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935 Galileo Difference

GS over 6 years ago

New thread to discuss performance difference with GPS + Galileo as compared with other options (GPS or GPS+GLONASS).

One run for me on road on usual route in Southeastern US, GPS + Galileo, and no perceived difference in elevation, track accuracy, distance or pace. Perhaps a little quicker to lock satellites before activity start but only perception. Really hadn't noticed a difference between GPS and GPS + GLONASS either, prior to update.

0 Former Member over 6 years ago

Btw I rather like the "GNSS View" app on iOS. A good looking clean UI, and easy to use app to show your satellite situation for the day. Now if I only knew how many actually connected :)

0 lustyd over 6 years ago

The position fix doesn't work the way you'd generally expect it to. I think it was DCRainmaker that asked a while ago and got an explanation. if you have 2xGPS and 1xGLONASS you won't get a fix. You need a minimum of 3 satelites from each to get a fix, and then the watch calculates the average position of the two - this could be a bad thing, and probably usually is because one will always have a worse fix than the other. This will be more true of Galileo which has considerably more modern gubbins than GPS so in theory will give a more accurate fix. If you then taint that with the GPS fix you'd have to ask why you put Galileo in there at all. Obviously this all assumes a complete set of Galileo satelites which is currently not the case.
Navigationally too, most sailors are aware that if you make a "cocked hat" on the chart there is a far higher chance that you're not in that triangle than that you are! This certainly will be true of GPS too, so realistically from a maths point of view, the position it gives is very unlikely to be your actual position :D
From a battery perspective too, if the device is calculating 2 or 3 positions and then calculating the average that's not a good thing.

0 FlipStone over 6 years ago

So, did a 15k run today with Galileo+GPS and although I think the track was actually a little bit better compared to normal gps the battery hit was significant... As in ~50% more!

Run with GPS only:
https://connect.garmin.com/modern/activity/2766139746

Run with GPS+GALILEO:
https://connect.garmin.com/modern/activity/2817861339

Time and distance wise to identical runs, but battery usage with gps only was ~6% and with gps+galileo ~9%.

Tracking with gps+galileo was about perfect, tracked the roads greatly (only some jump when going under a bridge, gps only was less sensitive with this) although gps only was also tracking great for me... just some minor deviations from the road.

So while galileo does seem to add some precision in my/this case, the battery hit is absolutely not worth it... Perhaps when walking (lower speed and thus less precise) it can really make a difference but again, battery hit is just too much for me atm.

0 biondi27 over 6 years ago

I live in the caribbean and I can see at least 3 Galileo satellite at any given time. First run in the city, with tall buildings and the precision is much worse, second run in the park at a different hour and the result is the same, much worse than GPS alone. I don't know if the watch himself can't do all the calculations needed to make use of so many satellites but it is the same with my phone, precision is not different going fron Galaxy S7 (not supporting Galileo) to S8 (supporting Galileo).

0 timgrose over 6 years ago

Am in the UK. After a couple of runs, I can see parts where Galileo does a little better (than a 645 on my other wrist with GPS only) but not a huge difference - largely as GPS only or GPS+GLONASS is generally pretty good for me. Need to try a few more to see if really helps.

0 AgentMax over 6 years ago

I did a run yesterday with GPS+Galileo. Cannot see any improvement in track quality compared to GPS only (central europe, flat, good weather). Might be different in the mountains or otherwise difficult environment.

Fore me it got worse. Same is with GLONASS. Personally I will stay at GPS (until Galileo only will be available).

0 Tom Shane over 6 years ago

I'm in Czech Republic, I have no side by side comparison, but my tracks with Galileo, both walking and biking, are very good, certainly not worse. I also noticed the instant pace is almost perfect while walking.

Bike: https://connect.garmin.com/modern/activity/2818625805
Hike: https://connect.garmin.com/modern/activity/2816386695

0 AgentMax over 6 years ago

These "spikes" shown on your track came to my track with Galileo. Without its a smooth line.ciq.forums.garmin.com/.../1370102.png

0 Former Member over 6 years ago

I saw also slight zigzagging on my first run with Galileo beta on F5, on other hand there is perhaps less offset from actual path than with gps + glonass. Similar to the pictures above. Distance was a slightly long for this run but still within acceptable margin of error.

0 Tom Shane over 6 years ago

These "spikes" shown on your track came to my track with Galileo. Without its a smooth line.

Well, maybe my track is not a good example after all. I was walking with my dog and there was a lot of mud in some places, so I was zig-zagging a lot, so in my case, it wouldn't be a straight line anyway.