Lone Sentinel: Single-Receiver Sensitivity to RF Interference

July 1, 2011By

Using signal-to-noise measurements from a single commercial-grade L1 GPS receiver, it is possible to detect interference or jamming that is above the thermal noise floor and below a power that causes loss of position. read more

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How GPS and GLONASS Got Together — and Other Recent Events

June 1, 2011By

The recent broadcast of the first CDMA signal from the new GLONASS-K satellite culminates a long series of events that began in 1989. A key participant gives a first-hand account of the history of many meetings, formal and informal, that created true interoperability between the two major satellite systems, giving users a modern GNSS in action. read more

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Innovation: Doppler-Aided Positioning

May 1, 2011By
Figure 1. Satellite tracking and carrier-phase anomaly summary during the observation time-span. These data were collected in a dense urban environment in both static and kinematic mode. The superimposed red-points show epochs where carrier-phase observables are either missing or contaminated with cycle slips, loss of locks, and/or other measurement anomalies.

Improving Single-Frequency RTK in the Urban Enviornment
A look at how Doppler measurements can be used to smooth noisy code-based pseudoranges to improve the precision of autonomous positioning as well as to improve the availability of single-frequency real-time kinematic positioning, especially in urban environments. read more

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The System: Second Report by LightSquared/GPS Technical Working Group Maps Terrain, Does Not Yet Explore

May 1, 2011By

Plus: GLONASS CDMA Tracked, Third Beidou-2 Launched The second report from non‐governmental members of the LightSquared/GPS Technical Working Group (TWG) was filed with the Federal Communications Commission (FCC) on April 15. For those anxious to see actual results of interference/desensitization of GPS receivers by the proposed LightSquared terrestrial signal — or, conversely, absence of said results — the report does not contain... read more

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Future Wave: L1C Signal Performance and Receiver Design

April 1, 2011By

The new GPS L1C signal will be broadcast by the Block III satellites, with first launches as early as 2014. L1C innovations significantly enhance PNT performance as well as interoperability with other GNSS signals. The authors describe the benefits of its new features and how best to make use of each one. read more

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Innovation: Realistic Randomization

March 1, 2011By
Figure 3. Data collection, Gamla Stan (Old Town), Stockholm (route and street view).

New Way to Test GNSS Receivers
In this month’s article, we look at an approach to GNSS receiver testing that uses realistic randomization of signal amplitudes based on histograms of carrier-to-noise-density ratios observed in real-world environments. It can be applied to any simulator scenario, independent of scenario details (position, date, time, motion trajectory, and so on), making it possible to control relevant parameters such as the number of satellites in view and the resulting dilution of precision independent of signal-strength distribution. The method is amenable to standardization and could help the industry to improve the testing methodology for positioning devices — to one that is more meaningfully related to real-world performance and user experience. read more

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Galileo Test Environment Open for Business

February 14, 2011By

The Galileo Test and Development Environment (GATE) in Berchtesgaden, Germany, officially opened on February 4. System operator IFEN GmbH announced GATE's availability for use by commercial and organizational entities seeking to test equipment with the coming Galileo signals. read more

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u-blox, Rohde & Schwarz Successfully Simulate Galileo with u-blox Platform

February 14, 2011By

u-blox and Rohde & Schwarz (R&S), a supplier of test and measurement equipment, have successfully concluded a simulation of the European Galileo satellite positioning system. The test, carried out with the R&S SMBV100A vector signal generator and its GNSS simulation options, verified the u-blox proof-of-concept and the compatibility of u-blox receiver technology with the Galileo transmission protocol. read more

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