June 2010

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A robust and precise navigation system uses multiple sensors. This article explores a 3-D sonar image technology that works deep underwater in times and places where high security is key and GNSS cannot go.

Interference, jamming, and spoofing are hot topics in the GNSS community. How do you trust your receiver? The authors use work they’ve done on spoofing to upgrade existing GPS user equipment for improved accuracy, robustness, and resistance to deceptive signals.

A good deal of attention is focused on Compass (Beidou-2) GNSS. But China also has a regional system called CAPS — for Chinese Area Positioning System. Here’s the story about its history, system architecture, problems and advantages.

In the final two installments of the series, the author describes what
GPS orbits would look like from various perspectives and
explains how to solve for range and range-rate corrections at a GPS
base station.

The publicly-funded German UniTaS IV project investigates problems in the application of satellite navigation for aviation.  The authors studied adaptive beamforming antennas, a GNSS landing system that incorporates inertial sensors with a ground-based augmentation system (GBAS), multi-constellation RAIM (receiver autonomous integrity monitoring), and jamming, spoofing, and authentication of signals. Here are their results. (Part I of II)

In 2000 the United States turned off GPS selective availability. The consequences of that decision — probably immeasurable at that moment — are still rippling through the world today as the number of GPS receivers in use soars toward the billions.

What is the acquisition ambiguity function and how is it expressed
mathematically?

Nassau County, New York; Slettestrand, Denmark; Trieste, Italy; Abuja, Nigeria; Kiev/Kyiv, Ukraine; NASA solar observatory