CN115718276A - TDOA (time difference of arrival) short baseline positioning method and system with zero error of base station position - Google Patents

Abstract

The invention discloses a TDOA short baseline positioning method and a system for zero error of base station position, comprising the following steps: s1, measuring the linear distance between base stations by using a high-precision length measuring instrument, wherein the number of the base stations is N, and N is more than 3; s2, selecting any base station as a coordinate origin, constructing a local coordinate system of the base station, and acquiring coordinates of each base station in the local coordinate system; s3, acquiring time from a radiation source signal to each base station, and calculating an estimated position coordinate of the radiation source in a local coordinate system according to the coordinates of each base station; s4, acquiring longitude and latitude coordinates of any two base stations in an absolute geographic coordinate system, and converting the estimated position coordinates of the radiation source in a local coordinate system into the geographic coordinates of the radiation source in the absolute geographic coordinate system; the system comprises a perception base station, a high-precision length measuring instrument, a local coordinate processing model and a geographic coordinate processing model; the invention realizes the zero error of the base station position, completely eliminates the influence of the base station position error on the positioning precision, and realizes the TDOA short baseline positioning on engineering.

Description

A TDOA short baseline positioning method and system with zero error in base station position

technical field

The present invention relates to the technical field of wireless communication, and more specifically relates to a TDOA short baseline positioning method and system with zero error in base station position.

Background technique

The precise positioning of wireless signal radiation source is an important research direction of wireless signal processing. With the development of wireless communication equipment and information technology, the application range of radiation source precise positioning technology is becoming wider and wider, especially in rescue, transportation, logistics, black broadcast search, etc. In the field of radiation, the demand and role of high-precision radiation source positioning are increasing day by day.

The passive positioning technology of non-cooperative radiation sources does not need to radiate electromagnetic wave signals, and does not require prior information of radiation source signals. It only extracts relevant characteristic parameters from received radiation source signals to calculate the position of radiation sources, which has good concealment and miniaturized equipment. It has the advantages of low cost, high positioning accuracy, and simple application scenarios.

Commonly used passive positioning methods include Time Difference of Arrival (TDOA), Angle of Arrival (AOA), Received Signal Strength (RSS), Frequency Difference of Arrival (FDOA), etc. , have their own advantages and disadvantages. TDOA calculates the location of the radiation source based on the time difference between the same signal reaching the receiving antennas of different base stations. The positioning accuracy is the highest. Three base stations realize two-dimensional positioning, and four base stations realize three-dimensional positioning. The requirements for base station equipment are relatively high, and base station layout, base station position accuracy, and synchronization Clock accuracy, synchronous trigger signal accuracy, etc. will all have an impact on positioning accuracy. Because the TDOA algorithm calculates the arrival time difference of the received signals between the base stations, and then calculates the position of the radiation source in combination with the base station position, the positioning accuracy of the TDOA algorithm is related to the position accuracy of the base station.

The baseline length (distance between base stations) of the existing TDOA positioning method is usually at the km level, that is, the long baseline, and GPS/Beidou receivers are generally used to determine the location of the base stations.

However, the above methods have the following problems: the positioning error of ordinary GPS/Beidou receivers is usually m level or even 10m level; the positioning accuracy of RTK equipment can reach m level or above, but the cost is high. Especially under short baseline conditions, the minimum baseline length can be 100m. At this time, the TDOA algorithm must ensure that the received signal arrival distance difference between different base stations is at the m level, so that the accurate calculation can be performed. Therefore, the base station positioning deviation and The arrival distance difference of the received signals of different base stations is equal to or even greater than the same order of magnitude, which makes the TDOA calculation results deviate greatly and even cannot be solved.

Therefore, how to provide a TDOA short baseline positioning method and system with zero base station position error is an urgent problem to be solved by those skilled in the art.

Contents of the invention

In view of this, the present invention provides a TDOA short baseline positioning method and system with zero base station position error, which can realize zero base station position error, completely eliminate the influence of base station position error on positioning accuracy, and enable TDOA short baseline positioning in engineering. To achieve, the GPS/Beidou receiver only provides the geographic anchor point of the base station, which is used to calculate the actual latitude and longitude coordinates of the radiation source. At the same time, it can also be used for other positioning methods that are sensitive to base station position errors to improve positioning accuracy.

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

A TDOA short baseline positioning method with zero error in base station position, comprising the following steps:

S1. Use a high-precision length measuring instrument to measure the straight-line distance between each base station, the number of base stations is N, and N>3;

S2. Select any base station as the coordinate origin, build a local coordinate system of the base station, and obtain the coordinates of each base station in the local coordinate system;

S3. Obtain the time when the radiation source signal arrives at each base station, and calculate the estimated position coordinates of the radiation source in the local coordinate system according to the coordinates of each base station;

S4. Obtain the latitude and longitude coordinates of any two base stations in the absolute geographic coordinate system, and convert the estimated position coordinates of the radiation source in the local coordinate system into geographic coordinates of the radiation source in the absolute geographic coordinate system.

Preferably, the specific content of S2 includes:

S21. Select four base stations from the N base stations, and select any base station 1 as the coordinate origin, which are respectively base station 2, base station 3 and base station 4 in counterclockwise order, and take base station 1 along the straight line direction of base station 2 as the positive x-axis Direction, taking the positions of base station 3 and base station 4 as the positive direction of the y-axis to construct the local coordinate system of the base station;

S22. Obtain the coordinates of base station 1, base station 2, base station 3 and base station 4 in the local coordinate system as:

The coordinates of base station 1 are:

(x ₁ ,y ₁ )=(0,0)

The coordinates of base station 2 are:

(x ₁ ,y ₂ )=(l _12, 0)

The coordinates of base station 3 are:

x ₃ =l ₁₂ -l ₂₃ ×cos(α ₁₂₃ )

y ₃ =l ₂₃ ×sin(α ₁₂₃ )

The coordinates of base station 4 are:

x ₄ =l ₁₂ -l ₂₄ ×cos(α ₁₂₄ )

y ₄ =l ₂₄ ×sin(α ₁₂₄ )

Wherein, l ₁₂ , l ₁₃ , l ₂₃ and l ₂₄ are the straight-line distances between the base stations respectively, and α ₁₂₃ and α ₁₂₄ are the angles formed between the base stations.

Preferably, the specific content of S3 includes:

Among them, the coordinates of the radiation source RF are (x, y), the coordinates of the base station i are (X _i , Y _i ), and R _i is the distance from the i-th base station to the radiation source, where: i=1,2... , N, N is the number of base stations;

E _ij =E _i -E _j

R _ij =cE _ij

E _i and E _j are the time when the radiation source signal reaches base station i and j respectively, E _ij is the theoretical value of delay difference between base station i and j, R _ij is the theory of distance difference between base station i and j, c is the wave propagation speed;

f _i (x, y) is the difference between the i-th base station and base station 1 to the radiation source:

为实际测量的估计距离差，ε_i1为估计误差；The distance difference between the i-th base station and base station 1

is the estimated distance difference measured actually, and _εi1 is the estimated error;

Expand f _i (x,y) in Taylor series at (x ₀ ,y ₀ ) and keep only the first two items:

Among them, (x ₀ , y ₀ ) is a preset initial value, then x=x ₀ +δ _x , y=y ₀ +δ _y , f _i,0 is f _i (x,y) in (x ₀ , y ₀ ), the above formula is written in matrix form as:

Aδ=R+e

Using the weighted least squares method to solve the above formula, the solution is:

δ＝[A ^T Q ^-1 A] ^-1 A ^T Q ^-1 R

Where Q is the TDOA covariance matrix;

经过k次迭代得到的辐射源RF的位置(x^k,y^k)即为估计位置。Set x ₁ =x ₀ +δ _x , y ₁ =y ₀ +δ _y , repeat the above process until δ _x and δ _y are small enough to meet the preset threshold ε, so that

The position (x ^k , y ^k ) of the radiation source RF obtained after k iterations is the estimated position.

Preferably, in S4, GPS or Beidou receivers are used to obtain the latitude and longitude coordinates of any two base stations in the base stations.

Preferably, the specific content of S4 includes:

S41. Obtain the translation amount of the coordinate system according to the latitude and longitude coordinates of any two base stations 1 and 2;

S42. Calculate and obtain the rotation angle of the coordinate system according to the latitude and longitude coordinates of any two base stations, the distance between the two base stations, and the empirical formula for latitude and longitude conversion;

S43. Obtain the rotation angle of the radiation source RF relative to the base station A in the geographic coordinate system according to the rotation angle of the coordinate system and the estimated position coordinates of the radiation source in the local coordinate system;

S44. Acquire the geographical coordinates of the radiation source RF according to the latitude and longitude and the coordinate empirical formula.

Preferably, the amount of translation in S41 is:

S ₀ =(LA ₁ ,LO ₁ )

The rotation angle of the coordinate system in S42 is:

l _12' ＝R _e ×(LA ₂ -LA ₁ )

l _22' ＝R _e ×(LO ₂ -LO ₁ )×cos(LA ₁ )

Among them, (LA ₁ , LO ₁ ) is the latitude and longitude coordinates of base station 1, (LA ₂ , LO ₂ ) is the latitude and longitude coordinates of base station 2, 2' and RF' are respectively the distance between base station 2 and radiation source RF along the latitude line of base station 1 Projection, ∠α _212' is the angle between base station 2 and 2' and base station 1, l _12' and l _22' are the distances from base station 1 to base station 2 and 2' respectively, R _e is the earth where base station 1 is located radius;

In S43, the rotation angle of the radiation source S relative to the rotation angle coordinate system of A in geographic coordinates is:

Wherein, (x ^k , y ^k ) is the estimated position coordinate of the radiation source RF in the local coordinate system;

The geographic coordinates (LA _RF , LO _RF ) of the radiation source RF in S44 are:

Among them, the distance between base station 1 and radiation source RF and RF' is:

l _1RF' = l _1RF cos(R _S )

l _RFRF' = l _1RF sin(R _S ).

Preferably, when base station 2 is located on the west side of base station A, that is, ∠α _212' is greater than 90 degrees, the rotation angle is:

A TDOA short-baseline positioning system with zero error in the position of the base station, including a sensing base station, a high-precision length measuring instrument, a local coordinate processing model, and a geographic coordinate processing model;

Sensing base station, used to sense the radiation source signal and obtain the time from the radiation source signal to each base station, the number of base stations is N, N>3;

High-precision length measuring instrument for measuring the straight-line distance between base stations;

The local coordinate processing model is used to select any base station as the coordinate origin, construct the local coordinate system of the base station, and obtain the coordinates of each base station in the local coordinate system; it is also used to calculate the Estimated location coordinates of the radiation source in the local coordinate system;

The geographic coordinate processing model is used to obtain the latitude and longitude coordinates of any two base stations in the absolute geographic coordinate system, and convert the estimated position coordinates of the radiation source in the local coordinate system into the geographic coordinates of the radiation source in the absolute geographic coordinate system.

Preferably, the local coordinate processing model includes a local coordinate construction unit, a first data acquisition unit and a first data processing unit;

The local coordinate construction unit is used to select four base stations from N base stations, and select any base station 1 as the origin of coordinates, which are respectively base station 2, base station 3 and base station 4 in counterclockwise order, and base station 1 along the line of base station 2 The direction is the positive direction of the x-axis, and the positions of the base station 3 and the base station 4 are taken as the positive direction of the y-axis to construct the local coordinate system of the base station;

The first data acquisition unit is used to acquire the coordinates of the base stations 1, 2, 3 and 4 in the local coordinate system according to the linear distance between the base stations;

The first data processing unit is configured to calculate the estimated position coordinates of the radiation source in the local coordinate system according to the time when the radiation source signal arrives at each base station and the coordinates of each base station.

Preferably, the geographic coordinate processing model includes a second data acquisition unit, a second data processing module and a third data processing unit;

The second data acquisition unit is configured to acquire the latitude and longitude coordinates of any two base stations 1 and 2, acquire the distance data between the two base stations, and acquire the estimated position coordinates of the radiation source in the local coordinate system;

The second data processing unit is used to obtain the translation of the coordinate system according to the latitude and longitude coordinates of any two base stations 1 and 2; it is also used to calculate and obtain the rotation of the coordinate system according to the latitude and longitude coordinates of any two base stations, the distance between the two base stations and the empirical formula for latitude and longitude conversion horn;

The third data processing unit is used to obtain the rotation angle of the radiation source relative to the base station 1 in the geographic coordinate system according to the rotation angle of the coordinate system and the estimated position coordinates of the radiation source in the local coordinate system, and is also used to obtain according to the latitude and longitude and coordinate empirical formulas The geographic coordinates of the radiation source.

It can be known from the above-mentioned technical solutions that, compared with the prior art, the present invention discloses a TDOA short baseline positioning method and system with zero error in the position of the base station, and uses a high-precision ranging instrument to accurately measure the actual distance between the base stations. In the process of TDOA calculation, the zero error of the base station position is realized, which completely eliminates the influence of the base station position error on the positioning accuracy, and enables the TDOA short baseline positioning to be realized in engineering; In the process of converting the position into a local coordinate system for TDOA calculation, the present invention directly uses the high-precision ranging results for calculation, which reduces the complexity of the algorithm and greatly reduces the error influence of the GPS/Beidou receiver itself.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

The accompanying drawing of Fig. 1 is the schematic structural diagram of the four-base station TDOA short baseline positioning implementation scheme provided by the present invention;

FIG. 2 is a schematic diagram of the geographical coordinates of any two base stations A and B and radiation sources provided by the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The embodiment of the present invention discloses a TDOA short baseline positioning method with zero error in base station position, comprising the following steps:

S1. Use a high-precision length measuring instrument to measure the straight-line distance between each base station, the number of base stations is N, and N>3;

S2. Select any base station as the coordinate origin, build a local coordinate system of the base station, and obtain the coordinates of each base station in the local coordinate system;

S3. Obtain the time when the radiation source signal arrives at each base station, and calculate the estimated position coordinates of the radiation source in the local coordinate system according to the coordinates of each base station;

S4. Obtain the latitude and longitude coordinates of any two base stations in the absolute geographic coordinate system, and convert the estimated position coordinates of the radiation source in the local coordinate system into geographic coordinates of the radiation source in the absolute geographic coordinate system.

In practical applications, high-precision length measuring instruments such as tape measure, laser rangefinder, telescope rangefinder and total station are used to measure the straight-line distance between base stations.

The distance error between the base stations measured by the high-precision range finder can reach the centimeter level, and the inclination angle error can reach within one degree, and the error can be ignored. Therefore, error-free relative coordinates between base stations can be calculated, so that the influence of base station position errors on positioning accuracy can be completely eliminated during the positioning calculation and settlement process.

Preferably, the specific content of S2 includes:

S21. Select four base stations from the N base stations, and select any base station 1 as the coordinate origin, which are respectively base station 2, base station 3 and base station 4 in counterclockwise order, and take base station 1 along the straight line direction of base station 2 as the positive x-axis Direction, taking the positions of base station 3 and base station 4 as the positive direction of the y-axis to construct the local coordinate system of the base station;

S22. Obtain the coordinates of base station 1, base station 2, base station 3 and base station 4 in the local coordinate system as:

The coordinates of base station 1 are:

(x ₁ ,y ₁ )=(0,0)

The coordinates of base station 2 are:

(x ₁ ,y ₂ )=(l ₁₂ ,0)

The coordinates of base station 3 are:

x ₃ =l ₁₂ -l ₂₃ ×cos(α ₁₂₃ )

y ₃ =l ₂₃ ×sin(α ₁₂₃ )

The coordinates of base station 4 are:

x ₄ =l ₁₂ -l ₂₄ ×cos(α ₁₂₄ )

y ₄ =l ₂₄ ×sin(α ₁₂₄ )

Wherein, l ₁₂ , l ₁₃ , l ₂₃ and l ₂₄ are the straight-line distances between the base stations respectively, and α ₁₂₃ and α ₁₂₄ are the angles formed between the base stations.

In this embodiment, the order of base stations A, B, C, and D is defined counterclockwise to ensure that the ordinates of base stations C and D are all positive values, which is convenient for subsequent orientation estimation, and the relative orientation is consistent with the actual situation, as shown in figure 1.

In practical applications, if it is necessary to calculate the three-dimensional coordinates of the radiation source, high-precision length measuring instruments such as telescope range finders and total stations are used to measure the horizontal angle between the base stations at the same time, and the z coordinates of each base station are calculated according to the cosine law.

In practical applications, two-step least squares Chan algorithm or Taylor series Taylor expansion are used to calculate the position of the target radiation source. This implementation uses the Taylor algorithm as an example.

In order to further implement the above technical solutions, the specific content of S3 includes:

Among them, the coordinates of the radiation source RF are (x, y), the coordinates of the base station i are (X _i , Y _i ), and R _i is the distance from the i-th base station to the radiation source, where: i=1,2... , N, N is the number of base stations;

E _ij =E _i -E _j

R _ij =cE _ij

E _i and E _j are the time when the radiation source signal reaches base station i and j respectively, E _ij is the theoretical value of delay difference between base station i and j, R _ij is the theory of distance difference between base station i and j, c is the wave propagation speed;

f _i (x, y) is the difference between the i-th base station and base station 1 to the radiation source:

为实际测量的估计距离差，ε_i1为估计误差；The distance difference between the i-th base station and base station 1

is the estimated distance difference measured actually, and _εi1 is the estimated error;

Expand f _i (x,y) in Taylor series at (x ₀ ,y ₀ ) and keep only the first two items:

Among them, (x ₀ , y ₀ ) is a preset initial value, then x=x ₀ +δ _x , y=y ₀ +δ _y , f _i,0 is f _i (x,y) in (x ₀ , y ₀ ), the above formula is written in matrix form as:

Aδ=R+e

Using the weighted least squares method to solve the above formula, the solution is:

δ＝[A ^T Q ^-1 A] ^-1 A ^T Q ^-1 R

Where Q is the TDOA covariance matrix;

经过k次迭代得到的辐射源RF的位置(x^k,y^k)即为估计位置。Set x ₁ =x ₀ +δ _x , y ₁ =y ₀ +δ _y , repeat the above process until δ _x and δ _y are small enough to meet the preset threshold ε, so that

The position (x ^k , y ^k ) of the radiation source RF obtained after k iterations is the estimated position.

In order to further implement the above technical solution, in S4, the GPS or Beidou receiver is used to obtain the latitude and longitude coordinates of any two base stations in the base stations.

In order to further implement the above technical solutions, the specific content of S4 includes:

S41. Obtain the translation amount of the coordinate system according to the latitude and longitude coordinates of any two base stations 1 and 2;

S42. Calculate and obtain the rotation angle of the coordinate system according to the latitude and longitude coordinates of any two base stations, the distance between the two base stations, and the empirical formula for latitude and longitude conversion;

S43. Obtain the rotation angle of the radiation source RF relative to the base station 1 in the geographic coordinate system according to the rotation angle of the coordinate system and the estimated position coordinates of the radiation source in the local coordinate system;

S44. Acquire the geographical coordinates of the radiation source RF according to the latitude and longitude and the coordinate empirical formula.

In order to further implement the above technical scheme, the amount of translation in S41 is:

S ₀ =(LA ₁ ,LO ₁ )

The rotation angle of the coordinate system in S42 is:

l _12' ＝R _e ×(LA ₂ -LA ₁ )

l _22' ＝R _e ×(LO ₂ -LO ₁ )×cos(LA ₁ )

Among them, (LA ₁ , LO ₁ ) is the latitude and longitude coordinates of base station 1, (LA ₂ , LO ₂ ) is the latitude and longitude coordinates of base station 2, 2' and RF' are respectively the distance between base station 2 and radiation source RF along the latitude line of base station 1 Projection, ∠α _212' is the angle between base station 2 and 2' and base station 1, l _12' and l _22' are the distances from base station 1 to base station 2 and 2' respectively, R _e is the earth where base station 1 is located radius;

In this implementation, considering that the scale of the distance between base stations is extremely small relative to the earth's radian, the error of converting the coordinates by using the empirical formula can be ignored.

In S43, the rotation angle of the radiation source S relative to the rotation angle coordinate system of A in geographic coordinates is:

Wherein, (x ^k , y ^k ) is the estimated position coordinate of the radiation source RF in the local coordinate system;

The geographic coordinates (LA _RF , LO _RF ) of the radiation source RF in S44 are:

Among them, the distance between base station 1 and radiation source RF and RF' is:

l _1RF' = l _1RF cos(R _S )

l _RFRF' = l _1RF sin(R _S ).

取值范围为

考虑到B可能位于A的西侧，因此并不一定等于

必须考虑B相对于A的实际方位判断。In another embodiment, due to

The value range is

Considering that B may be on the west side of A, it is not necessarily equal to

The actual orientation judgment of B relative to A must be considered.

In order to further implement the above technical solution, when the base station 2 is located on the west side of the base station A, that is, ∠α _212' is greater than 90 degrees, the rotation angle is:

A TDOA short-baseline positioning system with zero error in the position of the base station, including a sensing base station, a high-precision length measuring instrument, a local coordinate processing model, and a geographic coordinate processing model

Sensing base station, used to sense the radiation source signal and obtain the time from the radiation source signal to each base station, the number of base stations is N, N>3;

High-precision length measuring instrument for measuring the straight-line distance between base stations;

The local coordinate processing model is used to select any base station as the coordinate origin, construct the local coordinate system of the base station, and obtain the coordinates of each base station in the local coordinate system; it is also used to calculate the Estimated location coordinates of the radiation source in the local coordinate system;

The geographic coordinate processing model is used to obtain the latitude and longitude coordinates of any two base stations in the absolute geographic coordinate system, and convert the estimated position coordinates of the radiation source in the local coordinate system into the geographic coordinates of the radiation source in the absolute geographic coordinate system.

In order to further implement the above technical solution, the local coordinate processing model includes a local coordinate construction unit, a first data acquisition unit and a first data processing unit;

The local coordinate construction unit is used to select four base stations from N base stations, and select any base station 1 as the origin of coordinates, which are respectively base station 2, base station 3 and base station 4 in counterclockwise order, and base station 1 along the line of base station 2 The direction is the positive direction of the x-axis, and the positions of the base station 3 and the base station 4 are taken as the positive direction of the y-axis to construct the local coordinate system of the base station;

The first data acquisition unit is used to acquire the coordinates of the base stations 1, 2, 3 and 4 in the local coordinate system according to the linear distance between the base stations;

The first data processing unit is configured to calculate the estimated position coordinates of the radiation source in the local coordinate system according to the time when the radiation source signal arrives at each base station and the coordinates of each base station.

In order to further implement the above technical solution, the geographic coordinate processing model includes a second data acquisition unit, a second data processing module and a third data processing unit;

The second data acquisition unit is configured to acquire the latitude and longitude coordinates of any two base stations 1 and 2, acquire the distance data between the two base stations, and acquire the estimated position coordinates of the radiation source in the local coordinate system;

The second data processing unit is used to obtain the translation of the coordinate system according to the latitude and longitude coordinates of any two base stations 1 and 2; it is also used to calculate and obtain the rotation of the coordinate system according to the latitude and longitude coordinates of any two base stations, the distance between the two base stations and the empirical formula for latitude and longitude conversion horn;

The third data processing unit is used to obtain the rotation angle of the radiation source relative to the base station 1 in the geographic coordinate system according to the rotation angle of the coordinate system and the estimated position coordinates of the radiation source in the local coordinate system, and is also used to obtain according to the latitude and longitude and coordinate empirical formulas Geographical coordinates of the radiation source

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for the related information, please refer to the description of the method part.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A TDOA short baseline positioning method with zero error of base station position is characterized by comprising the following steps:

s1, measuring linear distances among base stations by using a high-precision length measuring instrument, wherein the number of the base stations is N, and N is more than 3;

s2, selecting any base station as a coordinate origin, constructing a local coordinate system of the base station, and acquiring coordinates of each base station in the local coordinate system;

s3, acquiring time from a radiation source signal to each base station, and calculating an estimated position coordinate of the radiation source in a local coordinate system according to the coordinates of each base station;

s4, acquiring longitude and latitude coordinates of any two base stations in an absolute geographic coordinate system, and converting the estimated position coordinates of the radiation source in the local coordinate system into the geographic coordinates of the radiation source in the absolute geographic coordinate system.

2. The TDOA short baseline positioning method with zero error of bs location as claimed in claim 1, wherein the details of S2 include:

s21, selecting four base stations from the N base stations, selecting any base station 1 as a coordinate origin, and respectively setting the base stations 2, 3 and 4 in a counterclockwise sequence, and establishing a local coordinate system of the base stations by taking the straight line direction of the base station 1 along the base station 2 as the positive direction of an x axis and the positions of the base stations 3 and 4 as the positive direction of a y axis;

s22, obtaining the coordinates of the base station 1, the base station 2, the base station 3 and the base station 4 in a local coordinate system as follows:

the coordinates of the base station 1 are:

(x ₁ ,y ₁ )＝(0,0)

the coordinates of the base station 2 are:

(x ₁ ,y ₂ )＝(l ₁₂ ,0)

the coordinates of the base station 3 are:

x ₃ ＝l ₁₂ -l ₂₃ ×cos(α ₁₂₃ )

y ₃ ＝l ₂₃ ×sin(α ₁₂₃ )

the coordinates of the base station 4 are:

x ₄ ＝l ₁₂ -l ₂₄ ×cos(α ₁₂₄ )

y ₄ ＝l ₂₄ ×sin(α ₁₂₄ )

wherein l ₁₂ 、l ₁₃ 、l ₂₃ And l ₂₄ Respectively, the linear distance, alpha, between the base stations ₁₂₃ And alpha ₁₂₄ The included angle formed between the base stations.

3. The method for TDOA short baseline positioning with zero error of BS location according to claim 1, wherein S3 comprises:

wherein the coordinates of the radiation source RF are (X, y) and the coordinates of the base station i are (X) _i ,Y _i ) Ri is the distance from the ith base station to the radiation source, wherein: i =1,2, where N is the number of base stations;

E _ij ＝E _i -E _j

R _ij ＝cE _ij

E _i and E _j The times of arrival of the radiation source signals at base stations i and j, respectively, E _ij Is the theoretical value of the time delay difference between base stations i and j, R _ij C is the propagation speed of the electric wave;

f _i (x, y) is the difference between the distance from the ith base station and the distance from the base station 1 to the radiation source:

distance difference from ith base station to base station 1

For the actual measured estimated distance difference, epsilon _i1 To estimate the error;

will f is mixed _i (x, y) in (x) ₀ ,y ₀ ) The Taylor series expansion is taken and only the first two terms are retained:

wherein (x) ₀ ,y ₀ ) Is preset to an initial value, then x = x ₀ +δ _x ，y＝y ₀ +δ _y ，f _i，0 Is f _i (x, y) in (x) ₀ ,y ₀ ) The function value at (c), written as a matrix form:

Aδ＝R+e

solving the above formula by using a weighted least square method to obtain a solution:

δ＝[A ^T Q ^-1 A] ^-1 A ^T Q ^-1 R

wherein Q is a TDOA covariance matrix;

let x be ₁ ＝x ₀ +δ _x ,y ₁ ＝y ₀ +δ _y Repeating the above process until delta _x And delta _y Is small enough and satisfies a predetermined threshold epsilon

Position (x) of the radiation source RF over k iterations ^k ,y ^k ) I.e. the estimated position.

4. The method of claim 1, wherein in S4, GPS or a beidou receiver is used to obtain longitude and latitude coordinates of any two of the bss.

5. The TDOA short baseline positioning method with zero error of bs location as claimed in claim 1, wherein the details of S4 include:

s41, obtaining a translation amount of a coordinate system according to longitude and latitude coordinates of any two base stations 1 and 2;

s42, calculating according to longitude and latitude coordinates of any two base stations, the distance between the two base stations and a longitude and latitude conversion empirical formula to obtain a coordinate system rotation angle;

s43, obtaining the rotation angle of the radiation source RF relative to the base station A under the geographic coordinate system according to the rotation angle of the coordinate system and the estimated position coordinates of the radiation source in the local coordinate system;

and S44, acquiring the geographic coordinates of the radiation source RF according to the longitude and latitude and coordinate empirical formula.

6. The method for TDOA short baseline positioning with zero error of BS position as claimed in claim 5, wherein the translation amount in S41 is:

S ₀ ＝(LA ₁ ,LO ₁ )

the rotation angle of the coordinate system in S42 is:

l _12' ＝R _e ×(LA ₂ -LA ₁ )

l _22' ＝R _e ×(LO ₂ -LO ₁ )×cos(LA ₁ )

wherein (LA) ₁ ,LO ₁ ) Is the latitude and longitude coordinate of the base station 1, (LA) ₂ ,LO ₂ ) Is latitude and longitude coordinates of the base station 2, 2 'and RF' are projections of the base station 2 and the radiation source RF along the latitude line of the base station 1 respectively, and the angle alpha _212’ Is the angle formed by base stations 2 and 2' and base station 1,/ _12' And l _22' Distance, R, of base station 1 from base stations 2 and 2', respectively _e The radius of the earth at which the base station 1 is located;

in S43, the rotation angle of the radiation source S in the geographic coordinates relative to the rotation angle coordinate system of a is:

wherein (x) ^k ,y ^k ) Estimated position coordinates in a local coordinate system for the radiation source RF;

geographic coordinates (LA) of the radiation source RF in S44 _RF ,LO _RF ) Comprises the following steps:

wherein the distances between the base station 1 and the radiation sources RF and RF' are:

l _1RF’ ＝l _1RF cos(R _S )

l _RFRF' ＝l _1RF sin(R _S )。

7. the method for TDOA short baseline positioning with zero error of BS location as claimed in claim 6, wherein when BS 2 is located at the west side of BS A- _212’ Greater than 90 degrees, the rotation angle is:

8. a TDOA short baseline positioning system of base station position zero error based on the TDOA short baseline positioning method of base station position zero error described in any one of claims 1-7, which is characterized by comprising a perception base station, a high-precision length measuring instrument, a local coordinate processing model and a geographic coordinate processing model;

the sensing base stations are used for sensing the radiation source signals and acquiring the time from the radiation source signals to each base station, the number of the base stations is N, and N is more than 3;

the high-precision length measuring instrument is used for measuring the linear distance between the base stations;

the local coordinate processing model is used for selecting any base station as a coordinate origin, constructing a local coordinate system of the base station and acquiring the coordinate of each base station in the local coordinate system; the system is also used for calculating the estimated position coordinates of the radiation source in a local coordinate system according to the time from the radiation source signal to each base station and the coordinates of each base station;

and the geographic coordinate processing model is used for acquiring longitude and latitude coordinates of any two base stations in an absolute geographic coordinate system and converting the estimated position coordinates of the radiation source in the local coordinate system into the geographic coordinates of the radiation source in the absolute geographic coordinate system.

9. The TDOA short-baseline positioning system with zero-error base station position as claimed in claim 8, wherein the local coordinate processing model includes a local coordinate constructing unit, a first data obtaining unit and a first data processing unit;

the local coordinate construction unit is used for selecting four base stations from the N base stations optionally, selecting any one base station 1 as a coordinate origin, respectively setting the base stations 2, 3 and 4 in a counterclockwise sequence, and constructing a local coordinate system of the base stations by taking the straight line direction of the base station 1 along the base station 2 as the positive direction of an x axis and the positions of the base stations 3 and 4 as the positive direction of a y axis;

a first data acquisition unit, which is used for acquiring the coordinates of the base stations 1,2, 3 and 4 in the local coordinate system according to the linear distance among the base stations;

and the first data processing unit is used for calculating the estimated position coordinates of the radiation source in the local coordinate system according to the time from the radiation source signal to each base station and the coordinates of each base station.

10. The TDOA short-baseline positioning system with zero base station position error as recited in claim 8, wherein the geographic coordinate processing model includes a second data acquisition unit, a second data processing module and a third data processing unit;

the second data acquisition unit is used for acquiring longitude and latitude coordinates of any two base stations 1 and 2, acquiring distance data of the two base stations and acquiring estimated position coordinates of the radiation source in a local coordinate system;

the second data processing unit is used for obtaining the translation amount of the coordinate system according to the longitude and latitude coordinates of any two base stations 1 and 2; the system is also used for calculating and obtaining a coordinate system rotation angle according to the longitude and latitude coordinates of any two base stations, the distance between the two base stations and a longitude and latitude conversion empirical formula;

and the third data processing unit is used for obtaining the rotation angle of the radiation source relative to the base station A under the geographic coordinate system according to the rotation angle of the coordinate system and the estimated position coordinate of the radiation source in the local coordinate system, and is also used for obtaining the geographic coordinate of the radiation source according to longitude and latitude and a coordinate empirical formula.

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