GNSS: The New GPS

First of all, on behalf of all of us here at GPS World magazine, allow me to welcome you to 2015. We wish you a healthy and prosperous new year!

I’d like to start out the new year stating the obvious for some of you, maybe most of you…perhaps all of you: GNSS is the new GPS.

In the high-precision GNSS community, I think this is already our mindset, and has been for quite some time. The benefit of using signals from as many satellite navigation systems to the high-precision user is obvious. We saw this with the adoption of GLONASS more than a decade ago. It’s to the point now that even many consumer receivers (such as my Samsung Galaxy S5) utilize both GPS and GLONASS satellites.

I think it’s pretty obvious we’ll see the same phenomenon with Galileo (Europe) and BDS (China’s BeiDou system). It’s exciting to think about what high-precision GNSS positioning is going to look like just 2-3 years from now. Think about how much better RTK positioning will be with 30+ satellites in view. By the way, that’s already a reality in China where BDS has 14 regional satellites in addition to GPS and GLONASS. It’s the best place in the world for RTK positioning due to the number of satellites in view at any one time, and it might be the reason that China consumes more RTK receivers than the rest of the world combined.

BDS coverage area.

BDS satellite orbit map.

I certainly look forward to the deployment of Galileo and BDS. It will only make us more productive in accomplishing our work. Yet I’m reminded frequently when reading mainstream news headlines that Galileo, BDS, and GLONASS compete with GPS. Even some of those who hold GPS dear to their hearts, such as those who were involved in the development, promotion and deployment of GPS, view the other satellite systems as competition.

Maybe that’s not a bad thing because competitors push each other to perform better. However, where it might hurt is when it comes to support, such as funding. Galileo, in particular, because it’s funded with civil funds instead of defense funds like GPS and GLONASS, has been criticized as a wasteful use of resources because GPS already exists. What more can it add, they ask? The mainstream media doesn’t have a clue that the satellite navigation systems are complementary rather than competitive. You and I know that more satellites generally equates to increased productivity no matter who owns/operates the satellite that is sending the signal. I cringe when I read these headlines:

News Headlines

GPS and its Three Main Competitors: Galileo, Beidou, GLONASS

GPS vs. Galileo; Where Are They Headed?

China Spreads Alternative To U.S. GPS System

China’s Beidou Navigation Satellite System More Precise than GPS in Certain Areas

GPS vs GLONASS: Which Is Best for Tracking Applications?

Generally, I dismiss the mainstream media in the GNSS arena, but these misleading articles can have an impact on funding of the various GNSS, such as Galileo. Politicians and various purse-string holders can be influenced by these stories.

Galileo Moving Forward

The Europeans are pushing forward after the recent hiccup when the first two Full Operation Capability (FOC) Galileo satellites were inserted in the incorrect orbits due to an improper fuel line installation on the rocket launcher resulting in the satellites being inserted in an orbit far below its intended orbit (an elliptical orbit, 49.8 degrees at 26,200 km, vs. the intended circular orbit, 55 degrees at 29,900 km).

In October 2014, shortly after the faulty launch, the outlook for the two satellites was bleak. The consensus was that there was no feasible method to move the satellites to their intended orbits. The good news was that besides the fact that they were in New York instead of Los Angeles :-), they checked out healthy, were properly oriented to the sun, and were “thermally stable.” Would they join GPS SVN-49 in being demoted to permanent test mode status, never being allowed to join the operational constellation, further delaying the deployment of Galileo? Not so.

In late October, flight engineers used a series of fuel burns, using more than 75 percent of its fuel payload, to boost the satellite 3,500 km further into space, into a more circular orbit. While the original, incorrect orbit “prevented their use for navigation services because they were too low during part of their orbit to sense the horizon and correctly determine their own position,” the new orbit, not quite the intended orbit, seems sufficient to allow the satellite to perform most of its intended duties, including being incorporated into Galileo’s operational constellation.

The first live test was completed on December 9, 2014, when the satellite was one of four Galileo satellites that delivered a position fix of better than two meters. Furthermore, in a January 1 article published on GPS World’s website, Peter Steigenberger and André Hauschild of the German Aerospace Center wrote that the rogue Galileo FOC satellites can likely be used by commercial, multi-frequency, high-precision GNSS receivers for carrier-phase positioning. One drawback is that because the satellite’s orbit doesn’t fall within the limits of the standard Galileo almanac, it may take receivers longer to begin tracking the satellite.

Flight engineers are now working on maneuvering the second rogue Galileo satellite in the same manner, hoping for the same result.

All in all, this is about as good of a result that could possibly be expected. My hat’s off to the folks who made this happen.

Meanwhile, the next four Galileo FOC satellites are moving through the production process. Originally slated for a December launch, I suspect last year’s launch anomaly had the Galileo folks double-triple-quadruple checking, dotting i’s and crossing T’s, so make sure the next launch has the best chance of success. They haven’t announced a new launch schedule yet, but I would guess it’s likely in the next six months, with quarterly launches resuming if things goes smoothly. If all goes well, we could be benefiting from 10 healthy Galileo satellites by the end of the year.

Thanks, and see you next time.

Follow me on Twitter at https://twitter.com/GPSGIS_Eric