Which activities doesn’t use accelerometer when gps signal is weak?

I got the Garmin instinct recently and using it to run everyday. I really like the in and out of this watch. Just like everyone, I notice my run distance is 3% short in places where trees are on the sidewalks. I read the forums and investigated in the fit file, I notices my fit file has a lot stale 1 second same coordinate entries peppered in the content. Very rarely there are 2 sec same coord entries together. I notice garmin algorithm kicks in and using your arm waving degree to predict distance traveled in that 1 or 2 sec. I do agree it is necessary if you are under a tunnel or temporarily lost gps signal, you don’t want use a straight line from a to b where gps signal is lost, tunnel could be curved, etc. It is a good solution for longer time gps timeout. However, for my runs on the street, it is cause inaccurate avg pace, for example, 10min a mile is 18 secs difference for pacing. I think I regularly check my watch, wiping sweat, and sometimes I don’t swing my arm as hard. It causes underreported distance for those 1 sec gps timeout.

My question is since I know the route I am running don’t have long time gps time out. is there any activity profile I can use which doesn’t rely on accelerometer, just connect the gps location dots every second? That will resolve my distance variability issue when I run. I like to remove the 3% range changes. I upload to strava and they use gps distance when I correct the distance and it is always very consistent. I like to use that method instead on my Garmin instinct.

i will use the “other” profile, and maybe cycling profile to see if it doesn’t use accelerometer to predict distance when gps timeout, however, I want to know if any garmin gurus already know the answer so I don’t need to test this out myself for every outdoor profile. I did search the site and didn’t find anyone mention this. So I think it is good to bring this out and discuss so more people might brainstorm and solve this issue together. I know it is a long post, thank you for reading this far.

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6563734 over 3 years ago +1 verified

Wow, I cannot believe it worked when I run using ‘other’ using gps only as the activity! In fit file, position long and lat are never the same in my half hour one second record run entry on the street…

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+1 6563734 over 3 years ago

Wow, I cannot believe it worked when I run using ‘other’ using gps only as the activity! In fit file, position long and lat are never the same in my half hour one second record run entry on the street under the trees. Therefore distance in sequence was never the same.

Under the same route, if I use my run profile fit file always has around 25-35 1 sec same coord in half hour run, and accelerometer is used to calculate the distance added to the accum distance which to me always under report the distance. Therefore, my avg pace is not trustworthy because it is always 5-15 sec worse. I don’t know if I run on target pace or not.

other activity is great for running route that you known the gps lines that are ok but distance is short comparing open the activity in gpx format! You know fit file under state your run distance thus your pace as well. With the other activity you can trust the average pace and all other numbers you see on the watch, and it is useful and compatible now during running session for partial obstructed running route.
And the great thing is you can always change other activity to running activity in garmin connect and strava later after they are imported, so no harm done.

for running route that has tunnels or very high tall building which make gps track difficult, run activity is still the best option.

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here is the fit file for run activity, every sec it logs, even if gps coord is the same, but not using coord difference but using accelerometer algo adding the net distance traveled: first col is time, always increase in 1 or 2 sec? 2nd and 3rd col is coord, you notice 2nd and 3rd line is the same. 4th is accum distance, which you will see is the same for 2nd and 3rd line. However, in 4th line when new coord received, it only add accelerometer calc pace, see it is under reported, AND THE SECOND I TRAVEL BETWEEN 2ND AND 3RD ENTRY IS ZERO! 5th column is the distance added, so you see for 3 seconds between line 2 to 4, only 2 sec distance is added. 1 sec is missing. If you have a lot of these entry, your distance and pace will be off.

1005493183	xxxxxx	xxxxxx	128.23	3.02
1005493185	Xxx269	Xxx482	131.55	3.32
1005493186	Xxx269	Xxx482	131.55	0.00
1005493187	xxxxxx	xxxxxx	134.27	2.72
1005493188	xxxxxx	xxxxxx	137.33	3.06

See screen shot below, I have a lot 0 distance increase for those 1 sec entry, so they add up.

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here is the fit file for other activity: first column you see 4 secs changed no gps (today is running I guess bad reception but gps route looks good), 2nd and 3rd is lat and long coord, 4th is a cruel way for me to diff the distance from previous coord. 5th is fit distance, 6th is distance difference. you can see it is just connect the gps’s dots, and if gps signal is not there, no entry in fit file! I checked using filters, no dup coord in the whole fit file!!! Which is good for my type of run!

1005665670	xxx	xxx	592	774.38	3.35
1005665674	xxx	xxx	1639	783.58	9.20

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now garmin is lined up with strava! I can use the pace now to pace myself on my watch during the run. Friday run is using other activity, the others are using run activity. See it under report 2%, that is 11-13 sec difference for pacing per mile.

Garmin

Strava

I see the elevation for Friday other activity run is a little high, to make sure, I correct the elevation in strava, same distance, so no noice data in my test.

why strava report 3.15 and garmin has 3.14? In fit file distance calculated is 5060.65, that is 3.1445.... I guess there are difference in rounding decimals when connect 1746 entry of gps’s dot.

i just want to reiterate garmin instinct is such a good value and powerful function product, the quality and software is good. It is just too powerful that most of us don’t know how to use it. Also manual for the product is not detailed enough so we have to dig in like detectives ourself to customize the device to our unique usage.

if your test come back as good as mine, please share it in other forums, garmin is a good product, accelerometer has its usage. For most people and route they take I think it is not needed. Simple gps dot calculated distance is more accurate. I understand how frustrated people feel if they cannot use the numbers during running, I was there myself. So please spread the word if the result confirm by you is good so we all can enjoy competing with ourselves. =)

0 2659339 over 3 years ago in reply to 6563734

The 5th column in the original FIT is the SPEED, isn't it? In the SMART-recording mode you'll never find these zero speed entries.
As for activity other than running - yes, some ppl were using cycling profiles to get more realistic pace.

0 6563734 over 3 years ago in reply to 2659339

Sorry I didn’t make it clear, I add columns in the fit file for quicker analysis. I want to quick spot where distance didn’t increase in the file so after distance I add column to put distance diff value, then I use filter to find all zeros.

for my garmin instinct, first I want to try cycling as well, since arm is not moving in that profile, however even change format to pace, I cannot find pace data field to add to the data screen, that is why I used other activity profile.

0 2659339 over 3 years ago in reply to 6563734

thank you for the clarification

0 6563734 over 3 years ago in reply to 6563734

I will post my activity one last time, to double verify use other activity will not use accelerometer and just connect the gps route dots and match export gpx distance or strava corrected distance: