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| Center | Mountpoints* | Description |
| APM | SSR*00APM# | GPS+GLO+GAL+BDS RT orbits and clocks based on internal APM Ultra Rapid product. |
| BKG | SSR*00BKG# | GPS+GLO+GAL RT orbits, clocks and code biases based on CODE orbits and biases; yaw angle in addition. |
| CAS | SSR*00CAS# | GPS+GLO+GAL+BDS RT orbits and clocks based on GFZ orbits. |
| CAS | SSR*01CAS# | GPS+GLO+GAL+BDS RT orbits and clocks based on GFZ orbits. Also includes VTEC from Global Ionospheric Map, yaw angle, code and phase biases. |
| CAS | IONO00CAS# | VTEC from Global Ionospheric Map. |
| CHC | SSR*00CHC1 | GPS+GLO+GAL+BDS RT orbits and clocks. Also includes code and phase biases. |
| CNES | SSR*00CNE# | GPS+GLO+GAL+BDS RT orbits and clocks based on GFZ orbits. Also includes VTEC from Global Ionospheric Map, yaw angle, code and phase biases. |
| CNES | IONO00CNE1 | VTEC from Global Ionospheric Map. |
| GFZ | SSR*00GFZ# | GPS+GLO+GAL+BDS orbits and clocks based on internal GFZ orbits every 2 hours. Also includes code biases. |
| GMV | SSR*00GMV# | GPS+GLO+GAL+BDS RT orbits and clocks based on GMV-generated orbits. Stream in RTCM format delivers code biases. |
| JPL | SSRA11JPL0 | GPS RT orbits and clocks. |
| JPL | SSRA12JPL0 | GPS RT orbits and clocks. |
| JPL | SSRA21JPL0 | GPS+GLO RT orbits and clocks. |
| JPL | SSRA22JPL0 | GPS+GLO RT orbits and clocks. |
| NRCan | SSRA00NRC0 | GPS RT orbits and clocks based on hourly orbits from NRCan software. Also includes code biases. |
| SHAO | SSR*00SHA# | GPS+GLO+GAL+BDS RT orbits and clocks. Also includes code biases. |
| SHAO | SSR*01SHA# | GPS+GLO+GAL+BDS RT orbits and clocks. Also includes code and phase biases. |
| UPC | IONO00UPC1 | VTEC from Global Ionospheric Map. |
| WHU | SSR*00WHU# | GPS+GLO+GAL+BDS RT orbits and clocks based on IGU (GPS) and IGS WHU AC orbits. |
| WHU | OSBC00WHU1 | Observable Specific signal Biases (OSB) for GPS: L1/L2/L5, Galileo: E1/E5a/E5b/E6/E5, BDS-2: B1I/B2I/B3I, BDS-3: B1I/B1C/B2a/B2b/B2/B3I. Satellite orbits and clocks are fixed and used from SSRC00WHU0. Moreover, multi-frequency raw ambiguities are all fixed during the data processing of estimating phase OSBs. |
* The mountpoints prefix SSRC and SSRA indicate CoM and APC orbits, respectively.
# The last digit describes the SSR format: 1: IGS-SSR, 0: RTCM-SSR .
APM00
| RT orbit modelling | |
| Software | Bernese GNSS Software 5.4 |
| Constellation | GREC |
| Details | GPS: Nominal (yaw-steering) attitude (Kouba 2009 for eclipse), GLONASS: Nominal (yaw-steering) attitude (Dilssner et al. 2011 for eclipse), Galileo: Nominal attitude according to GSA (2019) , BeiDou-3: Yaw steering, BeiDou-2: Yaw steering + orbit normal (Dilssner et al. 2017). |
| RT clock modelling | |
| Software | MGP (Multi GNSS Processor) |
| Constellation | GREC |
| Filter | General least-square |
| Strategy | Dual-thread undifferenced clock processing strategy. |
| Observations | Dual-frequency code and phase observations in full-parameter thread and phase observations in high-rate thread. |
| Parameters | Orbits are fixed to the 3-hour prediction part of APM ultra-rapid products. Satellite/receiver clock offsets are estimated as white-noises, ambiguities are estimated as constants for each continue arc, ZWD are estimated as random-walk noises. |
| RT phase bias modelling | |
| Software | / |
| Constellation | / |
| Filter | / |
| Details | / |
| RT code bias modelling | |
| Software | / |
| Constellation | / |
| Details | / |
| RT VTEC modelling | |
| Software | / |
| Details | / |
BKG00
| RT orbit modelling | |
| Software | RETICLE (DLR) |
| Constellation | GRE |
| Details | CODE Ultra Rapid Product |
| RT clock modelling | |
| Software | RETICLE (DLR) |
| Constellation | GRE |
| Filter | Kalman filter |
| Strategy | Estimates of clock offset and drift along with other parameters using a federated Kalman-filter. |
| Observations | Dual-frequency code, phase, and C/N0 observations. |
| Parameters | Each of these filters parameterizes satellite clock offsets tracked by the receiver, one receiver clock offset for each constellation tracked by the receiver, a wet zenith delay correction to an a-priori tropospheric model, DCBs for all pseudo-range observations other than the selected clock reference signals, slant ionospheric delays and carrier-phase ambiguities for all carrier-phase observations. |
| RT phase bias modelling | |
| Software | / |
| Constellation | / |
| Filter | / |
| Details | / |
| RT code bias modelling | |
| Software | RETICLE (DLR) |
| Constellation | GRE |
| Details | CODE IGS 30-day bias solution for G/R/E satellites is introduced |
| RT VTEC modelling | |
| Software | / |
| Details | / |
CAS00
| RT orbit modelling | |
| Software | / |
| Constellation | GREC |
| Details | GBM ultra-rapid products |
| RT clock modelling | |
| Software | GNSS Data Analysis Software-RT (GNSSDAS-RT) |
| Constellation | GEC |
| Filter | Square root information filter (SRIF) |
| Strategy | Estimates of clock offset and drift along with other parameters using a federated Kalman-filter. |
| Observations | Dual-frequency code, phase, and C/N0 observations. |
| Parameters | Each of these filters parameterizes satellite clock offsets tracked by the receiver, one receiver clock offset for each constellation tracked by the receiver, a wet zenith delay correction to an a-priori tropospheric model, DCBs for all pseudo-range observations other than the selected clock reference signals, slant ionospheric delays and carrier-phase ambiguities for all carrier-phase observations. |
| RT phase bias modelling | |
| Software | / |
| Constellation | / |
| Filter | / |
| Details | / |
| RT code bias modelling | |
| Software | / |
| Constellation | GREC |
| Details | / |
| RT VTEC modelling | |
| Software | / |
| Details | / |
CAS01
| RT orbit modelling | |
| Software | Bernese GNSS Software 5.4 |
| Constellation | GEC |
| Details | combined with GBM ultra-rapid products |
| RT clock modelling | |
| Software | BDSmart-rtPCE |
| Constellation | GEC |
| Filter | Kalman filter |
| Strategy | Dual-thread undifferenced clock processing strategy, integrate estimation of clocks and phase biases. |
| Observations | Dual-frequency code and carrier-phase observations in full-parameter thread and code and carrier-range observations in high-rate thread. |
| Parameters | Float ambiguity estimations and ambiguity resolution are performed within the full-parameter module and synchronized in real time with the high-rate module along with ZWD. |
| RT phase bias modelling | |
| Software | BDSmart-rtPCE |
| Constellation | GEC |
| Filter | Least-squares |
| Details | Integrated estimation method of clocks and UPDs. Linear transformation to triple-frequency OSBs. WL and EWL ambiguities generated from MW combinations, IFCB derived from epoch-differenced GFIF combinations, and IF ambiguities obtained from the clock estimation. |
| RT code bias modelling | |
| Software | BDSMART-ION |
| Constellation | GEC |
| Details | CAS daily multi-GNSS Observation-Specific code Biases (OSBs) solutions with satellite PCO corrections applied. |
| RT VTEC modelling | |
| Software | BDSMART-rtION |
| Details | Modeling-plus-predicting approach for ionospheric VTEC modeling directly using spherical harmonic fitting. |
CHC00
| RT orbit modelling | |
| Software | CHCNAV Precise Orbit Determination (CPOD V2.0) |
| Constellation | GREC |
| Details | First, the ultra-rapid product is generated with CPOD software. Then, the self-generated product is combined with other ultra-rapid products from many analysis center including WHU,GFZ,CODE and so on. |
| RT clock modelling | |
| Software | Satellite Wide-area Augmentation System software (SWAS-PCE V3.0) |
| Constellation | GREC |
| Filter | Kalman filter |
| Strategy | / |
| Observations | Dual-frequency code and phase observation. |
| Parameters | Satellite orbits fixed to latest ultra-rapid solution; Receiver and satellite clocks estimated per epoch; ZWD estimated as random walk process; Phase ambiguities estimated as constant. |
| RT phase bias modelling | |
| Software | SWAS-UPD V3.0 |
| Constellation | GREC |
| Filter | Kalman filter |
| Details | Parameter estimation is performed using a UPD model, and the results are linearly transformed into OSB form for real-time service. WL and EWL ambiguities combinations generated from raw ambiguities based on Un-differenced and Un-combined PPP ; IFCB not estimated and absorbed by the ambiguity at the third frequency. |
| RT code bias modelling | |
| Software | / |
| Constellation | GREC |
| Details | Taken from CAS daily multi-GNSS difference code biases products. |
| RT VTEC modelling | |
| Software | / |
| Details | / |
GFZ00
| RT orbit modelling | |
| Software | EPOS-RT |
| Constellation | GRE |
| Details | Nominal yaw attitude + maneuvers; GPS IIR and IIIA based on Kouba (2008, GPS Solution), GPS IIF based on Dilssner (2010, Inside GNSS), GLONASS based on Dilssner et al. (2010, ASR), Galileo according to EUSPA meta data release. |
| RT clock modelling | |
| Software | EPOS-RT |
| Constellation | GRE |
| Filter | Recursive least-squares |
| Strategy | Recursive least-squares adjustment using a filtering approach. |
| Observations | Dual-frequency code and carrier-phase observations |
| Parameters | Satellite orbits fixed to latest ultra-rapid solution; Receiver and satellite clocks estimated per epoch; ZWD estimated as random walk process; ISBs estimated as constant; Phase ambiguities estimated as constant. |
| RT phase bias modelling | |
| Software | / |
| Constellation | / |
| Filter | / |
| Details | / |
| RT code bias modelling | |
| Software | / |
| Constellation | GRE |
| Details | Taken from daily CODE rapid product. |
| RT VTEC modelling | |
| Software | / |
| Details | / |
NRC00
| RT orbit modelling | |
| Software | Bernese GNSS Software 5.2 |
| Constellation | G |
| Details | Input orbit: CGS 1-hour prediction IGS Antenna model; GPS yaw model (Bar-Sever 1996; Kouba 2009) |
| RT clock modelling | |
| Software | HPGNSSC |
| Constellation | G |
| Filter | / |
| Strategy | Decoupled clock model estimation, reference signal of clocks: C1W/C2W |
| Observations | Dual frequency observations of 120 stations |
| Parameters | |
| RT phase bias modelling | |
| Software | / |
| Constellation | / |
| Filter | / |
| Details | / |
| RT code bias modelling | |
| Software | HPGNSSC |
| Constellation | G (C1C, C1W, C2W, C2C) |
| Details | Clocks provided are phase clocks based on decoupled clocks. Message 1265 used for YAW only because clock messages contain iono-free phase clock signal. Code biases supported also in high-rate to capture full equipment delay signal(s) |
| RT VTEC modelling | |
| Software | / |
| Details | / |
WHU00
| RT orbit modelling | |
| Software | PANDA |
| Constellation | GREC |
| Details | Nominal yaw attitude + maneuvers; GPS (Kouba 2009), GLONASS (Kouba 2013), Galileo (GSA), BDS GEO: nominal mode, BDS-2 C07, C08, C09, C10, C12, C13: yaw-steering and orbit normal mode (Guo et al. 2013). The rest BDS-2 as well as BDS-3 MEO/IGSO CAST satellites (Wang et al. 2018), BDS-3 MEO SECM satellites (Yang et al. 2023). |
| RT clock modelling | |
| Software | FUSING |
| Constellation | GREC |
| Filter | Square root information filter (SRIF) |
| Strategy | Multiple threads are used to separately handle data collection, station preprocessing, network processing, blocked matrix computation, real-time SSR correction coding and sending. |
| Observations | Dual-frequency code and phase observation. |
| Parameters | Satellite orbits fixed to 1h-prediction part of WHU NRT orbits; receiver and satellite clocks estimated as white noise process, one receiver clock for each constellation; ZWD estimated as random walk process; carrier phase ambiguities estimated as constant for each arc, with integer ambiguity-resolution applied. |
| RT phase bias modelling | |
| Software | / |
| Constellation | / |
| Filter | / |
| Details | / |
| RT code bias modelling | |
| Software | / |
| Constellation | GREC |
| Details | / |
| RT VTEC modelling | |
| Software | / |
| Details | / |
OSBC00WHU1
The real-time code and phase OSB products of WHU have now been streamed to the mountpoint OSBC00WHU1 at products.igs-ip.net. The products include multi-frequency corrections for GPS, Galileo and BDS-2/BDS-3. In detail, we calculated GPS L1/L2/L5, Galileo E1/E5a/E5b/E5, BDS-2 B1I/B2I/B3I and BDS-3 B1I/B1C/B2a/B2b/B2ab/B3I OSBs based on global-distribution IGS stations. The method for generating phase OSBs are given in Geng et al. (2022). Satellite orbits and clocks are fixed using the SSR corrections on SSRC00WHU0. Moreover, multi-frequency raw ambiguities are all fixed during the data processing of estimating phase OSBs.
| Constellation and frequencies | GPS: L1/L2/L5 Galileo: E1/E5a/E5b/E6/E5 BDS-2: B1I/B2I/B3I BDS-3: B1I/B1C/B2a/B2b/B2/B3I |
| Code OSB used | produced by WHU |
| Satellite orbit and clock used | based on SSRC99WHU0 |
| PCO correction for MW | YES |
| Ambiguity fixing | YES |
| Sampling rate | estimation intervall: 300s, sending intervall: 5s |
| Antenna PCO and PCV | IGS20.atx |
| Products convention | IGS SSR format |
| Unit | Meter |
| Mountpoint | OSBC00WHU1 |
The RTS provides combined GNSS satellite orbit and clock correction, code bias and ionosphere information. In the past IGS RTS correction were formatted according to the RTCM SSR standard for State Space Representation. Because the standard extension for other GNSS beyond GPS and GLONASS is still under development within RTCM, products are provided in the IGS-SSR format. Data streams use the NTRIP protocol. RTS corrected products refer to the International Terrestrial Reference Frame 2020 (ITRF 2020).
The product streams available in the RTS are combination solutions generated by processing individual Real Time solutions from participating Real-time Analysis Centers (RTAC). The effect of combining the different RTAC results is a more reliable and stable performance than that of any single AC’s product. Operational responsibility for the official combination products lies with the IGS Real Time Analysis Center Coordinator (RTACC).
The official products currently include multi-GNSS corrections to the satellite orbits and clocks and code biases. There are also product streams that provide Real Time combined global ionospheric models (Liu et al. 2021). All product streams are described in more detail below:
- SSRA02IGS1/SSRC02IGS1 (previously IGS02/IGC02): Kalman filter combination produced using BKG’s BNC software. The Kalman filter solution requires a few minutes convergence time to reach full accuracy. Once converged, the accuracy is maintained unless there is a reason to restart the software. A mechanism is in place to avoid publishing results during the convergence period. The orbit information is extracted from one of the incoming AC solutions. In the Kalman Filter approach satellite clocks estimated by individual Analyses Centers (ACs) are used as pseudo-observations within the adjustment process. Each observation is modelled as a linear function of three estimated parameters: AC specific offset, satellite specific offset common to all ACs, and the actual satellite clock correction which represents the result of the combination. These three parameter types differ in their statistical properties. The satellite clock offsets are assumed to be static parameters while AC specific and satellite specific offsets are stochastic parameters with appropriate white noise. The solution is regularized by a set of minimal constraints. A recursive algorithm is used to detect orbit outliers. The largest difference between AC specific and mean satellite positions is computed. If this exceeds a threshold, the corrections of the affiliated AC are ignored for the affected epoch. This product has now transitioned to the official multi-GNSS combination solution, including corrections for GPS, GLONASS and Galileo satellites. The combination is done system-wise for the reference signals as specified in the IGS RTWG and mentioned below.
- SSRA03IGS1/SSRC03IGS1 (previously IGS03/IGC03): Kalman filter combination using BKG’s BNC software (see description for SSRA02IGS1/SSRC02IGS1 above). It is a multi-GNSS product as well, including corrections for GPS, GLONASS, Galileo and BeiDou.
- IONO00IGS1: Real Time combined VTEC Global Ionospheric Model in IGS-SSR format (spherical harmonics to degree 15), with a temporal resolution of 20 minutes. The combination is performed by UPC from solutions provided by a number of Real Time Ionospheric Analysis Centers.
- IONO01IGS1:Real Time combined VTEC Global Ionospheric Model in IGS-SSR format (spherical harmonics to degree 15). The combination is performed by CAS.
| Stream Name | Description | Ref Point | IGS-SSR Messages* | Software |
| SSRA02IGS1 | Orbit/Clock Correction, Kalman Filter Combination | APC | 4076_021(10), 4076_022(10), 4076_041(10), 4076_042(10), 4076_061(10), 4076_062(10) | BKG |
| SSRC02IGS1 | Orbit/Clock Correction, Kalman Filter Combination | CoM | 4076_021(10), 4076_022(10), 4076_041(10), 4076_042(10), 4076_061(10), 4076_062(10) | BKG |
| SSRA03IGS1 | Orbit/Clock Correction, Kalman Filter Combination | APC | 4076_021(10), 4076_022(10), 4076_041(10), 4076_042(10), 4076_061(10), 4076_062(10), 4076_101(10), 4076_102(10) | BKG |
| SSRC03IGS1 | Orbit/Clock Correction, Kalman Filter Combination | CoM | 4076_021(10), 4076_022(10), 4076_041(10), 4076_042(10), 4076_061(10), 4076_062(10), 4076_101(10), 4076_102(10) | BKG |
| IONO00IGS1 | Global Ionospheric Model | 4076_201(15) | UPC | |
| IONO01IGS1 | Global Ionospheric Model | 4076_201(15) | CAS |
*The figures in brackets next to each message ID denote the message sample interval in seconds.
Content Description of the RTS Product Streams
The RTS products are disseminated in the form of IGS-SSR streams. The technical content of the RTS products is described in the table below.
Orbit corrections are provided as along-track, cross-track and radial offsets to the Broadcast Ephemeris in the Earth-centered, Earth-fixed reference frame. After applying corrections, the satellite position is referred to the antenna reference point defined in the IGS-SSR standard or to the satellite Center of Mass (CoM streams). Clock corrections are given as offsets to the broadcast ephemeris satellite clock corrections.
The SSR format provides for the dissemination of signal code biases, which are the biases to apply to the pseudo ranges for the signals that are processed in generating the RTS solution. The official RTS combination is done system-wise for the following reference signals as specified in the IGS RTWG:
- GPS: 1W/2W
- GLO: 1P/2P
- GAL: 1C/5Q
- BDS: 2I/6I
Assuming that the ACs generate ionosphere-free clocks based on their individual chosen signals, the ionosphere-free code biases for the RTS reference signals are determined from the supplied code biases. These are subtracted from each individual clock before combination, resulting in combined code-bias-free and ionosphere-free clocks. This fact can be used to set the ionosphere-free linear combination of two Observable-specific Signal Biases (OSBs; those of the reference signals) to zero in order to calculate all other OSBs. For this, the PCO-corrected satellite DCB product CAS1OPSRAP_YYYYDOY0000_01D_01D_DCB.BIA, which is computed by the Institute of Geodesy and Geophysics (IGG) of the Chinese Academy of Sciences (CAS) is used and send out as SSR code bias together with the combined clocks. These SINEX Bias files are archived at CDDIS.
Product files are extracted and uploaded to CDDIS and BKG GNSS Data Center also from the RT combined product streams SSRC02IGS1 and SSRC03IGS1:
- IGS2OPSRTS_YYYYDOY0000_01D_01M_OSB.BIA.gz
- IGS2OPSRTS_YYYYDOY0000_01D_10S_CLK.CLK.gz
- IGS2OPSRTS_YYYYDOY0000_01D_30S_ORB.SP3.gz
- IGS3OPSRTS_YYYYDOY0000_01D_01M_OSB.BIA.gz
- IGS3OPSRTS_YYYYDOY0000_01D_10S_CLK.CLK.gz
- IGS3OPSRTS_YYYYDOY0000_01D_30S_ORB.SP3.gz
Additional product streams including individual Analysis Center product streams, broadcast ephemeris and streamed GNSS observation data are available through the RT Product Distribution Centers.
References
Liu, Q., Hernández-Pajares, M., Yang, H., Monte-Moreno, E., Roma-Dollase, D., García-Rigo, A., Li, Z., Wang, N., Laurichesse, D., Blot, A., Zhao, Q., Zhang, Q., Hauschild, A., Agrotis, L., Schmitz, M., Wübbena, G., Stürze, A., Krankowski, A., Schaer, S., Feltens, J., Komjathy, A.,and Ghoddousi-Fard, R. (2021). The cooperative IGS RT-GIMs: a reliable estimation of the global ionospheric electron content distribution in real time. ESSD, 13 (9), 4567-4582. doi: 10.5194/essd-13-4567-2021
Content Description of the Broadcast Ephemeris Streams
RTS also provides real-time access to broadcast ephemeris. Several streams are generated which carry only ephemeris data and no observations. Incoming ephemeris are checked for errors and inconsistencies and then merged, encoded and uploaded to NTRIP broadcasters with a high repetition rate:
| Data Stream | GNSS | Description |
| BCEP00BKG0 | G, R, E, C, J, SBAS | Derived from receiver data of the IGS RT network. The stream is produced by BKG’s BNC software and encoded as RTCM V3 messages. The repeat interval is 5s. |
| BCEP01BKG0 | G | Similar to BCEP00BKG0 for GPS only |
| BCEP02BKG0 | R | Similar to BCEP00BKG0 for GLONASS only |
| BCEP03BKG0 | E | Similar to BCEP00BKG0 for Galileo only |
| BCEP04BKG0 | C | Similar to BCEP00BKG0 for Beidou only |
| BCEP05BKG0 | J | Similar to BCEP00BKG0 for QZSS only |
| BCEP06BKG0 | reserved for IRNS/Navic only [currently no data] | |
| BCEP07BKG0 | SBAS | Similar to BCEP00BKG0 for SBAS only |
| BCEP00CAS0 | G, R, E, C, J | Derived from data of the IGS Real-Time tracking network. The data stream is provided by CAS’s software BDSMART. This data stream does not include additional ephemeris integrity monitoring (cf. IGS-RTWG-Mail 333). |
| BCEP01CAS0 | G, R, E, C, J | Derived from data of the IGS Real-Time tracking network. The data stream is provided by CAS’s software BDSMART. This data stream is generated with CAS’s ephemeris integrity monitoring algorithms (cf. IGS-RTWG-Mail 333) [currently no data] |
| BCEP00GMV0 | G, R, E, C, J | Derived from data of the IGS Real-Time tracking network. The data stream is provided by GMV’s software magicGNSS |
| BCEP01JPL0 | G, R, E | Derived from data of the IGS Real-Time tracking network. The data stream is provided by JPL’s software GIPSY |
| BCEP02JPL0 | G, R, E | Derived from data of the IGS Real-Time tracking network. The data stream is provided by JPL’s software GIPSY |
Last Updated on 3 Dec 2025 17:00 UTC