Global Navigation Satellite Systems Engineering, Policy, and Design
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
Photo: Wikimedia CommonsAttorneys for LightSquared Subsidiary LLC submitted a proposed work plan on Friday (February 25, 2011) for analyzing potential interference to GPS devices. The plan, required by the FCC as a condition of its granting a waiver to its Ancillary Terrestrial Component (ATC) rule for mobile satellite services (MSS), proposes to establish a working group (WG) to study the GPS overload/desensitization.
By Inside GNSS
The first new-generation satellite GLONASS-K of the GLONASS navigation system has reached its targeted orbit, the Russian Federal Space Agency (Roscosmos) announced today (February 26, 2011).
The Soyuz-2.1b rocket lifted off from Plesetsk cosmodrome at 6:07 a.m. (Moscow time) this morning. The GLONASS-K spacecraft was carried into its planned orbit by a Fregat booster at 9:41 a.m. Moscow time, according to Roscosmos public affairs office, which reported that the satellite separated from the booster as planned.
By Inside GNSS
In his State of the Union address on January 25, President Obama held up the Global Positioning System as a prime example of government providing “cutting-edge scientists and inventors with the support that they need” to create world-leading, job-creating innovation.
The following day, the Federal Communications Commission (FCC) International Bureau approved a conditional waiver allowing LightSquared Subsidiary LLC to build tens of thousands of terrestrial transmitters for wireless communications in frequencies on either side of the GPS L1 band.
By Inside GNSS
GINA On-Board Unit (OBU)For at least the past two decades, managing traffic on Europe’s road networks has been a growing concern for European policy makers and citizens alike. While demand for transport has consistently increased over the years, Europe’s road network capacity has failed to keep pace, leading to increasing levels of congestion and pollution.
By Inside GNSS
