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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.
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.
ITRF
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
* 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.
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.
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.
(ren/cen)