High-precision positioning to improve as next-gen GNSS begins

A four-satellite dispenser for Galileo’s Ariane 5 is shown during shaker testing at Airbus Defence and Space near Bordeaux, France. The dispenser has had four Galileo engineering models attached to it for test purposes. (Photo: ESA)

In Geospatial Solutions’ sister publication, GPS World magazine, I’ve written quite a bit about how high-precision GNSS is going to significantly improve over the next few years.

Most GNSS users have receivers capable of using GPS (31 satellites) and Glonass (about 24 satellites). That generally equates to between 13 and 20 satellites in view with a clear sky and average terrain. However, add in variable terrain, some trees and perhaps a nearby building or two, and it can be a challenge to find enough solid satellites to track to obtain a high-precision GNSS position (less than a meter).

As the demand for high-precision GNSS positioning continues to grow, users are going to want to work in increasingly more difficult environments where high-precision GNSS struggles. More satellites will help, but they won’t come from GPS, nor GLONASS.

The GPS constellation is currently full, and is not going to grow any larger than 31 satellites (due to limitation in current GPS ground control software) in the foreseeable future. Even if GPS could fly more satellites, the orbit design accommodates only 27 satellites. GLONASS appears happy at 24 satellites and is not expanding anytime soon.

The answer lies in Europe, with China following.

After two decades of start, stop, restart, retool, regroup and start again, Europe’s Galileo constellation is real — very real. It’s all fun and games until Galileo starts launching four satellites at a time, which it is scheduled to start doing in a couple of months. Those four new satellites, added to the 12 in orbit (plus two in odd orbits), should be enough for Galileo to begin initial operation in Q4 of this year. Then, each new launch of four additional Galileo satellites will only improve the reliability and robustness of high-precision positioning. That’s a big deal for high-precision GNSS users.

Get ready for another jump in performance in high-precision GNSS positioning.

Do you remember the value that GLONASS added to GPS-only receivers 10-plus years ago? It was a premium feature on high-precision GNSS receivers in those days. Now, GLONASS is a standard feature on your smartphone.

Not very long from now, we’ll be making similar comments about Galileo. Satellite positioning in general, and high-precision GNSS positioning specifically, are satellite-hungry. As high-precision GNSS technology continues to embed itself deeper into a wide variety of industries, users will expect the technology to work. Some of those expectations, maybe many expectations, will be unreasonable. In dense urban environments? Under heavy tree canopy? In rugged terrain?

Unreasonable expectations are O.K. — that’s what pushes GNSS product managers and GNSS engineers to think outside of the box. More satellites will help meet some of the unreasonable user expectations.

What’s even better is that China’s global BeiDou system isn’t far behind Galileo. China’s regional BeiDou system (16 satellites in regional orbits over China) already makes China the best place in the world for high-precision GNSS positioning. Like Galileo, China’s global constellation is said to consist of 30 satellites.

That means in the not-too-distant future (about 2018 for Galileo and 2020 for BeiDou):

31 x GPS
24 x GLONASS
30 x Galileo
30 x BeiDou
Total: 115

This translates into more than double the satellites in view that we have at this point in time. But, you don’t have to wait. Galileo satellites are usable this year if your receiver has been designed to use them. With each new Galileo launch, you’ll have access to four more satellites until the constellation reaches 30. The same goes for BeiDou.

Don’t take this wrong, GPS isn’t done. Not by a long shot. However, historically speaking, at one satellite per rocket launch, it’s only averaging about one launch every six months. To complicate things, the U.S. Air Force has launched all of the current GPS model (IIF) satellites and aren’t ready to launch GPS III satellites yet. See Don Jewell’s August column in GPS World magazine for details.

The good news is that the user community doesn’t have to rely on an expanded GPS constellation to improve performance any more than the “gold standard” it has become. The difference-makers are going to be Galileo beginning this year and BeiDou beginning in 2018. So, get ready folks, and fasten your seatbelt. The next generation of GNSS is about ready to begin, and your geodatabase is about ready to get a double-shot of Vitamin B.

Follow me on Twitter @GPSGIS_Eric.