Evolution of GPS Systems Architecture and Its Impacts
Thomas, Michael L., Communications of the IIMA
There is no denying the impact that GPS has had on our daily lives both in the United States and worldwide. Far beyond the small screen on the dashboards of automobiles that many drivers have come to rely on in place of the paper road maps we grew up with, GPS is now a ubiquitous technology that is utilized for applications in transportation, financial systems, cell phone technology, air traffic communications, emergency services and many others. Over time, GPS has become something almost like a utility. Civil agencies, commercial firms and many individuals use some type of GPS receiver to navigate from one location to another. Firms in the private sector use the technology to route vehicles, not only in the maritime sector but in mass transit as well. The aviation industry has implemented its use to augment navigation and increase the safety and efficiency of commercial flight systems. The timing signal that GPS broadcasts has become critical various economic activities that include and as diverse as electrical power grids, financial networks and communication systems.
Figure 1 shows military and nonmilitary users of GPS technology reported by Bogosian (2003). Not too bad for a piece of technology that was originally intended for use only as a weapon system, but quite often much of the technology used by the U. S. milita ry today either starts out or ends up as what is called "dual use." This is not a new idea but in fact represents what has become a long term trend. Unfortunately, the very fact of GPS' utility in so many daily applications is the very reason that the United States Air Force (USAF), the Executive Agent for the management of the GPS constellation, is presently considering other technologies for its eventual replacement. The fact that it has become so widespread and the signal so open source also has increased its vulnerabilities to the point that many senior leaders in the USAF consider it to be too unreliable for long term use as a piece of a weapons delivery solutions. The situation has become serious enough that the USAF Chief of Staff Gen. Norton Schwartz has addressed the issue directly in his opening remarks at a national security conference in Washington D.C. on January 20, 2010 (Hoffman, 2010), where he stated:
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"Global positioning has transformed an entire universe of war-fighting capability. Our dependence on precision navigation in time will continue to grow," (Schwartz said in the opening address to the conference, sponsored by the Institute of Foreign Policy and Tufts University's Fletcher School). "It seems critical to me that the joint force reduce its dependence on GPS aid." (1)
General Schwartz went on to speak to the possibilities of an enemy jamming a GPS signal needed by the military or, alternatively and even worse, to make use of some type of spoofing technique to reroute a weapon to a location other than its intended target. This spawns the following questions: How likely are these scenarios? How big a threat is it to U. S. national security?
Manufacturing 7% Tracking 10% Vessel voyage 2% Military affairs 1% GIS 8% Car navigation 35% Survey 7% Hand held 26% Aviation 8% Figure 2: Distribution of GPS Users in the United States ("GPS", 2006, July) Note: Table made from bar graph.
The Air Force Institute of Technology (AFIT) is a leading source of research and development for the USAF. Located at Wright Patterson AFB, near Dayton, Ohio, it sponsors and educates the next generation of USAF technical leaders in areas of science and technology critical to the future of the force's ability to achieve and sustain air dominance. In a review of the list of Thesis titles (2) for work done in the last five years, the examples of an alternative to GPS are many, including in 2010 alone:
* Gravity Gradiometry and Map Matching: An Aid to Aircraft Inertial Navigation Systems. …