The Western Canada Deformation Array: Continuous GPS
Network Operations at PGC.

M. Schmidt, H. Dragert, Y. Lu
Geological Survey of Canada
Pacific Geoscience Centre, Sidney, B.C.

	The primary purpose of the continuous GPS program at the Pacific Geoscience
Centre (PGC) is to provide precise positional data for regional crustal
deformation analyses under the Earthquake Hazards Program of the Geological
Survey of Canada. A secondary thrust is the provision of continuous GPS data to
allow analysis of post glacial rebound in central Canada and the United States.
Data from about 20 Canadian and 30 U.S. sites operated by various agencies are
collected on a daily basis to provide the fundamental data for these scientific
tasks. Data collection for most stations of the Western Canada Deformation Array
(WCDA) is carried out at PGC on a Unix platform controlling automated script
processes that can access multiple modems on separate telephone lines. Data
retrievals are carried out at intervals of 1, 4, or 24 hours from these sites
depending on the need for closer data quality monitoring or more timely delivery
of data. Data files collected by other agencies are retrieved using automated
FTP processes executed hourly or daily.

	Both the dialup and FTP processes incorporate RINEX conversion, data
validation, and data posting. Conversions of Conan, Turbo, Trimble, and Leica
binary formats are facilitated automatically using UNAVCO's "TEQC" program. All
RINEX file header information is generated on the fly using ancillary site log
files which contain a complete time-stamped history of site meta-data. Data
validation and quality checks are done using the programs GIMP and PACE from the
Geodetic Survey of Canada, as well as UNAVCO's TEQC, all of which produce text
and plot summaries. In addition single-line summaries from each of these
processes are appended to monthly and/or yearly summary files which permit a
rapid and effective overview of day-to-day performance of individual sites.
RINEX data files are posted automatically on PGC's anonymous ftp server
(sikanni.pgc.nrcan.gc.ca) and pushed to other host computers. Once final IGS
orbits are available, subsets of daily files are automatically analyzed using
the Bernese 4.2 software to provide daily positions with a precision of a few
millimetres and daily and weekly SINEX files for ITRF densification and global
geodynamic studies.
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