Matteo Luccio
In 1973, on March 1, Xerox launched the Alto, the first computer designed from its inception to support an operating system based on a graphical user interface; on April 3, Martin Cooper of Motorola made the first cellphone call, from 6th Avenue in New York City; and TCP, Ethernet, and fiber optics were created.
That same year, over Labor Day weekend, a dozen people in a small conference room on the top floor of a nearly deserted Pentagon, at a meeting called and chaired by Brad Parkinson that became known as “Lonely Halls,” made the key design choices for the Global Positioning System. None of those fundamentals have changed in the intervening half century, during which GPS was developed, launched, and modernized and became a worldwide utility underpinning many critical economic sectors — including precision agriculture, financial services, location-based services, mining, surveying and telecommunications.
At the time, Parkinson — a United States Air Force colonel with a Ph.D. in astronautical engineering from Stanford University, three years of experience in inertial guidance, and 26 combat missions in AC-130 gunships — was the first director of the GPS Joint Program Office in Los Angeles. As he and his co-authors recalled in a detailed two-part history of GPS (see the May and June 2010 issues of GPS World), the aspects of GPS that were defined at Lonely Halls included:
- Simultaneous passive ranging to four satellites in inclined orbits, ensuring user equipment would not require a synchronized atomic clock.
- A signal structure using CDMA modulation, including both a precision military code and a clear acquisition one that would be freely available to civil users worldwide.
- Two GPS broadcast frequencies in the L band.
- A family of user equipment prototypes, including a low-cost set that would demonstrate civilian use.
I recently asked Parkinson how GPS today differs from the design that came out of the Lonely Halls meeting. “The fundamental answer is that it’s identical,” he said, “in terms of design, the atomic clock, the CDMA signal, and four satellites to eliminate the need for a user clock. What has been evolving, of course, is that we’ve added another frequency and several new signals, including those for the military and L1C.”
From the very beginning, Parkinson encouraged civilians to use the system, correctly predicting that “they would apply their research and design talents to drive the size, weight and power requirements of the receivers down and the family of applications up,” he said. “That’s exactly what happened, in my opinion.”
Which applications surprised him the most? “Our revolution has been enabled by the advent of integrated circuits in terms of size and cost,” he said. For example, RTK has now given dynamic users access to centimeter accuracies.
“We were driven by visions of the many beneficial applications of GPS; visions that were not yet shared by the Air Force. GPS is a testimony to my team’s engineering competency, their tenacity, and their resourcefulness. I, and the whole world, owe them a large debt for the benevolent revolution they created.”
Matteo Luccio | Editor-in-Chief
mluccio@northcoastmedia.net