CN117254261A - Ultra-wideband direction-finding positioning array antenna suitable for long and narrow space and positioning method thereof - Google Patents
Ultra-wideband direction-finding positioning array antenna suitable for long and narrow space and positioning method thereof Download PDFInfo
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Abstract
The invention provides an ultra-wideband direction-finding positioning array antenna suitable for a long and narrow space and a positioning method thereof, and relates to the field of navigation positioning and communication. The array antenna comprises 9 antenna array elements which are arranged on a horizontal line and a vertical line which are vertically intersected, wherein the horizontal line is positioned in a horizontal plane, the vertical line is perpendicular to the horizontal plane, and the horizontal line and the vertical line are divided into four branches by an intersection point; among the 9 antenna elements, one antenna element is located on the intersection point, the other 8 antenna elements are divided into two groups, the 4 antenna elements of the first group are respectively located on the four branches, the distance between the first group and the intersection point is half wavelength, and the 4 antenna elements of the second group are respectively located on the four branches, and the distance between the second group and the intersection point is greater than half wavelength. The array antenna adopts a combination form of long and short base lines to adapt to the three-dimensional position direction finding and positioning requirements in long and narrow space, can provide more receiving and transmitting signal paths, and improves the accuracy of angle measurement.
Description
Technical Field
The invention relates to the field of navigation positioning and communication, in particular to an ultra-wideband direction-finding positioning array antenna suitable for long and narrow space and a positioning method thereof.
Background
The UWB direction finding system based on interferometer system has the principle that on the premise that the distance between a target and an array is far greater than the array scale, the incoming wave directions of each array element are approximately parallel, the corresponding phase difference is obtained by measuring the phase difference of the two array elements and combining the signal frequency, and the incident angle is obtained according to the relationship among the phase difference, the array element distance, the signal frequency and the incident angle.
For phase interferometer angle measurement, the angle of arrival is relative to phase
Is obtained by full differentiation
It can be seen that from the equation, factors affecting angular accuracy include wavelength errors and baseline errors, and analysis of the equation can lead to the following conclusion:
(1) The measurement angle error is inversely proportional to the base line length d, and the longer the base line, the smaller the error of the measurement angle, but the base line cannot be infinitely increased due to the limitation of the base line arrangement condition in real engineering.
(2) The measurement angle error is inversely proportional to the cos θ value, the greater the cos θ value, the higher the measurement accuracy, and when cos θ=1, (θ=0°), the measurement accuracy is the highest, and when cos θ=0 (θ=90°), the error is infinite, and the direction cannot be measured.
When the method of combining long and short baselines is adopted, the distance between the targets and the length of the baselines do not satisfy the relation far greater, so the incoming wave directions among the array elements are not approximately parallel, namely, the interferometer angle measurement method under the near field is adopted, the distances between the targets and the different baselines are required to be measured respectively, and then the angle calculation is carried out by adopting a triangular formula.
Due to the nature of the underground elongated space, there are problems with current uniform circular arrays, rectangular arrays, linear arrays for angle measurement in this scenario:
(1) In terms of environmental adaptability, the uniform circular array, the linear array and the rectangular array are relatively sensitive to environmental changes, such as temperature, humidity, noise and the like, and these factors can influence the electrical parameters of the antenna elements and the transmission characteristics of signals, so that the accuracy and the stability of angle measurement are affected. The design of the unit cross/font array can be favorable for a low coupling effect coupling error elimination algorithm of the far-end array element, and the phase mode excitation of the antenna element can be adaptively adjusted, so that the robustness and the reliability of angle measurement are improved.
(2) In terms of system complexity, uniform circular arrays, linear arrays and rectangular arrays all require more hardware and software resources to control antenna elements and process signals, which increases the cost and power consumption of the system and may cause delays and failures of the system. The design of the cross/font array provided by the patent can utilize the characteristic of combination of long and short base lines, so that the number of antenna elements and the number of signal channels are reduced, and the complexity and the cost of the system are reduced.
(3) In the aspect of application scenes, the uniform circular array, the linear array and the rectangular array are suitable for angle measurement of open space or far field sources, such as radar, satellite communication, wireless positioning and the like. The design unit cross/font array can utilize a near field source DOA estimation method to realize angle measurement of a near field source or an underground space source, such as seismic monitoring, underground detection, tunnel navigation and the like. In addition, the antenna pointing angle adjusting module which is designed aiming at the space with different scales is used for adjusting the beam pointing, so that the cross/font array provided by the patent is more flexible.
Disclosure of Invention
In view of the above, the present invention provides an ultra wideband direction-finding positioning array antenna and a positioning method thereof suitable for a long and narrow space. The invention can complete target positioning in the high-precision angle measurement area set distance measurement, and jointly realize space partition high-precision positioning in the area with larger distance measurement angle measurement positioning error by adopting a TDOA positioning mode.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
an ultra-wideband direction-finding positioning array antenna suitable for a long and narrow space comprises 9 antenna array elements which are arranged on a horizontal line and a vertical line which are vertically intersected, wherein the horizontal line is positioned in a horizontal plane, the vertical line is perpendicular to the horizontal plane, and the horizontal line and the vertical line are divided into four branches by an intersection point; one antenna element is positioned on the intersection point, the other 8 antenna elements are divided into two groups, the 4 antenna elements of the first group are respectively positioned on four branches, the distance between the first group and the intersection point is half-wavelength, namely 0.5λ, the 4 antenna elements of the second group are respectively positioned on the four branches, and the distance between the second group and the intersection point is d, and d is more than 0.5λ; the value of d is determined by:
step 1, setting an initial value of d to be an arbitrary value larger than 0.5λ;
step 2, setting an incident angle, measuring the phase difference delta phi according to an interferometer angle measurement method, and measuring the amplitude A, B reaching two opposite antennas in the second group according to a receiving signal of a receiver;
step 3, taking the initial value of d as an iteration initial value, and carrying out iterative calculation by using the following formula:
wherein A and B are constants, lambda is wavelength, delta phi is phase difference, n is iteration number, d n Is the value of the nth iteration; lambda (lambda) 1 Is a lagrange multiplier, satisfying the following formula:
and 5, when the iteration value is stable, obtaining a value which is the finally determined d value.
The incident angle correction method based on the ultra-wideband direction-finding positioning array antenna comprises the following steps:
(1) The method comprises the steps that a first group of 4 near-end antenna array elements and a second group of 4 far-end antenna array elements simultaneously receive signals from a near-field source, and the phase difference and the initial arrival angle of the signals are measured by using the first group of 4 near-end antenna array elements;
(2) Calculating uncoupled signal parameters of the first group of antenna elements according to the arrival angle and the distance from the first group of antenna elements and the second group of antenna elements to the intersection point;
(3) The real phase of each array element is measured, and a phase coupling matrix C= [ C ] is constructed according to the coupling effect among the array elements mn ] M×N Wherein m=n=9, the diagonal elements of c are all 1, and the other elements of c satisfy c mn ＝c nm The method is obtained by the following operation:
wherein,for coupling the actually measured phase values of the array elements, < >>Is the phase of the uncoupled array element, f is the frequency, d n,m Is the distance between the array element n and the array element m;
(4) Transpose the phase coupling matrix C to obtain a coupling coefficient matrixUsing a coupling coefficient matrix->Compensating the phase of the received signal of the main array element:
wherein x is m For the phase parameter of the original measured signal, y n For the uncoupled received signal phase derived from the uncoupled signal phase parameter,representation->The element of the m-th row and n-th column;
(5) Using compensated signalsThe interferometer angle estimation method under the near field is adopted again, so that a more accurate estimation value of the arrival angle of the signal source is obtained;
(6) And (2) repeating the steps (2-5) and iterating the phase difference and the arrival angle between the array elements until the estimated value converges or the maximum iteration number is reached, so as to obtain an accurate angle value for eliminating the coupling error.
An ultra-wideband direction-finding positioning array antenna suitable for a long and narrow space comprises 7 antenna array elements which are arranged on a horizontal line and a vertical line which are vertically intersected, wherein the horizontal line is positioned in a horizontal plane, the vertical line is perpendicular to the horizontal plane, the horizontal line and the vertical line are divided into two horizontal branches and one branch above the horizontal plane by an intersection point, and three branches are formed; among the 7 antenna elements, one antenna element is positioned on the intersection point, the other 6 antenna elements are divided into two groups, the 3 antenna elements of the first group are respectively positioned on three branches, the distance between the 3 antenna elements of the first group and the intersection point is half-wavelength, namely 0.5λ, the 3 antenna elements of the second group are respectively positioned on the three branches, and the distance between the 3 antenna elements of the second group and the intersection point is d, and d is more than 0.5λ; the value of d is determined by:
step 1, setting an initial value of d to be an arbitrary value larger than 0.5λ;
step 2, setting an incident angle, measuring the phase difference delta phi according to an interferometer angle measurement method, and measuring the amplitude A, B reaching two opposite antennas in the second group according to a receiving signal of a receiver;
step 3, taking the initial value of d as an iteration initial value, and carrying out iterative calculation by using the following formula:
wherein A and B are constants, lambda is wavelength, delta phi is phase difference, n is iteration number, d n Is the value of the nth iteration; lambda (lambda) 1 Is a lagrange multiplier, satisfying the following formula:
and 5, when the iteration value is stable, obtaining a value which is the finally determined d value.
The incident angle correction method based on the ultra-wideband direction-finding positioning array antenna comprises the following steps:
(1) The method comprises the steps that a first group of 3 near-end antenna array elements and a second group of 3 far-end antenna array elements simultaneously receive signals from a near-field source, and the phase difference and the initial arrival angle of the signals are measured by using the first group of 3 near-end antenna array elements;
(2) Calculating uncoupled signal parameters of the first group of antenna elements according to the arrival angle and the distance from the first group of antenna elements and the second group of antenna elements to the intersection point;
(3) The real phase of each array element is measured, and a phase coupling matrix C= [ C ] is constructed according to the coupling effect among the array elements mn ] M×N Wherein m=n=7, the diagonal elements of c are all 1, and the other elements of c satisfy c mn ＝c nm The method is obtained by the following operation:
wherein,for coupling the actually measured phase values of the array elements, < >>Is the phase of the uncoupled array element, f is the frequency, d n,m Is the distance between the array element n and the array element m;
(4) Transpose the phase coupling matrix C to obtain a coupling coefficient matrixUsing a coupling coefficient matrix->Compensating the phase of the received signal of the main array element:
wherein x is m For the phase parameter of the original measured signal, y n For the uncoupled received signal phase derived from the uncoupled signal phase parameter,representation->The element of the m-th row and n-th column;
(5) Using compensated signalsThe interferometer angle estimation method under the near field is adopted again, so that a more accurate estimation value of the arrival angle of the signal source is obtained;
(6) And (2) repeating the steps (2-5) and iterating the phase difference and the arrival angle between the array elements until the estimated value converges or the maximum iteration number is reached, so as to obtain an accurate angle value for eliminating the coupling error.
Compared with the background technology, the invention has the following advantages:
(1) The cross/font array designed by the invention has stronger environmental adaptability on one hand, can be favorable for a low coupling effect coupling error elimination algorithm of a far-end array element, and can adaptively adjust the phase mode excitation of the antenna element; on the other hand, the number of array elements is reduced by combining long and short baselines, so that the complexity is reduced; finally, aiming at the structural characteristics of the long and narrow space, a special array configuration is innovatively designed, and the problem of low array element utilization rate of the existing array configuration in the long and narrow space is solved.
(2) The invention provides a space partition high-precision positioning method based on a cross/font array, wherein a cross/font antenna structure is deployed in a long and narrow space or a limited space, an antenna pointing angle adjusting mechanism is designed for adjusting beam pointing aiming at spaces with different scales, so that the high-precision angle measurement area is maximized in the space, the target positioning is completed in a high-precision angle measurement area in combination with distance measurement, and the space partition high-precision positioning is realized in a TDOA positioning mode in a region with larger distance measurement angle measurement positioning error.
Drawings
FIG. 1 is a schematic diagram of a cross-shaped array in accordance with an embodiment of the present invention.
FIG. 2 is a schematic diagram of a font array according to an embodiment of the present invention.
Fig. 3 is a flow chart of the incidence angle feedback correction of the far-end element low coupling effect for coupling error cancellation of the present invention.
FIG. 4 is a block diagram of a partition locating process according to the present invention.
Fig. 5 is a diagram of simulation results of angular ranging positioning coverage.
FIG. 6 is a plot of the results of a partition positioning simulation.
Detailed Description
The invention is further described below with reference to the drawings and detailed description.
The ultra-wideband direction-finding positioning array antenna suitable for long and narrow space adopts special antenna array design, and comprises N antenna array elements which are distributed in a cross shape or a square shape, and adopts a long and short base line combined form to adapt to the three-dimensional position direction-finding positioning requirement in long and narrow space. This anamorphic configuration can provide more receive and transmit signal paths, while combining long baselines for high direction finding accuracy with short baselines for disambiguation, to improve angular accuracy. Second, the baseline length difference of the cross/zig-zag arrangement in two perpendicular directions can be used to increase the direction-finding accuracy of azimuth and pitch angles, respectively, as it increases the testability of the arrival phase differences of the measurement signals in horizontal and perpendicular directions. In addition, the situation that the traditional equal-baseline array antenna receives serious array element coupling is considered in the antenna design, and the long and short baseline length is designed according to the problem, so that the effect of reducing coupling errors is achieved. Finally, the cross/font antenna structure is deployed in a long and narrow space or a limited space, and an antenna pointing angle adjusting module is designed for adjusting beam pointing aiming at spaces with different scales, so that the high-precision angle measurement area is maximized in the space.
In order to realize the array antenna, firstly, the arrangement of array elements with long and short baselines on a cross/I-shaped antenna frame is determined, and then the length of the long baselines is determined according to two limiting conditions of sensitivity and sight range. And then, according to the scale of the field space and the position of the array arrangement, determining the array element beam pointing when the maximum angular coverage is reached under the beam width. In the case where the array is arranged on a side wall or a central top in an elongated space, the array is arranged on the wall with the bottom side of the array being parallel to the wall, and the central top being arranged in both cases, for ease of installation. The received signals of the array elements are then compensated using an angle of incidence feedback correction method based on the low coupling effect of the remote array elements. Finally, the positioning of the angle measurement combined ranging is carried out on each position, and the following method is adopted at the position (the position outside the beam width) with large angle measurement and positioning error: each array element on the antenna is regarded as a different base station, and the positioning is performed by using a TDOA (time difference of arrival) method, so that the positioning accuracy is higher than that of angle measurement and ranging positioning. The method divides the area into two parts, and adopts different positioning algorithms according to different positions to realize the high-precision positioning of the subareas.
The specific mode of carrying out partition positioning by adopting the array antenna array is as follows:
(1) Firstly, designing a cross/font array, adopting a directional antenna with a certain beam width, and selecting in two array configurations according to different mounting positions;
(2) According to the specific spatial dimensions of different scenes and the positions of array arrangement, determining the array element beam direction when the maximum angle coverage is reached under the beam width;
(3) Compensating the received signals of the array elements by using an incidence angle feedback correction method based on the low coupling effect of the far-end array elements;
(4) And finally, carrying out angle measurement and ranging combined positioning on each position, dividing the region into two parts, and respectively adopting an angle measurement and ranging combined positioning algorithm and a TDOA positioning algorithm according to different positions to realize partition high-precision positioning.
The following are more specific examples:
1. the cross-shaped and font-shaped array structure is shown in fig. 1 and 2:
1) Taking a cross array structure as an example, long baseline array elements A, B, C, D are distributed at four ends, short baseline array elements a, b, c, d are distributed at positions close to cross intersections, and array elements at the center of the array are O.
2) The baseline length determination method comprises the following steps: the design of the short baseline can adopt the common half wavelength of the array design, and the long baseline design needs to be designed in length, and the length of the long baseline is limited by the view angle range (angle measurement range) and the signal sensitivity according to the research, and the influence of the two factors is discussed below.
(1) Viewing angle range
Assume that there are two antennas located at the origin O and point a, respectively, with a distance between them of baseline length b. We want to measure a remote source S, which is at an angle θ to OA. Since the signal source S is far from the antenna, we can consider the signal it emits as a plane wave. The phase difference of the signals received by antennas O and a then depends on their relative position with respect to the signal source. Can be expressed by the following formula:
where λ is the wavelength of the signal, r 2 And r 1 Is the distance of antennas a and O from signal source S. Due to r 2 And r 1 All are large and their difference can be calculated approximately using the cosine law:
r 2 -r 1 ＝dcosθ
if it is desired to measure the viewing angle θ from the phase difference, a blur problem needs to be solved because the phase difference is periodic, i.e., Δφ+2nφ and Δφ correspond to the same viewing angle, where n is any integer. To solve this problem, it is necessary to limit the viewing angle range to one period, i.e., -pi < ΔΦ < pi. Then, the relationship between the viewing angle range and the base line length is:
(2) Signal sensitivity
Signal sensitivity refers to the minimum signal strength that an antenna can receive, which is related to the signal-to-noise ratio (SNR). SNR refers to the ratio of signal strength to noise strength, which reflects the quality of the signal. In general, the higher the SNR, the higher the signal sensitivity.
The signal strength is related to the distance and direction of the signal source, which follows the inverse ratio law, namely:
where P is the signal strength and r is the distance of the signal source from the antenna. Since the source is assumed to be far from the antenna, r can be considered a constant. Then the signal strength depends only on the direction of the signal source.
The direction of the signal source may be represented by a viewing angle θ, which is the angle of the signal source from the baseline. Since there are two antennas, θ can be measured using the phase difference between them. The relationship between phase difference and baseline length d is known as:
where λ is the wavelength of the signal. To simplify the problem, it is assumed that the phase difference is known and within one period, i.e. -pi < ΔΦ < pi. Then, θ can be found as:
since the signal strength is related to θ, it can be represented by a function f (θ). The specific form of this function depends on the radiation pattern of the antenna, i.e. the degree of response of the antenna to signals in different directions. One common radiation pattern is the cosine function, namely:
f(θ)＝Acosθ
wherein a is a constant. This radiation pattern means that the antenna is most sensitive to signals directly in front (θ=0) and not to signals on the side (θ= ±2pi). Of course, this is only an idealized case, and in practice the antenna may have a more complex radiation pattern. If the signal strength is represented by such a radiation pattern, then f (θ) can be substituted for θ to yield:
this is the relationship between signal strength and baseline length d and phase difference Δφ. The noise strength is related to an environmental factor, which is typically a random variable. It can be represented by a function g (d). The specific form of this function depends on the noise source and characteristics. One possible assumption is that the noise strength is proportional to the baseline length, i.e.:
g(d)＝Bd
wherein B is a constant. This assumption means that the longer the baseline length, the greater the noise disturbance. Of course, this is simply a simplified case, and in practice, noise may have more complex distributions and dependencies.
If the noise strength is expressed by this assumption, the SNR can be obtained as:
this is the relationship between SNR and baseline length d and phase difference Δφ.
Signal sensitivity refers to the minimum signal strength that an antenna can receive, which has a threshold relationship with SNR, namely:
P>P min ＝g(d)SNR min
wherein P is min Is the signal sensitivity, SNR min Is the minimum acceptable SNR. Substituting the above formula, the relationship between the signal sensitivity and the baseline length d and the phase difference ΔΦ can be obtained:
the selection of the baseline length can be regarded as an optimization problem by deriving a baseline length formula under the influence of signal sensitivity, a view angle range and a disambiguation difficulty according to an optimization theory, namely, an objective function is maximized or minimized under the condition that a certain constraint condition is met. In this problem, it can be assumed that the objective function is the signal sensitivity P min The constraint is the view angle range and the blur difficulty. This problem can be expressed by the following formula:
where d is the baseline length, λ is the wavelength of the signal, and θ is the viewing angle. The relationship between signal sensitivity and baseline length d and phase difference Δφ is known as:
wherein A and B are constants, SNR min Is the minimum acceptable SNR. To simplify the problem, it is assumed that the phase difference is known and within one period, i.e. -pi<Δφ<π。
To solve this optimization problem, the Lagrangian multiplier method, which is a commonly used method to deal with optimization problems with constraints, can be used. The basic idea is to construct a Lagrangian function that contains an objective function and constraints, and to introduce Lagrangian multipliers that represent the effect of the constraints on the objective function. Then, the extreme points of the Lagrangian function are solved, which are the optimal solutions for the original problem.
In this problem, the lagrangian function can be constructed as follows:
wherein lambda is 1 And lambda (lambda) 2 Is the lagrange multiplier. Lambda (lambda) 1 ,λ 2 Is a parameter used for representing the influence degree of constraint conditions on an objective function, lambda 1 Coefficient, lambda, representing the extent to which the view range constraint affects the target 2 The specific numerical value of the Lagrangian multiplier is determined by a numerical optimization algorithm and does not need to be set manually. These multipliers are part of the solution of the optimization problem, and there will be solutions of the corresponding lagrangian multipliers while obtaining the optimal solution d if the constraint is satisfied.
In order to solve the extreme points of the Lagrangian function, it is necessary to apply it to the values d, λ 1 And lambda (lambda) 2 The partial derivatives are calculated and made equal to zero. Thus, the following system of equations can be obtained:
can be simplified and obtained
This is a term for d and lambda 1 Can be solved numericallyIt is, for example, newton's method. The basic idea of newton's method is to start with an initial value and to use the derivative of the function to gradually approximate the root of the equation. In order to use newton's method, it is necessary to know the first derivative of the function, namely:
the value of d can then be solved for using the following iterative formula:
where n is the number of iterations and dn is the value of the nth iteration. When dn converges to a stable value, the root of the equation, the optimal value of the baseline length.
The short baseline length is finally determined to be half-wavelength 0.5λ and the long baseline length is 5λ, and ac=bd=5λ, ao=bo=co=do=0.5λ is set for the purpose of reducing the array size.
The incident angle feedback correction method based on the array antenna, as shown in fig. 3, comprises the following steps:
(1) As shown in fig. 1, a, b, c, d is four uncoupled array elements, A, B, C, D is four uncoupled array elements, and it is assumed that there is a cross antenna array consisting of M uncoupled array elements and N uncoupled remote array elements, and signals from a near field source are received, and the phase difference and angle of arrival are measured using the M uncoupled array elements.
(2) The N remote array elements are used to receive the signal, and are considered to have no coupling effect because they are far enough apart from the nearest array element.
(3) And calculating the uncoupled signal phase parameter of the coupled array element according to the initial calculated angle and the baseline length between the remote array element and the coupled array element.
(4) The relation between the actual received signal of the coupled array element and the phase parameter of the uncoupled signal, the array element distance of the array antenna is d, and the coupling effect among the array elements is considered, and the phase of the signal received by the m-th array element is as follows:
wherein,for the true phase of the m th array element, +.>The phase of the m-th element after being influenced by coupling can be expressed as the coupling coefficient c of the m-1-th element to the m-th element because the phase is influenced by two adjacent elements to the greatest extent m-1,m Multiplying the m-1 th element phase +.>The m+1th element affects the same.
The far-end array element has no coupling influence (the influence is the smallest), so the uncoupled phase expression of the mth array element can be obtained by a plurality of far-end array elements, under the ideal condition of no coupling, the signal propagates at the speed of light c, and when the propagation distance increases d 1 When the signal is shifted in phaseThe distance from the mth array element to the reference point (such as a certain far-end array element) in the linear array is d 1 Then the signal propagates from the signal source to the mth array element and d is greater than the far-end array element 1 Propagation distance of sin theta, phase shift generated according to distance increment is +.>Obtaining a phase coupling matrix as C= [ C ] according to the derived uncoupled phase and the received signal expression under the condition that the measured phase can obtain uncoupled phase mn ] M×N According to the far-end array element, the coupling-free phase of the m array elements is deduced, and according to the symmetry of the array elements, the conversion relation between the coupling coefficients can be obtained, and C in the coupling matrix C mn Carry-over formulaAnd (5) solving.
(5) Using the determined coupling coefficient matrixCompensating the phase of the received signal of the main matrix element, i.e.
Wherein x is m For the phase parameter of the original measured signal, y n Is the uncoupled received signal phase derived from the uncoupled signal phase parameter.
(6) Using compensated signal phaseAnd the interferometer angle estimation method under the near field is adopted again to obtain more accurate estimation values of the azimuth angle and the distance parameters of the signal source.
(7) Repeating the steps 3-6 until the estimated value converges or the maximum iteration number is reached.
The partition positioning flow chart is shown in fig. 4, the coverage range of angle measurement and distance measurement positioning is shown in fig. 5, the partition positioning simulation result chart is shown in fig. 6, and the partition positioning method comprises the following steps:
(1) The simulation generates a long and narrow space, taking the following dimensions as examples: it is 50m long, 5m wide and 4m high, and the base station position is set at the red spot position as in fig. 5, coordinates (0, -2.5,3). The beam width is 60 degrees, and the array elements are initially directed parallel to the ground and the wall;
(2) Setting the directional deflection angles alpha of array elements from 0 to 90 degrees, and carrying out angle measurement and distance measurement simulation on each point on a space plane under each deflection angle;
(3) If the relative angle of the position can fall in the beam width under the condition of considering the deflection angle, the angle measurement precision is high, and the positioning error does not exceed the threshold after the positioning is performed by combining the ranging, the position can be covered by the ranging and angle measurement positioning method, and the reflection is the TDOA positioning coverage area;
(4) And comparing coverage rates under all deflection angles, wherein the deflection angle with the highest coverage rate is the optimal deflection angle, the corresponding coverage rate is a ranging angle measurement positioning coverage area, and the rest is a TDOA positioning coverage area.
The array antenna provided by the invention adopts a form of combining a long base line and a short base line so as to adapt to the three-dimensional position direction finding and positioning requirements in a long and narrow space. This anamorphic configuration can provide more receive and transmit signal paths, while combining long baselines for high direction finding accuracy with short baselines for disambiguation, to improve angular accuracy. The cross/zig-zag arrangement is also advantageous in that its baseline length difference in two perpendicular directions can be used to increase the direction-finding accuracy of azimuth and pitch angles, respectively, as it increases the testability of the arrival phase differences of the measurement signals in the horizontal and vertical directions. In addition, the length relation of the long and short baselines is calculated according to the limitations of sensitivity and sight line range in the antenna design, and the complete antenna structure and array design are formed. The situation that the traditional equal-baseline array antenna receives serious coupling of array elements is considered in the antenna design, the long and short baseline length is designed according to the problem, and the coupling error of the whole antenna is corrected by adopting the array elements with no coupling error at the far end, so that the antenna has the effect of reducing the coupling error.
In a word, the cross/font antenna structure of the invention can be deployed in a long and narrow space or a limited space, and an antenna pointing angle adjusting mechanism is designed for adjusting beam pointing aiming at spaces with different scales, so that the high-precision angle measurement area is maximized in the space, the target positioning is completed by collecting ranging in the high-precision angle measurement area, and the space partition high-precision positioning is jointly realized by adopting a TDOA positioning mode in the area with larger ranging angle measurement positioning error.
Claims (4)
1. The ultra-wideband direction-finding positioning array antenna suitable for the long and narrow space is characterized by comprising 9 antenna array elements which are arranged on a horizontal line and a vertical line which are vertically intersected, wherein the horizontal line is positioned in a horizontal plane, the vertical line is perpendicular to the horizontal plane, and the horizontal line and the vertical line are divided into four branches by intersection points; one antenna element is positioned on the intersection point, the other 8 antenna elements are divided into two groups, the 4 antenna elements of the first group are respectively positioned on four branches, the distance between the first group and the intersection point is half-wavelength, namely 0.5λ, the 4 antenna elements of the second group are respectively positioned on the four branches, and the distance between the second group and the intersection point is d, and d is more than 0.5λ; the value of d is determined by:
step 1, setting an initial value of d to be an arbitrary value larger than 0.5λ;
step 2, setting an incident angle, measuring the phase difference delta phi according to an interferometer angle measurement method, and measuring the amplitude A, B reaching two opposite antennas in the second group according to a receiving signal of a receiver;
step 3, taking the initial value of d as an iteration initial value, and carrying out iterative calculation by using the following formula:
wherein A and B are constants, lambda is wavelength, delta phi is phase difference, n is iteration number, d n Is the value of the nth iteration; lambda (lambda) 1 Is a lagrange multiplier, satisfying the following formula:
and 5, when the iteration value is stable, obtaining a value which is the finally determined d value.
2. The method for correcting the incident angle based on the ultra-wideband direction-finding positioning array antenna according to claim 1, comprising the following steps:
(1) The method comprises the steps that a first group of 4 near-end antenna array elements and a second group of 4 far-end antenna array elements simultaneously receive signals from a near-field source, and the phase difference and the initial arrival angle of the signals are measured by using the first group of 4 near-end antenna array elements;
(2) Calculating uncoupled signal parameters of the first group of antenna elements according to the arrival angle and the distance from the first group of antenna elements and the second group of antenna elements to the intersection point;
(3) The real phase of each array element is measured, and a phase coupling matrix C= [ C ] is constructed according to the coupling effect among the array elements mn ] M×N Wherein m=n=9, the diagonal elements of c are all 1, and the other elements of c satisfy c mn ＝c nm The method is obtained by the following operation:
wherein,for coupling the actually measured phase values of the array elements, < >>Is the phase of the uncoupled array element, f is the frequency, d n,m Is the distance between the array element n and the array element m;
(4) Transpose the phase coupling matrix C to obtain a coupling coefficient matrixUsing a coupling coefficient matrix->Compensating the phase of the received signal of the main array element:
wherein x is m For the phase parameter of the original measured signal, y n For the uncoupled received signal phase derived from the uncoupled signal phase parameter,representation->The element of the m-th row and n-th column;
(5) Using compensated signalsThe interferometer angle estimation method under the near field is adopted again, so that a more accurate estimation value of the arrival angle of the signal source is obtained;
(6) And (2) repeating the steps (2-5) and iterating the phase difference and the arrival angle between the array elements until the estimated value converges or the maximum iteration number is reached, so as to obtain an accurate angle value for eliminating the coupling error.
3. The ultra-wideband direction-finding positioning array antenna suitable for the long and narrow space is characterized by comprising 7 antenna array elements which are arranged on a horizontal line and a vertical line which are vertically intersected, wherein the horizontal line is positioned in a horizontal plane, the vertical line is perpendicular to the horizontal plane, the horizontal line and the vertical line are divided into two horizontal branches and one branch above the horizontal plane by an intersection point, and the three branches are all arranged; among the 7 antenna elements, one antenna element is positioned on the intersection point, the other 6 antenna elements are divided into two groups, the 3 antenna elements of the first group are respectively positioned on three branches, the distance between the 3 antenna elements of the first group and the intersection point is half-wavelength, namely 0.5λ, the 3 antenna elements of the second group are respectively positioned on the three branches, and the distance between the 3 antenna elements of the second group and the intersection point is d, and d is more than 0.5λ; the value of d is determined by:
step 1, setting an initial value of d to be an arbitrary value larger than 0.5λ;
step 2, setting an incident angle, measuring the phase difference delta phi according to an interferometer angle measurement method, and measuring the amplitude A, B reaching two opposite antennas in the second group according to a receiving signal of a receiver;
step 3, taking the initial value of d as an iteration initial value, and carrying out iterative calculation by using the following formula:
wherein A and B are constants, lambda is wavelength, delta phi is phase difference, n is iteration number, d n Is the value of the nth iteration; lambda (lambda) 1 Is a lagrange multiplier, satisfying the following formula:
and 5, when the iteration value is stable, obtaining a value which is the finally determined d value.
4. A method for correcting an incident angle based on an ultra wideband direction finding positioning array antenna as claimed in claim 3, comprising the steps of:
(1) The method comprises the steps that a first group of 3 near-end antenna array elements and a second group of 3 far-end antenna array elements simultaneously receive signals from a near-field source, and the phase difference and the initial arrival angle of the signals are measured by using the first group of 3 near-end antenna array elements;
(2) Calculating uncoupled signal parameters of the first group of antenna elements according to the arrival angle and the distance from the first group of antenna elements and the second group of antenna elements to the intersection point;
(3) The real phase of each array element is measured, and a phase coupling matrix C= [ C ] is constructed according to the coupling effect among the array elements mn ] M×N Wherein m=n=7, the diagonal elements of c are all 1, and the other elements of c satisfy c mn ＝c nm The method is obtained by the following operation:
wherein,for coupling the actually measured phase values of the array elements, < >>Is the phase of the uncoupled array element, f is the frequency, d n,m Is the distance between the array element n and the array element m;
(4) Transpose the phase coupling matrix C to obtain a coupling coefficient matrixUsing a coupling coefficient matrix->Compensating the phase of the received signal of the main array element:
wherein x is m For the phase parameter of the original measured signal, y n For the uncoupled received signal phase derived from the uncoupled signal phase parameter,representation->The element of the m-th row and n-th column;
(5) Using compensated signalsThe interferometer angle estimation method under the near field is adopted again, so that a more accurate estimation value of the arrival angle of the signal source is obtained;
(6) And (2) repeating the steps (2-5) and iterating the phase difference and the arrival angle between the array elements until the estimated value converges or the maximum iteration number is reached, so as to obtain an accurate angle value for eliminating the coupling error.
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