IGS Real Time Pilot Project: Analysis Centre Activities

1. IGS Real Time Pilot Project: Analysis Centre Activities Loukis Agrotis 4 June 2008

2. Objectives Schedule Analysis Centre Status RT Processing Issues and Challenges Conclusions Outline

3. Objectives • Generation and Dissemination of a Real Time Combination Product • Accurate (clocks < 0.5 ns, predicted orbits <5 cm ) • With low latency ( <? ) • 5-10 sec from observation time should be achievable • High Availability • Low Downtime • Available to a potentially large user set • High Reliability • But with no “service guarantees” • These are for commercial providers to offer

4. April 08: AC teleconferences and formal PP kick-off June 08: Clock RINEX and SP3 Products from 3 ACs Start routine comparisons Develop and validate tools for combination solution Prototype process on ESOC FTP server (to be eventually transitioned to CDDIS) July 08: Start Disseminating Comparisons Sept 08: Batch Combination Product Jan 09: RT Product Dissemination by ACs All ACs Operational March 09: RT Combination Product Available Schedule

5. Analysis Centre Status

6. Analysis Centre Status

7. Issues and Challenges Product and Data Formats • Formats for RT products • Formats still to be defined and agreed • Main issue that could hold back progress of RT PP • Formats for Data • Predominant data formats are RTCM, RT-IGS / SOC and BINEX for GPS • Main challenge for data formats is support for generic GNSS (GLONASS, Galileo, Compass) and higher accuracies • Discussions now taking place on future requirements thanks to the good efforts of NRCan and BKG • Objective is to find the best fit among currently proposed format revisions and to influence their evolution so that our requirements are met. • Transport Protocols • NTRIP via HTTP, TCP or UDP • UDPRelay • Either or both could be used to disseminate the RT Combination Product

8. Issues and Challenges Network Issues • Excellent results are possible thanks to the contributions of a number of agencies • Large area with no network coverage results in network fragmentation. Example from 22 April shows circled stations and satellites which experienced jumps in our solution. • Densification of the network is being actively pursued

9. Issues and Challenges Network Issues • The clock correction plots show that all clocks in the South-East have jumped by the same amount, while the remaining clocks were unaffected • Several similar occurrences of this phenomenon have been observed

10. Issues and Challenges Filter Tuning Issues • Jump experienced in PRN19 at start of new pass with CAS1 • CAS1 clock appears to reset with each new pass • Changes needed to the tuning of the filter so that the CAS1 clock behaviour is better modelled

11. Conclusions • RT PP is now active, thanks to the enthusiasm and support of the participating groups, particularly NRCan and BKG. • Success of the AC activity relies on the generation of high quality RT products but also on making the correct decisions on formats and protocols to ensure a wide distribution • Densification of the network in areas of low coverage is a priority • An IGS RT service will complement and increase the usefulness of the various commercial offerings for this type of service - it should not be viewed as competition to any of the current offerings of potential participants.