News in 2019

14th Meeting of the International Committee on Global Navigation Satellite Systems (ICG-14)

9-13 December 2019, Bangalore, India

The Fourteen Meeting of the International Committee on Global Navigation Satellite Systems (ICG) was held in Bangalore, India from 9 to 13 December 2019. The ICG has been formed as a result of recommendations of the UN Committee on the Peaceful Use of Outer Space (COPUOS), as ratified by the General Assembly of the UN. The International Federation of Surveyors (FIG) is an Associate Member of the ICG and has been involved since the start. FIG co-chairs ICG Working Group D on Reference Frames, Timing and Applications in partnership with the International GNSS Services (IGS) and the International Association of Geodesy (IAG). I attended ICG-14 as the FIG representative to ICG.

From left to right: Allison Craddock (IGS), Jerome Delporte (CNES), and Suelynn Choy (FIG) representing Working Group D on Reference Frames, Timing and Applications at ICG-14.


The Working Group on Reference Frames, Timing and Applications (WG-D) noted significant progress on the geodetic and timing references by the GNSS Providers. Specific progress was noted: (1) the refinement of the alignments of GNSS reference frames to the ITRF, and (2) the information on the GNSS timing references and the inter-comparisons of GNSS time offsets. WG-D noted that the templates on geodetic and timing references currently provided on the ICG website should be updated by the GNSS Providers to contain the most current information.

It was noted that the work of ICG and WG-D has made significant progress in the realization of GNSS reference frames, and especially with their alignment to ITRF. This progress includes deformation of the terrestrial scale. As this work progresses into a high-accuracy positioning community service, participants are encouraged to consider how to address potential reference frame interoperability issues.

Knowledge of satellite physical and geometrical properties related to the shape, mass, optical properties, dimensions and locations of radiating antennas permits improved orbit modelling, which in turn increases the accuracy of satellite ephemerides and clock correction determination. WG-D acknowledges that there has been some progress made in the provision of satellite properties by the GNSS Providers based on the ICG Recommendation #23, and in accordance with the IGS whitepaper titled “Satellite and Operations Information for Generation of Precise GNSS Orbit and Clock Products”. The IGS collects and makes available GNSS satellite properties to the user community. Access to satellite metadata is essential for enabling scientific applications and for high accuracy precise positioning. WG-D also noted that provision of GNSS satellite phase center offset enables determination of the ITRF scale by GNSS. WG-D acknowledges the release of additional satellite metadata for QZSS, Galileo and BDS.

WG-D noted little progress on the ICG Recommendation #12. Some Providers are providing GNSS data from their tracking stations to the IGS. WG-D will continue to monitor progress. WG-D continues to contribute to the IGMA initiative, in particular through involvement in the IGMA-IGS Joint Trial Project.

WG-D noted progress on the ICG Recommendation #21 on monitoring the offsets between GNSS times. Studies have been conducted by some Providers and the timing community identifying several methods to improve their time offset determination and impact on positioning. Additional work is necessary for the Providers to assess the accuracy goals in the determination of the GNSS time offsets and impact on positioning, so as to specify a recommended method to determine and monitor them. The common session between WGs S and D concluded that a further focused workshop should address these questions in 2020 by inviting receiver manufacturers to discuss multi-GNSS positioning and interoperability.

The Task Force on Timing References of WG-D has noted significant progress related to the ICG Recommendation #20 as BIPM is on the verge of extending the provision of UTC – UTC(k)_GNSS to Galileo and BDS. WG-D also noted the excellent performance of UTCr in particular since July 2017. It is recalled that the creation of UTCr by the BIPM was initiated by the ICG Recommendation #19.

WG-D acknowledges contributions from India and presentations of NavIC time scale, time transfer and space-based clock. WG-D notes interest by NavIC to propose an update regarding the ICG Recommendation #20 in the next ICG.

With respect to education and capacity building in developing countries, WG-D members also participated in education, outreach, and community engagement projects, in partnership with WG-C. Linkages between ICG capacity building initiatives and the Sendai Framework for Disaster Risk Reduction were also introduced.

WGs D and C chairs recognize synergies between the two WGs activities in GNSS, Geodesy and Reference Frames. It is suggested and agreed by both WGs to continue to work together and contribute to capacity building on GNSS and utilisation of GNSS in Geodesy and Reference Frames.

WG-D held a joint meeting with WGs B and S to discuss “Interoperability of GNSS Precise Point Positioning (PPP) Services”. The joint meeting discussions highlighted the importance to harmonize key aspects of System Provided PPP services, which subsequently led to a recommendation to establish a Task Force under WG-S Interoperability Sub-group.


At the end of each meeting, the ICG issues a Joint Statement outlining the highlights of the broad scope of work across the ICG. Various presentations were made at the plenary sessions and working group sessions of the meeting and they form a very useful snap shot of the state of the art with the various GNSS and also with issues across key user groups.

The Joint Statement from ICG-14, working groups’ notes, all presentations and other official documentations e.g., recommendations, will be available on the ICG Information portal:

UNOOSA will host ICG-15 in 2020 in Vienna, Austria.


Suelynn Choy
December 2019