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| Science Forum Index » Geology - Satellite Navigation Forum » Upgrade of GPS Control System to Be Tested... |
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| Sam Wormley... |
 Posted: Tue Oct 27, 2009 5:55 pm |
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Upgrade of GPS Control System to Be Tested
http://www.gpsworld.com/gnss-system/news/upgrade-gps-control-system-be-tested-9063?print=1
October 22, 2009
You may have seen the somewhat cryptic NANU, a Notice Advisory to Navstar Users, issued by
the Air Force’s 2nd Space Operations Squadron (2SOPS) a few days ago:
TWO SVS WILL BE USED FOR TESTING IN A HEALTHY STATUS DURING UPCOMING TE#4. SVN 30/PRN 30
WILL BE USED ON 29 OCTOBER/J302 AND SVN 54/PRN 18 WILL BE USED ON 30 OCTOBER/J303.
This general message to all GPS users was accompanied by a series of NANUs forecasting
outages of PRN30 and PRN18 over a two-week period extending from 23 October to 4 November.
So, what is “TE#4” and why are PRN30 and PRN18 being used?
TE#4 is Transition Exercise #4 and refers to testing of a new version of the Architecture
Evolution Plan (AEP) — the new GPS control segment and its associated software. The
current software version operated at Schriever AFB is 5.4. TE#4 involves the transition to
AEP 5.5. As described by Lt. Col. Deanna Burt, commander of 2 SOPS, “AEP 5.5 brings on
line the ability to command and control the new IIF satellites as well as an over the air
rekey and distribution system for our military P(Y) users. This alleviates the
requirement for military users to carry a paper [cryptographic] key and to have to
continually reload to gain access to the P(Y) code.”
Testing of AEP 5.5 will be carried out from the Alternate Master Control Station at
Vandenberg AFB using two satellites, PRN30 and PRN18. These two satellites will be set
unhealthy at times during the test period. PRN30 is a Block IIA satellite while PRN18 is a
non-modernized Block IIR satellite. According to Lt. Col. Burt, these two satellites were
chosen based on position dilution of precision calculations to ensure that the outages
would not significantly impact the user community.
TE#4 is the last development checkout of AEP 5.5 before 2 SOPS goes live with the new
software in late November. The testing over the next two weeks will ensure that all
aspects of the software have been thoroughly checked so that when it goes on line it will
be transparent to users.
Software version 5.5 is the last major software modification in the AEP. |
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