March 30, 2012
Equations: Peer-to-Peer Cooperative Positioning
Return to main article: "Peer-to-Peer Cooperative Positioning"
By Inside GNSS
Global Navigation Satellite Systems Engineering, Policy, and Design
Global Navigation Satellite Systems Engineering, Policy, and Design
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
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. ICE BREAKER
Nome, Alaska USA
√ Two 2 1/2 pound GPS-guided UAVs that tolerate extreme cold helped bring fuel to snowbound Nome, Alaska over two weeks in January. On daily photographic missions, the Aeryon Scouts helped University of Fairbanks researchers map ice thickness in the frozen harbor so a Coast Guard icebreaker could slowly guide a Russian fuel tanker close enough to pump the fuel to shore.
Why Washington continues to talk about deficits while the country is talking about jobs and foreclosures is kind of a mystery, but let’s play along.
Following the failure of Congress’s would-be budget-cutting committee that wasn’t so super, the Department of Defense is facing about $500 billion in mandatory cuts over the next 10 years.
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.
By Inside GNSS
FIGURE 2: Pseudorange computation based on transmission. On the left side, the satellites are transmitting mes¬sages synchronously. On the right side, the four subframes are received asynchronously, due to the different propagation time. The TLM word is taken as a referene. The time differences ?i are computed on the basis of the relative arrival times of the front of the first bit of the TLM word.Q: How can pseudorange measurements be generated from code tracking?
A: Every GNSS receiver processes the received signals to obtain an estimate of the propagation time of the signal from the satellites to the receiver. These propagation times are then expressed in meters to solve for the user position using trilateration.
By Inside GNSS
