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Below are the recommendations resulting from the IGS Network Workshop conducted in Annapolis Maryland in November 1998. Following these recommendations is a set of action items that were clearly defined by those participating at the workshop.

Recommendations are generally made to the IGS Governing Board, require a response in terms of acceptance or rejection of the recommendation, and if accepted, follow with defined actions from the relevant IGS component(s). Recommendations and actions are then reviewed by the GB until they are completed and closed. The following recommendations will be reviewed by the Governing Board at its next meeting.

Recommendations are also to alert the GB of critical issues, such as R3 below.

Network Workshop Recommendations

R1. IGS sites should be reviewed and classified according to their functional characteristics to support various IGS applications (e.g., POD, LEO, time transfer, etc.). Compliance with published (or developing) documentation on station requirements, standards and guidelines should be reviewed for each site.

R2. Implementation of additional stations in Africa, Asia, and oceanic regions should be actively pursued to improve the robustness and geographic distribution of the IGS network.

R3. All IGS components should be aware of the Y2K and GPS week 1024 rollover issues, and carefully plan operations during these events to ensure that IGS systems will experience minimal impact. The IGS Network Coordinator will have the CBIS act as a clearinghouse for information on these issues and any plans that may develop. Test data sets and software should be made available through the CBIS to the data and analysis centers.

R4. The IGS should develop a long-term strategy for sustainable growth and development to guarantee the standardization, data quality, and longevity of the IGS infrastructure.

R5. A plan should be developed to coordinate the upgrade and standardization of a uniform, global network of IGS stations (50-100 sites) to support mm-accuracy applications (ITRF, LEO, ionosphere, troposphere, etc.), to the extent possible.

R6. A global communications solution for the IGS network data paths should be investigated, planned, and implemented.

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Network Workshop Action Items

Actions are followed by a * indicate a short note of the responsible component/person or status. Schedule for completion of all items have not yet been detailed.

Stations and Sites

Station Naming

A1. The ŒFour CharacterŒ station naming conventions must be resolved and procedures developed for adherence to this convention. The proposal forwarded by the ACs should be reviewed by all IGS components, especially the Data Centers, and a final solution must be achieved.
* CB moderate discussion and resolution.

Station changes

A2. Changes affecting the IGS stations must be carefully documented and advertised. The process for notification of station changes and historical logging of changes must be improved and defined.
* IC and CB.

A3. Guidelines for implementing and documenting hardware and/or station changes should be developed and incorporated into station guidelines documentation. The acceptance criteria for IGS stations should include physical site characteristics
* IC and NC, similar to above.

A4. An IGS working group should be formed to focus on issues of antenna calibration and radome effects.
* Question as to if this should fall within the IC and report as a subcommittee to the IC?

Future Applications

A5. Network requirements for emerging IGS projects and applications should be developed. The document ŒProcedures for Becoming an IGS Station¹ should be reviewed and amended to include additional station requirements unique to IGS projects and applications.
* IC, WG chairs and CB.

A6. Compliance with published (or developing) documentation on station requirements, standards and guidelines should be reviewed for each site (follows with station classification).
* CB and IC.

IGS Station Accreditation

A7. It is recommended that periodic "accreditation" of IGS sites be performed. An IGS site certification plaque should be presented to each station, noting period of accreditation.
* The process of accreditation should be developed after the standards and guidelines for the stations have been reviewed and accepted, including the requirements for the Œapplication networks¹. The CB and relevant components will provide input and review, especially ACC, AAC, DCs.

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A8. The 47 sites used for the IGS ITRF realization should take special care in terms of heightened awareness and advisories to users, particularly (ACs). These sites should maximize uptime, minimize changes, and notify when anomalies occur.
* Notify the relevant stations of importance. Heightened monitoring and advisories by the CB and stations managers.

Documentation Related

A9. Rigorous standardization of site logs should be implemented, with all necessary information included. Automatic site log generating and editing programs should be developed.
A. Add monument and marker information (keywords)
B. Add timing-related information (e.g., cable lengths, include modification date)
C. Review section on auxiliary information
D. Include URL of auxiliary information (CB or station/operational center)
E. Strongly remind sites to provide auxiliary information
F. Antenna part/serial number should be included in the RINEX header
* CB and IC to take action.

A10. Analysis center processing should be consistent with the current file available through the CBIS for the SINEX file information blocks.
* ACC and CB and IRFC. CB works to create consistency in the fundamental information supplied to SINEX template, ACC ensure ACs use, and IRFC provides the feedback to CB and ACC.

A11. IGS analysis centers should report solutions only for the sites that have proper documentation available through the IGS Central Bureau, e.g., DOMES number, site log file, as well as data from a least one global or regional data center.
* AC, ACs, AACs, CB and GDC, RDC. The CB will generate the list of stations with compliant documentation on the CBIS. Methods for determining cross reference of this list with data holdings and analysis reporting must be developed. CB, IC, AAC, DCs will lead.

A12. An official IGS document derived from the "Physical Site Specifications" document presented at the workshop should be generated and made available at the CBIS.
* IC and CB.

A13. File formats should be maintained across files, tables, and lists to ensure automated comparison software functions correctly.
* How to approach this -- which files? Clarify this issue, identify and prioritize specific files. IC.

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Data Center Issues

Data Quality

A14. Data Centers should implement strategies for handling low quality data, problematic data, or non-compliant station data so that these data are excluded from the analysis center submissions and IGS combination.
* It is not clear that this is a data center issue or even one that should be handled solely by the Data Centers. Refer this action to the Network Coordinator, GDC, ACC, and IC for problem resolution.

A15. A standards and guidelines document should be developed for data centers in consort with the CB. An evaluation process should be conducted for all data centers.
* GDC and CB, for standards and guidelines. The GB for the evaluation and review. Note that the new Terms of Reference incorporate the periodic review of all IGS components.

Data Flow

A16. Existing data flow paths initiated in the ŒIGS Network Benchmarking¹ should be evaluated and optimized to improve timeliness of data delivery. This includes optimizing data transfers with Œdata-push¹ philosophy techniques. Backup and redundant data flow paths should be identified and tested.
* CB and UNAVCO to complete the benchmarking. Work with DCs to review data flow between operational centers and GDCs, evaluate and document how ACs are accessing data. IC and NC to develop redundant plans for network operations.

A17. Hourly data should be incorporated into the IGS data flow at the Global Data Center level and plans developed to handle the high rate LEO data.
* GDC plans and LEO WG, CB.

Data Archiving

A18. A review of the results from SIO quality-checking program should be initiated, and issues such as plans for re-RINEXing of older data addressed. Such data operations should be performed by the data source where possible. Plans need to be developed for correcting problems found in historic data archives and for synchronizing the data center archives.
* SIO to take the lead, discussions with DCs, GDCs, ACC, and IC.

A19. IGS Data Centers should be involved with the development of the seamless archive in order to evaluate this development and assess IGS contributions and benefits.
* SIO, CDDIS, and JPL involved. Will report on progress and findings at next IGS meeting.

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Network Coordination and Monitoring

Monitoring and Communication

A20. To improve the sense of community among the responsible IGS network people, the Network Coordinator will coordinate the development guidelines, goals, and objectives for a station managers reference manual, and develop tools and recommended usage where appropriate.
* Implicit, will obtain support from other members of the IC (and UNAVCO).

A21. With assistance from regional network managers, the Network Coordinator will develop tools and compile recommendations for improved monitoring of the IGS network. Targeted communications will be used to take action on events as needed.
* ibid.

A22. Using existing metrics, the Central Bureau should be responsible for communicating with station operators regarding poor performance and/or problems in documentation of site configuration.
* Implicit, NC with support of ACC, GDC, IC where needed.

A23. The CBIS should enable communication vehicles (e.g., newsgroups, mail lists, etc.) of varying scopes for the IGS components and projects (e.g. site operations issues, data center issues, general issues, etc.) .
* CB is in process of installing a new CBIS platform with the capabilities for enabling these communications.


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Last Updated:
For further information contact: Carey Noll, CDDIS Manager, NASA GSFC