GPS Disconnected & over calculating distance

[r1flyguy]

Just completed a 10km hike.  The GPS disconnected after 2km and the sense recorded my walk as 14km!!! Why are fit bit products so continually poor? My hiking buddies Apple Watch was perfect on distance etc and recorded the route!

I bought the sense as my charge 4 was just as bad!! And the sense was ‘supposed’ to be standalone gps and didn’t need my iPhone! Again Fitbit coming up well short in its claims 

what’s going on????

[Rich_Laue]

If the gps disconnected, the Sense continued to estimate your distance based on stride setting times steps. 

Sounds like your stride settling is incorrect. 

[t.parker]

@r1flyguy to add what @Rich_Laue says (which is right) in general Fitbit uses stride length to compute your distance (regardless of whether you use GPS or not, GPS has nothing to do with the distance), however, the GPS will affect stride length if you use automatic stride length computation. I suggest using manual stride length as bad GPS may trash it for you on the next walk/run.

[SunsetRunner]

Hi, everyone.

@Rich_Laue  and @t.parker , I've read several posts of yours in several threads along the past months and came to always appreciate and respect your opinions, cause you guys clearly know a lot about everything Sense and more.

But it happens I have some professional experience working with different kinds of GPS. Maybe 15 years or more, since before President Bill Clinton, in 2000, finally ordered GPS intentional random error, that had always been in place for everyone other than american military and their allies, to be removed, finally allowing us, common citizens of the world, to have access to GPS full accuracy (Clinton did that not for an act of kindness, but because meanwhile USA and NATO potential or real enemies had figured out how to remove themselves that random error, making it pointless). And then came access to Glonass and Galileo satellites, etc., allowing GPS accuracy to continuously improve until what we have today.

Even today I wrote part of my opinion about Sense GPS accuracy on another thread, here (my 2nd, 3rd and 4th posts).

Sense GPS accuracy seems indeed of lower quality when compared to the best GPS devices on the market, including all or most of the well known brands competing with Fitbit.

Defining an accurate stride length when you cover distances of several km/miles is not easy, mainly when you go off road, because the length of each step changes along the whole path, either because your speed varies along the way, or the step length differs if you are going up or down, or because off road rugged terrain makes you continuously change from short to long steps.

Taking all this into account (and what I wrote on that thread I mentioned above), even if you use Sense to automatically calculate your always changing stride based on its GPS data, if the GPS data has not great quality and, even more, if it looses the satellites signals for several km/miles, in the end you will get distance errors, that I now estimate can be approximately between 5% to 15% most of the times, but can be bigger, as @r1flyguy  reported.

Reading  @r1flyguy  10km hike experience, I think he has every reason not to be happy with Sense GPS and the total distance error it provided in that case.

[r1flyguy]

I’ve previously owned the Ionic (really poor strap design, replaced several times over 2 years) that stopped working 2 months out of warranty. The charge 4 whose GPS rarely worked but distance calculation were pretty good now the ‘Sense’ which is meant to be the flagship but so far is no better if not worse than the charge 4 for its ability to maintain GPS connectivity and distance. 
I think once this gives up a week out of warranty I’ll go to Apple Watch as they seem to be far better in almost all areas!!

you know what they say “buy cheap, buy twice” and again the theory proves to be correct! 

[SunsetRunner]

@r1flyguy , can you please tell if you were in the middle of trees or some other covering when your Sense GPS failed during your hike?

Because if you were, I understand. If you were always under open sky, then I don't, then there must be some other reason to explain those km without GPS signal.