ETL 1110-1-184
01 Oct 1998
the national network. For GIS data collection (using code phase
and/or where 1-meter accuracy is desired) CORS can be used as the
primary reference station, provided a station is within or near
(~150 miles) the project area. A map showing the location of the
sites can be found on the CORS homepage
(http://www.ngs.noaa.gov/CORS). When using CORS as a primary
reference or base station for code or carrier phase positioning,
it is important to identify the datum that the coordinates are
based on for those sites.
(2) Availability. CORS currently operates in an experimental
mode and will continue to do so until the network is declared
fully operational. The final system is expected to consist of
100-200 stations. At this time, NGS has not implemented full
CORS integrity monitoring. NGS will do its best to ensure the
reliability of this service, but in the interim, users of the
CORS data should be aware that NGS can not guarantee:
-- All current sites will be operational at all times or
will be kept as part of the final network configuration;
-- All posted GPS data, positional information, utility
software, or ancillary is 100 percent correct and without
error; and
-- Any additional proposed sites will remain operational or
will be kept as part of the network.
(3) Accessing the Data. To use the CORS network, the user
must have Internet access and make sure the post-processing
software accepts RINEX 2 data. Data for each site is stored on
the CORS homepage for a period of 31 days. Data collected before
the 31-day on-line period can be obtained from NGS through a
special request. However, this request is limited to no more than
15 days of data for one station per request or equivalent space
for several sites. Beyond this amount, NGS may charge a fee for
processing the request.
(4) Additional Information.
Appendix B provides more
information on the CORS system.
7. Proponency and Technical Support. The HQUSACE proponent for
this technical letter is Engineering Division, Directorate of
Civil Works, ATTN: CECW-EP. Technical assistance may be obtained
from the Geospatial Engineering Branch, U.S. Army Topographic
Engineering Center, ATTN: CETEC-TD-G, 7701 Telegraph Road,
Alexandria, VA 22315-3864, (703) 428-6767.
FOR THE COMMANDER:
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