Global Navigation Satellite Systems Engineering, Policy, and Design
Global Navigation Satellite Systems Engineering, Policy, and Design
Most of us who have ever gotten onto an airplane know the drill: when the doors are closed and sealed and the pilots push back from the terminal, the mobile phones are turned off — along with other portable electronic devices.
There’s a reason for that. Airline operators and the Federal Aviation Administration wish to avoid any possible interference with the aircraft’s avionics that support its navigation and communications functions.
By Dee Ann Divis
Q: Does the magnitude of the GNSS receiver clock offset matter?
A: It is well known that GNSS receiver clocks drift relative to the stable atomic time scale that ultimately defines a particular GNSS system in the first place. GNSS receiver manufacturers, however, try to limit the magnitude of the time offset to within some predefined range.
By Inside GNSS
For the complete story, including figures, graphs, and images, please download the PDF of the article, above.
Integer carrier-phase ambiguity resolution is the key to fast and high-precision GNSS positioning and navigation. It is the process of resolving the unknown cycle ambiguities of the carrier-phase data as integers. Once this has been done successfully, the very precise carrier-phase data will act as pseudorange data, thus making very precise positioning and navigation possible.
By Inside GNSS
Equation: signal variance for a “ring of scatterers” modelIndoor GNSS propagation environments are characterized by multiple reflected signal paths (multipath) terminating at the receiver. Consequently, the received signal’s amplitude, phase, and perceived angle of arrival attributes vary randomly as the receiver moves. This has created significant interest among receiver designers and manufacturers to develop powerful processing for GNSS handsets such that these can operate effectively in indoor faded environments.
By Inside GNSS
Figures 1 & 2For the complete story, including figures, graphs, and images, please download the PDF of the article, above.
Growing dependence on GNSS for positioning, navigation, and timing (PNT) has raised a parallel concern about the potential risks of signal interference. The popular press has recently highlighted accounts of car thieves using GPS jammers, solar flares pumping out L-band radiation, and faulty television sets causing havoc to GPS receivers across an entire harbor.
By Inside GNSS
The GPS community is seething over a January 26 decision by the Federal Communications Commission (FCC) giving a conditional go ahead to a new broadband network with the potential to overwhelm GPS receivers across the country.
By Dee Ann Divis
Figure 1 & Table 1For the complete story, including figures, graphs, and images, please download the PDF of the article, above.
Recent years have seen GPS receivers built in as a standard feature in many consumer products. A growing number of mobile phones, personal navigation devices, netbooks and tablets are equipped with GPS receiver chips and navigation software that enable consumers to navigate from A to B or find their nearest coffee shop. According to Berg Insight, annual shipments of GPS-equipped mobile phones are estimated to reach 960 million devices in 2014.
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. HAPPY BIRTHDAY!
Los Angeles, California USA
√ Congratulations to SVN 23, a GPS IIA satellite, for 20 glorious years. The GPS Directorate expects 12–18 months more of active duty from the overachieving space vehicle, which was expected to last only 7½ years. (Meanwhile, Europe’s first Galileo test satellite, GIOVE-A, was expected to last 27 months and is still cookin’ after five years.)
Return to main article: GNSS Interoperability
Most people probably don’t associate engineers and linguistic virtuosity.
The attitude is unfair, of course, as with so many stereotypes.
And also untrue.
For example, as the number of existing or planned GNSS systems grew during the past few years, the expression “Your signal is my noise” has recurred in the engineering community with increasing frequency.
I consider that an elegant, if ominous, turn of phrase. A simple declarative sentence, pithy, with an ironic edge, yet almost lyrical.
By Inside GNSS
FIGURE 1 (a, b, c) & FIGURE 2For the complete story, including figures, graphs, and images, please download the PDF of the article, above.
In the early stages of developing space-based radionavigation, the spectrum compactness of ranging signals was not proclaimed among the material priorities. Conventional bi-phase shift keying (BPSK) modulations, although they consume a rather large amount of spectrum, were adopted as the basis for both GPS and GLONASS signals.
By Inside GNSS
