Global Navigation Satellite Systems Engineering, Policy, and Design
After three years in Chapter 11, the company whose planned wireless broadband system threatened to overload GPS receivers across the United States is preparing to emerge from bankruptcy.
By Dee Ann DivisIt’s 10 p.m. somewhere over the vast oceans that comprise three-quarters of the Earth’s surface. Do you know where your airplane is?
Well, you could, but maybe you don’t.
The anniversary of the disappearance of Malaysia Airlines flight MH370 came and went in March with the fate of the Boeing 777 still unknown.
It didn’t have to happen.
By Inside GNSS
Equations 1 – 4Working 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
Equations 1 – 11Q: 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 GNSS
Carlo des Dorides, El?bieta Bie?kowskaLast 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 Gutierrez
Prof. David LastThe 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 DivisThese 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 Divis
A 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 GNSS
No 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 Divis
It 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 GNSSEvery so often, anthropologists — and maybe a few mathematicians — have a field day puzzling over the origins of our positional base-10 numeral system.
Oh, not the historical origins themselves, the Hindu-Arabic innovations beginning in the 5th and 6th centuries. That’s all pretty much agreed.
No, I’m referring to the possible physiological inspirations, the readily visible digits at the ends of our limbs: 10 fingers, 10 toes.
Coincidence? Does nature have coincidents, or does it abhor them like vacuums — o horror vacui?
By Inside GNSS
GPS Space Service Volume (SSV) Requirements/Performance ParametersNew space missions such as the robotic repair and recovery of damaged or errant communication satellites may become possible with the aid of an emerging class of receivers that is able to use GPS signals for navigation in orbits thousands of kilometers above the middle Earth orbit (MEO) GPS constellation itself.
By Dee Ann Divis
Russia’s involvement in the Ukraine crisis has turned much of public opinion in the West against that country, in particular souring the relationship between the European Union (EU) and Russia. And, while the ceasefire signed in September technically is still in force, the EU-Russia rift is far from smoothed over.
By Peter Gutierrez
