National Executive Committee (EXCOM) for Space- Based Positioning, Navigation & Timing (PNT)

摘要

The EXCOM advises senior national government leadership and coordinates federal agencies about policy matters concerning the GPS, its augmentations, and related systems. The deputy secretaries of Defense and Transportation jointly chair the EXCOM. Executive Committee membership includes equivalent-level officials from NASA, the departments of State, Commerce, Homeland Security, Agriculture, Interior, and the Joint Chiefs of Staff. Components of the Executive Office of the President and other selected agencies participate as observers.The National Natural Resources Canada, Geodetic Survey Division Natural Resources Canada, Geodetic Survey Division operates the Canadian Active Control System (CACS), a national network of continuously operating GPS tracking stations. Products derived from CACS include GPS observation data, precise GPS orbits, and precise GPS clock corrections.The system supports the positioning requirements of a broad range of users, including the most demanding post-mission scientific applications, providing coordinates in either the Canadian Spatial Reference System (CSRS) orthe International Terrestrial Reference Frame (ITRF). An online Precise Point Positioning (CSRS-PPP) service allows GPS users from around the world to recover accurate positions from a single GPS receiver by submitting their RINEX observation data via the Internet. Information about access to CACS, data availability, and other geodetic products is available 24 hours a day from a free online subscription service (CSRS Online Database).