MGEX
BeiDou

This page provides an overview of the Satellites in the BeiDou Navigation Satellite System (BDS). Technical parameters of the indivdual satellites and related conventions applied within the MGEX project are summarized in the Spacecraft Characteristics section. Furthermore, a list of Events of interest for the BDS data processing is given.

Satellites

The regional BeiDou Navigation Satellite System (BDS-2, earlier referred to as COMPASS) comprises a total of 15 launched satellites out of which 13 were fully operational in 2015.

In mid 2015, China started the build-up of the 3rd generation BeiDou system (BDS-3) which will shall offer a fully global navigation service by 2020. So far, 5 BDS-3 in-orbit validation satellites have been launched.

BeiDou-2
Common Name SVN Int. Sat. ID NORAD ID PRN Notes
BEIDOU M1 C001 2007-011A 31115 C30 Decommissioned
BEIDOU G2 C002 2009-018A 34779 n/a Inactive; uncontrolled
BEIDOU G1 C003 2010-001A 36287 C01 140.0° E
BEIDOU G3 C004 2010-024A 36590 C03 110.5° (moved from 84.0° to new position between Nov 7 and 22, 2012)
BEIDOU G4 C006 2010-057A 37210 C04 160.0° E
BEIDOU IGSO 1 C005 2010-036A 36828 C06 ~122° E
BEIDOU IGSO 2 C007 2010-068A 37256 C07 ~119° E
BEIDOU IGSO 3 C008 2011-013A 37384 C08 ~120° E
BEIDOU IGSO 4 C009 2011-038A 37763 C09 ~96.5° E
BEIDOU IGSO 5 C010 2011-073A 37948 C10 ~92.5° E
BEIDOU G5 C011 2012-008A 38091 C05 58.75° E
BEIDOU M3 C012 2012-018A 38250 C11 Slot A07
BEIDOU M4 C013 2012-018B 38251 C12 Slot A08
BEIDOU M5 C014 2012-050A 38774 C13 Slot B03; End of signal transmission 21 Oct. 2014
BEIDOU M6 C015 2012-050B 38775 C14 Slot B04
BEIDOU G6 C016 2012-059A 38953 C02 80.3°E
BEIDOU IGSO 6 C017 2016-021A 41434 C15/C13 ~95° E; launched 2016/03/29; PRN switch from C15 to C13 on 2016/10/11
BEIDOU G7 C018 2016-037A 41586 C17 launched 2016/06/12

BeiDou-3
Common Name SVN Int. Sat. ID NORAD ID PRN Notes
BEIDOU I1-S C101 2015-019A 40549 C31 launched 2015/03/30
BEIDOU M1-S C102 2015-037A 40748 C33 Slot A06, launched 2015/07/30
BEIDOU M2-S C103 2015-037B 40749 C34 Slot A01, launched 2015/07/30
BEIDOU I2-S C104 2015-053A 40938 C32 launched 2015/09/29
BEIDOU M3-S C105 2016-006A 41315 C35 Slot B01; launched 2016/02/01

In the absence of official space vehicle numbers (SVNs), preliminary numbers for the above satellites have been assigend for use within the MGEX project based on the launch sequence of the respective spacecraft. PRN numbers have been associated with the individual satellites based on comparison of transmitted ranging codes with code sequences in the BeiDou Interface Control Document (ICD). The latest version of the Open Service Signal ICD ( BeiDou Navigation Satellite System Signal In Space Interface Control Document - Open Service Signal (Version 2.1)) covers the B1I and B2I signals and has been released in November 2016.

Spacecraft Characteristics

A comprehensive collection of technical information with associated references for the BeiDou satellites can be obtained at the CNSS page of ESA's eoPortal .

BeiDou-2
Parameter GEO IGSO MEO
Launch mass 4600 kg 4200 kg
Dry mass 1550 kg 1900 kg
Body size ~1.8 m x ~2.2 m x ~2.5 m ~1.8 m x ~2.2 m x ~2.5 m ~1.8 m x ~2.2 m x ~2.5 m
Solar array size 2 x 3 x 2.2 m x 1.7 m 2 x 3 x 2.2 m x 1.7 m 2 x 3 x 2.2 m x 1.7 m
Span width ~17.7 m ~17.7 m ~17.7 m
Cross section ~27 m2 ~27 m2 ~27 m2
SRP acceleration 102 nm/s2 122 nm/s2

The BeiDou-2 spacecraft are equipped with broadband GNSS antennas for the B1, B2, and B3 frequency bands as well as a laser retroreflector array (LRA) for satellite laser ranging.

The BeiDou-3 will transmit legacy B1 signals similar to the BeiDou-2 satellites as well as modernized signals in the L1, E5, and B3 band.



Fig. 1 Spacecraft reference system and sensor location for the IGSO/MEO (left) and GEO satellites (right) of the BeiDou-2 regional navigation system. Reproduced from DOI 10.1016/j.asr.2015.06.019 with permission of Elsevier; satellite images courtesy CSNO.

Phase center coordinates of the BeiDou-2 GNSS antenna and the LRA as recommended for use within the MGEX project are provided in the following table. A machine-readable version of the phase center offset information for each satellite is provided as part of the IGS08 ANTEX product.

All values refer to the IGS-specific spacecraft coordinate system illustrated in Fig. 1. This system is aligned with the main body axes and originates in the plane opposite to the antenna. For all three spacecraft types
  • the +zIGS-axis is oriented along the boresight direction of the antenna,
  • the +yIGS-axis is parallel to the rotation axis of the solar panels, and
  • the +xIGS-axis completes a right handed system.
The detailed orientation of the +xIGS and +yIGS-axes for the BeiDOu-2 satellites is defined as shown in the drawings. The GNSS antenna is shifted in +xIGS-direction relative to the center of the front panel, while the LRA is located in the -xIGS/-yIGS-corner. On GEO satellites, the +xIGS-panel holds the C-band telecommunication antenna.

BeiDou-2 GEO/IGSO/MEO
  Coordinates (w.r.t. origin) Coordinates (w.r.t. CoM) Reference
xIGS yIGS zIGS xIGS yIGS zIGS
GNSS Antenna B1, B2, B3       +600.0 mm 0.0 mm +1100.0 mm
LRA G1 +1152.0 mm +0.2 mm +0.0 mm [1]
I3, I5 +1075.6 mm +0.0 mm -0.4 mm [1]
M1, M3 +1082.0 mm -0.4 mm -0.5 mm [1]
CoM (BoL) G1 +608.8 mm -570.2 mm +1093.0 mm       [1]
I3, I5 +673.0 mm -573.0 mm +1093.0 mm       [1]
M1, M3 +649.9 mm -562.5 mm +1112.3 mm       [1]

For the modelling of satellite laser ranging measurements nominal coordinates of the effective LRA reflection point have been specified by the China Satellite Navigation Engineering Center as part of the ILRS mission support request.

Due to a lack of publicly available antenna phase center offsets for the BeiDou satellites, conventional values of (+0.6 m, 0.0 m, +1.1 m) are recommended for orbit and clock determination of the BeiDou-2 GEO/IGSO/MEO satellites until further notice. The values provide a first estimate of the actual phase center relative to the center of mass based on the images and models.

Based on actual BeiDou GNSS observations, refined x-offsets of about +0.55 m values and z-offsets of 3-4 m and 2.0-2.5 m have been determined in [2] for the BeiDou-2 IGSO and MEO satellites, respectively, using a ionosphere-free B1/B2 combination. Even larger z-offsets were obtained for the ionosphere-free B1/B3 combination.

The attitude of the BeiDou satellites is actively controlled to orient the +zIGS axis towards the Earth. For the MEO and IGSO satellites a yaw steering attitude is employed, in which the satellite is continuously rotated about the +zIGS axis to maintain the yIGS-axis perpendicular to the plane made up by the Sun, Earth, and satellite. Similar to the IGS satellites, the +xIGS-axis is pointed towards the sun-lit hemisphere. For the GEO satellites an orbit normal mode is adopted, in which the +yIGS is oriented perpendicular to the orbital plan. The orbit normal mode is also employed by the MEO/IGSO satellite when the Sun elevation above the orbital plane is less than about 4°. An overview of BeiDou-2 attitude modes and related mathematical formulations are provided in [3]. Mode transitions at low β-angles are further discussed in [4].

References

[1] ILRS BeiDou (COMPASS) Center of Mass Information
[2] Dilssner F., Springer T., Schönemann E., Enderle W.; Estimation of satellite antenna phase center corrections for BeiDou. IGS Workshop, Pasadena, California, USA (2014).
[3] Montenbruck O., Schmid R., Mercier F., Steigenberger P., Noll C., Fatkulin R., Kogure S., Ganeshan A. S. (2015) GNSS satellite geometry and attitude models. Advances in Space Research 56(6):1015-1029. DOI 10.1016/j.asr.2015.06.019
[4] Dai X., Ge M., Lou Y., Shi C., Wickert J., Schuh H. (2015) Estimating the yaw-attitude of BDS IGSO and MEO satellites. Journal of Geodesy 89(10):1005-1018. DOI 10.1007/s00190-015-0829-x

Events

Date UTC Satellite PRN Description Notes
2012/04/06 ~05:00 G1 C01 E/W Maneuver dV=-0.09 m/s TUM/DLR orbit analysis
2012/05/02 11:01 G1 C01 E/W Maneuver dV=-0.10 m/s TUM orbit analysis
2012/05/28 08:59 G1 C01 E/W Maneuver dV=-0.10 m/s TUM orbit analysis
2012/04/16 ~09:00 G3 C03 E/W Maneuver dV=-0.08 m/s TUM/DLR orbit analysis
2012/04/23 07:32 G4 C04 E/W Maneuver dV=-0.03 m/s TUM orbit analysis
2012/04/10 n/a G5 C05 E/W Maneuver dV=+0.13 m/s TUM/DLR orbit analysis
2012/05/23 n/a G5 C05 E/W Maneuver TUM orbit analysis; badly observed
2012/05/09 08:40 I1 C06 Maneuver dV(RTN)=(0.00,-0.45,+0.18) m/s TUM orbit analysis
2012/05/16 10:00 I2 C07 Maneuver dV(RTN)=(0.00,-0.57,-0.40) m/s TUM orbit analysis
2012/04/27 01:00 I4 C09 Maneuver dV(RTN)=(-0.05,-0.32,-0.06) m/s TUM orbit analysis
2012/05/06 08:18 M3 C12 Start of signal transmission CONGO/MGEX monitoring
2012/05/06 10:04 M2 C11 Start of signal transmission CONGO/MGEX monitoring
2012/09/25 M5 C13 Start of signal transmission Trimble/CONGO/MGEX monitoring
2012/09/25 M6 C14 Start of signal transmission Trimble/CONGO/MGEX monitoring
2012/11/01 G6 C02 Start of signal transmission Trimble monitoring
2012/11/22 G3 C03 Moved from 84.0°E (before 2012/11/01) to 110.5°E CANSPACE
2014/10/21 04:15 M5 C13 End of signal transmission MGEX monitoring
2015/05/04 I1-S C31 Start of signal transmission MGEX monitoring
2015/07/31 3M1 C33 Start of signal transmission MGEX monitoring
2015/08/08 3M2 C34 Start of signal transmission MGEX monitoring
2015/10/05 I2-S C32 Start of signal transmission MGEX monitoring
2016/04/06 I6 C15 Start of signal transmission MGEX monitoring
2016/10/11 4:52 I6 C15 End of signal transmission MGEX monitoring
2016/10/11 7:42 I6 C13 Restart of signal transmission with different PRN MGEX monitoring


Last Updated: 2017/04/05 06:34:48
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