TAG: Block IIF satellite

U.S. Air Force puts more power into GPS Block IIR-M C/A-code

April 1, 2017By
Figure 2. Plot of L1 C/A-code C/N0 over time for consecutive passes of satellite PRN 05 (SVN 50) tracked by a Leica GR10 receiver located in Kourou, French Guiana, on Feb. 6–8, 2017. The satellite’s unhealthy period on Feb. 7 is indicated by the gray shaded area.

By Peter Steigenberger, André Hauschild, Steffen Thoelert and Richard B. Langley Between Feb. 7, 05:02 UTC and Feb. 8, 12:30 UTC, 2017, all seven operational GPS Block IIR-M satellites were consecutively subject to short periods of unavailability. These official outage periods, when the satellite signals were set unhealthy and deemed unusable, were announced ahead of time through Notice Advisories to... read more

Air Force successfully launches GPS IIF-12 satellite

February 8, 2016By
A United Launch Alliance (ULA) Atlas V rocket carrying the GPS IIF-12 mission lifted off from Space Launch Complex 41 at Cape Canaveral. (Photo: ULA)

The U.S. Air Force successfully launched the 12th Boeing-built GPS IIF satellite aboard a United Launch Alliance Atlas V Evolved Expendable Launch Vehicle from Space Launch Complex 41, Cape Canaveral Air Force Station, Fla., at 8:38 a.m. EST (5:38 a.m. PST) on Feb. 5. “Today’s launch is a significant achievement in the history of GPS, as we launch the last of... read more

GPS Glitch Two Years Older than First Stated

April 15, 2015By

On Wednesday, the GPS Directorate said further data analysis shows that a technical error affecting some Boeing GPS IIF satellites first appeared in 2011, two years earlier than originally stated, according to a Reuters report. The error first appeared one year after the GPS IIF satellites became operational. The error affects the way the ground control system builds and uploads messages transmitted by the satellites, but... read more

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GPS IIF-9 Launches Wednesday

March 23, 2015By

The U.S. Air Force’s ninth GPS Block IIF satellite (GPS IIF-9) is set to launch Wednesday at 2:36 p.m. EDT (1836 GMT)  from Space Launch Complex 37 at Cape Canaveral Air Force Station, Fla. The GPS IIF-9 will ride aboard a United Launch Alliance (ULA) Delta IV rocket, marking the 29th Delta IV launch and the 57th operational GPS satellite to launch on... read more

Air Force Working on Glitch for GPS IIF Satellites

March 23, 2015By

The U.S. Air Force is working to resolve a technical error that affected some Boeing GPS satellites, according to a report by Reuters. The error does not affect the accuracy of GPS signals. It involves the ground-based software used to index some messages transmitted by GPS IIF satellites built by Boeing, Air Force Space Command said according to Reuters. Still, officials are investigating other possible causes.... read more

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CNAV Performance ‘Matches or Slightly Outperforms’ Legacy Signals

March 19, 2015By

A quarterly meeting of the U.S. GPS Program’s interagency Civil Navigation Signals (CNAV) Tiger Team on March 5 focused on the new L2C and L5 GPS civil signals. “CNAV Message Types 10, 11, 30 and 33 are currently transmitted on seven GPS IIR-M (L2C) and eight GPS IIF satellites (L2C and L5),” wrote Rick Hamilton, CGSIC Executive Secretariat, USCG Navigation Center, in a status email to the Civil Global Positioning System Service... read more

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The System: Three’s the Challenge

August 1, 2010By

A small variance in the L5 signal, which remains well within signal specifications and will not affect pseudorange measurements, may show some impact on triple-frequency combinations of the signal’s carrier phase in high-precision applications. Observations suggest a temperature-dependent line bias in one or more carriers as a likely cause of the observed variation in the tri-carrier combination of L1, L2, and L5. read more

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Parkinson Prescribes Remedy for GAO Report Alarm

May 26, 2009By

Brad Parkinson, the first GPS Program Office director, chief architect and advocate for GPS, submitted written testimony to Congress on mitigation options for possible GPS brownouts. His presentation comes in reference to the recent GAO report highlighting the risk that the GPS constellation may fall below the minimum level of 24 satellites required for full operational capability. In his opening, Parkinson states that GAO correctly points out the possibility that the GPS constellation will be reduced to less than the current number of 30 to 32 satellites. In fact, it is possible that the constellation will be at a level of less than 24 satellites. I would like to focus on the options that would help reduce this risk." read more