Technical Reason for Distance Inaccuracy?

[mbanole]

Is there a technical reason why my Blaze is not accurate when measuring my distance on a walk? I run MapMyWalk along with the Blaze and the distances always differ, with the Blaze being anywhere from 80-90% accurate compared to the MapMyWalk distance (which is always consistent).

I have done everything I can think of and followed all the suggestions on the forum, but it is never accurate. Is there a technical reason why two measures using the same GPS get entirely different readings?

I know this has been discussed many times before, but I have yet to see a technical reason why they would differ.

Thanks.

[Rich_Laue]

@mbanole before we can answer this, we would need to know which mode you used to track the walk.

Lets look at mapmywalk, it uses GPS to measure the distance, then uses your calculated stride to calculate ( think of taling an educated guess) of the steps taken.

Now lets look at the Fitbit tracker, it counts your steps, multiplies this number by your stride to calculate  (think of it as taking an educated guess) to come up with a distance walked.

Now lets look at the stride, by difault Fitbit takes your age, gender, height, not sure what else, then says ok an average person like this will have a stride of "xx". This is great, if everyone is like an average person. Now look around you, do we all look average? No, we are individuals.

So what to do. We need to calculate our stride and let fitbit know what it is.

So by doing this, will it make the distance more accurate, yes. Will it be consistent,  mabey. You see many people find there stride changes a little from day to day, tired, your mood, whats on your mind, injury can all affect the stride.

What i did was take a weeks (5 days) of walks, on the same course.

Added the total distances together.

Added the total steps together

Used these totals to come up with an average stride.

So is my distance spot on? Not always, but close enough. You see while i got an average stride, very seldom is my stride average.

[mbanole]

Thanks for the reply.

However, it is my understanding that both methods use the GPS on my iPhone. I wouldn't think stride length comes into play regarding actual distance traveled. Unless I am missing something...

[Rich_Laue]

As i started out with, not knowing which of the 3 ways, the 4th won't give d8stance, tye events where recorded, it is hard to give a direct answer to your question.

Your last post makes me think you used the fitbit app to record your route with the result of a map produced. Fitbit does use GPS to calculate the distance. 

You could also have recorded on the blaze with the connected GPS. Distance is still calculated using the stride.

It could also have been recorded using the Blaze without the phone or connected gps. 

[mbanole]

I am using connected GPS. It does produce a map.

Are you saying that although I am using connected GPS, it still uses stride to calculate distance? Logically, this makes zero sense. Why go to the trouble of connecting to GPS and bringing your phone, if it doesn't matter to the distance calculated?

Not being argumentative, just trying to look at this logically. 

[Rich_Laue]

Ok ill will deduce that your carrying the phone with you, and starting the run with the Blaze in connected to the phones GPS.

Yez tgat is what im saying, my test and others have found that in walk mode, the stride is used to calculate distance. Fitbit says that only in run mode, the stride can be properly calculated. This telss me tgat run and walk mode are handled differently when it comes to distance. Why is this, who knows, Fitbit hasn't given a response yet.

Now the good news is with the last update to the Charge 2 my tests show tyat the GPS now calculates the distance. My hope is that this change comes to the Blaze with the next update.

[bbarrera]

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@mbanole wrote:

Are you saying that although I am using connected GPS, it still uses stride to calculate distance? Logically, this makes zero sense. Why go to the trouble of connecting to GPS and bringing your phone, if it doesn't matter to the distance calculated?

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@mbanole Yes, that is what he is saying. And good luck trying to find that information in official Fitbit help or the Blaze webpages. I believe a Fitbit moderator confirmed that walk mode uses stride based distance estimates, however I can't find that post right now. Withholding that information in the Users Manual and on the official help site is shameful and misleading, and frankly a form of deceptive advertising. The Blaze has been available for about a year now, its mind boggling that this hasn't been documented or fixed.

Yes, I agree, having a "connected GPS" walking mode and not using it for distance makes zero sense. I could just use my phone as Fitbit step tracker and get both a map and distance from GPS using Fitbit apps' MobileRun feature. Or go to a well respected competitor and get real GPS and waterproofing that allows you to swim with the tracker or sports watch.

[mbanole]

@bbarrera thank you for writing what I was just about to say regarding the lack of transparency and misleading (deceptive) advertising. They even mention looking for the "gear" symbol to indicate Connected GPS (which Walk does have)...LOL!

I am embarrassed now how frustrated I have been getting with the two tracking methods not matching (Connected GPS and MapMyWalk). I started using MapMyWalk and adjusting my Blaze workout for my own sanity. 

Tomorrow I am going to run MapMyWalk and MobileRun together just to finally see matching values (I hope).

Thanks for the clarification!

[Rich_Laue]

There really is no reason to use both MMR and MMW they essentialy are the same progam, along with MapMyRide, MapMyHike, MapMyFitness, 

All released by Under Armor

[mbanole]

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@mbanole wrote:

Tomorrow I am going to run MapMyWalk and MobileRun together just to finally see matching values (I hope). 

MobileRun, not MapMyRun.   If both results are consistent, as expected, will just use the Fitbit product. Just at this time I do not trust the Fitbit product until I see it. 🙂

Update: Just did a sample walk of .52 miles. Slight .01 difference. Will see what the 4 mile loop shows tomorrow, but looks much better so far (even for me, Mr. OCD).

[bbarrera]

I would expect Fitbit app's MobileRun and MMW app to show consistent distance as they are using the same GPS feed. There might be minor distance differences, as many apps will smooth the GPS data and that could result in small differences.