One System, Two Narratives - GPS Declassified: From Smart Bombs to Smartphones - page 64

original agreement was that we would have both, side tones and pseudo
random noise. To me that made the most sense. You could have the sid-
etones for civilians and pseudo random noise for the military. If you
needed to turn off the civilians, you just turn off that modulation. 28
Former navseg chairman Sonnemann was asked to provide his perspective
on the elements that were synthesized to create gps:
Question: In your estimation what percentage of the gps system that
emerged owes its technological origin to 621b?
Answer: The signal structure—100 percent.
Question: The same question for Timation?
Answer: The orbiting satellites (Timation) with precision atomic clocks—100
percent. 29
However, the spread-spectrum signal structure was invented in World War
II by the actress Hedy Lamarr and avant-garde composer George Antheil. 30
They deserve at least some of the credit for the signal used by gps.
The Atomic Clocks
The Defense Systems Acquisition Review Council (dsarc) accepted the com-
promise on December 17, 1973. A major change was augmenting crystal oscil-
lators with rubidium atomic clocks in nts-1. Holmes described how that came
about in an article for the defense industry magazine Countermeasures : “How-
ever, six months before the nts-1 scheduled launch date a rubidium clock
made by Efratom [a German company—the clock was developed by Ernst
Jechart and Gerhard Huebner] was brought to the attention of Mr. Easton.
Being an atomic clock, the rubidium oscillator offered the promise of both
higher accuracy and higher, long-term stability. With joint program office
approval, nrl decided to take the risk and install it, even though time avail-
able for testing and installation of space-qualiied parts was minimal.” 31
For the second nts satellite, Robert Kern and Arthur McCoubrey, who were
leaders in developing atomic clock technology, built the first cesium atomic
clock placed in orbit. nts-2, launched in June 1977, provided useful informa-
tion for gps's further development, as reported at the time by Aviation Week
& Space Technology : “Development test version of the Defense Department's
NavStar global positioning system tracked an instrumented usaf/Lockheed
c-141 with three-dimensional accuracies of 3-4 meters (10-13 feet) during a