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AW 2 GPS Accuracy - Mine is off slightly.

igrover

igrover

macrumors 6502
Original poster
Jun 9, 2007
270
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So this morning I travelled a very well know route that has been recorded with both my Garmin 235 and my iPhone 6. Both of these devices measured very close to the same distance, within 10-15 steps variance between the two over the course of a mile.

Today I took the new AW 2 with me and turned off bluetooth on the phone so the watch was forced to use its GPS. At the normal one mile marker the watch was reading .96 miles. At the conclusion of the route when the distance is normally 1.98 miles the watch was reading 1.91 miles.

Although for me the watch GPS measurement is much better than the AW 1 stand alone method of using the accelerometer I must admit to being disappointed. I could live with this small variance at shorter distances however when you go above 5 miles the variance would be too great.

Anyone else have any GPS observations?
 
I think it has to be calibrated a couple times with the phone present to be most accurate. My watch indicated that the first two times I walked with it. Maybe give that a try.
 
Why would you need to calibrate the watch that has a stand alone GPS chip? I thought that was only necessary if you were using the accelerometer to measure distance.
 
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I don't think calibration applies to GPS use. That is for stride length and non-GPS.

Give it some more runs. I have a 5 mile route, and my Garmins have a 0.02 mile standard deviation over hundreds of runs. My iPhone GPS running app distances have been around 0.1 mile SD. So the difference between your two is within my observed stastical bound. I suspect the AWS2 will likely be on the order of 0.1 SD or higher to achieve the claimed 5 hour battery life.
 
exxxviii said:
I don't think calibration applies to GPS use. That is for stride length and non-GPS.

Give it some more runs. I have a 5 mile route, and my Garmins have a 0.02 mile standard deviation over hundreds of runs. My iPhone GPS running app distances have been around 0.1 mile SD. So the difference between your two is within my observed stastical bound. I suspect the AWS2 will likely be on the order of 0.1 SD or higher to achieve the claimed 5 hour battery life.
Click to expand...
https://support.apple.com/en-gb/HT204516

Read above. It does
 
That's the calibration for stride length. It has been the same since the introduction of the watch. It is highly unlikely that affects distance accuracy while using GPS, especially if the device has good reception.
 
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Given we have no idea how the watch utilises the chip calibrating adds to the accuracy.

At the end of the day the gps chip may be polled every few minutes with the other sensors adding to the gaps in data.
 
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And just to make sure everyone does not think I am holding the Apple Watch 2 to a higher standard in regard to GPS accuracy here is a link to some GPS comparison data between watches and smartphones.:

http://fellrnr.com/wiki/Best_Running_Watch

I do understand that there is a difference between devices. Just concerned at the moment why my Garmin 235 and iPhone 6 were basically the same and the AW 2 is the outlier.
 
The AW is probably not taking as many GPS readings as the garmin to save battery. We know that you can set a garmin to 1 second recording for absolute accuracy. Apple won't tell us what its doing, in my view its just not good enough compared to Garmin if you want to be serious about running and fitness
 
I think with any device you use you should give it s fee runs before you decide it's overall accuracy. I just ran five miles today with just the Watch and it recorded 4.98. I'll take that all day, but it was also my first real standalone run.
 
Update:

Day 2 on the same route. Today the watch showed .98 miles at the usual 1 mile marker and finished at 1.96 miles for the usual 1.98 mile route.

Interesting. Nothing else changed.
 
I've done 2 outdoor runs (different routes) with the new watch. Both were exactly what I was used to on previous devices (phones and garmin/tomtom watches). One thing I've always watched closely was my current pace as it showed on any of these devices. I was quite happy with how quickly the pace was updated on the Apple Watch with respect to the speed I was running at.

Also, I really don't think there's any calibration needed for the GPS Apple Watch. When using the original watch it always warned you the first few times about calibrating when starting a run. The Series 2 never did.
 
After you get about 20 runs in, post the mean and standard deviation of the Garmin (as a control) and the AWS2. If the AWS2 has a SD of about 0.1 miles, then this variation would be within statistical norms.
 
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I just read that the AW2 doesn't report elevation when going on a run. I find this hard to believe since Altitude is pretty much a byproduct of GPS unless you only have a lock on three satellites (you need four to get 3D co-ordinates). I think what they might mean is that the built in recording app doesn't report elevation (I don't have my AW2 yet so can't comment on this). I'm hoping 3rd party apps like Runkeeper will report Elevation, but I guess we have to wait and see since there don't appear to be any that use the GPS functionality yet.
 
mitty said:
I just read that the AW2 doesn't report elevation when going on a run. I find this hard to believe since Altitude is pretty much a byproduct of GPS unless you only have a lock on three satellites (you need four to get 3D co-ordinates). I think what they might mean is that the built in recording app doesn't report elevation (I don't have my AW2 yet so can't comment on this). I'm hoping 3rd party apps like Runkeeper will report Elevation, but I guess we have to wait and see since there don't appear to be any that use the GPS functionality yet.
Click to expand...
This is probably worth further research. It could simply mean that the UI on the phone is not presenting either an elevation chart or elevation gain/loss for the splits. That would not surprise me. It could also be a reference to whether or not the watch is using a barometric altimeter.

I have not used Runkeeper in months, but when I did, on the AWS0, it captured and reported elevation from the phone's GPS. I would expect it does the same when it is eventually enhanced to use the watch's GPS.

Edit: If you are referring to the recent The Verve review, the headline and first section are grossly misleading. The AWS2 does not have a barometric altimeter, but the device is still capable of tracking elevation via GPS. Apple's barometric altimeter omission is a gap relative to most other comparable trackers on the market, but GPS elevation is still there.
 
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Just some personal observation about elevation:

When using the original Apple Watch on OS 3 beta, the workout summary in the activity app would show the total elevation gain for a run, even when running without the phone. I'm quite sure it was just using map data from the route to calculate the elevation over the course of the run.

Now with the Series 2, the workout summary in the activity app does not report the elevation gain. I wonder if it would report it if running with the phone as well.
 
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