Where Are We? - GPS Declassified: From Smart Bombs to Smartphones - page 171

well Collins, Coherent Navigation, and academic experts in 2009 demon-
strated the feasibility of the High Integrity gps program, an augmentation
system sometimes called igps or higps. The program uses Iridium's constel-
lation of sixty-six low-earth-orbiting satellites to broadcast powerful signals
with embedded gps data, allowing military receivers to lock onto gps signals
faster and maintain them under substantial enemy jamming while in a mov-
ing vehicle. 185 Boeing completed the first phase of implementation in 2011,
modifying the computers and software that control Iridium satellites, and is
now working on the nrl's higps operations center, reference stations, and
user equipment. 186
The Air Force finally launched the first iif satellite, svn 62, in May 2010.
gps officials acknowledged in September that during the standard three-month
test period they had discovered a software problem in the cross-links that allow
satellites to communicate with each other. 187 The problem degraded the sys-
tem that detects nuclear detonations but did not affect the satellite's naviga-
tion and timing signals, so it joined the operational fleet. However, the issue
postponed the second iif launch until 2011, when the software fix would be
transmitted to the orbiting satellite. 188 The cross-link software glitch came on
the heels of news that surfaced in June about another iif-related software prob-
lem that January. Compatibility issues left as many as ten thousand military
receivers useless for several days after crews installed new ground control
software for the iifs. 189 The Air Force delayed the June launch of the second
iif satellite for two weeks and shut off the orbiting satellite's military signal
while fixing another issue, described first as an anomaly and later as an elec-
trical problem. 190 Depending on their point of view, observers have blamed
the iif program's troubles and bad publicity on complacency, poor oversight,
inherent design flaws, overly ambitious production plans, the challenges of
increasingly complex technology, heightened media scrutiny, and gremlins.
After all, how many people have set up a new computer without any glitches?
But the $121 million spent on average per satellite makes public interest and
concern understandable.
Although fears of a complete gps failure receded, the gao warning focused
broader attention on brownouts. 191 These are temporary periods of an hour or
two, widely scattered geographically and throughout the year, when too few
satellites are visible for high-precision users such as farmers and heavy equip-
ment operators. Having thirty satellites in the constellation for several years
had reduced this inconvenience. If the constellation drops to twenty-four or