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January 17, 2008

AFIT Releases GPS System Engineering Case Study

The GPS constellation, as illustrated 30 years ago.

While awaiting the arrival of the definitive history of the Global Positioning System, students of the premier GNSS program might want to take a look at a systems engineering case study released last month by the Center for Systems Engineering at the Air Force Institute of Technology (AFIT), Wright-Patterson AFB, Ohio.

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By Glen Gibbons
December 19, 2007

Additional GPS IIR-M Satellite Launched, Quickly Begins Transmitting

The U.S. Air Force launched the fifth modernized GPS Block II Replenishment (IIR-M) satellite at 3:04 p.m. EST (20:04 UTC) December 20 from Cape Canaveral Air Force Station, Florida, (December 20) aboard a United Launch Alliance Delta II rocket. Air Force controllers set the spacecraft to "healthy" status on January 2, in what is probably a record time of 13 days.

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By Glen Gibbons
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GPS Wing Exercises MUE Contract Options

The U.S. Air Force has exercised new options on contracts with three companies for development of GPS Modernized User Equipment (MUE) for future military applications.

Under the new awards, Raytheon will receive $65 million; Rockwell Collins, $50.7 million; and L-3/Interstate Electronics Corporation, $36 million. All options were awarded on or about October 19.

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By Glen Gibbons
December 7, 2007

GNSS, the Book

SpringerGeosciences has announced release of the latest book by Bernhard Hofmann-Wellenhof: GNSS — Global Navigation Satellite Systems: GPS, GLONASS, Galileo & More. Coauthors are Herbert Lichtenegger and Elmar Wasle.

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By Inside GNSS
October 6, 2007

Block IIF Satellite Heads for Key Tests

Boeing technicians and first Block IIF satellite

The Boeing Company has successfully assembled and integrated all flight hardware onto the first GPS Block IIF (follow-on generation) satellite. Launch is now scheduled for the second half of 2008.

GPS llF spacecraft will bring new capabilities to the GPS constellation, such as a new encrypted military code, a new civil signal, crosslink enhancements, increased signal power, and longer design life. Boeing is building 12 GPS Block IIF satellites under contract from the GPS Wing at the Space and Missile Systems Center at Los Angeles Air Force Base.

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By Glen Gibbons
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September 26, 2007

GLONASS has “preliminary approval” to transmit CDMA GLONASS signals at L1, L5

GLONASS has gotten “preliminary approval” to add code division multiple access (CDMA) signals to future satellites.

Since its initiation in the early 1980s, the Russian GNSS system has employed frequency division multiple access (FDMA) techniques in which the same code is used for the signals broadcast by the system, with individual spacecraft being distinguished from one another by a specific frequency allocation. Russia would almost certainly continue broadcasting FDMA signals on existing frequencies.

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By Glen Gibbons
September 15, 2007

USAF evolves GPS architecture with $800 million upgrade to ground control segment

On September 14, Air Force crews at Schriever AFB, Colorado, completed the initial phase of an $800 million upgrade to the GPS operational control segment.

Operators in the 2nd Space Operations Squadron (2SOPS) of the USAF 50th Space Wing migrated control of the GPS satellite constellation and ground monitoring facilities from a 1970s-era mainframe computer to a distributed IT infrastructure with advanced automated features. The 50th Space Wing, through the 2nd SOPS, performs the satellite command and control mission for the Global Positioning System.

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By Inside GNSS
September 9, 2007

It’s MBOC for common Galileo-GPS civil signal

The United States and the European Union (EU) have agreed to use the multiplexed binary offset carrier (MBOC) for a common GPS-Galileo signal for civilian use. In the future, this will enable combined GNSS receivers to track the GPS and Galileo signals with higher accuracy, even in challenging environments that include multipath, noise, and interference.

These signals will be implemented on the Galileo Open Service and the GPS IIIA new L1 civil signal known as L1C.

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By Inside GNSS
August 30, 2007

Sunspots Blank GNSS Receivers

Researchers at Cornell University recently released their analysis of the effects of solar radio bursts (SRBs) during a solar flare last December that produced “unprecedented” fades in received GPS signal power at L1 and L2 over an extended period.

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By Inside GNSS
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