GNSS Opinions

LightSquared, FCC Rebuttals Distort Record

June 14, 2011By

A claim frequently made by LightSquared spokesperson Jeff Carlisle, and recently by FCC chairman Julius Genachowski, that the GPS industry knew long ago about LightSquared’s plan for powerful terrestrial transmitters, would be a telling point — if it were true. But it is not. The verifiable fact is that the GPS industry knew about and agreed to a plan by a previous version of the company, for a different purpose, with a different business concept, and employing a completely different technological approach, one that would not have harmed GPS transmissions and disabled GPS users the way the current plan does. Calling the 2010 LightSquared plan the same as the 2003 Motient plan is running a wolf in sheep’s clothing. read more

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Out in Front: One and One

December 1, 2010By

Two figures for your holiday mulling here. I keep putting one and one together, and coming up with three. The first one points to a value of $1,000 billion. Or, as we like to say, one trillion dollars. That has a nice ring to it. The second one hovers at a lower level, around $230 billion, not nearly as melodic as the first. But if the second one creates the first one, how much magic is there in that — do you see what I’m saying? read more

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Galileo from the Top: Interview with the EC’s Paul Verhoef

November 20, 2010By

Paul Verhoef, the European Commission’s program manager for European Union (EU) satellite navigation programs — namely Galileo — discussed current issues at some length with GPS World, in a conversation on November 10. He addressed aspects of interoperability with GPS and prospects for further development in that area, the need for an ongoing political commitment by the EU to Galileo, the challenges of financing, the prospects for an 18-satellite constellation (which he dismisses as unrealistic), military considerations for both Galileo and GPS, and the recent uncertainty around Galileo’s Public Regulated Service. read more

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Out in Front: Beyond Cute

September 1, 2010By

Michibiki has more Twitter followers than you and me put together. All of you, and all of me with my 17 followers. Michibiki hit 16,284 when I signed on just now, and she (he?) has not yet even emerged upon the global stage. Perhaps by the time you read this, if the September 11 launch date holds true, s/he will be an orbiting, broadcasting entity. read more

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The System: Three’s the Challenge

August 1, 2010By

A small variance in the L5 signal, which remains well within signal specifications and will not affect pseudorange measurements, may show some impact on triple-frequency combinations of the signal’s carrier phase in high-precision applications. Observations suggest a temperature-dependent line bias in one or more carriers as a likely cause of the observed variation in the tri-carrier combination of L1, L2, and L5. read more

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The System: An L5 Surprise

August 1, 2010By

Researchers at the German Aerospace Center say they have found a small variance in the L5 signal on IIF-1. The signal variation results in no more than a 5-centimeter error with a predictable periodicity of about six hours. The GPS Wing is studying the issue and expects to resolve it before setting the satellite healthy, in another month or so according to the schedule. read more

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Expert Advice: Remembering. And Resolving

August 1, 2010By

Few outside the position, navigation, and timing (PNT) community will also recall that the day before the 9/11 attacks, the U.S. government released a landmark document that described the vulnerabilities of services provided by GPS to disruption, whether by attack or inadvertent interference. The Department of Transportation Volpe Center’s GPS vulnerability assessment recommended that services utilizing GPS-provided PNT seek alternative sources of these services. What decisions and actions have the findings and recommendations of this report promoted? The answer is most disturbing. read more

Expert Advice: Moore’s Law and GNSS

July 1, 2010By

I started my relationship with GNSS and Moore’s Law in 1985, writing software for GPS tracking loops on the Advanced Range Instrumentation Aircraft program at the Applied Physics Laboratory of Johns Hopkins University for the U.S. Air Force. The project’s purpose was to navigate a large jet to accurately fly a pattern to drop buoys into the ocean. That receiver had seven circuit boards (six trackers and one navigator) mounted on a VME backplane in a 19-inch rack mount in the back of a C-130, and was about the size and weight of suitcase. read more

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