Monitoring & Controlling The Gps; Gps Information Sources - AvMap EKP-IV User Manual

ceiver accepts and demodulates the broadcast corrections, which are then re-
layed to the GPS receiver. The GPS receiver applies the corrections to the
navigation data it uses to compute a position solution and displays differen-
tially corrected data. Care must be taken to ensure that the DGPS receiver and
the GPS receiver are compatible for this procedure to be successful.
7.3.4 MONITORING & CONTROLLING THE GPS
The Global Positioning System is monitored and controlled by the U.S. Air
Force, which is responsible for updating and maintaining exact satellite posi-
tion and signal data accuracy. It is also responsible for performing maintenance
on the satellites, which may require the satellite being taken off-line. Since the
system is subject to periodic updates and changes, the almanac data broadcast
by the satellites is current for a limited time — generally about 14 days.

7.3.5 GPS INFORMATION SOURCES

The needs of the worldwide civil GPS user community are served by the Civil
GPS Information Center (GPSIC) in Virginia. The GPSIC is operated and
maintained by the U.S. Coast Guard for the U.S. Department of Transporta-
tion. Its primary function is to provide information on the Global Positioning
System and satellite status and to serve as a point of contact.
The GPSIC has general GPS literature available free upon request. The Center
also maintains up-to-date almanac data and Operational Advisory Broadcasts
containing current constellation status and planned satellite outages.
There are three ways to quickly obtain current information about the Global
Positioning System from the GPSIC:
1. Recorded phone message at (703) 313-5907
2. WebSite: www.navcen.uscg.mil
3. Live information at phone (703) 313-5900
There are several GPS bulletin board services outside the United States,
including:
South Africa
Germany
Norway
United Kingdom+44 (602) 422111 full access is available only to members of
There are other sources for GPS information, ranging from free, governmen-
tally produced literature to purchased professional literature and seminars. The
geography department of your local college or the local office of the National
Geodetic Survey may be able to help.
54
+27 (12) 803 8318
+49 (69) 6333 418 Internet via TELNET: 141.74.240.25
German X.25 Network, Datex-P (from Sprintnet preferred):
45050262720
+47 32124045 or +47 32118369
the UK Civil Satnav Group
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