GPS World, March 2016

SYSTEM SYSTEMS OF GPS IIF Aloft and Active Microseconds Go Missing in GPS Ground Control Glitch 12 GPS WORLD WWW GPSWORLD COM MARCH 2016 Policy and System Developments GPS Galileo GLONASS BeiDou T he 12th and final Block IIF satellite launched on Feb 9 is active All inview tracking stations of the International GNSS Service IGS network began receiving its signals Feb 10 The satellites designation is PRN32 SVN70 The 50th Space Wing accepted satellite control authority of the GPS IIF satellite from the GPS Directorate during a ceremony held Feb 12 at Schriever Air Force Base Colorado This satellite is the last in a demanding schedule of IIF satellite launches the units have teamed together to support six launches in just 18 months said Lt Col Todd Benson on behalf of the 2nd and 19th Space Operations Squadrons SVN 70 will replace the legacy SVN 41 which will be moved to another location and provide auxiliary support to the GPS constellation The oldest GPS satellite in the constellation SVN 23 has been removed from the broadcast almanac to make room for GPS IIF 12 Launched Nov 26 1990 SVN 23 was decommissioned after 25 years of service GPS IIF 12 marks the 12th satellite launched in under six years between May 2010 and Feb 2016 and the seventh in the last 21 months said Lt Gen Samuel Greaves Space and Missile Systems Center commander and Air Force program executive officer for space This incredible track record is the result of the remarkable relationship between SMC our operators within the 14th Air Force and our ULA Boeing industry partners IGS orbit products will now cover 57 satellites 32 GPS plus 25 GLONASS T iming receivers of several companies around the world were hit by hours of system warnings after 15 GPS satellites broadcast the wrong time off by 13 microseconds on Jan 26 At 12 49 a m MST on that date the 2nd Space Operations Squadron 2 SOPS at the 50th Space Wing Schriever Air Force Base Colo verified users were experiencing GPS timing issues Further investigation revealed an issue in the GPS ground software that only affected the time on legacy L band signals This change occurred when the oldest vehicle SVN 23 was removed from the constellation While core navigation systems were working normally the Coordinated Universal Time timing signal was off by 13 microseconds which exceeded design specifications The issue was resolved at 6 10 a m MST however global users may have experienced GPS timing issues for several hours U S St r ategic Commands Commercial Integration Cell operating out of the Joint Space Operations Center effectively served as the portal to determine the scope of commercial user impacts The Joint Space Operations Center at Vandenberg Air Force Base did not receive any reports of issues with GPS aided munitions and determined that the timing error was not attributable to any type of outside interference such as jamming or spoofing Operator procedures were modified to preclude a repeat of this issue until the ground system software is corrected and the 50th Space Wing will conduct an Operational Review Board to review procedures and impacts on users Commercial and Civil users who experienced impacts can contact the U S Coast Guard Navigation Center at 703 313 5900 A week after the incident Chronos Technology reported that problems for its clients nearly 100 timing equipment users in more than 50 countries around the world continued for two days after the anomaly first appeared Telecommunications financial and utility companies among others rely on the highly precise accuracy of time measurements to control the flow of data through their networks When the 13 microsecond error was detected it produced thousands of system warnings at some companies The problem did not affect other GPS users in navigation survey transportation or other sectors