Design & Test

Letter to the Editor: History Articles Set Record Straight

October 1, 2010By

I was relieved to see that the facts related to the conception of GPS were clearly laid out in the two-part article “GPS Heroes” (May and June issues). During the past few years, erroneous information about the early years of GPS development has circulated in some military, engineering, and scientific circles.These stories centered on some version of the idea that GPS’ design originated with the Naval Research Laboratory (NRL) and within the patent submitted for Timation by the NRL’s Roger Easton; the U.S. Air Force and The Aerospace Corporation were conspicuously missing from the various scenarios that credited Roger Easton with “inventing” GPS. read more

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Spoofing Detection and Mitigation with a Moving Handheld Receiver

September 1, 2010By
Nielsen-Opener

A single spoofing source has a different spatial signal distribution from the authentic GPS signal. An antenna array can estimate the spatial distribution of the received signal and thus discriminate the spoofing signal from the authentic one. Moving a handheld receiver with a single antenna during signal capture snapshots produces a form of a synthetic array, highly effective in discriminating spoofing signals sourced from a point-source jammer. read more

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Challenged Positions: Dynamic Sensor Network, Distributed GPS Aperture, and Inter-nodal Ranging Signals

September 1, 2010By
Opening-fire

A performance assessment demonstrates the ability of a networked group of users to locate themselves and each other, navigate, and operate under adverse conditions in which an individual user would be impaired. The technique for robust GPS positioning in a dynamic sensor network uses a distributed GPS aperture and RF ranging signals among the network nodes. read more

Spectracom Releases 8-Channel GPS Simulator for Nav Device Testing

June 25, 2010By

Spectracom's new 8-channel GPS constellation simulator, the Pendulum GSG-54, provides a wide-range of capabilities for in-line production testing of devices integrating GPS receivers due to its ease-of-operation and fast test cycles, according to the company. Its versatility also supports engineering organizations’ efforts for integrating GPS receivers into devices under development. read more

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Part 2: The Origins of GPS, Fighting to Survive

June 1, 2010By
At the JPO. Frank Butterfield of Aerospace, Col. Parkinson, and Cdr. Bill Huston, deputy JPO director from the U.S. Navy,
in the early 1970s. A model of a Phase I GPS satellite stands on the table between the latter two.

GPS Phase I program approval meant that the real work could begin. The conclusion of a two-part history, told by the people who made it. read more

Part 1: The Origins of GPS, and the Pioneers Who Launched the System

May 1, 2010By
Mathematician Bill Guier (l) and physicist George Weiffenbach (r), told APL Research Center director Frank T. McClure (c), about their success using Doppler tracking for satellites. “McClure’s brain started going into fast forward,” remembered John Dassoulas. “Knowing the navigational challenges the U.S. Navy faced, McClure said, ‘Well, if you can find out where the satellite is, you ought to be able to turn that problem upside down and find out where you are.’ “

The original system study, the key innovations, and the forgotten heroes of the world’s first — and still greatest — global navigation satellite system. True history, told by the people who made it. Part One of a Two-Part Special Feature. read more

Innovation: Accuracy versus Precision

May 1, 2010By
In-8a

A Primer on GPS Truth
True to its word origins, accuracy demands careful and thoughtful work. This article provides a close look at the differences between the precision and accuracy of GPS-determined positions, and should alleviate the confusion between the terms — making abuse of the truth perhaps less likely in the business of GPS positioning. read more

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Aeroflex Introduces Portable Positional Simulator for GPS/Galileo Receivers

April 12, 2010By

A-Aeroflex has introduced the GPSG-1000, a portable GPS and Galileo positional simulator. The GPSG-1000 is lightweight and configurable. It fills a gap in the market by providing a low-cost 12-channel test set that creates three-dimensional simulations, A-Aeroflex said. read more

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