One System, Two Narratives - GPS Declassified: From Smart Bombs to Smartphones - page 54

tagon had logical reasons to pursue a single, all-purpose satellite navigation
system, differing needs among the services made joint development difficult.
The Department of Defense established the Navigation Satellite Executive
Steering Group, or navseg, in 1968. It was a tri-service group with the title of
chairman rotating annually among the services. Harry Sonnemann was spe-
cial assistant for electronics in the Office of the Assistant Secretary of the Navy
(Research and Development) from 1968 to 1976. He was a member of navseg
from its founding to its dissolution and was its chairman from 1969 to 1970
and from 1972 to 1973. He states, “The Special Assistants responsible for over-
sight of Communications and Navigation Systems in the Offices of the Assis-
tant Secretaries (r&d) of the Army, Navy including the Marine Corps, and Air
Force, served as the Senior Members of . . . navseg.” 4 The Joint Chiefs of Staff
established joint service requirements for a new space-based navigation sys-
tem, including the ability for users to precisely position themselves in three
dimensions and to precisely determine their velocity continuously, worldwide. 5
navseg examined the services' different design schemes, which varied in the
number of satellites, their altitudes above the earth, and their orbital inclina-
tions (angle compared to the equator); the types of radio signals used; and the
methods of controlling the satellites from the ground.
The 1969 Electronics and Aerospace Systems Conference mentioned ear-
lier featured three papers advocating low-, medium-, and high-altitude satel-
lite navigation systems. Three Aerospace Corporation engineers, J. B. Woodford,
W. C. Melton, and R. L. Dutcher, delivered the paper “Satellite Systems for
Navigation Using 24-Hour Orbits.” Their preferred constellation—the one used
for Project 621b—had one satellite in a synchronous equatorial orbit and three
or four satellites in inclined elliptical orbits. Three or four such constellations
could provide nearly global coverage. A master ground station and two or more
calibration stations continuously tracked and sent time and position informa-
tion to the satellites, which then retransmitted signals to the receiver. The sys-
tem required the ground stations to be in the same area as the satellite
constellations, since the synchronous satellite remains relatively stationary
over a point on the earth. This was a major weakness for military applications.
For example, the European constellation required ground stations in that area.
A wag working on Timation in the 1970s commented that the 621b European
constellation would have required its ground station to be in Moscow. 6 During
a war, these stations would have been prime targets for direct attack or jam-
ming the uplinks. A 621b satellite constellation could also have been destroyed