A method for establishing a three-dimensional space coordinate system based on true north of the earth

Abstract

The present invention discloses a method for establishing a three-dimensional space coordinate system based on the true north of the earth. First, the geodetic coordinates of the observation pier in the antenna system installation area are obtained, and the base workpiece reference point of the antenna system is obtained as the origin O of the coordinate system; then the geodetic coordinates and Gaussian coordinates of the reference point are measured, and the reference plane of the coordinate system is established; the geodetic azimuth γ between the origin O and the pointing point A is calculated; then O is taken as the origin of the coordinate system, the Z1 axis passes through the O point and is vertically upward perpendicular to the reference plane P, the X1 axis points to the A point, and the Y1 axis is determined by the right-hand coordinate system rule to establish a reference coordinate system O-X1Y1Z1; finally, the Z1 axis is rotated counterclockwise around the Z1 axis by an angle γ, and the positive direction of the X axis of the coordinate system points to the true north of the earth, so as to obtain a three-dimensional space coordinate system based on the true north of the earth. The present invention solves the engineering application problem of establishing a three-dimensional space coordinate system with the true north of the earth as the X axis pointing, and obtains reliable, efficient and high-precision measurement effects in the precision measurement tasks of the directional multi-beam antenna, the installation of the full-space spherical phased array antenna structure and the calibration stage of the antenna system.

Description

Technical Field

[0001] The invention relates to the field of installation measurement of special precision industrial equipment, and in particular to a method for establishing a three-dimensional space coordinate system in the installation measurement of a directional multi-beam antenna and a full-space spherical phased array antenna. Background Art

[0002] Directional multi-beam antennas and full-space spherical phased array antennas are both satellite communication earth station antennas shared by multiple satellites and multiple frequency bands. They have the characteristics of large communication capacity, multi-purpose use of one station, compact structure and low construction cost, and have become a hot spot in current antenna technology research. Directional multi-beam antennas are composed of a main reflector and a feed system. The structural form is divided into "integrated" and "separated". Both the main reflector and the feed system need to point to the satellite synchronous orbit; the full-space spherical phased array antenna is composed of multiple array surfaces and a large number of array elements. The former requires precise measurement of the main reflector and feed system pointing to the satellite synchronous orbit during the installation phase, and the latter requires precise calibration of the geodetic coordinates of the array elements during the testing phase. Therefore, how to establish a three-dimensional spatial coordinate system based on the true north of the earth with the antenna system's own reference point has become a key technology.

[0003] According to the current research status at home and abroad, the author Feng Qiqiang et al. published a method of using a dual theodolite measurement system to convert antenna measurement data to the geodetic coordinate system through a common point for data processing and analysis in the journal "Radio Engineering" Vol. 45, No. 1, pp. 58-60. Since the geodetic coordinate system is a coordinate system based on the earth's ellipsoid, this method is difficult to intuitively guide the installation and measurement of the antenna structure system. The author Li Zongchun et al. published a method of using a dual theodolite measurement system to restore the antenna design coordinate system through the measurement pier and control network in the journal "Marine Surveying and Mapping" Vol. 25, No. 1, pp. 26-29, but did not give the concept and construction method of the antenna design coordinate system. The six measurement observation piers described in the article are used to set up the theodolite measurement system. Due to the measurement range limitation of the dual theodolite measurement system itself, the observation pier is close to the antenna, and the observation pier needs to reach a certain height, so its construction cost is relatively high. Summary of the invention

[0004] Technical issues to be solved

[0005] In applications such as precise measurement of the main reflector of a directional multi-beam antenna and the pointing of the feed system to the satellite synchronous orbit, the pointing accuracy of the directional multi-beam antenna is required to be better than ±0.015°, and the position accuracy of the feed system relative to the main beam of the main reflector of the antenna is required to be better than ±2mm. Therefore, the installation and measurement and adjustment phases of the directional multi-beam antenna system need to be carried out in a unified coordinate system pointing to the geodetic north. However, the current methods for establishing a three-dimensional spatial coordinate system based on the true north of the earth generally have the problems of high cost, insufficient accuracy and reliability.

[0006] Technical Solution

[0007] To this end, the present invention proposes a method for establishing a three-dimensional space coordinate system based on the true north of the earth. The method is established based on the basic workpiece reference point of the antenna system itself, which is more suitable for the installation measurement of the antenna system and the adjustment of the guiding structural indicators. The known geodetic coordinate known points required in the antenna installation area are widely distributed and at a low height, and the construction cost is low. This method has been successfully applied in the installation measurement of directional multi-beam antennas.

[0008] The technical solution of the present invention is:

[0009] The method for establishing a three-dimensional space coordinate system based on true north of the earth comprises the following steps:

[0010] Step 1: Obtain the geodetic coordinates of the observation pier in the antenna system installation area;

[0011] Step 2: Obtain the base workpiece reference point of the antenna system as the origin O of the coordinate system;

[0012] Step 3: Obtain the geodetic coordinates and Gaussian coordinates of the base workpiece reference point of the antenna system;

[0013] Step 4: Establish the coordinate system reference plane;

[0014] Step 5: Calculate the geodetic azimuth γ between the origin O of the coordinate system and the pointing point A according to the Bessel method geodetic inverse calculation formula;

[0015] Step 6: With O as the origin of the coordinate system, the Z1 axis passes through point O and points vertically upward perpendicular to the reference plane P, the X1 axis points to point A, and the Y1 axis is determined by the right-hand coordinate system rule to establish the reference coordinate system O-X1Y1Z1;

[0016] Step 7: Based on the earth azimuth angle γ between the origin O of the coordinate system and the pointing point A obtained in step 5, that is, the rotation angle between OA and the true north of the earth, rotate counterclockwise around the Z1 axis by an angle γ. At this time, the positive direction of the X-axis of the coordinate system points to the true north of the earth. The obtained new coordinate system is named O-XYZ, which is a three-dimensional space coordinate system based on the true north of the earth.

[0017] Furthermore, the process of obtaining the geodetic coordinates of the observation pier in the antenna system installation area in step 1 is as follows:

[0018] Step 1.1: Build at least three mandatory centering observation piers A, B, and C in the antenna system installation area;

[0019] Step 1.2: Observe the ABC triangulation network through a satellite positioning receiver; when processing satellite positioning data in the WGS-84 coordinate system, use the precise ephemeris solution of the observation station to obtain the geodetic coordinates of point A, and use the calculation result of point A as the control network benchmark data for local area network adjustment to obtain the azimuth benchmark and the geodetic coordinates and Gaussian plane coordinates of points B and C, which are used as the geodetic coordinates of the origin of the coordinate system of the measuring antenna system and the azimuth benchmark for establishing a three-dimensional space coordinate system based on geodetic north.

[0020] Furthermore, in step 1.2, three dual-band satellite positioning receivers are used to observe the ABC triangulation network, and the synchronous loop is continuously observed for 12 h.

[0021] Furthermore, in step 2, the process of obtaining the geometric center of the antenna system basic workpiece as the origin O of the coordinate system is: using a total station to measure the geometric center or reference hole position of the antenna system basic workpiece, and obtaining the reference point as the origin O of the coordinate system.

[0022] Furthermore, in step 3, the geodetic coordinates and Gaussian coordinates of the antenna system basic workpiece reference point are obtained as follows:

[0023] Step 3.1: According to the Gaussian plane coordinates (X A , Y A )、(X B , Y B ), using the Gaussian coordinate inverse formula

[0024]

[0025] Calculate the AB coordinate azimuth α AB ;

[0026] Step 3.2: Transfer formula based on coordinate azimuth

[0027]

[0028] Calculate the BO coordinate azimuth α BO ; Where β is the horizontal angle ∠ABO;

[0029] Step 3.3: Calculate the formula based on Gaussian coordinate increment

[0030] Δ X =L BO *cosα BO

[0031] Δ Y =L BO *sinα BO

[0032] X O =X B +ΔX

[0033] Y O =Y B +Δ Y

[0034] Calculate the Gaussian plane coordinates (X O , Y O ), where L BO is the horizontal distance from point BO, Δ X , Δ Y are the increments of the Gaussian plane coordinates of point O relative to the Gaussian plane coordinates of point B;

[0035] Step 3.4: Inverse calculation formula based on Gauss projection

[0036]

[0037]

[0038] L O =L0+l

[0039] Calculate the geodetic longitude and latitude L of the origin O of the coordinate system O , B O ; Where L0 is the longitude of the central meridian, l is the difference between the longitude of point O and the longitude of the central meridian L0, B f is the latitude of the bottom point corresponding to point O, M f is the meridian curvature radius, N f is the radius of curvature of the yoke, t f =tan B f , e ＇2 is the second eccentricity of the reference ellipsoid.

[0040] Furthermore, in step 4, the process of establishing the coordinate system reference plane is as follows: in the three-dimensional measurement software, discrete points are created that are equal to the geodetic height of the coordinate system origin O, the plane coordinate range is consistent with the measurement area, and the reference plane P is created by fitting multiple points.

[0041] Furthermore, in step 5, the process of calculating the geodetic azimuth between the origin O of the coordinate system and the pointing point A according to the Bessel method geodetic inverse calculation formula is:

[0042] According to the formula

[0043]

[0044]

[0045]

[0046] L=L A -L O

[0047] a1=sinu1 sinu2 a2=cosu1 cosu2

[0048] b1=cosu1 sinu2 b2=sinu1 cosu2

[0049] Perform auxiliary calculations, where e 2 is the first oblate heart rate of the reference ellipsoid, (B O , L O )、(B A , L A ) are the latitude and longitude of the geodetic coordinates of points O and A respectively;

[0050] Use the successive approximation method to simultaneously calculate the local azimuth angle of the starting point, the spherical length, and the longitude difference λ = L + δ. When approaching for the first time, take δ = 0:

[0051] p=cos u2 sinλq=b1-b2 cosλ

[0052]

[0053] sinσ=p sinα OA +q cosα OA cosσ=a1+a2cosλ

[0054]

[0055] sinA0=cosu1 sinγ OA x=2a1-(cosA0) 2 cosσ

[0056] δ=[ασ-β'xsinσ]sinA0

[0057] Coefficients α and β ＇ Calculated by the formula:

[0058]

[0059] Use the calculated δ to calculate λ1=l+δ, recalculate δ2 according to the above formula, and then use δ2 to calculate λ2, and iterate until the last two δ are the same or less than the given allowable value; λ, γ, σ, x and sinA0 all use the results of the last calculation.

[0060] Beneficial Effects

[0061] The present invention proposes a three-dimensional space coordinate system method based on the true north of the earth by an indirect method of creating a reference coordinate system, and realizes the engineering application in directional multi-beam antennas. Three dual-band GPS receivers were used to observe the ABC triangulation network. The synchronous loop observed continuously for 12 hours. When processing GPS data in the WGS-84 coordinate system, the precise ephemeris solution of the observation station was used. The point accuracy can reach the millimeter level, and the local azimuth accuracy is better than ±5″. The TDRA6000 total station measurement system has a range of 300m. The coordinate measurement accuracy within the measurement range reaches the sub-millimeter level, and the angle measurement accuracy is as high as 0.5″. The total station measurement system has the measurement advantage of free station setting. Therefore, the measurement position can be selected as needed in the antenna installation area, which is more suitable for on-site operations of complex projects. The geodetic north three-dimensional space coordinate system established according to the datum point of the basic workpiece of the directional multi-beam antenna can be unified with the theoretical coordinate system of the antenna structure, and the conversion parameters of the geodetic north three-dimensional space coordinate system to the local coordinate system of each structural component can be obtained based on the theoretical relationship of the structural components. It is more intuitive and convenient to obtain the local coordinate system of each structural component from the geodetic north three-dimensional space coordinate system to guide the measurement and adjustment of the structural components. Therefore, the three-dimensional space coordinate system method based on the true north of the earth of the present invention has the characteristics of high efficiency, high precision and reliability, while saving a lot of manpower and material resources, reducing the cost of antenna construction, and providing a beneficial solution for the installation and measurement of special precision industrial equipment.

[0062] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0064] Figure 1 Schematic diagram of the three-dimensional space coordinate system based on the true north of the earth

[0065] Figure 2 Coordinate azimuth diagram

[0066] Figure 3 Schematic diagram of coordinate azimuth transmission

[0067] Figure 4 Schematic diagram of Gaussian coordinate increment calculation

[0068] Figure 5 Schematic diagram of the azimuth of the Great Place

[0069] Figure 6 Schematic diagram of the rotation angle between the geodetic line OA and the true north of the earth

[0070] Figure 7 Reference coordinate system diagram

[0071] Figure 8 Schematic diagram of the three-dimensional space coordinate system based on the true north of the earth obtained by rotating the reference coordinate system around the Z axis by an angle of γ

[0072] Fig. 9 Schematic diagram of the main reflector, feed system and antenna system coordinate system O-XYZ with the X-axis pointing to the true north of the earth for a directional multi-beam antenna system

[0073] Fig.10 Schematic diagram of the observation pier building in the directional multi-beam antenna installation area

[0074] Fig.11 Transition section center diagram

[0075] Fig.12 Schematic diagram of geodetic coordinate calculation of transition section center O

[0076] Fig.13 Schematic diagram of calculation of the azimuth angle γ between the transition section center O and the pointing point A

[0077] Fig.14 Transition section reference coordinate system O-X1Y1Z1

[0078] Fig.15 As shown, the reference coordinate system O-X1Y1Z1 rotates counterclockwise around the Z1 axis by γ to obtain the antenna system coordinate system O-XYZ with the X axis pointing to the geodetic north. DETAILED DESCRIPTION

[0079] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0080] like Fig. 9 As shown in the figure, a directional multi-beam antenna includes a main reflector and a feed system, which are separated in space. The main reflector is fixed, and the feed system is composed of multiple feed groups, which correspond to different satellites and point to the synchronous satellite orbit. The pointing accuracy is required to be better than ±0.015°, and the position accuracy of the feed system relative to the main beam of the main reflector is required to be better than ±2mm. Therefore, the structural installation, measurement, and adjustment stages of the directional multi-beam antenna system need to be carried out in the three-dimensional space coordinate system O-XYZ based on the true north of the earth.

[0081] The following describes the steps for establishing the three-dimensional space coordinate system O-XYZ based on the true north of the earth:

[0082] Step 1: Fig.10As shown in the figure, three mandatory centering observation piers A, B, and C (determined by the scope of the installation area) are built in the antenna system equipment installation area, 1.5m-2m above the ground, and three dual-band GPS receivers are used to observe the ABC triangulation network, and the synchronous loop is continuously observed for 12 hours. When processing GPS data in the WGS-84 coordinate system, the precise ephemeris solution of the observation station is used to obtain the geodetic coordinates of A, and the calculation result of point A is used as the control network benchmark data for local area network adjustment to obtain the azimuth benchmark and the geodetic coordinates and Gaussian plane coordinates of points B and C, which are used as the geodetic coordinates of the origin of the directional multi-beam antenna coordinate system and the azimuth benchmark for establishing the three-dimensional space coordinate system based on the geodetic north.

[0083] Step 2: Use the TDRA 6000 total station measurement system to measure the geometric center or reference hole position of the basic workpiece, obtain the reference point of the basic workpiece as the origin O of the coordinate system, and measure the A, B, and C observation piers in parallel to calculate the Gaussian plane coordinates and geodetic coordinates of the origin O of the coordinate system. The basic workpiece reference point can be the geometric center of the basic workpiece, such as a circular structure or a rectangular structure, or it can be indirectly obtained from the reference hole position pre-processed during machining.

[0084] like Fig.11 As shown in the figure, the transition section at the root of the main reflector of the directional multi-beam antenna system is the basic workpiece of the antenna system. The circumferential center O of the transition section is measured by the TDRA6000 total station as the origin of the three-dimensional space coordinate system O-XYZ of the true north of the earth.

[0085] Step 3: Calculate the Gaussian plane coordinates and geodetic coordinates of the origin O of the coordinate system (i.e., the base workpiece reference point of the antenna system) from the spatial position relationship between the origin O of the coordinate system and the A and B observation piers: horizontal distance, horizontal rotation angle, and the geodetic coordinates and Gaussian coordinates of the A and B observation piers. Fig.12 As shown, the geodetic longitude and latitude and Gaussian plane coordinates of points A and B, as well as the three internal angles and three side lengths of the plane triangle △ABO are known. The Gaussian plane coordinates and geodetic coordinates of the center O of the transition section are calculated through the following process.

[0086] Step 3.1: According to the Gaussian plane coordinates (X A , Y A )、(X B , Y B ), using the Gaussian coordinate inverse formula

[0087]

[0088] Calculate the AB coordinate azimuth α AB ;

[0089] Step 3.2: Transfer formula based on coordinate azimuth

[0090]

[0091] Calculate the BO coordinate azimuth α BO ; Where β is the horizontal angle ∠ABO;

[0092] Step 3.3: Calculate the formula based on Gaussian coordinate increment

[0093] Δ X =L BO *cosα BO

[0094] Δ Y =L BO *sinα BO

[0095] X O =X B +Δ X

[0096] Y O =Y B +Δ Y

[0097] Calculate the Gaussian plane coordinates (X O , Y O ), where L BO is the horizontal distance from point BO, Δ X , Δ Y are the increments of the Gaussian plane coordinates of point O relative to the Gaussian plane coordinates of point B;

[0098] Step 3.4: Inverse calculation formula based on Gauss projection

[0099]

[0100]

[0101] L O =L0+l

[0102] Calculate the geodetic longitude and latitude L of the origin O of the coordinate system O , B O ; Where L0 is the longitude of the central meridian, l is the difference between the longitude of point O and the longitude of the central meridian L0, B f is the latitude of the bottom point corresponding to point O, M f is the meridian curvature radius, N f is the radius of curvature of the yoke, t f =tan B f , e ＇2 is the second eccentricity of the reference ellipsoid.

[0103] Step 4: Since the size of special precision industrial equipment is generally in the range of several meters to several hundred meters, in the 3D measurement software, create discrete points equal to the geodetic height of the coordinate system origin O. The plane coordinate range is consistent with the measurement area, and create the reference plane P by fitting the discrete points.

[0104] Step 5: From the geodetic coordinates of point O (B O , L O ) and the geodetic coordinates of point A (B A , L A ), calculate the geodetic azimuth γ of the geodetic line OA according to the Bessel method geodetic inverse calculation formula.

[0105] The specific process is:

[0106] Auxiliary calculation:

[0107]

[0108]

[0109]

[0110] L=L A -L O

[0111] a1=sinu1 sinu2 a2=cosu1 cosu2

[0112] b1=cosu1 sinu2 b2=sinu1 cosu2

[0113] Where e 2 is the first oblate heart rate of the reference ellipsoid, (B O , L O )、(B A , L A ) are the latitude and longitude of the geodetic coordinates of points O and A respectively.

[0114] Use the successive approximation method to simultaneously calculate the local azimuth angle of the starting point, the spherical length, and the longitude difference λ = L + δ. When approaching for the first time, take δ = 0:

[0115] p=cos u2 sinλq=b1-b2 cosλ

[0116]

[0117] sinσ=p sinα OA +q cosα OA cosσ=a1+a2cosλ

[0118]

[0119] sinA0=cosu1 sinγ OA x=2a1-(cosA0) 2 cosσ

[0120] δ=[ασ-β'xsinσ]sinA0

[0121] Coefficients α and β ＇ Calculated by the formula:

[0122]

[0123] Use the calculated δ to calculate λ1=l+δ, recalculate δ2 according to the above steps, and then use δ2 to calculate λ2, and iterate until the last two δ are the same or less than the given allowable value. λ, γ, σ, x and sinA0 all use the results of the last calculation.

[0124] like Fig.13 As shown, the geodetic azimuth angle γ of OA is calculated from the transition section center O and the pointing point A of known geodetic coordinates.

[0125] Step 6: With O as the origin of the coordinate system, the Z1 axis passes through point O and points vertically upward perpendicular to the reference plane P, the X1 axis points to point A, and the Y1 axis is determined by the right-hand coordinate system rule to establish the reference coordinate system O-X1Y1Z1, as shown in Fig.14 shown.

[0126] Step 7: According to the earth azimuth angle γ between the origin O of the coordinate system and the pointing point A obtained in step 5, that is, the rotation angle between OA and the true north of the earth, rotate counterclockwise around the Z1 axis by an angle γ. At this time, the positive direction of the X axis of the coordinate system points to the true north of the earth. The obtained new coordinate system is named O-XYZ, which is a three-dimensional space coordinate system based on the true north of the earth, such as Fig.15 shown.

[0127] like Fig. 9As shown, in the antenna system coordinate system O-XYZ with the X-axis pointing to the true north of the earth, the main reflector and feed system of the directional multi-beam antenna are installed, measured and adjusted. Three dual-band GPS receivers were used to observe the ABC triangulation network. The synchronous loop continuously observed for 12 hours. When processing GPS data in the WGS-84 coordinate system, the precise ephemeris solution of the observation station was used. The point accuracy can reach millimeter level, and the local azimuth accuracy is better than ±5″. The entire antenna installation area is about 50m×40m. The coordinate measurement accuracy of the TDRA6000 total station is ±0.7㎜, and the angle measurement accuracy is as high as 0.5″. The total station measurement system has the measurement advantage of free station setting. Therefore, the measurement position can be selected as needed in the antenna installation area, which is more suitable for on-site operations of complex projects. The geodetic north three-dimensional space coordinate system established according to the datum point of the basic workpiece of the directional multi-beam antenna can be unified with the theoretical coordinate system of the antenna structure. The conversion parameters of the geodetic north three-dimensional space coordinate system to the local coordinate system of each structural component can be obtained according to the theoretical relationship of the structural components. It is more intuitive and convenient to obtain the local coordinate system of each structural component from the geodetic north three-dimensional space coordinate system to guide the measurement and adjustment of the structural components. Finally, the pointing accuracy of the directional multi-beam antenna is better than ±0.012°, and the main beam position accuracy of the feed system relative to the main reflector is better than ±1.5㎜. Subsequently, the electrical performance index test of the directional multi-beam antenna system met the design requirements, verifying that the three-dimensional space coordinate system method based on the true north of the earth is feasible, reliable, efficient and high-precision.

[0128] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for establishing a three-dimensional space coordinate system based on true north of the earth, characterized in that: The following steps are involved: Step 1: Get the geodetic coordinates of the observation pier in the antenna system installation area: Step 1.1: Build at least three mandatory centering observation piers A, B, and C in the antenna system installation area; Step 1.2: Observe the ABC triangulation network through a satellite positioning receiver; when processing satellite positioning data in the WGS-84 coordinate system, use the precise ephemeris of the observation station to obtain the geodetic coordinates of point A, and use the calculation result of point A as the control network benchmark data for local area network adjustment to obtain the azimuth benchmark and the geodetic coordinates and Gaussian plane coordinates of points B and C, which are used as the geodetic coordinates of the origin of the coordinate system of the measuring antenna system and the azimuth benchmark for establishing a three-dimensional space coordinate system based on geodetic north; Step 2: Obtain the base workpiece reference point of the antenna system as the origin O of the coordinate system; Step 3: Obtain the geodetic coordinates and Gaussian coordinates of the base workpiece reference point of the antenna system; Step 4: Establish the coordinate system reference plane P; Step 5: Calculate the geodetic azimuth γ between the origin O of the coordinate system and the pointing point A according to the Bessel method geodetic inverse calculation formula; Step 6: With O as the origin of the coordinate system, the Z1 axis passes through point O and points vertically upward perpendicular to the reference plane P, the X1 axis points to point A, and the Y1 axis is determined by the right-hand coordinate system rule to establish the reference coordinate system O-X1Y1Z1; Step 7: Based on the earth azimuth angle γ between the origin O of the coordinate system and the pointing point A obtained in step 5, that is, the rotation angle between OA and the true north of the earth, rotate counterclockwise around the Z1 axis by an angle γ. At this time, the positive direction of the X-axis of the coordinate system points to the true north of the earth. The obtained new coordinate system is named O-XYZ, which is a three-dimensional space coordinate system based on the true north of the earth.

2. A method for establishing a three-dimensional space coordinate system based on true north of the earth according to claim 1, characterized in that: In step 1.2, three dual-band satellite positioning receivers are used to observe the ABC triangulation network, and the synchronous loop is continuously observed for 12 hours.

3. The method for establishing a three-dimensional space coordinate system based on true north of the earth according to claim 1, characterized in that: In step 2, the process of obtaining the geometric center of the antenna system basic workpiece as the origin O of the coordinate system is: using a total station to measure the geometric center or reference hole position of the antenna system basic workpiece, and obtaining the reference point as the origin O of the coordinate system.

4. The method for establishing a three-dimensional space coordinate system based on true north of the earth according to claim 1, characterized in that: In step 3, the geodetic coordinates and Gaussian coordinates of the antenna system basic workpiece reference point are obtained as follows: Step 3.1: According to the Gaussian plane coordinates (X A , Y A )、(X B , Y B ), using the Gaussian coordinate inverse formula Calculate the AB coordinate azimuth α AB ; Step 3.2: Transfer formula based on coordinate azimuth Calculate the BO coordinate azimuth α BO ; Where β is the horizontal angle ∠ABO; Step 3.3: Calculate the formula based on Gaussian coordinate increment Δ X =L BO *cosα BO D Y =L BO *sina BO X O =X B +Δ X AND O =And B +Δ Y Calculate the Gaussian plane coordinates (X O , Y O ), where L BO is the horizontal distance from point BO, Δ X , Δ Y are the increments of the Gaussian plane coordinates of point O relative to the Gaussian plane coordinates of point B; Step 3.4: Inverse calculation formula based on Gauss projection L O =L0+l Calculate the geodetic longitude and latitude L of the origin O of the coordinate system O , B O ; Where L0 is the longitude of the central meridian, l is the difference between the longitude of point O and the longitude of the central meridian L0, B f is the latitude of the bottom point corresponding to point O, M f is the meridian curvature radius, N f is the radius of curvature of the yoke, t f =tan B f , e' 2 is the second eccentricity of the reference ellipsoid.

5. The method for establishing a three-dimensional space coordinate system based on true north of the earth according to claim 1, characterized in that: In step 4, the process of establishing the coordinate system reference plane is as follows: in the 3D measurement software, create discrete points that are equal to the geodetic height of the coordinate system origin O, the plane coordinate range is consistent with the measurement area, and create the reference plane P by fitting multiple points.

6. The method for establishing a three-dimensional space coordinate system based on true north of the earth according to claim 4, characterized in that: In step 5, the process of calculating the geodetic azimuth between the origin O of the coordinate system and the pointing point A according to the Bessel method geodetic inverse calculation formula is as follows: According to the formula L=L A -L O a1=sinu1 sinu2 a2=cos u1 cosu2 b1=cos u1 sinu2 b2=sinu1 cos u2 Perform auxiliary calculations, where e 2 is the first oblate heart rate of the reference ellipsoid, (B O , L O )、(B A , L A ) are the latitude and longitude of the geodetic coordinates of points O and A respectively; Use the successive approximation method to simultaneously calculate the local azimuth angle of the starting point, the spherical length, and the longitude difference λ = L + δ. When approaching for the first time, take δ = 0: p=cos u2 sinλq=b1-b2 cosλ sinσ=p sinα OA +q cosα OA cosσ=a1+a2 cosλ sinA0=cosu1sinγ OA x=2a1-(cosA0) 2 cosσ δ=[ασ-β'xsinσ]sinA0 Coefficients α and β ＇ Calculated by the formula: Use the calculated δ to calculate λ1=l+δ, recalculate δ2 according to the above formula, and then use δ2 to calculate λ2, and iterate until the last two δ are the same or less than the given allowable value; λ, γ, σ, x and sinA0 all use the results of the last calculation.

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