This article looks at accuracy issues surrounding GALILEO positional tracking on sports devices such as those from Garmin and the principle of sports accuracy applies to other uses of GALILEO satellites.

GALILEO – What’s the big deal?

Positional accuracy should really be described in terms of GNSS. We use the term GPS which really refers to the US system of satellites that we usually use with sporty devices. GLONASS is the Russian system, BeiDou the Chinese one and GALILEO is the European one. There are other regional ones too and these can work together to give a multiband GNSS ‘solution’.

Sports devices and other navigational devices can use one system or a combination. GLONASS is probably of a similar level of accuracy to GPS. The advantage of using both together is that there are simply MORE SATELLITES TO CHOOSE FROM and hence there is an increased chance of getting a good GNSS fix in areas of tricky reception. GALILEO throws yet more satellites into that mix and ALSO offers the potential of increased accuracy. We are talking accuracy of GLONASS or GPS as being +/-5m and GALILEO being +/-1m. So GALILEO is a potentially big improvement.

This will translate into us being able to have a much more accurate and pretty track in our sports software to show us where we’ve been. Hmmm. But increased accuracy MIGHT also give us usable instant pace as well as improved and more responsive navigation.

Against that we might wonder if Garmin’s antennae are up to the job and we might wonder if the GALILEO system is fully operational and we might wonder if Garmin has a single- or dual-band GALILEO implementation (it’s single-band). But I don’t think it really matters, all we need to know is will our sporty-gadget experience with GNSS be improved as of NOW?

Initial reports on forums are suggesting a tentative ‘YES, A LITTLE BIT‘ in answer to that question I just posed.

I’ve heard it all before though. And you probably have too. I’ve tested a lot of sports watches for their GNSS accuracy and, despite my initial excitement for the GLONASS release, I reckon that GLONASS usually decreases accuracy. Well, I thought GLONASS always seemed to decrease accuracy but then I noticed in some TREE-COVERED or URBAN scenarios with taller buildings, that reception was sometimes improved – albeit unpredictably so. But it was still in the broad realms of ‘Not great‘.

I got to the point where I mostly do GPS-only testing. Life is too short.

My First Test with GPS+GALILEO

I have a long and greatly imagined series of things to do with GALILEO and running shoes. However, I stopped myself before I got too excited and decided, this evening, to embark on a sanity check run.

So I did a few repeated runs along the same route with various GNSS devices. It was a hard route as far as GNSS reception goes.

If GALILEO flunks this test then I’m probably not going to be too bothered with it going forwards.

The Test

I usually incorporate a 10-mile test route into my GNSS testing, which also includes many other real-world scenarios. 10 miles is not a trivial distance and I am in the middle of races and tapering. So I decided just to do the hard part of my 10-mile route which incorporates: good tree cover; lots of 2/3 story buildings; some LARGE buildings; a bridge (under one and over one); and an impossible GNSS tunnel.

The test route was about a mile long and handily ends at Sigma Sports (my local bike store) so I can drool over some extremely expensive bikes before returning to the start of the route which will allow the watch to get a good GNSS soak of whatever GPS/GALILEO/GLONASS combination was about to come.

The image on the right shows an overview of the 1-mile route and is orientated correctly North-South. Some of the images below are rotated 90 degrees clockwise as they fit the page better that way but they show segments of the EXACT same tracks shown to the right.

Here’s what I did with the Garmin, Suunto and Polar. It’s no coincidence that I chose the V800 and SPARTAN SPORT, they are 2 of the best GPS devices (the 935 isn’t but I still use it anyway #STRYD)

Run 1

• Garmin 935 – GPS+GALILEO, right arm. Normal wrist position.
• Polar V800 – GPS, right arm next to Garmin 935. Facing the right way
• Suunto Spartan Sport – GPS, left arm

Run 2

• Garmin 935 – GPS+GLONASS, right arm. Normal wrist position.
• Suunto Spartan Sport – GPS, left arm

Run 3

• Garmin 935 – GPS, right arm. Normal wrist position.
• Suunto Spartan Sport – GPS, left arm

I ran the exact same route to the nearest 50cm left or right and the sky was clear.

Legend/Key

Image 1 – The 3x Suunto Runs

I’m showing this first image of the 3x Suunto Runs (1 watch, 3 runs) as it demonstrates the variation that one device can have on the same route on the same day.

So there are some quite large variations. Maybe the blue track is the best. From the VERY many runs I’ve done on this section, I would say that the 3 Suunto SPARTAN tracks shown above are DEFINITELY WELL on the GOOD side of average. But you can see as well as me that in the middle under the words ‘River Thames’ there is probably a 10m gap between the blue and orange lines. Clear improvement is possible in some situations.

Image 2 – Zoom-In and Add V800

This adds in the V800 to the 3x Suuntos. The V800 is similarly good, possibly better.

Image 3 / 4 – Galileo

Let’s leave the other devices for a minute and concentrate on the 3x Garmin runs.

These are the 3 Garmin runs. Which one is Galileo?

Well. The pink one is GLONASS. That clearly went wrong and that is exactly the sort of thing I have experienced many times with GLONASS, sometimes much worse than that.

The red one is the Galileo track and it’s probably the better of the 3 over this entire section but not so great on the top right.

Here are the same 3 Garmin tracks on the other part of the track. With just tree cover as the issue, they look pretty similar to me at the start of the route.

Image 5 – All of them

You’re still looking for the red line being the GALILEO track. Looking from the right, it does seem like it is the more extreme of all the lines as I run from right to left. It IS further up than it should be but it’s tracking the DIRECTION of the correct line pretty well.

It has mixed performance compared to the others at the left side of the image

Image 6 – The Correct Route – Part 1

I appreciate I’ve confused you with lots of multi-coloured lines but hopefully they will pre-empt answers to some of the questions below.

Now I look at the best Suunto track, Galileo and the V800. BUT I will also try to draw on the CORRECT route (white)

The Green, V800 line is the closest to the correct route in white. The Galileo is still ‘Good’ but I would say the Suunto was slightly more Good. But, hey, they’re all good. I wouldn’t normally class Garmins like that. I’d more say Garmins were on the good side of acceptable.

Image 7 – The Correct Route – Part 2

This final image is perhaps more enlightening. The errors in part 1 were relatively trivial but here you can finally see that we are talking about big errors in tracking. These seem to be caused by 1) signals bouncing off buildings take longer to get to the watch and come from the wrong direction, this seems to throw the tracked route away from the building you are running close to and 2) guesses made in the long tunnel on Horse Fair (bottom right)

Clearly, the V800 (green) is best again. But both the other two are better than the average watch performs on the bottom right-hand side, even though it looks bad 🙂

What is GPS 3? GPS III vs GALILEO and GLONASS – which is best?

Very Tentative Conclusions

On the basis of a mere 3 miles of running today, I am certainly not going to suggest that you buy or upgrade your watch. Sample size 1 and all that.

I satisfied my curiosity that Galileo does seem to offer a POTENTIAL improvement.

Unfortunately and TENTATIVELY, it looks to me that Galileo has brought Garmin up to the ‘Good’ category but still not as good as the V800 or one of the better Suuntos using only GPS.

My guess would be that INSTANT PACE WILL BE IMPROVED but don’t throw away your running pod yet. It still won’t be as good as that.

So rather than dismissing Galileo out-of-hand, it looks like there IS something to have an extended interest in (or to even get mildly excited about). More research shall now ensue.