Global Navigation Satellite Systems Engineering, Policy, and Design
Members of Congress — who have not finished next year’s appropriations, face half a dozen major tax and program fixes set to expire, and have their own re-elections to worry about — must quickly decide how to handle a tsunami of federal budget cuts that experts say could sweep the economy back into recession.
By Dee Ann Divis
Q: What are the tradeoffs between using L1-only and L1+L2 for PPP?
A: Precise point positioning (PPP) is a technique that can compute positions with a high accuracy anywhere on the globe using a single GNSS receiver. It relies on highly accurate satellite position and clock data that can be downloaded from the International GNSS Service (IGS) or obtained in real-time from a number of service providers, using either the Internet or satellite links.
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. GROWTH SPURT
California/Nevada, USA
√ The age of the Sierra Nevada mountains — home of Yosemite Valley and Lake Tahoe — is puzzling to geodesists. Integrating GPS and inSAR, Universities of Nevada and Glasgow teams studied the area’s uplift and found that it is growing by 1 to 2 millimeters per year. The verdict? The entire range could have arisen in less than 3 million years.
As Desi Arnaz often said to Lucille Ball during an “I Love Lucy” episode on TV, “You’ve got some ’splaining to do.”
I refer, of course, to the untoward and unexpected initiative by the British Ministry of Defense (MoD) to patent the technical innovations that underlie the planned next generation of civil GNSS signals.
By Dee Ann Divis
Return to main Washington View article: "USPTO Nears Approval of Troubling British Patent on New GPS Civil Signal"
By Dee Ann Divis
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 18591996 soccer game in the Midwest, (Rick Dikeman image)Nouméa ground station after the floodA pencil and a coffee cup show the size of NASA’s teeny tiny PhoneSatBonus Hotspot: Naro Tartaruga AUVPacific lamprey spawning (photo by Jeremy Monroe, Fresh Waters Illustrated)“Return of the Bucentaurn to the Molo on Ascension Day”, by (Giovanni Antonio Canal) CanalettoThe 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 diagramHotspot 6: Beluga A300 600ST1. 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
