201103 March/April 2011 Archives - Page 2 of 2 - Inside GNSS

201103 March/April 2011

March 14, 2011

GNSS Receiver Clocks

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.

Read More >

By Inside GNSS

Integer Aperture Estimation

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.

Read More >

By Inside GNSS

Coherent Integration Time Limits

Equation: signal variance for a “ring of scatterers” model

Indoor 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.

Read More >

By Inside GNSS

The Civilian Battlefield

Figures 1 & 2

For 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.

Read More >

By Inside GNSS

GNSS Inside Mobile Phones

Figure 1 & Table 1

For 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.

Read More >

By Inside GNSS
February 27, 2011

LightSquared, GPS Industry Council Propose Process for Assessing GPS Interference Risks

Photo: Wikimedia Commons

Attorneys 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.

Read More >

By Inside GNSS
February 26, 2011

Russia’s First GLONASS-K In Orbit, CDMA Signals Coming

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.

Read More >

By Inside GNSS
January 30, 2011

GPS/ GNSS Community Feels New Telecom Interference Threat from LightSquared

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.

Read More >

By Inside GNSS
July 27, 2010

Meet GINA

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.

Read More >

By Inside GNSS