[IGSMAIL-5623]: GPS control segment upgrade

[Jim.Ray]

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IGS Electronic Mail      30 Jul 11:22:06 PDT 2007      Message Number 5623
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Author: Jim Ray (forward to GPS users)

The U.S. Air Force has announced that a major upgrade is
planned for the GPS control segment (referred to as the
Architecture Evolution Plan, or AEP).  AEP will swap out
the entire master control station, which uses a 1970s-era
legacy system, to a modern design based on current
technology.  Among other things, this change is required
in order to implement new capabilities, such as the next
generation of IIF satellites.

The AEP change is scheduled to occur during the second week
of September, over a period of 4-6 days.  The transition will
phase in a few satellites at a time and will be completely
reversible if anything goes wrong.  Before it begins, the
old and new ground control systems will be synchronized to
the millimeter level so that the most demanding users will
experience a seamless change.

The civil community has been asked to disseminate the word
about the upcoming change as widely as possible.  Should any
anomalies be detected during the transition period, users
should follow the normal notification procedures via the U.S.
Coast Guard Navigation Center (www.navcen.uscg.gov).