GPS & HRM Inaccuracies: Series 4 versus Series 3

James.K.Polk

macrumors 6502a
Original poster
Aug 31, 2015
766
265
When running, my Series 4 is consistently producing worse GPS track and significantly worse HRM charts than my fiancee's Series 3, even on identical runs.

Screenshots are here from a recent shakeout run - the more accurate charts (taken on iPhone 8) are hers, mine are on the 8+.

Does anyone have experience with this?
 

PeytonT123

macrumors regular
Oct 17, 2018
119
43
US
I don't have a Series 3 to compare, but my Series 4 GPS is always a little bit off. When I use it to log runs and then upload it to RunKeeper (or Strava, and "correct distance",) it decreases the distance that the watch initially said I ran.
 
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James.K.Polk

macrumors 6502a
Original poster
Aug 31, 2015
766
265
I don't have a Series 3 to compare, but my Series 4 GPS is always a little bit off. When I use it to log runs and then upload it to RunKeeper (or Strava, and "correct distance",) it decreases the distance that the watch initially said I ran.
That solves the overall distance problem, for sure, but doesn't really correct the generally bad GPS track itself.
 

vanhalen26

macrumors newbie
Nov 14, 2018
22
3
Are you near tall buildings? That always throws my GPS off, whether Apple or Garmin (I wear both). I find the readings on my series 4 and Garmin very similar in more open areas but both get wild swings in areas with taller buildings. I think it was called signal reflection or something like that - the gps signal bounces off buildings. It’s annoying when trying to dial in a pace. I ran a half a week and a half ago and it started in a downtown core and was a mess until we left the downtown. I just use the garmin for my stats as a I run, and the Apple for my music!
 

Significant1

macrumors 6502a
Dec 20, 2014
720
214
Did you both run without phone?

Don't know about HR. Do you have a tatoo on your arm. Did you wear it tight.
 

Significant1

macrumors 6502a
Dec 20, 2014
720
214
I run without phone (it’s cell watch), no tattoo, yes I wear it comfortably tight.
But what about your fiancee?

I ask to make sure you compare watch gps to watch gps and not watch gps to iphone gps.

You could try, if it is better on the other arm. You could also try switch watches next time you go for a run. But that is easier said, than done, since it will mess with health statistics, unless you either delete the workout afterwards (you can manually add a workout on the right phones, so it is not all lost) or do a full unpair/pair switch.
 

James.K.Polk

macrumors 6502a
Original poster
Aug 31, 2015
766
265
Did you both run without phone?

Don't know about HR. Do you have a tatoo on your arm. Did you wear it tight.
Neither of us carry phones, and I do wear it tight - about as tight as comfortable. I wear the Sport Band. No tattoos.
 

PeytonT123

macrumors regular
Oct 17, 2018
119
43
US
That solves the overall distance problem, for sure, but doesn't really correct the generally bad GPS track itself.
Yeah, I wish they could fix it. I wonder if it’s a hardware issue or something that could be fixed with a software update. It traces runs perfectly, I never see errors on the map itself....but it always seems to overshoot the distance and say a certain area on a map is a larger distance than it actually is.

That also makes the pace alert feature inaccurate.