# Presentation: 672518

## RECENT ENHANCEMENTS TO THE CDDIS

- IGS Network Systems Workshop
- November 2-5, 1998
- Annapolis, MD
- Carey E. Noll
- Manager, CDDIS
- NASA GSFC
- Greenbelt, MD

## OVERVIEW

- CDDIS has served as a global data center for the International GPS Service for Geodynamics (IGS) since its start in June 1992, providing on-line access to data from over 160 sites daily
- Operational and regional data centers (JPL, NOAA, NRCan, ESA, NIMA, etc.) deposit data
- Approximately 1 Mbyte/site/day of GPS data in compressed format are archived each day from a network of over 160 sites
- CDDIS makes RINEX observation data available with  Hatanaka compression (yyd.Z files) and without (yyo.Z files)

## OVERVIEW(Continued)

- UNAVCO’s teqc s/w run on all incoming data
- Metadata is extracted from GPS data and an on-line data base inventory is maintained to keep track of all data received
- Daily status files are generated with information extracted from RINEX header (e.g., receiver and antenna type, antenna height) as well as hour delay in delivery
- On average, 45% of all data are available to the IGS analysis centers and GPS user community within one hour of the end of the observation day; 65% are available within three hours and 75% are available within six hours

## RECENT DEVELOPMENTS

- DEC AlphaServer 4000 was purchased in 1997 and became operational July 1, 1998
- Started migration of GPS data archive from magneto-optical disks to CD-ROM
- Two-thirds of 1997 have been written to CD-ROM and are now accessible
- One year of GPS data available on-line
- All IGS products (since June 1992) are on-line
- VAX computer (cddis.gsfc.nasa.gov) utilized for tape migration, email, etc.

## CDDIS HARDWARE CONFIGURATION

- Components
- AlphaServer 4000
- 512 Mbytes memory
- ~210 Gbytes on-line magnetic disk space
- ~100 Gbytes for GPS data and products
- GLONASS, SLR, VLBI, DORIS data also on-line
- Digital UNIX
- 600 slot CD-ROM JVC jukebox
- Host name cddisa.gsfc.nasa.gov (128.183.204.168)

## NEW DATA SETS

- Hatanaka compression (yyd.Z files)
- CDDIS continues to provide access to compressed RINEX observation files (yyo.Z)
- Daily GPS data subdirectories:
- Daily status file
- O (RINEX observation data)
- D (RINEX observation data, Hatanaka compression)
- M (RINEX meteorological data)
- N (RINEX broadcast ephemeris data)
- S (output from teqc)
- Near real-time GPS data
- Hourly files, 15 minute delay
- 31 stations
- Retained for three days
- Since mid 1998

## NEW DATA PRODUCTS

- Ionosphere products
- Global ionosphere maps of total electron content (TEC)
- IONEX format
- Daily files
- Five ACs
- Since June 1998
- Troposphere products
- Combined zenith path delay (ZPD)
- Weekly files
- GFZ
- Since January 1997

## NUMBER OF HOSTS ACCESSES(1997)

## NUMBER OF GPS-RELATED FILES TRANSFERRED(1997) 

## DISTRIBUTION OF IGS USERS(1997)

## IGEX’98 CAMPAIGN

- Sponsored by IAG Commission VIII (CSTG), IGS, ION, and IERS
- Main objectives:
- Set up a GLONASS observation network
- Test GLONASS data processing s/w
- Determine GLONASS orbits of  at least meter-quality
- Connect GPS and GLONASS time systems
- Compare receiver equipment performance
- Others
- Campaign runs from Oct. 19, 1998 through January 22, 1999
- Nearly 100 receivers proposed; currently nearly 40 are operational

## IGEX’98 CAMPAIGN(continued)

- IGEX infrastructure modeled after IGS
- Both CDDIS and IGS are Global Data Centers for IGEX
- GLONASS data:
- Daily files at 30-second sampling
- Observation, GPS and GLONASS navigation files
- RINEX format
- IGEX products:
- Precise orbits, clock info, ERP
- Station coordinates
- For more information see IGEX’98 web site:
- 	http://lareg.ensg.ign.fr/IGEX

## FUTURE PLANS

- Continue migration of older GPS to CD-ROM
- Purchase additional disk space
- Implement data validation routines and check historical data
- Investigate common directory structure among IGS data centers