Global Navigation Satellite Systems Engineering, Policy, and Design
Global Navigation Satellite Systems Engineering, Policy, and Design
FIGURE 2: Example of a national geoid (upper diagram) and a correction surface for the transformation from the new orthometric height system to the old height system (lower diagram). Country is Switzerland. Geoid undulations range from 45 to 55 meters in ETRS89 and from -5 to +5 meters in the national System CH1903+. Lower diagram: Correction surface to transform from the new orthometric height system (LHN95) to the old height system LN02 with corrections from -0.10 to 0.55 meters.Q: How do GNSS-derived heights differ from other height systems?
A: Height estimation using GNSS always seems to be trickier than horizontal coordinate estimation.
Why?
On the one hand, the GNSS technique has error sources that are more critical in the vertical direction. Height estimates are weaker because of a combination of satellite geometry, the presence of strong correlations to other parameters, such as atmospheric delays, and the antenna phase center model applied during data analysis.
By Inside GNSS
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 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. DEAD IN THE WATER
San Francisco, California and Washington D.C., USA
Return to main article: "Peer-to-Peer Cooperative Positioning"
By Inside GNSS
Return to main article: "Peer-to-Peer Cooperative Positioning"
By Inside GNSS
Oh no! Not another learning experience!
Bumper sticker wisdom after the fact, but better late than never.
As this issue of Inside GNSS heads off to the printer, the regulatory phase of the GPS/LightSquared controversy appears to be winding down, and the litigation phase warming up.
By Dee Ann Divis
The firefight between LightSquared and the GPS community has sparked regulatory brush fires around Washington with the Federal Communications Commission (FCC), Congress, a half dozen executive agencies, and numerous companies moving to address a new and likely larger battle over receiver standards, radio frequency spectrum efficiency, and RF spectrum protection.
By Dee Ann Divis
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.
Q: What is Coarse Time Positioning and how does it work?
A: Coarse time positioning is used to provide a position fix using inaccurate time information when tracking sufficiently weak GNSS signals such that the navigation message cannot be extracted reliably. This article presents the key aspects of coarse positioning, including some of its challenges. To start, however, we begin by looking at the role of time within a GNSS receiver.
By Inside GNSS
Return to main article: "Code Tracking and Pseudoranges"
By Inside GNSS
