So, first, who needs three more worldwide satnav systems, when we already have GPS? Why do these others want to spend billions just to keep up with the U.S.? There are two reasons: one political and the other practical. Politically, GPS has become a (not the) dominant technology in almost every part of human life around the world, in government, national security, industry and private life, with more than a billion receivers being used daily for thousands of applications, from simple to critical.
Introduction to the Global Positioning System
The GPS industry’s failure to comply with the Department of Defense’s receiver filtering standards is the root cause of potential interference issues involving LightSquared’s proposed broadband wireless network, the company has told the FCC.
Testifying before Congress in May, Stanford University professor Brad Parkinson–the chief architect of GPS and the original GPS program manager before his retirement from the USAF–echoed the concern of the Government Accountability Office (GAO) that there will be insufficient backup satellites to fill gaps in the constellation before the DOD’s forecast 2014 launches of its next-generation GPS III units. (see AIN, June, page one.)
The DOT Volpe Center’s September 10 report on the vulnerability of GPS to jamming and other interference, in addition to the events of the following day, have greatly heightened national concerns about the security of the satellite system and the degree of dependence that should be placed on it as the backbone of our future ATC system.
To counter the possibility of jammed and “spoofed” signals, the authors of a U.S. Department of Transportation report on GPS vulnerability released on September 10 recommend that GPS not be relied upon as the sole source in critical applications, including precision approaches.
In light of last year’s DOT study of the vulnerability of GPS to unintentional interference and intentional jamming, Boeing and Rockwell Collins suggest that loran-C could be a viable backup for GPS. These suggestions will be presented formally at a NASA conference this month.
Concerned about attempts by adversaries to jam global positioning satellite system signals–as occurred with only limited success during the recent Iraq conflict–the U.S. Air Force is moving ahead with plans to field a new-generation constellation of satellites, called GPS III. After a months-long logjam, the Air Force next month will begin accepting requests for proposals to develop and deploy the satellites sometime between 2010 and 2013.
In 1997 the President’s Commission on Critical Infrastructure Protection, which was charged with examining threats to our national security, recommended an assessment be made of the vulnerability of the U.S. transportation infrastructure if it had to rely on GPS.
GPS Satellite SVN-15 will celebrate its 16th birthday in space this month, and by next spring it will have circled the earth 12,000 times (roughly twice a day), continuously transmitting navigation signals to us. That’s amazing performance, especially considering that its original orbital life was expected to be 7.5 years.