GNSS

The System: IRNSS Signal Close up

September 1, 2013By and

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

This article is tagged with and posted in Augmentation & Assistance, Galileo, GLONASS, GPS Modernization, The System

Expert Advice: Laser Reflectors to Ride on Board GPS III

September 1, 2013By
Figure 2. Structure and products of the Global Geodetic Observing System related to GPS performance.

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

Innovation: Under Cover

September 1, 2013By
FIGURE 1. Artist’s impression of the synthetic-aperture GNSS system for surveying in a forest.

Synthetic-Aperture GNSS Signal Processing
We 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

This article is tagged with , , and posted in Algorithms & Methods, From the Magazine, Innovation

Expert Advice: Looking Back to the Early Days of GPS

September 1, 2013By

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

Out in Front: Geospatial on Everything

September 1, 2013By

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

This article is tagged with and posted in From the Editor, GNSS Opinions

Signal Quality of Galileo, BeiDou

September 1, 2013By
Figure 1. 30-meter high-gain antenna.

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

Extra Life for IIRs, IIR-Ms

August 29, 2013By

U.S. Air Force engineers are testing on-orbit a technique to extend the life of the 19 GPS IIR and IIR-M satellites on orbit, roughly 60 percent of the current constellation. A new charging method may reduce the rate of satellite battery degradation, thereby extending satellite operational life. If the technique passes the test, the initiative could add a combined 20... read more

This article is tagged with , and posted in GNSS News, GPS Modernization, Latest News

Looking High in the Sky from Down Under

August 29, 2013By

A few months ago I wrote in the magazine’s Out in Front column about the surprising abundance of BeiDou-centric papers to be presented at the upcoming ION GNSS+ conference, to which I very much look forward — both the abundance and the conference as a whole. With GLONASS encountering stormy weather of late, and Galileo plugging steadily along but not... read more

This article is tagged with and posted in BeiDou/Compass, GNSS Opinions, Newsletter Editorials