IRNSS Signal Close up By Richard Langley, Steffen Thoelert, and Michael Meurer The spectrum of signals from IRNSS-1A, the first satellite in the Indian Regional Navigation Satellite System, as recorded by German Aerospace Center researchers in late July, appears to be consistent with a combination of BPSK(1) and BOC(5,2) modulation. Figure 1 shows that, centered at 1176.45 MHz, the signal... read more
By James J. Miller and John LaBrecque, NASA Headquarters, and A.J. Oria, Overlook Systems Technologies, Inc. Satellite laser ranging (SLR) and the results of combining SLR with GPS in the future will translate into significant performance advancements for generations to come, once it is fully implemented as part of the GPS III architecture. Simply put, SLR techniques will improve GPS... read more
Synthetic-Aperture GNSS Signal ProcessingWe take a look at a novel GNSS signal-processing technique, which uses the principles of SAR to improve code and carrier-phase observations in degraded environments such as under forest canopy. The technique can simultaneously reject multipath signals while maximizing the direct line-of-sight signal power from a satellite. Along with a specially programmed software receiver, it uses either a single conventional antenna mounted, say, on a pedestrian’s backpack for GIS applications or a special rotating antenna for high-accuracy surveying. Want to learn more? Read on. read more
By Len Jacobson Besides my family and friends, two major influences have guided my life. One is GPS, and the other is flying, although I’m not a pilot. Most of the flying was on business trips for GPS. I’ve been writing a book about my experiences and how I helped in a small way to bring GPS to the world.... read more
GPS World Publisher Learns about GIS By Alan Cameron Everything has a geospatial aspect. Everything. Past, present, future. Over grits, coffee, and the airborne delicacy purveyed at the Flying Biscuit Cafe (right out of the oven, right into your mouth) in Sandy Springs, Georgia, I absorbed this high-tech homily. You’ve heard of the European financial crisis. Trace it back to... read more
Future positioning and navigation applications of modernizing and newly established GNSSs will require a higher degree of signal accuracy and precision. Thus, rigorous and detailed analysis of the signal quality of recently launched satellites, including the discovery of any possible imperfections in their performance, will have important implications for future users. read more
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