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Aerospace and Defense

August 17, 2015

Appropriations Impasse Could Stall U.S. GPS Programs

The federal government is once again approaching the end of its fiscal year without the appropriations necessary to keep the doors open come October 1 — a reality that could undermine GPS modernization and related programs.

Congress, now in the midst of its August recess, will have just 12 days to sort things out when members return after Labor Day. Under the best of circumstances, lawmakers would almost certainly need to pass a continuing resolution (CR) to extend current spending levels and buy themselves time to hammer out budgetary deals.

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By Inside GNSS
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Officials Delay First GNSS Authorization Request; Light-Squared Tries to Leverage Issue

The U.S. stance on satellite navigation has long supported international cooperation and a degree of interoperability. In 2010 the Obama administration even adopted a space policy that said foreign satnav services could be used “to augment and strengthen the resiliency of GPS.”

That was easier in the abstract, however, when the only fully functional GNSS was GPS. Now, with other GNSS services coming online, American officials want to think things through again.

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By Dee Ann Divis
July 15, 2015

10th GPS IIF Satellite on Its Way to Orbit

The U.S. Air Force and its mission partners successfully launched the 10th Boeing-built GPS IIF satellite aboard a United Launch Alliance Atlas V from Cape Canaveral Air Force Stations today (July 15, 2015).

The spacecraft is destined for plane C/slot 3 of the GPS constellation

The launch almost coincided with Friday’s 20th anniversary of the declaration of full operational capability (FOC) for the GPS constellation, which occurred on July 17, 1995.

Just two GPS IIF satellites remain to be launched — Atlas V rockets will be used to launch both.

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By Inside GNSS
July 10, 2015

GPS Directorate Gains New Leader

Col. Steve Whitney now heads GPS Directorate

Colonel Steve Whitney was sworn in Wednesday (July 8, 2015) as the director of the Global Positioning Systems (GPS) Directorate, Space and Missile Systems Center, Air Force Space Command, Los Angeles Air Force Base, California.

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By Inside GNSS
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Software-Defined GNSS Simulator: A Step Forward

A few studies (by universities and industry) have shown the feasibility of simulation of real-time digital intermediate frequency (IF) signals based on a graphics processor unit (GPU). And a couple of articles have also demonstrated use of a universal software radio peripheral (USRP)–based software-defined radio (SDR) as a simulator (in playback mode) in real test environments.

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By Inside GNSS

First Position Fix with IRNSS

Figure 1

The Indian Regional Navigation Satellite System (IRNSS) is an Indian Space Research Organisation (ISRO) initiative to build an independent satellite navigation system that provides precise position, velocity, and time (PVT) to users across the Indian region.

The primary objective of IRNSS is to achieve position accuracy of 20 meters (2σ) for dual-frequency users over India and the primary service area (a region extending to about 1,500 kilometers or 930 miles).

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By Inside GNSS
May 20, 2015

Estimating the Short-Term Stability of In-Orbit GNSS Clocks

Global navigation satellite systems provide position, velocity, and time (PVT) solutions to users whose receivers calculate position based on one-way ranging from satellites. As is well-understood, a key step in the positioning process involves a determination of the difference between the time of signal transmission identified in the satellite’s broadcast navigation message and the time of its reception by user equipment.

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By Inside GNSS
May 14, 2015

USAF Draft RFP Would Re-Open Competition for GPS Satellite Launch Services

GPS Block IIF-5 on its way from Cape Canaveral on February 20, 2014. Photo by Ben Cooper, United Launch Alliance

[Updated May 26, 2015] The U.S. Air Force released a draft request for proposal (RFP) yesterday (May 13, 2015) for GPS III Launch Services, including launch vehicle production, mission integration, and launch operations. The Space Exploration Technologies Corporation — better known as SpaceX and headed by Elon Musk — may well enter the competition.

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By Inside GNSS
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