Global Navigation Satellite Systems Engineering, Policy, and Design
In this article, we will take a look at the various GNSS signals from the perspective of their cost-benefit tradeoffs. First, we’ll look at the evolution of consumer GPS architecture to date — where acquisition speed and sensitivity have been the main drivers of receiver architecture. That architecture has evolved rapidly to take full advantage of the characteristics of the GPS C/A code.
By Inside GNSS
The Air Force is slowing GPS modernization and dropping part of the funding for dual launch of satellites, said defense officials describing the President’s Fiscal Year 2015 (FY15) budget on Wednesday (March 5, 2014).
Air Force Undersecretary Eric Fanning said the Air Force would continue to “honor our investments and obligations” regarding the Global Positioning System but would “reprofile” the GPS III program so that it meets constellation sustainment demands.
By Inside GNSS
Message Type 30: satellite clock data, and corrections for ionospheric and group delay. From IS–GPS–200GIn a Federal Register notice issued today (March 5, 2014), the U.S. Department of Transportation (DoT) invited public comments on U.S. Air Force plans to implement preoperational L2C and L5 civil navigation (CNAV) messages on GPS Block IIR-M and IIF satellites next month.
By Inside GNSS
Modifications in the battery charging protocol of on-orbit GPS satellites are expected to substantially extend the mission life of the spacecraft — a particularly timely development as technical and financial difficulties have raised doubts about keeping the system’s next-generation Block III satellites on schedule for launch readiness.
By Inside GNSS
Lawmakers overseeing the Coast Guard approved language this week that would stop the agency from dismantling facilities needed for eLoran, a proposed system that has gained wide support as a backup in case GPS signals are jammed, blocked, spoofed, or otherwise rendered unusable.
In “markups” or adjustments to language in the FY 2015 Coast Guard authorization bill, a House transportation subcommittee proposes to halt the tearing down of stations in the Coast Guard’s old Loran-C navigation system, which was turned off in 2010.
By Inside GNSS
The fifth GPS Block IIF satellites is scheduled for launch from Cape Canaveral on February 20 after concerns regarding a 2012 launch anomaly led the Air Force to scrub a planned launch last fall. A Delta IV M+ will carry the spacecraft into orbit.
Additional GPS IIF launches this year are tentatively set for May (Delta IV M+) and July (Atlas V rocket). The last GPS launch (GPS IIF-4) took place on May 13, 2013.
The GPS program sustained a cut of more than six percent from the levels in the president’s proposed budget for Fiscal Year 2014 (FY14), increasing the likelihood that the Next Generation Operational Control System (OCX) will be delayed and putting pressure on budgets in future years to make up for cuts to modernization efforts.
By Inside GNSS
John PorcariThe U.S. Department of Transportation (DoT) is asking the Air Force to cancel its plan to add navigation data to two key civil GPS signals this year, saying they are concerned that the approach and “nonstandard engineering tools” military officials plan to use could put GPS users at risk.
By Inside GNSS
Weiss at the helm during sailboat outing to San Juan Islands (top), Marc Weiss and wife, Pam (bottom)SIDEBAR: Marc Weiss’ Compass Points
In a career spanning nearly the entire history of GNSS-enhanced metrology, Marc Weiss has been a key participant in projects that laid the foundation for accurate synchronization of atomic clocks around the world.
By Inside GNSS
Receiver (on the right) and antenna (on the left) comprised the on-board unit used in both data collectionsWorking Papers explore the technical and scientific themes that underpin GNSS programs and applications. This regular column is coordinated by Prof. Dr.-Ing. Günter Hein, head of Europe’s Galileo Operations and Evolution.
By Inside GNSS
The GPS program is setting a new space-system standard for cyberdefense, and now the federal government is creating a framework to help operators of critical infrastructure that largely rely on GPS to do the same.
The need to raise the bar is clear. Malicious coders, often backed by hostile nation-states or criminal organizations, are using automated tools to continuously probe for weaknesses:
By Dee Ann Divis
The GPS program appears well positioned to weather another round of budget cuts, although some contractors that support the program may not be so fortunate.
“I would expect GPS will be relatively protected (with) continued investment and modernization of the satellite constellation.” said Robert Levinson, a senior defense analyst for Bloomberg Government during an October 28 briefing.
“GPS is in fairly good shape,” confirmed an expert familiar with the Air Force’s budget.
By Inside GNSS
Spirent GSS6425 Record and Playback SystemSpirent Communications has unveiled a new system for recording real-world GNSS RF signals and replaying them in the lab.
“Record and Replay” is popular as a more rigorous — and, crucially, repeatable — approach to GPS and GNSS testing than using live signals in real time, where satellite positions and atmospheric conditions are constantly changing.
By Inside GNSS
