Connected GPS Pace and Distance is Inaccurate

[DanielMena9]

Went on a run today with my Charge 2 on one wrist and Charge HR on my other wrist. Also had RunKeeper to measure my distance. I started my run with about the same number of steps on both FIT devices. 

After the run, my Charge HR had almost 2K more steps than my Charge 2. In addition, my GPS map on FitBit matched my Runkeeper map which is about a 3.5 mile run BUT FitBit pegged the same route as 1.73 miles >.> 

Why doesn't this device work as advertised? I really like the design and feel of Charge 2 but if it can't do its job accurately, all is for not and I will be shorting FIT as it appears to be a widespread issue (I have maps and photos if someone from FIT wants the data).

Moderator Edit: Edited thread title.

[SunsetRunner]

Unfortunately I don't have 12 fingers, but do have the memory available to know I just passed 1000.

About stopping and starting, I wanted to see how accurate the map would be in a straight line vs. doing a circle route. That test is next.

It's definitely you with the attitude and huge contribution to this thread. Bravo. 

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[Rollerskier]

Perhaps Fitbit has also upgraded the hardware on the Charge 2 not only the Firmware so todays model is more accurate? I bought mine when it was launched first time.

[SunsetRunner]

Perhaps you are right. I've had my Charge 2 since last Xmas and despite the upgrades it still produces an error in the data.

Merry Christmas.

(7.5% contribution with actual data.)

[hawkeye1952]

We all know that the charge 2 has problems with the gps.  Because of the problems it affects other data that is based on your distance.

This is today walk.

Fitbit                   distance 1.50  average  pace 20.16    hearth rate 108  calories 360

 Endomondo       distance 1.55  Average pace 19.40  heart rate 120 (chest strap)  calories  364

as you can see there is a difference in every area

[Rollerskier]

I tested earlier that using the Fitbit app simultaniously with another GPS app of the same phone increased the inaccuracy of the Fitbit app data.  I made several test runs on the same track with 2 phones. Running 2 apps on 1 phone and only Fitbit on the other. Then changed phones. Fitbit alone was always better than Fitbit with another GPS app. 

[hawkeye1952]

I did as you suggested. For the first mile it was close. Yet when I finished it was way off. fitbit 1.1 miles my main program 1.17 miles. heart rate 90 vs 127 calories 290 vs 307. Everything is off. The hearth rate is the main thing I watch.



George Howell Jr

[Rollerskier]

Thats the surprise with Fitbit.  Happens to me as well occasionally that it during the trip completely loose the track for a part of the distance before it recovers. Rest of the trip is ok.  When I walk along the sideways its easy to see the deviations when you end up walking on the wrong side of the street or inside the gardens. I think its might be due to that the GPS signal quality gets weaker or there are some kind of bugs in the program importing the data. If you loose the GPS signals completely it draws a strait line between the last 2 points. 

[SunsetRunner]

Hi, I know what you mean sometimes the track is all over the place.

Do you know how often the Connected GPS samples actual position or is that up to the mobile being used?

I use the Walk mode when I'm out and the track wobbles all over the place which I think adds to the inaccuracy of the results. Also my Charge 2 seems to add steps that I haven't taken.

Today I went for a walk and my tracker had the most steps and the farthest distance travelled.

FITBIT 16,266 steps -- 7.93 miles.

OMRON Pedometer 15,387 steps -- 7.2 miles.

Google Earth Track 7.12 miles.

I find that the more miles I travel on a walk, the bigger the error gets.

Merry Xmas.

[Rollerskier]

Based on the TCX-file it`s 1 GPS sample every 1 second.

If you walk 5 km/h(fast walking) that is 1,39m/s and 1,39 m between 2 datapoints.

If you run 15 km/h that`s 4,17 m/s

If you roller-ski 25 km/h thats 6,94 m/s

If you drive a car 80 km/h thats 22,22 m/s

I have seen thats the accuracy is better when driving than when walking due to less datapoints and better direction stability.

[SunsetRunner]

So my original post is deleted?

??????????

Anyway, 3rd test - figure 8 run around the neighborhood. 3.33km (I do 3 loops for a 10km).

Connected GPS result - 3.35km. 1 corner was cut quite incorrectly on the map. 1 time it looks like GPS disconnected and the map showed me crossing and re-crossing the road when I didn't.

So far I am happy with the purchase.

[hawkeye1952]

I am glad you liked your charge 2. Here where I have some big problems with it. If it is not tracking your route correctly. Then are the steps count correctly. Then sense the Hr is not correct. Then the number of calories are not correct.Which means that you are most likely under your recommended hr zone. where you get the most benefit from.


George Howell Jr

[SunsetRunner]

Hi thank you for the information regarding GPS sampling.

I have logged 17 walks using the "Connected GPS" mode of distances between 4 and 11 miles and have found that the Charge 2 tracker records a distance of +10.7% on average.

If I walk the same walks without using the "Connected GPS" modes the tracker is within 1% of the actual distance. Which I regard as acceptable. This is calculated using only the stride length X number of steps. **

I have shown these results ( via email ) and the recorded routes using the Fitbit app to Customer Support to try and help them understand that, in my opinion, the GPS sampling frequency is too high for accurate mapping at walking speeds. This combined with the mobile GPS accuracy produces the wavy track and the inconsistent accuracy in distance data.

All I get from them in return is referral to sections of the help files and a lot of apologies for the "trouble you are experiencing".

It seems to me that "Customer Support" are not empowered to actually "Help" with technical support type problems and just are using a flow chart to answer customers queries.

I actually asked them to show my data to the Technical Development team, but I received no feedback.

After many months of trialing different settings on my tracker and logging the results and sending the information by email to the "Support Team" I have reached the conclusion that I am wasting my time with FITBIT.

Because of the above, I can no longer trust any of the recorded data from my tracker and I have sold my Charge 2 on ebay. ( It is good enough as a rough guide, but I expected better.)

I will be replacing it with a well known brand Sports watch that has very good reviews, but does cost more.

If you stay with Fitbit I hope they start to listen to their customers and improve the trackers accuracy.

Happy New Year,

CliveP.

**  Note to above - When I was out on the walks my friend was using a Garmin handheld GPS device to record our routes and I have retraced the routes on Google Earth Pro and Ordnance Survey online maps. I used this data to verify the distance walked.

[Rollerskier]

Best of luck with your upcoming new brand CliceP.  If you find something that proves to be very accurate with GPS and HR please keep us updated. Has anyone been able to get in touch with Fitbit technical support?

[hawkeye1952]

I stop using the the gps part of it. I never had it with in 1%. I now have the epson prosense 57.after 1 week of using the gps. I find that it is within .024 of my main program. very accurate. including the hr


George Howell Jr

[hawkeye1952]

Right now I am using the Epson prosense 57. Gps is usually within 3 or 4 steps from where my main tracking program says 1 mile is. The heart rate is seems to be more on the money. Today my walk was 1.6 miles. Fitbit had it at 1.9 miles. 

[SunsetRunner]

Hello to all,

Well here it is, I swapped to a Garmin Vivoactive 3 smart sports watch and up to now I am very impressed.

I have not been able to walk out much recently because the weather here in NW England has been very poor with a lot of rain and cold winds, but I did manage a 6 mile walk yesterday and the Garmin results were very promising.

Garmin Vivoactive 3 - 12,376 steps -- 6.02 miles.

Google Earth Pro track -- 5.94 miles.

Omron 3 axis pedometer - 12,400 steps -- 5.8 miles.

As I said this was my first walk using the Garmins GPS Walk mode and I thought the results were pretty good.

I know the Garmin watch costs a lot more than the Fitbit Charge 2, but it is less than the Ionic.

CliveP.

[hawkeye1952]

I have also bought a new fitness watch/ Epson prosense 57.

Here how it stacks up.

Gps 99% on the money or 4 or 5 steps of from my main exercise program. Fitbit been all over the place..

Hr is very good. compare to the chest strap. Fitbit all over the place.
Step counting is very good. Only counts if you are moving. Fitbit any kind of movement counts as a step./ This prosense also allow you to look at the past 7 days of your step count on the watch. Same with the calories. The only draw back is that it only list 3 exercise on the watch.
George Howell Jr

[SunsetRunner]

Well it seems that Fitbit  Technical support are as elusive as the Loch Ness Monster 🙂

By the lack of involvement in this thread by Fitbit support or any of their "puppet" council members it looks like they are keeping their heads well down.

Since my last post the weather here in the UK has settled a bit and I have been able to get out on a few walks around my area.

The results using the Garmin Vivoactive 3 look good as far as GPS tracking / miles are concerned.

I don't have any way of measuring my HR so I cannot compare that data, but it does look reasonable.

My last 4 walks on 4 different routes measured very close between the device and the same track measured on Google Earth Pro.

GARMIN	GOOGLE	DIFF	% DIFF
MILES	MILES
6.02	5.94	0.08	0.01
6.20	5.94	0.26	0.04
5.16	4.99	0.17	0.03
6.16	6.00	0.16	0.03

I am very please with the results so far as they are far better than the +10.7% average difference I was getting using the Fitbit Charge 2 in Connected Gps mode.

I will continue to log my walks to see if the results remain as good.

Best of Luck,

CliveP.

[hawkeye1952]

That just about the same that I am getting with my Epson prosense 57. Very reliable gps watch. Since it also cold here and I wear a heaver jacket. It would seems that it has a effect on the signal a little.

[Malonew1]

I am having the same issues with my measured distance not recording accurately. My Charge HR is about a 1/2 mile off from distances I have measured both with gps and in a vehicle.