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GNSS constellations create four strong winds

Matteo Luccio

Matteo Luccio

First, there was one. In July 1995, the U.S. Air Force declared the Global Positioning System had met all the requirements for full operational capability (FOC). Soon thereafter, there were two. In December of that same year, Russia’s Globalnaya Navigazionnaya Sputnikovaya Sistema (Global Navigation Satellite System, or GLONASS), also achieved FOC. For a quarter century, that was it.

Then, last year, the number doubled, as both the European Union’s Galileo and China’s BeiDou Navigation Satellite System (BDS, named after the Big Dipper asterism, which is known in Chinese as ) achieved FOC.

The Indian Regional Navigation Satellite System (IRNSS, aka Navigation Indian Constellation, or NavIC, which means “sailor” or “navigator” in Hindi) and Japan’s Quasi-Zenith Satellite System (QZSS, also known as Michibiki) are not global yet, but plan to become so. Currently, NavIC is an autonomous regional satellite navigation system, and NavIC-based trackers are compulsory on commercial vehicles in India. QZSS currently complements GPS to improve coverage in East Asia and Oceania, but Japan plans to have an operational constellation of seven satellites for autonomous capability by 2023. The Korea Positioning System (KPS) plans to join the party by 2035.

Who’s next? Will it be another country or a private company? Given that the state-sponsored systems are free to end users, I don’t see what the business model would be for a private GNSS constellation, unless it were to piggyback on one built mainly for another purpose.

Surveyors who have begun to routinely use three or more constellations are over the moon. One, quoted in this month’s cover story, recalls that “the use of GPS for construction staking was an extremely risky proposition” because its residuals exceeded most construction tolerances. Using multiple GNSS constellations, however, has increased confidence in the accuracy of results to the point that some construction companies are relying on GNSS receivers for staking. Additionally, multi-constellation receivers can now increasingly be used under tree canopies and against structures, whether natural or built.

Whatever their mix of military, political and commercial motivations for building, deploying and operating their own GNSS constellations in addition to the original two, the European Union, China, India, Japan, Korea and whichever entity may follow are greatly improving satellite-based positioning, navigation and timing (PNT) for all users everywhere — by increasing accuracy, shortening the time to first fix, and making GNSS more impervious to jamming and spoofing.

In 1978, the year that the U.S. Department of Defense launched the first NAVSTAR GPS satellite (“NAVSTAR” was later dropped from the system’s name), Neil Young sang “Four Strong Winds” (originally written by Ian Tyson and performed by him with his wife Sylvia as the Canadian folk-duo Ian and Sylvia).

Now, GNSS has “four strong winds,” two lighter ones and several more breezes to follow. As a sailor and a navigator, I welcome them heartily. As this magazine’s editor-in-chief, I don’t mind that, like Jeep, Kleenex, Popsicle and Xerox, GPS probably will stick in popular culture as a generic term for global satellite navigation systems way past its accurate description of what is in the box.

Matteo Luccio | Editor-in-Chief

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