting multiple receiving phase difference data of each pair of antennas;

[0033] The average of the multiple received phase difference data after continuity correction is calculated as the phase difference zero bias parameter of the pair of antennas.

[0034] Optionally, the method of calculating the internal angle parameters of each group of antennas with three antennas as a unit group is characterized in that the specific steps include: performing sinusoidal curve fitting on multiple receiving phase difference data of three pairs of antennas in the group, and the fitting formula is: f(n)=a1×sin(n+a2), wherein the fitting parameter a1 represents the curve amplitude, which is proportional to the antenna spacing, and the fitting parameter a2 represents the placement deviation angle between the turntable direction angle at the initial position and the direction of the connection line of the pair of antennas;

[0035] The three internal angle parameters of the antenna group are calculated by the fitting parameter a1, and the calculation formula is:

[0036]

[0037]

[0038]

[0039] Alternatively, the three interior angle parameters are calculated by the fitting parameter a2, and the calculation formula is:

[0040]

[0041]

[0042]

[0043] The superscripts i, j, k of the parameters a1 and a2 represent the antenna numbers of the three pairs of antennas in the group.

[0044] Optionally, after the direction finding correction parameter is extracted successfully, the method may further include:

[0045] Each group of antennas calculates a difference between the azimuth data corresponding to the multiple angular positions and the reference azimuth data as the azimuth residual parameter of the group of antennas.

[0046] In addition, the present invention also discloses a multi-antenna base station direction finding method based on PDOA, which specifically includes:

[0047] Obtain the receiving phase difference value from the transmitting tag to each pair of antennas of the multi-antenna base station;

[0048] Subtract the corresponding phase difference zero bias parameter from the received phase difference value of each pair of antennas to obtain the zero bias corrected phase difference value;

[0049] Taking three antennas as a unit group, at least one group of antennas is selected, and the direction angle is calculated according to three pairs of zero-bias corrected phase difference values ​​and corresponding internal angle parameters of the group of antennas.

[0050] Optionally, after calculating the direction angle according to the three pairs of zero-bias corrected phase difference values ​​of the group of antennas and the corresponding internal angle parameters, the method may further include:

[0051] The direction angle is residually compensated according to the direction angle residual parameter of the group of antennas to obtain a corrected direction angle.

[0052] Among them, the residual compensation method can obtain the residual segment corresponding to the direction angle through a table lookup method, and then obtain the residual component corresponding to the direction angle within the segment through a certain weighting coefficient, and then compensate to the method angle.

[0053] The above technical solution of the present invention has at least the following beneficial effects:

[0054] 1) The obtained direction-finding correction parameters are written into the base station firmware as fixed system parameters, which can reduce the influence of several major error sources during real-time direction finding and effectively improve the direction-finding accuracy; 2) The method is basically fully automatic and does not require human intervention in the middle. It is simple and easy to use, and has a self-check function for evaluating parameter availability. The extracted direction-finding correction parameters are highly reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A flowchart of a method for extracting direction finding parameters of a multi-antenna base station provided in Embodiment 1 of the present invention;

[0056] Figure 2 A flowchart of a method for collecting receiving antenna phase difference data of each pair of antennas of a multi-antenna base station at multiple angular positions of a whole circumference of a direction finding plane at equal angular intervals provided in the second embodiment of the present invention;

[0057] Figure 3 A flowchart of another method for extracting direction finding parameters of a multi-antenna base station provided in Embodiment 3 of the present invention;

[0058] Figure 4 A flowchart of a multi-antenna base station direction finding method provided in Embodiment 4 of the present invention;

[0059] Figure 5 This is a flow chart of another multi-antenna base station direction finding method provided in Embodiment 5 of the present invention. DETAILED DESCRIPTION

[0060] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, they will be described in detail below with reference to the accompanying drawings and specific embodiments. The angles involved are all in radians and will not be described in detail below.

[0061] Figure 1 Flow chart of a method for extracting direction finding parameters of a multi-antenna base station provided in Embodiment 1 of the present invention. Figure 1 As shown, the following steps are included:

[0062] S101: D at equal angles θ Collect the receiving phase difference data of each pair of antennas in the multi-antenna base station at N angle positions around the direction finding plane Wherein, the subscripts i and j represent the antenna numbers of the pair, n = 0, D θ ,2D θ ,…,(N-1)D θ Indicates the cumulative rotation angle of the turntable corresponding to the angle position;

[0063] S102: Calculate the phase difference zero bias parameter of each pair of antennas according to the received phase difference data at the N angular positions The phase difference zero bias parameter It is used to correct the influence of fixed delay phase difference caused by non-signal transmission of a pair of antennas on direction finding, and is not affected by the change of direction angle;

[0064] S103: Obtaining zero-bias correction phase difference data at N angle positions after each pair of antennas eliminates the phase difference zero bias Take three antennas as a unit group to calculate the three internal angle parameters A of each group of antennas ijk , B ijk and C ijk , where the subscripts i, j and k represent the antenna numbers of the group, and the internal angle parameter refers to the internal angle of the triangle formed by the distances between the phase centers of the three antennas, which is used to correct the influence of the geometric layout structure of a group of antennas on direction finding;

[0065] S104: Each group of antennas corrects the phase difference data according to the zero bias of the N angular positions and the interior angle parameter A ijk , B ijk , C ijk , calculate the direction angle data θ corresponding to the N angle positions ijk (n);

[0066] S105: Determine the direction angle θ of the N angular positions ijk (n) Whether the monotonicity condition is satisfied; if so, the extraction of the direction finding correction parameters is considered successful; otherwise, the estimation of the direction finding correction parameters is considered to have failed.

[0067] Specifically, calculating the phase difference zero bias parameter of each pair of antennas according to the received phase difference data at the multiple angular positions includes:

[0068] 1) Continuously correct the multiple received phase difference data of each pair of antennas to avoid the angle 2π jump problem:

[0069]

[0070] 2) Calculate the mean of multiple received phase difference data after continuity correction as the phase difference zero bias parameter of the pair of antennas:

[0071]

[0072] Specifically, the internal angle parameters of each group of antennas are calculated using three antennas as a unit group, including:

[0073] 1) Correct the phase difference data of N zero bias of three pairs of antennas in the group and Sine curve fitting is performed respectively, and the fitting formula is: f(n) = a1 × sin(n + a2), where the fitting parameter a1 represents the curve amplitude, which is proportional to the antenna spacing, and the fitting parameter a2 represents the placement deviation angle between the turntable direction angle at the initial position and the direction of the connection line of the pair of antennas;

[0074] 2) The three internal angle parameters of the antenna group are calculated by the fitting parameters a1 of the three pairs of antennas. The calculation formula is:

[0075]

[0076]

[0077]

[0078] Alternatively, the three internal angle parameters are calculated by the fitting parameters a2 of the three pairs of antennas, and the calculation formula is:

[0079]

[0080]

[0081]

[0082] The superscripts i, j, k of the fitting parameters a1 and a2 represent the antenna numbers of the three pairs of antennas in the group.

[0083] In this embodiment, the number of antennas of the multi-antenna base station is at least greater than or equal to 3, and the number of angle positions N collected is recommended to be no less than 20 and a common divisor of 360, so that equal angle intervals can be obtained.

[0084] In this embodiment, the fitting parameter a1 reflects the amplitude of the whole cycle phase difference curve, which should theoretically satisfy the following: a1 = 2πd·co(sβ) / λ, where d is the spacing between the antenna pairs, β is the elevation angle between the incident signal and the antenna ground plane, and λ is the wavelength of the incident signal. Due to the shape and structure of the antenna, d actually needs to consider the distance from the antenna equivalent phase center to the ground; the fitting parameter a2 reflects the placement deviation angle between the turntable direction angle at the initial position caused by the placement during calibration and the direction of the connection between the pair of antennas, reflecting the difference in phase difference between the antenna pairs. For an ideal equilateral triangle array, the a2 between the three pairs of antennas should differ by For an ordinary triangular antenna array, the fitting parameters a1 and a2 reflect the geometric structure of the antenna from the sides and corners respectively, so the information provided is redundant. You can select one of them to calculate the internal angle parameters.

[0085] In this embodiment, there may be many specific methods for calculating the direction angle data corresponding to the N angle positions in step S104, and the present invention is not limited thereto. A common calculation method is given below:

[0086]

[0087] Among them, the direction angle θ ijk (n) is defined as the perpendicular line from antenna i to antenna j and antenna k as the 0 degree reference, and the rotation direction from antenna i to antenna j as the positive; the internal angle parameter A ijk , B ijk and C ijk The angle values ​​corresponding to antennas i, j and k respectively satisfy the triangle interior angle sum principle, that is: A ijk +B ijk +C ijk =π; In addition, it should be noted that the phase difference data of the three pairs of antennas and Requires (-π,π].

[0088] In this embodiment, step S105 determines the direction angle θ of the N angular positions. ijk (n) Before satisfying the monotonicity condition, the direction angle θ of the N angular positions should be ijk (n) Perform continuity correction, and then determine whether the following monotonicity condition is met: If the turntable rotates in the same direction angle θ ijk (n) is defined in the same positive direction, then monotonicity is expressed as θ ijk (0)<θ ijk (D θ )<…<θ ijk ((N-1)D θ); or, if the turntable rotates in the same direction as the angle θ ijk (n) is defined in the opposite direction, then monotonicity is expressed as θ ijk (0)>θ ijk (D θ )>…>θ ijk ((N-1)D θ ).

[0089] Figure 2 A flowchart of a method for collecting receiving antenna phase difference data of each pair of antennas of a multi-antenna base station at multiple angular positions of a whole circumference of a direction finding plane at equal angle intervals provided in the second embodiment of the present invention. Figure 2 As shown, the following steps are included:

[0090] Step S201: placing the multi-antenna base station at the center of the turntable, and making the direction finding plane parallel to the rotation plane of the turntable, placing the transmitting tag at a certain distance from the base station antenna as the LOS diameter, and sending a wireless signal to the multi-antenna base station at a certain frequency;

[0091] Step S202: Record the initial position as 0 degrees, and collect M continuous received phase data from the transmitting tag to each antenna of the multi-antenna base station at the current angle position m=0,1,…,M-1;

[0092] Step S203: Taking two antennas as a unit pair, determine whether the M continuously received phase data collected by each pair of antennas at the current angle position meet the phase stability condition; if so, proceed to step S206; otherwise, proceed to step S204;

[0093] Step S204: Determine whether the acquisition time at the current angle position exceeds the set time threshold T1; if so, proceed to step S205; otherwise, proceed to step S202;

[0094] Step S205: consider that the extraction of direction finding correction parameters has failed, and adjust the position of the transmitting tag and start again.

[0095] Step S206: recording the cumulative rotation angle value of the turntable at the current angle position as a reference direction angle, and calculating the receiving phase difference data of each pair of antennas corresponding to the reference direction angle value;

[0096] Step S207: Then, the turntable is started to rotate in one direction at a certain angle interval, enters the next angle position, and collects the receiving phase difference data of each pair of antennas according to the above steps S202-S206 until the turntable completes a 360-degree rotation of the direction-finding plane. Specifically, the step of judging whether the M continuous receiving phase data collected by each pair of antennas at the current angle position meets the phase stability condition in step S203 can be implemented by one of the following two methods, including:

[0097] Method 1:

[0098] 1) Calculate multiple continuous received phase difference data for each pair of antennas Normalize to (-π,π], and then make continuity correction:

[0099]

[0100] 2) Based on the multiple continuous received phase difference data after continuity correction, calculate the received phase difference variance V of each pair of antennas ij (n,m):

[0101]

[0102] 3) If the received phase difference variance of each pair of antennas is less than a certain threshold, it is considered that the phase stability condition is met; otherwise, it is considered that the phase stability condition is not met.

[0103] Method 2:

[0104] 1) Calculate multiple continuous received phase difference data for each pair of antennas

[0105] 2) Calculate the sine value S of the plurality of received phase difference data ij (n,m) and cosine value C ij (n,m);

[0106] 3) Calculate the square sum parameter U of the mean of the sine value and the mean of the cosine value of the plurality of received phase difference data ij (n,m):

[0107]

[0108] 4) If the square sum parameter of each pair of antennas is greater than a certain threshold, it is considered that the phase stability condition is met; otherwise, it is considered that the phase stability condition is not met.

[0109] Specifically, the calculation of the received phase difference data of each pair of antennas corresponding to the reference direction angle in step S206 corresponds to the determination in step S203 whether the M continuous received phase data collected by each pair of antennas at the current angle position meet the phase stability condition, which can be implemented in one of two ways, including:

[0110] Method 1: Calculate the average of the multiple receiving phase differences after the continuity correction for each pair of antennas as the phase difference data corresponding to the reference direction angle:

[0111]

[0112] Method 2: According to the mean of the sine values ​​and the mean of the cosine values ​​of the plurality of received phase difference data, the phase difference data corresponding to the reference direction angle is obtained by using an inverse tangent function:

[0113]

[0114] In this embodiment, method one adopts the method of directly adding the phase difference angle values ​​to calculate the mean, so it is necessary to perform continuity correction first to avoid the error introduced by the 2π jump problem of the angle; method two adopts the method of calculating the sine value and cosine value of each phase difference angle and adding them to get the mean, and then uses the inverse trigonometric function method to avoid the 2π jump problem, but it will involve more trigonometric function operations.

[0115] Figure 3 This is a flow chart of another method for extracting direction finding parameters of a multi-antenna base station provided in Embodiment 3 of the present invention. Figure 3 As shown, the following steps are included:

[0116] S301: At equal angle intervals D θ Collect the receiving phase difference data of each pair of antennas of the multi-antenna base station at N angle positions around the direction finding plane;

[0117] S302: Calculate the phase difference zero bias parameter of each pair of antennas according to the received phase difference data at the N angular positions, wherein the phase difference zero bias parameter is used to correct the influence of the fixed delay phase difference caused by non-signal transmission of a pair of antennas on direction finding, and is not affected by the change of the direction angle;

[0118] S303: Obtain zero-bias corrected phase difference data of N angle positions after each pair of antennas eliminates the phase difference zero bias, and calculate three internal angle parameters of each group of antennas with three antennas as a unit group, wherein the internal angle parameters refer to the internal angle angles of a triangle formed by the distances between the phase centers of the three antennas, and are used to correct the influence of the geometric layout structure of a group of antennas on direction finding;

[0119] S304: Each group of antennas calculates the directional angle data corresponding to the multiple angular positions according to the zero bias corrected phase difference data of the N angular positions and the internal angle parameters;

[0120] S305: Determine whether the direction angles of the N angular positions meet the monotonicity condition. If so, it is considered that the extraction of direction finding correction parameters is successful, and the process goes to step S306; otherwise, it is considered that the estimation of direction finding correction parameters fails.

[0121] S306: Each group of antennas calculates a directional angle residual parameter of the group of antennas according to the directional angle data corresponding to the N angular positions and the reference directional angle data.

[0122] In this embodiment, the direction finding correction parameters include the azimuth residual parameters of each group of antennas in addition to the phase difference zero bias of each pair of antennas and the internal angle parameters of each group of antennas. The azimuth residual parameters of the method include N×2 data, which are the azimuths of the N angular positions and the difference between the azimuth and the reference azimuth.

[0123] Figure 4 This is a flow chart of a multi-antenna base station direction finding method provided by Embodiment 4 of the present invention. Figure 4 As shown, the following steps are included:

[0124] S401: Obtaining a receiving phase difference value from a transmitting tag to each pair of antennas of a multi-antenna base station;

[0125] S402: Subtract the corresponding phase difference zero bias parameter from the received phase difference value of each pair of antennas to obtain a zero bias corrected phase difference value;

[0126] S403: Taking three antennas as a unit group, at least one group of antennas is selected, and the direction angle is calculated according to three pairs of zero-bias corrected phase difference values ​​and corresponding internal angle parameters of the group of antennas.

[0127] Figure 5 This is a flow chart of another multi-antenna base station direction finding method provided in Embodiment 5 of the present invention. Figure 5 As shown, the following steps are included:

[0128] S501: Obtain a receiving phase difference value from a transmitting tag to each pair of antennas of a multi-antenna base station;

[0129] S502: Subtract the corresponding phase difference zero bias parameter from the received phase difference value of each pair of antennas to obtain a zero bias corrected phase difference value;

[0130] S503: Taking three antennas as a unit group, at least one group of antennas is selected, and the direction angle is calculated according to three pairs of zero-bias corrected phase difference values ​​and corresponding internal angle parameters of the group of antennas;

[0131] S504: Perform residual compensation on the direction angle according to the direction angle residual parameter of the group of antennas to obtain a corrected direction angle.

[0132] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for extracting direction finding correction parameters of a multi-antenna base station, specifically comprising: The receiving phase difference data of each pair of antennas of the multi-antenna base station at multiple angle positions of the whole circumference of the direction finding plane are collected at equal angle intervals; Calculate the phase difference zero bias parameter of each pair of antennas according to the received phase difference data at the multiple angular positions, wherein the phase difference zero bias parameter is used to correct the influence of the fixed delay phase difference caused by the non-signal transmission of a pair of antennas on the direction finding; Obtain zero-bias corrected phase difference data at multiple angle positions after eliminating the phase difference zero bias of each pair of antennas, and calculate the internal angle parameters of each group of antennas with three antennas as a unit group. The internal angle parameters refer to the internal angle angle of a triangle formed by the distances between the phase centers of the three antennas, which are used to correct the influence of the geometric layout structure of a group of antennas on direction finding; Each group of antennas calculates the directional angle data corresponding to the multiple angular positions according to the zero bias corrected phase difference data at the multiple angular positions and the internal angle parameters; Determine whether the direction angles of the multiple angle positions meet the monotonicity condition, and if so, it is considered that the extraction of the direction finding correction parameter is successful; Otherwise, it is considered that the direction finding correction parameter estimation fails.

2. The method according to claim 1, characterized in that The receiving antenna phase difference data of each pair of antennas of a multi-antenna base station at multiple angle positions around the direction finding plane are collected at equal angle intervals, including: The multi-antenna base station is placed at the center of the turntable, and the direction-finding plane is parallel to the rotation plane of the turntable. The transmitting tag is placed at a certain distance from the base station antenna as the LOS diameter, and sends a wireless signal to the multi-antenna base station at a certain frequency; Record the initial position as 0 degrees, and collect multiple continuous reception phase data from the transmitting tag to each antenna of the multi-antenna base station at the current angle position; Taking two antennas as a unit pair, determining whether the plurality of continuously received phase data collected by each pair of antennas at a current angle position meets a phase stability condition; If the phase stability condition is met, the cumulative rotation angle value of the turntable at the current angle position is recorded as the reference direction angle, and the receiving phase difference data of each pair of antennas corresponding to the reference direction angle value is calculated; then, the turntable is started to rotate in one direction at a certain angle interval to enter the next angle position, and the receiving phase difference data of each pair of antennas is collected according to the steps of the previous angle position until the turntable completes a 360-degree rotation of the direction-finding plane; if the phase stability condition is not met, the receiving phase data of each antenna at this angle position is continued to be collected; If multiple consecutive received phase data of at least one pair of antennas do not meet the phase stability condition within a certain time threshold of the current angle position, it is considered that the extraction of the direction finding correction parameters has failed, and the transmitting tag position is adjusted to start again.

3. The method according to claim 1, characterized in that Calculating the phase difference zero bias parameter of each pair of antennas according to the received phase difference data at the multiple angular positions includes: Continuously correcting multiple receiving phase difference data of each pair of antennas; The average of the multiple received phase difference data after continuity correction is calculated as the phase difference zero bias parameter of the pair of antennas.

4. The method according to claim 2, characterized in that: The internal angle parameters of each group of antennas are calculated using three antennas as a unit group, including: Sine curve fitting is performed on multiple receiving phase difference data of the three pairs of antennas in the group. The fitting formula is: f(n) = a1×sin(n+a2), where the fitting parameter a1 represents the curve amplitude, which is proportional to the antenna spacing, the fitting parameter a2 represents the placement deviation angle between the turntable direction angle at the initial position and the direction of the connection line of the pair of antennas, and the parameter n represents the placement deviation angle at equal angle intervals D θ When collecting the received phase difference data of each pair of antennas of the multi-antenna base station at N angle positions in the whole circumference of the direction finding plane, the cumulative rotation angle of the turntable corresponding to the angle position, n = 0, D θ ,2D θ ,…,(N-1)D θ ; The three internal angle parameters of the antenna group are calculated by the fitting parameter a1, and the calculation formula is: Alternatively, the three interior angle parameters are calculated by the fitting parameter a2, and the calculation formula is: The superscripts i, j, k of the parameters a1 and a2 represent the antenna numbers of the three pairs of antennas in the group.

5. The method according to claim 2, characterized in that: After the direction finding correction parameters are extracted successfully, it also includes: Each group of antennas calculates a difference between the azimuth data corresponding to the multiple angular positions and the reference azimuth data as the azimuth residual parameter of the group of antennas.

6. The method according to claim 2, characterized in that Determining whether the plurality of continuously received phase data collected by each pair of antennas at the current angle position meets a phase stability condition includes: Calculate multiple continuous receiving phase difference data of each pair of antennas, normalize to (-π,π], and then perform continuity correction; Calculate the receiving phase difference variance of each pair of antennas according to the multiple continuous receiving phase difference data after continuity correction; If the received phase difference variance of each pair of antennas is less than a certain threshold, it is considered that the phase stability condition is met; otherwise, it is considered that the phase stability condition is not met; or, Calculate a plurality of continuous received phase difference data of each pair of antennas; Calculating sine values ​​and cosine values ​​of the plurality of received phase difference data; Calculate the square sum parameter of the mean of the sine value and the mean of the cosine value of the plurality of received phase difference data; If the square sum parameter of each pair of antennas is greater than a certain threshold, it is considered that the phase stability condition is met; otherwise, it is considered that the phase stability condition is not met.

7. The method according to claim 2, characterized in that Calculating the receiving phase difference data of each pair of antennas corresponding to the reference direction angle, including: Continuously correcting multiple receiving phase difference data of each pair of antennas; Calculate the average of the plurality of receiving phase differences after the continuity correction for each pair of antennas as the phase difference data corresponding to the reference direction angle; or, According to the average of the sine values ​​and the average of the cosine values ​​of the plurality of received phase difference data, the phase difference data corresponding to the reference direction angle is obtained by using an inverse tangent function.

8. A multi-antenna base station direction finding method according to the multi-antenna base station direction finding correction parameter extraction method according to claim 1, specifically comprising: Obtain the receiving phase difference value from the transmitting tag to each pair of antennas of the multi-antenna base station; Subtract the corresponding phase difference zero bias parameter from the received phase difference value of each pair of antennas to obtain the zero bias corrected phase difference value; Taking three antennas as a unit group, at least one group of antennas is selected, and the direction angle is calculated according to three pairs of zero-bias corrected phase difference values ​​and corresponding internal angle parameters of the group of antennas.

9. The method according to claim 8, characterized in that After calculating the direction angle according to the three pairs of receiving phase differences of the antenna group and the corresponding internal angle parameters, it also includes: The direction angle is residually compensated according to the direction angle residual parameter of the group of antennas to obtain a corrected direction angle.

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