Going Public - GPS Declassified: From Smart Bombs to Smartphones - page 94

stellation were in orbit—the first four launched in 1978 and two more in 1980—
all lifted into space by Atlas F rockets from Vandenberg Air Force Base in
California. navstar 7 would have been available, but the launch on Decem-
ber 18, 1981, failed. These six satellites provided about four hours of useable
coverage daily over the United States, but their orbital configuration brought
them into view four minutes earlier each day, making gps signals available
predominantly during daylight hours for six months of the year and predomi-
nantly at night for the other six months. 46
The Macrometer was nothing like the handheld or pocket-sized devices
common today. It was a cubical metal box roughly twenty-ive inches on each
side, weighing about 160 pounds, with a separate antenna that weighed another
forty pounds. Equally hefty was the price—$250,000 in 1982 dollars. 47 Trans-
porting these units to a survey site often required tethering them beneath a
helicopter. 48 Users stored the field data they collected in small cartridges and
processed the information later. Because technical limitations prevented the
use of gps signals for clock synchronization, surveyors needed two of these
behemoths, synchronized to each other, making the cost and effort suitable
only for larger projects. 49
While the Macrometer sounds massive by today's standards, it was svelte
compared to the first gps receiving unit Rockwell Collins built for the Air Force
to test the fledgling constellation in 1977. The Generalized Development Model
(gdm) was the size of a tall bookcase, weighed 270 pounds, and stood with two
high-backed seats for its operators atop a large, square pallet on casters,
designed for loading onto aircraft during flight tests. 50 The ti-4100, by com-
parison, was a trim ifty-three pounds, about the size and appearance of a small
microwave oven, with a separate six-inch, cone-shaped antenna and a hand-
held keypad and display screen connected by a coiled cord. 51 This receiver,
which could simultaneously track four gps satellites, marked a transition toward
more, and more practical, commercial applications.
In March 1985, with nine gps satellites in orbit, Texas Instruments intro-
duced a new software package called Satplan, which allowed users to create a
precise satellite availability schedule in tabular form by date and location. The
company's announcement, which appeared in such publications as Maritime
Reporter and Engineering News , called it “an enhancement that makes the Global
Positioning System (gps) more productive as a navigation/positioning tool.” 52
The software ran not on the receiver itself but on the ti Portable Professional
Computer (ppc). A quick review of its features illustrates how far both gps