Global Navigation Satellite Systems Engineering, Policy, and Design
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 Divis
Driving across the equator in Kenya, July 2009. TomTom ONE.Engineering specialties
Optimal estimation algorithms, e.g., Kalman filters, and signal processing.
GNSS event that most signified to you that GNSS had “arrived”
By Inside GNSS
Return to main article: "Galileo’s Commercial Service"
By Inside GNSS
Return to main article: "Galileo’s Commercial Service"
By Inside GNSS
Return to main article: "Galileo’s Commercial Service"
By Inside GNSS
One of 12 magnetograms recorded at Greenwich Observatory during the Great Geomagnetic Storm of 1859
1996 soccer game in the Midwest, (Rick Dikeman image)
Nouméa ground station after the flood
A pencil and a coffee cup show the size of NASA’s teeny tiny PhoneSat
Bonus Hotspot: Naro Tartaruga AUV
Pacific lamprey spawning (photo by Jeremy Monroe, Fresh Waters Illustrated)
“Return of the Bucentaurn to the Molo on Ascension Day”, by (Giovanni Antonio Canal) Canaletto
The U.S. Naval Observatory Alternate Master Clock at 2nd Space Operations Squadron, Schriever AFB in Colorado. This photo was taken in January, 2006 during the addition of a leap second. The USNO master clocks control GPS timing. They are accurate to within one second every 20 million years (Satellites are so picky! Humans, on the other hand, just want to know if we’re too late for lunch) USAF photo by A1C Jason Ridder. 
Detail of Compass/ BeiDou2 system diagram
Hotspot 6: Beluga A300 600ST
1. 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 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 GNSS
Figure 1; Tables 1 & 2After some years of concept studies and simulations, the Galileo Commercial Service is taking off. The journey has started toward what can be the most accurate and secure worldwide satellite-based navigation services for civil use.
By Inside GNSS
