Brad Parkinson, the first GPS Program Office Director, chief architect and advocate for GPS, submitted written testimony to Congress on mitigation options for possible GPS brownouts. His presentation comes in reference to the recent GAO report highlighting the risk that the GPS constellation may fal...
Read More →Withheld from the public for two years, since its completion in March 2007, the Independent Assessment Team (IAT) report has been let out of detention, just in time to counter recent efforts by the Obama administration, the Department of Homeland Security, and the U.S. Coast Guard to throttle the pr...
Read More →The United States Government Accountability Office (GAO) issued on May 7 an alarming report on the future of GPS, characterizing ongoing modernization efforts as shaky. The agency appears to single out the IIF program as the weak link between current stability and ensured future capability, calling ...
Read More →Lt. Col. David Goldstein, chief engineer for the GPS Wing, told the plenary session at the European Navigation Conference in Naples, Italy, that the Wing is experiencing some “out of family” measurements from the recently launched IIRM (20) satellite. This appears to corroborate some unofficial ...
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A portable spoofer implemented on a digital signal processor mounts a spoofing attack, characterizes spoofing effects, and suggests possible defense tactics. GNSS users and receiver manufacturers should explore and implement authentication methods against sophisticated spoofing attacks. By Todd E. H...
Read More →By Sandra Verhagen High-precision Global Navigation Satellite System (GNSS) positioning results are obtained with carrier phase measurements, once the integer cycle ambiguities have been successfully resolved. The position solution is obtained in four steps: 1. Float solution:least-squares, discardi...
Read More →By Inder Jeet Gupta It is well known that the phase center of a GNSS antenna can vary with the satellite direction. This phase center movement leads to aspect dependent carrier phase and code phase biases in the satellite signal. For precise geo-location, one needs to characterize the antenna-induce...
Read More →Why are the two GPS Transmitter frequencies (1575.42 and 1227.6 MHz) coherently selected integer multiples of 10.23 MHz master clock? Question posted on CANSPACE on October 30, 2006, by Sivaraman Ranganathan. The document defining the GPS signal, IS-GPS-200, states that “The carrier frequencie...
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