GB/T 39787-2021. Coordinate system of BeiDou navigation satellite system.
1 Scope
GB/T 39787 specifies the definition, implementation, maintenance and update requirements of the BeiDou satellite navigation system coordinate system, as well as the conversion method between the BeiDou satellite navigation system coordinate system and other geocentric coordinate systems.
GB/T 39787 applies to the construction, operation and application of the BeiDou satellite navigation system.
2 Normative references
The contents of the following documents constitute the essential provisions of this document through normative references in this text. Among them, for dated references, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies to this document.
GB/T 39267-2020 Beidou Satellite Navigation Terminology
3 Terms, Definitions and Abbreviations
3.1 Terms and Definitions
GB/T 39267-2020 defines and the following terms and definitions apply to this document.
3.1.1
International Terrestrial Reference Frameinternational terrestrial reference frame; ITRF
The coordinates and velocities of a set of globally distributed space geodetic observation stations used to implement the international terrestrial reference frame.
3.1.2
reference llipsoid
A rotating ellipsoid whose size and shape are defined by the equatorial semi-major axis and flattening, representing the earth and oriented.
3.1.3
Earth's gravity field
The collection of earth's position, gravity, geoid (or quasi-geoid), vertical deviation, etc.
3.1.4
China geodetic coordinate system 2000; CGCS2000
A geodetic coordinate system established by China. The origin of the coordinate system is located at the center of mass of the earth, the Z axis points to the direction of the reference pole (IRP) defined by the International Earth Rotation Service (IERS), the X axis is the intersection of the reference meridian plane (IRM) defined by IERS and the equatorial plane passing through the origin and orthogonal to the Z axis, and the Y axis satisfies the right-hand rule.
[Source: GB/T 39267- 2020, 2.2.5]
This document specifies the definition, implementation, maintenance and update requirements of the BeiDou satellite navigation system coordinate system, as well as the conversion method between the BeiDou satellite navigation system coordinate system and other geocentric coordinate systems. This document applies to the construction, operation and application of the BeiDou satellite navigation system.

ICS07.040
CCS A 75
National Standard of the People's Republic of China
GB/T 39787-2021
Coordinate system of BeiDou navigation satellite system
Coordinate system of BeiDou navigation satellite systemPublished on 2021-03-09
State Administration for Market Regulation
National Administration of Standardization
Implemented on 2021-10-01
GB/T 39787—2021
Normative references
3 Terms, definitions and abbreviations
3.1 Terms and definitions
3.2 Abbreviations
Coordinate system definition
Origin, scale and orientation
4.2 Reference sieve sphere
General provisions
Defined constants
Special application constants
4.2.1 Other constants
4.3 Related main models and parameters
5 Requirements for the implementation of the BeiDou coordinate system
General concepts
5.2 Requirements for BeiDou reference stations
5.3 Requirements for BeiDou observation data
5.4 Requirements for data processing
6 Requirements for the maintenance and update of the BeiDou reference frame
6.1 Requirements for maintaining the Beidou reference frame
General concepts
Maintenance requirements
6.2 Requirements for updating the Beidou reference frame
General concepts
Update requirements
7 Coordinate transformation
7.1 Transformation type
7.2 Transformation model and requirements
7.3 Selection of common points
Appendix A (current normative)
Derived geometric constant formula
Derived physical constant formula
Appendix B (normative)
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GB/T 39787—2021
This document is drafted in accordance with the provisions of GB/T 1.1-2020 Guidelines for standardization work, Part 1: Structure and drafting rules for standardization documents.
Please note that some of the contents of this document may involve patents, and the issuing organization of this document does not assume the responsibility for identifying these patents. This document was proposed by the Equipment Development Department of the Central Military Commission of China. This document is under the jurisdiction of the National Standardization Technical Committee for Beidou Satellite Navigation (SAC/IC544). The origin of this document: Xi'an Institute of Surveying and Mapping, Beijing Satellite Navigation Center. The main drafters of this document: Wei Ziqing, Wu Fumei, Liu Li, Jiao Yihai, Liu Ying, Zeng Anmin, Xu Shiyi, Fang Liu, Mingfeng, Guo Rong, Li Xiaojie and Weijia.
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1Scope
Beidou Satellite Navigation System Coordinate System
GB/T39787—2021
This document specifies the definition, implementation, maintenance and update requirements of the Beidou Satellite Navigation System coordinate system, as well as the conversion method between the Beidou Satellite Navigation System reference system and other geocentric reference systems. This document applies to the construction, operation and application of the Beidou satellite navigation system: 2 Normative referenced documents
The contents of the following documents constitute the indispensable terms of this document through normative references in the text. Among them, for referenced documents with dates, only the versions corresponding to such dates are applicable to this document; for referenced documents without dates, their latest versions (including all amendments) are applicable to this document.
G:B/T39267—2020 Beidou Satellite Navigation Terminology 3 Terms, Definitions and Abbreviations
3.1 Terms and Definitions
The terms and definitions defined in GB/T392672020 and the following terms and definitions apply to this document. 3.1.1
International Terrestrial Reference Frameinlernalionallerresrialreferenceframe; ITRF is a set of coordinates and velocities of globally distributed spatial geodetic observation stations used to implement the International Terrestrial Reference Frame. 3.1.2
reference ellipsoid
reference ellipsoid
a rotating ellipsoid whose size and shape are defined by the equatorial semi-major axis and the angular velocity, representing the earth and being positioned and fixed. 3.1.3
Earth's gravity field is the collection of the earth's position, gravity, geoid (or quasi-geoid), its linear deviation, etc. 3.1.4
2000 China geodetic coordinate system
tChina geodetic coordinate system 2000; CGCs200g is the geodetic coordinate system established by China. The coordinate system's starting point is the Earth's center of mass, its X-axis points to the reference pole (IRP) defined by the International Earth Rotation Service (IERS), the X-axis is the intersection of the reference surface (IRM) defined by IERS and the equatorial plane passing through the origin and orthogonal to the Z-axis, and the Y-axis satisfies the right-hand rule
_Source: GB/T39267—2020, 2.2.53.1.5
BeiDou coordinate system; BDCS BeiDou navigation satellite system coordinate system coordinate system ofBeiou navigation satellite system (BDS) is the geodetic coordinate system adopted by the BeiDou navigation satellite system (BDS). The definition of BDCS complies with the International Earth Rotation Service (IERS) specification and is consistent with the definition of CGCS2009.
Source: GB/T392672020, 2.2.6. Modified 1
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GB/T39787—2021
Beidou reference station BDCS reference stations A group of Beidou ground observation stations that track Beidou satellites in the Beidou coordinate system. Note: This includes the master control station, monitoring station and manned station for Beidou satellite orbit determination observation. 3.1.7
Beidou reference frame BDCSreferenceTrame reflects the coordinates and velocity of the Beidou reference station in the Beidou standard system. Note: The BeiDou multi-core frame is displayed as follows: BDCS (YYYY.DOY.YYYY represents the year, DOY represents the accumulated day of the year. BUCSYYYY.DOY) means that the frame is enabled from UTC 0:00 on the DOY day of the year YYYY 3.2
Abbreviations
The following abbreviations apply to this document:
BDS: BeiDou Navigation Satellite System BIH: Bereau Iniernalional del'Heure GNSS: Global Navigation Satellite System GLONASS: GLONASS Satellite Navigation System GPS: Global Positioning System GTRF: Galileo Terrestrial Reference Frame P7-90: P7-90 Coordinate System (Paratneterx of the Farth 1990 System)TCG: Geocentric Coordinate TimeWGS84: World Geocodetic System 1984 4 Coordinate System Definitions
4.1 Origin, Scale and Orientation
The definition of BICS is consistent with that of CGCS2000. The origin, scale, orientation of coordinate axes and their time evolution are defined in accordance with the following IERS definitions:
Origin: The center of mass of the entire Earth including oceans and atmosphere:a)
Scale: The length unit is meter (m). This scale is consistent with the TCG time coordinate of the geocentric local frame;b)
Orientation: Initially defined at 1984.0 is consistent with that of BIII: Orientation Time Evolution: The evolution of orientation with time is without global rotation relative to horizontal tectonic movements of the entire Earth. BICS is a right-angled rectangular coordinate system. The origin is located at the center of mass of the Earth, the Z axis points to the direction of the IERS reference plate, the X axis is the intersection of the IERS reference meridian and the line passing through the origin and perpendicular to the Z axis, and the Y axis completes the right-hand rectangular coordinate system, see Figures 1, 2
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4.2 Reference ellipsoid
General provisions
IF.RS reference ellipsoid
IERS reference ellipsoid
Figure 1 Beidou coordinate system reference ellipsoid
Reference ellipsoid
Earth mass center
GB/T39787-2021
BDCS reference sphere is the same as CGCS2OOO reference sphere, its geometric center coincides with the origin of BDCS, and its rotation axis is consistent with the Z input of BIDCS. BIS reference ellipsoid is also a constant ellipsoid with an equipotential surface of normal gravity field on the surface, and is defined by four constants (a+\, /, m), and the formulas and values ​​for the derivation of geometric zone numbers and physical constants should comply with Appendix A and Appendix B. 4.2.2 Definition constants
The definition constants of the BDCS reference sphere are as follows:
Semi-major axis: a=6378137.0m;
Gravity belt number including atmosphereGM (can also be expressed as n): 1-3986004.418×10-1m/: Flattening: f-1: 298.257222101;
d) Angular velocity of the earth's rotation: m=7292115.0×10+rad/sSpecial application constants
The special application constants used in the Beidou coordinate system are shown in Table 1. Table 1 Values ​​of special application constants
Used constant name
Gravity belt number excluding atmosphereGM/(m/s)Gravity constant of the earth's atmosphereGM/e/s)
Angular velocity of the earth in the precession reference frame a/(rad/s)GM=3986 030.9X10s
GM.-3.EX10
m* =7 292 11,K6 8X 10-
Wherein.
White J2000.0 Leopard bias century number T, d./36525; — since D) 2451545.0tT1's book world time (UT), received value ±0.5=1.5,±3.5..,=245545
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GB/T39787—2021
Other constants
Other constants used in the Beidou coordinate system are shown in Table 2, other effective names
Heaven and earth level position W./（m/\）
Earth position scale factor R./m
Dynamic fan rate H
Earth's principal moment of inertia A, BC/(kg·m
Related main models and parameters
Values ​​of other constants
W.= 62 686 8a6.0= 0.3Www.bzxZ.net
R-GM/W.-6363672.6_0.1
H-1/335.441 3
A - 8.C03 102 9 10
The BeiDou coordinate system should adopt the relevant models and parameters recommended by IERS, see Table 3Table 3Models and parameters recommended by BDCS
Model type
Earth gravity field model
Earth orientation parameters
Precession-nutation model
Solid crystal
Ocean tide model
Planetary ephemeris
Requirements for BeiDou coordinate system implementation
General concept
Model name
EGM2008 model
IERS Earth Orientation Parameters
IAU2000/2006 Model
IERS Model
FES2304 Model
The implementation of BeiDou reference system shall adopt special software, algorithms and models to process the observation data of BeiDou reference stations distributed around the world to obtain high-precision coordinates of BeiDou reference stations. The implementation process shall meet the requirements of BeiDou reference stations, observation data and data processing. 5.2
BeiDou Reference Station Requirements
The construction of BeiDou reference station shall avoid the following requirements: The observation pier of the reference station shall be built on stable bedrock, avoiding areas with settlement and displacement caused by unstable foundation surface; for areas that cannot be built on a
The stations on the bedrock should be treated with foundation to ensure the stability of the point position. The reference stations should be distributed evenly around the world as much as possible.
Beidou observation data requirements
Beidou reference station observation data should meet the following requirements:4
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a) Continuous measurement using BDS/GNSS receiver: GB/T39787—2021
b) The elevation angle of obstacles in the observation field of the reference station shall not exceed 15°; the reference station shall be away from high-power transmission sources, high-voltage lines and microwave radio signal transmission channels, and areas with strong electromagnetic fields; avoid areas that require strikes and environments with severe multipath effects: the observation instrument shall be forced to be centered.
Data processing requirements
The data processing implemented in the Beidou coordinate system should comply with the following requirements: Use a set of independent software for data processing and comparison: a
Select a number of globally evenly distributed, stable, reliable reference stations with a long observation time from the ITRF reference station as reference stations b)
stations (once the reference station is selected, it should be kept unchanged as much as possible): Collect data: Beidou reference station observation data, ITRF station observation data: c
Build a global network including Beidou reference stations and ITRF stations: Use loose constraints to solve the global network and obtain the relaxed solution: Use the general benchmark beam method to impose constraints on the global network to achieve the latest ITR frame alignment and obtain Beidou reference station coordinates;
Accuracy evaluation.
6 Beidou reference frame maintenance and update requirements
6.1 Beidou reference frame maintenance requirements
6.1.1 General concept
Beidou reference frame maintenance refers to processing the constructed global network data, analyzing the Beidou reference station coordinate time series, studying the coordinate change law, obtaining accurate Beidou reference station latitude, and correcting the coordinates: 6.1.2
Maintenance requirements
The maintenance of Beidou reference frame shall comply with the following requirements: use two sets of independent software for data processing and comparison; a
Collect data h)
Combined all the coordinate time series of the reference station and analyzed and processed them to obtain the reference station velocity; h)
Accuracy assessment:
Use the velocity obtained by solution to obtain the coordinates of the reference station at different solution epochs. Beidou reference frame update requirements
1 General concept
Beidou reference frame update refers to the processing of Beidou reference station data over the years to obtain Beidou reference station coordinates and their velocities aligned with the latest 1IRF frame.
2 Update requirements
Beidou reference frame update should comply with the following requirements: 5
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GB/T39787—2021
Use two sets of independent software for data processing and comparisona)
Regular update: Update once a year. Use the updated reference station coordinates and velocities to replace the previous version results. Special update: When the reference station (one or more) coordinates obtained by maintaining the solution and the currently used coordinate components exceed the limit of 3cm, an update is performed.
Frame update when the model or parameters change significantly: Collect data: all observation data of reference stations, all observation data of international IIRF stations: 1
2) Use the loose bundle to solve all global networks and obtain the relaxed solution; 3) Use the general benchmark constraint method to impose constraints on the global network to achieve alignment with the latest ITRF framework and obtain the Beidou reference station Huabiao;
4) Analyze the Beidou reference station coordinate time series to obtain coordinates and speed: 5) Accuracy evaluation.
e) Framework update when the model or parameters have not changed significantly: 1) Collect data: historical coordinate time series of reference stations, current reference station observation data, current ITRF reference station observation data; 2) Use loose constraints to solve the currently constructed global network and obtain a relaxed solution; 3) Use the international common benchmark constraint method to impose constraints on the global network to achieve alignment with the latest ITRF framework and obtain the Beidou reference station coordinates:
Analyze the Beidou reference station coordinate time series to remove various error effects and obtain the reference station coordinates and accuracy; 1)
5) Accuracy assessment
7 Coordinate transformation
7.1 Conversion type
The coordinate conversion of the North coordinate system mainly includes the conversion between BDCS and other common geocentric coordinate systems (CGCS2CO0, WGS81, GTRF, PZ-9O, etc.):
Conversion model and requirements
From coordinate system 1 to coordinate system 2, the seven-parameter model is adopted, see formula (1) X
In the formula:
ex-er-ez
Translation parameter, unit is meter (m);
Rotation parameter. Unit is radian (rad);
Scale change parameter, dimensionless,
The scope of application of the seven-parameter model depends on the consistency of coordinate accuracy or the uniformity of the network. If the coordinate accuracy of the two transformed coordinate systems is very consistent, then the national scope can be Use a set of transformation parameters. Otherwise, the transformation can be performed by region, with different transformation parameters used in different regions.
7.3 Selection of common points
The selection of common points should meet the following requirements:
Preferably, high-precision ground point coordinates in two coordinate systems are used as common points: a)
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b) Secondly, high-precision satellite positions in two coordinate systems are used as common points; ground points with high-precision precise ephemeris solutions in two coordinate systems can also be used as common points; d)
Or ground points with broadcast early ephemeris solutions in two coordinate systems can be used as common points,rrKaeerkAca
GB/T39787—2021
GB/T 39787—2021
The derived geometric constant formulas include:
Appendix A
(normative)
The derived geometric constant formulas
The first eccentricity of the meridian ellipse: The first eccentricity of the meridian circle of the BDCS reference ellipsoid is calculated according to formula (A.1) using the substitution method a
:
e—3J2+
Where:
The second-order band harmonic coefficient of the earth's force field
A w'a' e?
Geometric flattening: The geometric flattening of the BDCS reference ellipsoid is calculated according to formula (A.2): h)
or f=(ab)/a
f=1-(1-e)
Short axis: The short axis of the BDCS reference ellipsoid is calculated according to formula (A.3): ba(le)12
d) Line eccentricity: The line eccentricity of the BI)C reference ellipsoid is calculated according to formula (A.4): E-ae or E-(ah)
Polar radius of curvature: The polar radius of curvature of the BDCS reference ellipsoid is calculated according to formula (A.5): c=a(1-e)-1 or c=a/b
.(A.59
The meridian arc from the equator to the pole Length: The meridian arc length of the BIDCS reference ellipsoid from the equator to the pole is calculated according to the following formula (AS):
Q=α-e
Where:
Longitude of the earth
(l-esinB)
Precision ellipsoid area: The BIDCS reference ellipsoid area is calculated according to formula (A.7): g
h) Surface area: The BICS reference ellipsoid surface area is calculated according to formula (A.8): (1+1n1+e
i)) Arithmetic mean radius: The arithmetic mean radius of the BICS reference ellipsoid is calculated according to formula (A.9): R,=(alalb)/3
=a(1-f/3)
-u[2+ (1 —e)121/3
Radius of a sphere with the same area: 1DCS reference ball The radius of a sphere with the same area is calculated according to formula (A.10): R.=a
1—e2
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..-*.(A.6 )
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