Yesterday, I hiked Mt. Bierstadt – one of Colorado's 14ers. I started and stopped tracking my hike at the same time on both my Apple Watch Series 4 using the workout app and my iPhone 8 using the GPS Tracks app. I have found the GPS Tracks app to be very reliable in the past. When I finished, I had drastically different distances recorded: 7.7 mi on my phone, 9.4 mi on my watch.
GPX file from GPS Tracks: https://www.dropbox.com/s/k6iao43t32yykac/Bierstadt_hike.gpx?dl=0
My phone was polling every ~4 seconds. I don't know what rate the watch polls at. Does anyone else? I would think, because it is a low power device, it would be polling less frequently, but if was doing that, I should have gotten a shorter distance on the watch than on the phone. Does the watch workout also use data from the iPhone motion tracking? Does the watch distance rely strictly on GPS, or also on motion (usually when I hike, my hands are grasping my backpack shoulder straps, not swinging at my side)?
Anyway, just curious if anybody here has any insights into why there is such a great disparity between the two devices for the measured distances. Any thoughts are appreciated. I know that this is not a new topic, but thought I would at least add some data to what's already out there.
EDIT: I just noticed that if you zoom way in on the track in the Activity app on iOS, you can see many little dots. Presumably those dots represent when a GPS data point saved. If that is the case, it looks like the watch was polling closer to 0.5-1.0 seconds.
Also, the 7.7 mi matches what some have posted on AllTrails.
EDIT 2: Looks like the watch does indeed save a GPS data point every 1 second. I found this in my export Health data:
GPX file from GPS Tracks: https://www.dropbox.com/s/k6iao43t32yykac/Bierstadt_hike.gpx?dl=0
My phone was polling every ~4 seconds. I don't know what rate the watch polls at. Does anyone else? I would think, because it is a low power device, it would be polling less frequently, but if was doing that, I should have gotten a shorter distance on the watch than on the phone. Does the watch workout also use data from the iPhone motion tracking? Does the watch distance rely strictly on GPS, or also on motion (usually when I hike, my hands are grasping my backpack shoulder straps, not swinging at my side)?
Anyway, just curious if anybody here has any insights into why there is such a great disparity between the two devices for the measured distances. Any thoughts are appreciated. I know that this is not a new topic, but thought I would at least add some data to what's already out there.
EDIT: I just noticed that if you zoom way in on the track in the Activity app on iOS, you can see many little dots. Presumably those dots represent when a GPS data point saved. If that is the case, it looks like the watch was polling closer to 0.5-1.0 seconds.
Also, the 7.7 mi matches what some have posted on AllTrails.
EDIT 2: Looks like the watch does indeed save a GPS data point every 1 second. I found this in my export Health data:
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