201501 January/February 2015

The Party Crashers

These days getting the United States, Russia, China, and Europe to agree on a common policy seems to be an increasingly rare event.

That’s why the long-standing comity among system operators in the GNSS sphere is particularly notable and welcome. “Interoperable and compatible” is the first principle espoused by the four nations under the aegis of the International Committee on GNSS.

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By Dee Ann Divis
January 16, 2015

From Data Schemes to Supersonic Codes

A decade has passed since the first GNSS system-level authentication protocols were proposed, and yet the current ongoing discussion is still, “Do we really need GNSS signal authentication?” Indeed, the current argument is whether we need authentication at the system level (the satellite broadcast service) or whether user-based authentication (anti-spoofing) is sufficient for a number of application requirements.

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By Inside GNSS

FCC Raises Questions about U.S. Access to Non-GPS GNSS

No reality show contestant ever neared the finish line without the producers serving up another challenge. And so it is for would-be multi-GNSS users in the United States.

After dodging budget cuts, thwarting other teams’ attempts to grab critical frequencies, and dealing with jamming and technical problems, members of the U.S. GNSS community were thrown another curve late last year when they learned that signals from GLONASS and other international constellations must be authorized for use in the United States.

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By Dee Ann Divis

Why are carrier phase ambiguities integer?

It is well known that carrier phase ambiguities are integer values. Intuitively, this is hard to understand with a common counter-argument progressing along these lines: even if the receiver measures the instantaneous phase of the incoming signal (thus removing any fractional cycle component at the receiver end), the phase of the signal at the satellite cannot be guaranteed to be zero, so how can the ambiguity be integer?

In this article we explain why the carrier phase ambiguities are indeed integer.

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By Inside GNSS

Galileo’s Commercial Service

Figure 1; Tables 1 & 2

After some years of concept studies and simulations, the Galileo Commercial Service is taking off. The journey has started toward what can be the most accurate and secure worldwide satellite-based navigation services for civil use.

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By Inside GNSS

Frank van Diggelen: Riding the GNSS Wave

Running San Francisco Marathon, with daughter, Tanera. Note GPS watch.

SIDEBAR: Frank van Diggelen’s Compass Points

“It all traces back to my parents,” says Frank van Diggelen. “My father, Tromp van Diggelen, was a surfer. He taught me to surf and swim, in that order, when I was five. I was racing sailboats before I was 10, and there’s a lot of navigation there. Even when you’re just on a lake, the racing is all about reading the wind, understanding angles of convergence, velocity-made-good, and so on.”

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By Inside GNSS