Blaze Distance Measurement is Inaccurate

[MuzDownUnder]

I have been testing the Blaze vs the Surge on my last two walks. The Blaze is not reading distance correctly using Connected GPS. Here are the detailed results from the last quite slow walk.

Unit              Blaze    Surge           Notes

Time             41:50    41:42.22      I pressed the two starts and stops within 0.5 sec

Dist               2.59km 2.20km        The 2.20 is accurate - on both walks the Flaze was well over

Avg Pace      16'07"   18'55"          The surge is closer

Hrt Avg          86         80

Steps             2953     2920            The surge step counting is a little erratic

Elevation       36.57    36.57

My phone is a Samsung S5 running Android 5.0

[SunsetRunner]

How do we know that the Surge is maybe the device that is wrong.

[flying_nun]

You might want to check out this post: https://community.fitbit.com/t5/Blaze/Ran-with-Blaze-watch-today/m-p/1202116#U1202116

[Rich_Laue]

Your step counts are within the 5%, actually 1.1% so that is good.

Starting and stopping the clocks within .5 seconds could give you a difference of up to 1 second, so this is in lime.  Ie start Surge then .4 seconds later start Blaze, when done stop Blaze then .4 seconds later stop Surge,, you now are .8 seconds different.

SD creen shots of the paths ran would tell us more about the milage. 

[MuzDownUnder]

Here is a photo of my wife and my phones from doing the exact same walk together. She was using a ZIP and used the app to record the track & I used the Blaze only with connected GPS. We do this walk often and 4.8 is accurate

[MuzDownUnder]

I just took my Blaze on a car ride up to the shops and checked it against an App called Backcountry Navigator and the car trip meter. I used the bike exercise to measure the trip.

Car 4.8 km

Backcountry Navigator 4.9 km

Blaze 5.35 km

[Cracker65]

I did a similar comparison on Saturday for a walk I have done many times previously but recorded with RunKeeper. The comparison betwwen Blaze and RunKeeper is very different, considering both are using the iPhone GPS. RunKeeper distance is accurate.

Unit           Blaze         RunKeeper

Time         1:24:05       1:24:17

Distance   8.71km       7.98km

Pace         9':39"          10':33"

[MuzDownUnder]

Here's another just finished

Surge & App both 2.98km

Blaze 3.41km

[Fizzie94]

Is it possible that Blaze distance is based off of stride length? I know that wouldn't make any sense because its supposed to be using the GPS but that is the only reason I can think of for the differences that you are reporting.

[Cracker65]

Just completed another walk Blaze vs RunKeeper

Unit           Blaze         RunKeeper

Time          53:09         53:14

Distance   5.48km       4.87km

Pace         9':41"          10':55"

Steps       5736

Supposedly both are using the same GPS for logging

[Cracker65]

Just completed another walk Blaze vs RunKeeper using the exact same route as yesterday

Unit           Blaze         RunKeeper

Time          52:12         52:06

Distance   5.42km       4.87km

Pace         9':36"          10':42"

Steps        5707

My anaylsis is that the Blaze only uses the GPS to log points on the map and doesn't use the map for its calculations for distance, its no different than the Charge HR etc so I have to assume its distance is calculated by steps&stride. I will start messing around with my stride length to see if I can calibrate FitBit to be a more accurate reflection. Its a shame since I thought having GPS connection would offer more than just a map.

[11butterscotch]

@Cracker. Enter the same number for your walk and run stride, for this experiment it can be any number, do your comparison as above, and see if the step count x the stride length matches the blaze distance reading.

[MuzDownUnder]

I'm not sure this is right. My test driving in the car in the Bike setting had the same increased distance in the measure. I also have the correct step measurement in the setup page (84cm). If you look at the map in the photo with the reading of 5.88km the step count for this was 5981 which would equate to a stride length of 98cm and avg pace of 9'00". Both are clearly wrong and is longer and faster than I can manage.

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@Cracker65 wrote:

Just completed another walk Blaze vs RunKeeper using the exact same route as yesterday

Unit           Blaze         RunKeeper

Time          52:12         52:06

Distance   5.42km       4.87km

Pace         9':36"          10':42"

Steps        5707

My anaylsis is that the Blaze only uses the GPS to log points on the map and doesn't use the map for its calculations for distance, its no different than the Charge HR etc so I have to assume its distance is calculated by steps&stride. I will start messing around with my stride length to see if I can calibrate FitBit to be a more accurate reflection. Its a shame since I thought having GPS connection would offer more than just a map.

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[11butterscotch]

@MuzDownUnder how did you calculate your stride length? 98cm doesn't seem that long for say 5'6" height but i could totally be wrong on my metric conversions

[Rich_Laue]

@MuzDownUnder I'm not sure how typy can say it is no distant than the Charge HR which shows not have any GPS and can only goes at the distance based on the stride, which changes a little wroth every run, and sometimes dieing the same ruin.

[SunsetRunner]

I must admit @Rich_Laue I do have a laugh when I read your posts. I'm not sure if they're being auto translated or what but sometimes I really have to scratch my head to understand. Great contributions though. 🙂

[Cracker65]

Testing Day3....

Walk Results:

Unit           Blaze         RunKeeper

Time          54:14         54:16

Distance   5.59km       4.94km

Steps        5918

Also had changed stride length to 85cm (for both Walk&Run) - based on my calculations of RunKeeper and steps. Result is there is no difference with the error on distance being reported on the Blaze. I now have to assume it is GPS calculated and the FitBit dont quite have the algorythms correct. The only other difference is the map utility used by RunKeeper is Mapbox (OpenStreetMap) and FitBit appears to be using using Google for its overlay.

[MuzDownUnder]

I too have done another walk that we know the distance exactly and have done it many times and measured it over the years using a Garmin, Backcountry phone app, Firbit Surge, Fitbit Zip with app and Blaze

The Garmin, Backcountry app, Fitbit app & Surge all say exactly 3.00km and the Blaze gave me 3.4km this morning.

It seems to be very consistently reading about 10+% high on distance measurement.

Lets hope fitbit are watching this conversation and will fix this fairly quickly. 

[Rich_Laue]

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@SunsetRunner wrote:

I must admit @Rich_Laue I do have a laugh when I read your posts. I'm not sure if they're being auto translated or what but sometimes I really have to scratch my head to understand. Great contributions though. 🙂

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@SunsetRunner wrote:

I must admit @Rich_Laue I do have a laugh when I read your posts. I'm not sure if they're being auto translated or what but sometimes I really have to scratch my head to understand. Great contributions though. 🙂

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Im trying to get better at catching them, and have tried 3 different keyboards.

[SunsetRunner]

Interesting thread- I have noticed that the surge starts out with non GPS distance estimated from height etc, then calibrated after using GPS and becomes dead accurate for non GPS after calibrating.

I had hoped that the Blaze would do the same thing using connected GPS