Global Navigation Satellite Systems Engineering, Policy, and Design
Q: What is a maximum likelihood vector tracking receiver?
A: Vector tracking in GNSS receivers is based on the idea that instead of tracking each satellite’s signal separately, all signals are ultimately related to the position and velocity of the user antenna and thus can be tracked collectively. (See the discussion in this column in Sept/Oct 2012 issue of Inside GNSS by Drs. Lashley and Bevly for more information.)
By Inside GNSS
Every breath you take . . .
Every move you make
Every step you take
I’ll be watching you
I originally planned on titling this column, “Waiting to Inhale,” recalling these lyrics and an editorial I wrote more than four years ago about my sense of relief at the departure of the second Bush administration.
I called that one, “Waiting to Exhale.”
By Inside GNSS
EquationsWorking 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
[Updated June 3, 2013] With the budget vise tightening, top Pentagon managers are readying some potentially dramatic changes to the GPS constellation — changes that promise to lower both the cost of the satellites and the expense of putting them into orbit.
The first changes would be subtle and are linked to buying the next block of GPS III satellites — a decision that sources confirm will be made by the end of September.
By Dee Ann Divis
The fourth China Satellite Navigation Conference (CSNC 2013) wound up its three-day run on May 17 in Wuhan — by all measures a clear success for an event that has become the nation’s leading international GNSS forum.
A key take-away from the event: China is rapidly preparing to bring BeiDou products and technology into the international marketplace is encouraging its industry to build an internationally applicable knowledge base in standards, patent law, and intellectual property rights (IPR).
By Inside GNSS
Di Qiu at the site of her current employerSIDEBAR: Di Qiu’s Compass Points
Landing all-weather aircraft safely in storms. Protecting sensitive data not only through encryption but based on the location at which it is being accessed. Ensuring that accurate and timely information reaches first responders responding to emergencies.
Although still in the early part of her career, Di Qiu has already made significant contributions to these crucial applications of navigation technology.
By Inside GNSS
Taylor’s SeriesEngineering Specialties
Engineering Mentors
By Inside GNSS
It’s all about the backups now. The alternatives. The gap-fillers.
Back in the 1990s, when I first came across the U.S. Federal Radionavigation Plan (FRP), I learned that the rise of the Global Positioning System drove the biannual FRP process because of the expectation that GPS would enable the government to shut down many pieces in the hodgepodge of positioning, navigation, and timing (PNT) systems.
By Inside GNSS
Honestly, one gets the feeling that the European navigation community has finally had enough of talking and is ready to take Galileo out of the hands of politicians and put it into the hands of users, including businesses that can translate European GNSS into real products and services to be bought and sold.
The feeling has certainly been growing within the European navigation community, as evidenced by the conversations at the recent European Navigation Conference (ENC) in Vienna.
By Peter Gutierrez
Q: How do you deal with timing differences between GNSSs?
A: All GNSSs inherently depend on precise timekeeping to measure the satellite/receiver time of flight of signal propagation with sufficient accuracy to compute ranges/distances for multilateration calculations. Each GNSS ground segment therefore dedicates considerable effort to maintaining a highly stable atomic time scale as well as the corresponding offset to global standards such as UTC (Coordinated Universal Time).
By Inside GNSS
FIGURE 1: ISTA (left) and GATE (right) measuring vans at the parking place at the GATE site in BerchtesgadenWorking 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.
For the complete story, including figures, graphs, and images, please download the PDF of the article, above.
By Inside GNSS
Return to main article: "Assessing GNSS Data Message Performance"
By Inside GNSS
