Distance measuring inaccuracy

Hello,

Last two days I had possibility to test Walk activity on longer distances. While walking I spent some time indoors, I'm pretty sure GPS didn't have enough sky to get satellites. In the end of the trip I get info from Instinct I walked almost 28km. I knew it wast totally not true. Today I exported GPX and opened it in OkMap. I believe this program measures distance in simplest possible way. Result is 16km which is much more reasonable. I wonder where from is this difference which gives all statistics from Garmin into trashbin. I know GPS had problem with signal but I would expect that software would be able to just measure length of track instead of giving totally crazy numbers.

I have to admit, with clear sky in the mountains I didn't experience this issue. But when I walk I don't always remember to pause recording and then run it again and probably it will affect overall time of walk?

What's funny: I had with me Huawei phone, second person had Samsung, both were recording steps only in automatic mode (without GPS) and result was almost identical: 13.5km.

In this case this simple measuring method was the most accurate.

Regards Rafal

0 GeoffR over 4 years ago in reply to tmk2

Sounds like you expect the watch to determine that while on a run/hike/walk you've gone indoors vs under a tunnel or heavy tree canopy. That would be pretty fancy!

I don't think there are any indoor activities (on the Instinct) that invoke the GPS. Most of the outdoor activities do trigger the GPS. As the Instinct is positioned as an outdoor enthusiasts watch, this particular use case (outdoor - indoor - outdoor) seems pretty rare.

However, and as I said above, Garmin could probably tweak the algorithm to use steps (instead of the last measured pace that you suggest it uses) when GPS is lost. That seems like the only way to meet the OP's request: start a GPS activity that will keep track of total distance both inside and outside and draw an accurate path of the total activity. Also, the GPS tracking would need to be shutdown while indoors, otherwise the path could look very weird.

0 tmk2 over 4 years ago in reply to GeoffR

GeoffR said:
Sounds like you expect the watch to determine that while on a run/hike/walk you've gone indoors vs under a tunnel or heavy tree canopy. That would be pretty fancy!

No, it's quite easy, really. Whenever the GPS chip reports no GPS signal, then that's a good indicator of being indoors. There are garmin devices that can do that, i.e. they resort to other pace/distance measuring method when GPS signal is lost.

GeoffR said:
this particular use case (outdoor - indoor - outdoor) seems pretty rare.

Agreed. It's not that it's a showstopper or something.

In the meantime I made an interesting observation. I don't know how it behaves on the Instinct, but on the FR735XT this is an issue only Hike/Walk profile. In Run profile it behaves ok, i.e. it relies on a footpod or internal accelerometers, when GPS signal stops being available.