Global Navigation Satellite Systems Engineering, Policy, and Design
Francine Vannicola, Naval Research LaboratoryAs the forthcoming “Time and Navigation” opening next March at the Smithsonian National Air and Space Museum reminds us, modern navigation depends profoundly upon time — the more precise, accurate, and stable a navigation system’s timing is, the more precise, accurate, and stable its positioning capability.
By Inside GNSS
Dr. Todd Walter, Stanford UniversityContrary to a widely held public impression, the elimination of GPS Selective Availability in 2000 did not take care of the needs that many users have for enhanced GNSS capabilities.
Indeed, various “augmentations” have been developed to meet the requirements of some applications for better accuracy, availability, or integrity (the assurance of the quality of a signal) than are available from GNSS signals in space.
By Inside GNSS
Phil Ward, Navward GPS ConsultingThe threats just keep growing to a resource that hundreds of millions of people around the world have come to rely on for a myriad purposes.
GNSS is, after all, an RF technology, vulnerable in its own way to the kind of disruptive effects that turn an AM radio into a static-ridden howl as you drive under a powerline. And the radiated energy of signals arriving with from satellite sources tens of thousands of miles away are orders of magnitude weaker than those carrying the top 40 tunes broadcast by a local station.
By Inside GNSS
iNsight team members: (L to R) Zeynep Elmas and Terry Moore (Nottingham), Marek Ziebart (UCL), Mojtaba Bahrami (at that time of UCL), Carl Milner (then of Imperial), Alper Ucar (Westminster), Chris Hide (Nottingham), Shaojun Feng (Imperial), Ziyi Jiang (UCL) and Paul Groves (UCL). Not pictured, Washington Ochieng (Imperial) and Izzet Kale (Westminster).The diversity and redundancy provided by multiple, independent, compatible, and in some respects, interoperable GNSS systems must be a good thing, right?
Well, almost certainly. But as with many things in life and technology, the devil’s in the details. And, as the varied characteristics and design specifications of new GNSSes and regional systems become clearer, it may not be too early to sort out those details.
By Inside GNSS
Patrick Fenton, Vice President and Chief Technology Officer, NovAtel, Inc.In the RF (radio frequency) spectrum between 3 kHz and 300 GHz, national and international regulatory agencies have sliced and diced the available frequencies into a crazy quilt of allocations for particular uses. GNSS systems, for example, provide positioning, navigation, and timing services in scattered portions of the L-band between 1170 and 1610 MHz.
By Inside GNSS
Mike Perlmutter, Principal, Skylight NavigationA growing awareness of the limitations and vulnerabilities of GNSS — along with advances in inertial designs and manufacturing — has opened a new era in which these admirably complementary technologies are converging ever more often into integrated products.
By Inside GNSS
Dr. Anthony Pratt, Orbstar International Ltd.In the beginning, there was just the Global Positioning System. But it provided an astounding start to the world of GNSS.
Since the United States declared full operational capability (FOC) for GPS in 1995, two major things have occurred:
By Inside GNSS
Christopher HegartyPerhaps for the first time in the nearly 40 years of satellite navigation, all four GNSS programs and regional systems appear to have firm — if not always unencumbered — development paths ahead of them.
GPS, GLONASS, Galileo, Compass/Bei- Dou, Japan’s MSAS and QZSS, and India’s GAGAN and IRNSS systems are bringing new or modernizing elements into the world. Key program enablers — such things as budgets, satellite construction, launches and launch vehicles, new signal designs — all appear favorably aligned.
By Inside GNSS
Dr. Genene FisherOn any given day — especially cloudy winter days — most people may not give a lot of thought to the Sun.
More than 150 million kilometers (93.2 million miles) away, its remoteness belies the enormous forces at work in this yellow dwarf star with a mass 330,000 times that of Earth. If someone asked us to name its harmful effects, we might come up with sunburn, heat stroke, skin cancer.
But many in the GNSS community know better.
By Inside GNSS
Dr. Andrey Soloviev, QunavGNSS and inertial technologies have a complicated mutual history.
Once competitors for navigation and positioning applications, they now appear ever more frequently in complementary roles — often within the same solution or system design.
By Inside GNSS
