Columns and Editorials

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Are Reflected Signals Always Undesirable?

Rightfully, the GNSS community almost universally considers reflected signals to be problematic (the field GNSS reflectometry being an obvious exception). Reflected or non-line-of-sight (NLOS) signals combine with line-of-sight (LOS) signals to produce multipath effects, or if the LOS signal is absent NLOS signals can produce large ranging biases. Both phenomena increase measurement error and decrease positioning accuracy, especially in areas with lots of reflecting surfaces such as deep urban canyons.

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By Mark Petovello
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August 29, 2018

Ligado Fight Comes Down to Choice of Interference Standard

There was a flurry of filings July 9 just as the window closed for public comment on Ligado Networks’ proposal to repurpose satellite frequencies for a terrestrial network — a plan with the potential to interfere with GPS receivers.

The comments emerged as speculation swirled around a July 3 bid by EchoStar for Ligado spectrum supplier INMARSAT. The bid was rejected and, as of press time, EchoStar will have to wait six months before trying again.

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By Dee Ann Divis
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January 1, 2018

RNSS and the ITU Radio Regulations

All applications of satellite navigation show a strong growth. They can now rely on four global systems (GPS, GLONASS, Galileo and BeiDou) and additional regional systems, sometimes aiming for future global extension (QZSS, NavIC). All these systems and their applications rely on very limited satellite orbit spectrum. This article is providing background and insights on the growing pressure on this limited resource, giving rise to proposals for “sharing” spectrum. How satellite navigation will survive and find the necessary spectrum resources to grow is reviewed in details in the following paragraphs.

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By Ingo Baumann
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September 19, 2017

IMO and the GNSS

The maritime sector drives the global economy, with ships transporting more than 80% of world trade. Ships and ports have come to rely on global navigation satellite systems (GNSS) for a huge array of applications relating to position, velocity and precise universal and local time.

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By Ingo Baumann
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April 17, 2017

Europe’s GNSS Receiver Standard Nears Approval

European Union (EU) member countries are close to adopting a standard for satellite navigation receivers.

The proposed standard covers Satellite Earth Stations and Systems (SESS) as well as GNSS receivers operating in the bands 1164 MHz to 1300 MHz and 1559 MHz to 1610 MHz. Receivers must be able to withstand interference from adjacent bands at the listed levels.

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By Dee Ann Divis
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April 1, 2017

Would you prefer to have more signals or more satellites?

Q: Would you prefer to have more signals or more satellites?

A: This is somewhat of a classic GNSS question, but before getting to the answer, let’s seek some clarity about what is being asked. First, by definition, “more” signals or “more” systems must be referenced against some baseline configuration. This is commonly assumed to be a GPS L1 C/A solution, and this assumption is also used herein.

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