MGEX
Products

Precise Orbit and Clock Products

Orbit and clock products that become available as part of the MGEX data analysis are made available at the CDDIS MGEX product archive as well as mirror sites hosted by IGN and ENSG. The products are stored in weekly directories (identified by the 4-digit GPS week) and identified by a three letter analysis center ID identifying the contributing agency. Five MGEX analysis centers are presently contributing dedicated multi-GNSS products for MGEX on a routine basis:

  • Centre National d'Etudes Spatiales (CNES), Collecte Localisation Satellites (CLS), Groupe de Recherche de Géodésie Spatiale (GRGS)
  • Center for Orbit Determination in Europe (CODE)
  • GeoForschungsZentrum Potsdam (GFZ)
  • Technische Universität München (TUM)
  • Wuhan University

In addition, a copy of the QZSS final orbit and clock products generated by the Japan Aerospace Exploration Agency (JAXA) from their QZSS mission support network is made available to MGEX users on a courtesy basis.

First orbit and clock products for selecetd new constellations were provided by MGEX Analysis Center (AC) in mid 2012 (GPS week 1680). Since then an increasing number of multi-constellation products covering up to five global or regional navigation satellite systems has become available. In addition to precise ephemerides, clock products with sampling intervals down to 30 s as well as Earth orientation parameters and biases are generated by individual ACs.

An overview of products available as of Oct. 2015 is provided in the following table.

Institution ID Constellations Products References
CNES/CLS grm GPS+GLO+GAL Satellite orbits and clocks (15 min; *.sp3)
Satellite and station clocks (30 s; *.clk)
Site coordinates (*.snx)
Loyer et al. 2016
CODE com GPS+GLO+GAL+BDS+QZS Satellite orbits and clocks (15 min; *.sp3)
Satellite and station clocks (5 min; *.clk)
Earth orientation parameters (12 h; *.erp)
Biases (1 d; *.bia)
Prange et al. 2015, Prange et al. 2016
GFZ gfm,gfb GPS+GLO+GAL+BDS+QZS Satellite orbits and clocks (15 min; *.sp3)
Satellite and station clocks (30 s /5 min; *.clk)
Earth orientation parameters (1 d; *.erp)
Biases (1 d; *.bias)
Deng et al. 2014, Uhlemann et al. 2015
JAXA qzf GPS+QZS Satellite orbits and clocks (5 min; SP3) JAXA QZSS Final Products webpage
TUM tum GAL+QZS Satellite orbits and clocks (5 min; SP3) TUM MGEX webpage
Wuhan Univ. wum GPS+GLO+GAL+BDS+QZS Satellite orbits and clocks (15 min; *.sp3)
Satellite and station clocks (5 min; *.clk)
Earth orientation parameters (1 d; *.erp)
Guo et al. 2016

Orbit and clock analyses as well as SLR residuals based on the aforementioned MGEX products are posted on the MGEX Analysis web page. The analyses are updated on a weekly basis.

Broadcast Ephemerides

In addition to the aforementioned precise orbit and clock products, combined multi-GNSS broadcast ephemeris files are made available by BKG and TUM/DLR.

Institution File name Constellations Notes
BKG BRDC00WRD_R_yyyydddhhmm_01D_MN.rnx.gz GPS+GLO+GAL+BDS Converted from stream RTCM3EPH on http://mgex.igs-ip.net
TUM/DLR brdmdddn.yyp GPS+GLO+GAL+BDS +QZSS+IRNSS+SBAS

The brdm products are provided in the form of RINEX3 navigation files and made available in the annual MGEX BRDM archives of the Crustal Dynamics Data Information System (CDDIS) and the daily MGEX RINEX archives of the Institut Géographique National (IGN). BKG's product can independently be obtained from the BKG BRDC archive, which also provides near-real-time version updated at 15 min intervals in a sliding window mode.

As a special product, MGEX offers daily sets of GPS CNAV data recorded from a global subset of MGEX stations. Details of the contents and format are provided in the CNAV section of the MGEX GPS status page.

Differential Code Biases

Proper knowledge of differential code biases (DCBs) is essential in many navigation applications but also non-navigation aplciations such as ionospheric analysis and time transfer. With the plethora of new signals offered by modernized and new GNSSs, the need for a comprehensive multi-GNSS DCB product arises.

As part of the IGS Multi-GNSS Experiment (MGEX) two different DCB products are presently provided at the CDDIS and IGN product archives:

Institution Products Constellations and Signals Notes
CAS CAS0MGXRAP_yyyyddd0000_01D_01D_DCB.BSX.gz GPS(C1C,C1W,C2S/X,C2W)
GLO(C1C,C1P,C2C,C2P)
GAL(C1C/X,C5Q/X,C7Q/X,C8Q/X)
BDS(C2I,C6I,C7I)
Wang et al. 2015
DLR DLR0MGXFIN_yyyy0010000_nnu_07D_DCB.BSX.gz
DLR0MGXFIN_yyyy0010000_nnu_01D_DCB.BSX.gz
GPS(C1C,C1W,C2S/X,C2W)
GLO(C1C,C1P,C2C,C2P)
GAL(C1C/X,C5Q/X,C7Q/X,C8Q/X)
BDS(C2I,C6I,C7I)
Montenbruck et al. 2014

The DCB file names are based on a new naming scheme proposed for future MGEX products, which is inherited from the new RINEX3 file naming convenion and comprises five fields separated by underscores ("_"). The initial 10-char field specifies the analysis center (3-char), a version number (1-digit), the campaign/project (3-char) and a product type (3-char). The remaining fields provide the start epoch (11-digit year, day-of-year, hour, minute), the nominal product period (2-digit number and unit designator such as D (days), L (months), or Y (years), the sampling interval (2-digit number and unit designator), and, finally, the product type (3 chars.).

The CAS DCBs are provided in a preliminary version of the Bias SINEX (BSX) format whereas DLR used the Version 1.00 of February 2016 until I/2017 and the Version 1.00 of December 2016 starting with II/2017. The December 2016 version of the Bias SINEX format uses a 4-digit year number whereas the version of February 2016 uses a 2-digit year number for specifying the validity intervals.

The DCBs are derived from ionosphere-corrected pseudorange differences and cover all available signals of GPS, GLONASS, Galileo, and BeiDou. No DCBs are presently provided for QZSS, since the availability of only one spacecraft and the lack of a calibrated reference station do not allow a separation of satellite and station-specific DCBs.

Both DCB products offer continuous data since Jan. 1, 2013 but differ in the coverage and update rate. The satellite and station biass computed by the Institute of Geodesy and Geophysics (IGG) of the Chinese Academy of Sciences (CAS) in Wuhan are generated on a daily basis with a latency of 2-3 days and made available in daily BSX files. The DLR product is updated on a 3-monthly basis and comprises weekly averages of the satellite biases. In addition a full set of daily satellite AND station biases is provided for reference purposes and trend analyses. Note that station DCBs are not required in common positioning applications where they will typically be absorbed in clock offsets or inter-system biases.

Real-Time Products

Complementary to the multi-GNSS observation data provided in the real-time streams of individual MGEX stations, a distinct broadcast ephemeris stream (RTCM3EPH) is made available at the IGS-IP products caster. The stream is combined from a broadcast ephemerides delivered by a globally distributed set of stations and covers the complete GPS, GLONASS and Galileo constellation. For further information and alternative broadcast ephemeris streams users are referred to the BKG web page on Broadcast Ephemeris from EUREF & IGS Real-time GNSS Resources.



Last Updated: 2017/01/23 15:46:38
The Central Bureau is sponsored by the National Aeronautics and Space Administration (NASA) and managed for NASA by the Jet Propulsion Laboratory of the California Institute of Technology.