TAG: letters

Letters to the Editor

October 1, 2013By
Constellation snapshot for a specific date/time: GPS week 1749 (725) and GPS seconds 86400 = July 15, 2013, at midnight GPS Time.

Orbital Planes, Nightmares, Pioneers Good morning, Dr. Langley, I have a seven-year-old drawing of GPS satellites in their orbital planes that I found (can’t recall where) some years ago, either on a website or from a colleague who attended some GPS forum. Would you know of a site where I can find current information on GPS satellite locations, which ones... read more

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Letter to the Editor: Our First Mistake

December 1, 2012By

Our first mistake is to presume an environment of perfection and security. Nothing is foolproof and spoof-free. Every product or service is an envelope of packaging that can be opened, peeled back, reversed engineered, and replicated. I have seen “ultimate security” defeated repeatedly. GPS is no exception, of course. We put our signatures and seals on these things; enterprising competitors,... read more

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Letters to the Editor: Smartphone Revolution

January 1, 2010By

Readers comment on Frank van Diggelen's article "The Smartphone Revolution" from the December 2009 issue. read more

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