GNSS Hotspots | March 2015
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1. NAVSTAR GETS THE AX
Seal Beach, California
1. NAVSTAR GETS THE AX
Seal Beach, California
Working 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 GNSSQ: How does a GNSS receiver estimate velocity?
A: Stand-alone single-frequency GNSS receivers represent the largest slice of the commercial positioning market. Such receivers operate mainly in single point position (SPP) mode and estimate velocity either by differencing two consecutive positions (i.e., approximating the derivative of user position) or by using Doppler measurements related to user-satellite motion.
By Inside GNSSLast January, the European GNSS Agency (GSA) announced a new invitation to tender for the role of Galileo service operator (GSOp). Speaking at the recent EU Space Policy Conference in Brussels, GSA Executive Director Carlo des Dorides called it the largest contract ever to be awarded under the Galileo program.
“It will shape the future of Galileo,” he said.
By Peter GutierrezThe U.S. government appears to be closing in on a decision about whether to revive plans for an enhanced Loran (eLoran) system, as a backup for the position, navigation, and timing (PNT) information provided by GPS signals.
By Dee Ann DivisEngineering specialties
Optimal estimation algorithms, e.g., Kalman filters, and signal processing.
GNSS event that most signified to you that GNSS had “arrived”
By Inside GNSS1. SLAVE TRADE
Bangkok, Thailand
These days getting the United States, Russia, China, and Europe to agree on a common policy seems to be an increasingly rare event.
That’s why the long-standing comity among system operators in the GNSS sphere is particularly notable and welcome. “Interoperable and compatible” is the first principle espoused by the four nations under the aegis of the International Committee on GNSS.
By Dee Ann DivisA decade has passed since the first GNSS system-level authentication protocols were proposed, and yet the current ongoing discussion is still, “Do we really need GNSS signal authentication?” Indeed, the current argument is whether we need authentication at the system level (the satellite broadcast service) or whether user-based authentication (anti-spoofing) is sufficient for a number of application requirements.
By Inside GNSSNo reality show contestant ever neared the finish line without the producers serving up another challenge. And so it is for would-be multi-GNSS users in the United States.
After dodging budget cuts, thwarting other teams’ attempts to grab critical frequencies, and dealing with jamming and technical problems, members of the U.S. GNSS community were thrown another curve late last year when they learned that signals from GLONASS and other international constellations must be authorized for use in the United States.
By Dee Ann DivisIt is well known that carrier phase ambiguities are integer values. Intuitively, this is hard to understand with a common counter-argument progressing along these lines: even if the receiver measures the instantaneous phase of the incoming signal (thus removing any fractional cycle component at the receiver end), the phase of the signal at the satellite cannot be guaranteed to be zero, so how can the ambiguity be integer?
In this article we explain why the carrier phase ambiguities are indeed integer.
By Inside GNSSSIDEBAR: Frank van Diggelen’s Compass Points
“It all traces back to my parents,” says Frank van Diggelen. “My father, Tromp van Diggelen, was a surfer. He taught me to surf and swim, in that order, when I was five. I was racing sailboats before I was 10, and there’s a lot of navigation there. Even when you’re just on a lake, the racing is all about reading the wind, understanding angles of convergence, velocity-made-good, and so on.”
By Inside GNSS1. Tariffs
Beijing, China