Different distance with GPS/Ultratrack

I use UltraTrac frequently and successfully. It works great if you have an understanding of the technology. Distance accumulation will toggle between GPS and WDR and gives me more than acceptable results. If it isn't painfully obvious that WDR doesn't accumulate distance successfully on a bike, than I really can't think of a simplistic way to illustrate it. That's where common sense has to enter into the equation.

Execution is certainly different between the Fenix 3/5 series. The 5 uses a gyroscope to assist in course navigation. Since this thread is under 'Instinct' and the OP is using the Instinct, I can't definitely address the question since they appear to have a gyro supplemented track when the specs indicate that it lacks a gyro. The Instinct appears to be able to draw a nice track although distance accumulation will be hampered by the combination of WDR/bike.

UltraTrak works great for hiking for me. The earlier posts for bike riding using UltraTrak indicates too much distance is traveled between GPS position grabs, hence the large errors in the tracking.

You wouldn’t have much error in the hiking track LiquidSquid, in UltraTrak mode, as your not moving that fast.

UltraTrak works great for hiking for me. The earlier posts for bike riding using UltraTrak indicates too much distance is traveled between GPS position grabs, hence the large errors in the tracking.

You wouldn’t have much error in the hiking track LiquidSquid, in UltraTrak mode, as your not moving that fast.

Well, I'm glad it is working for you. Maybe I will give it another shot without dense foliage, as part of the problem may be poor GPS fixes. I am curios it you are willing to share one of your hikes using Ultra so I can compare to mine. I have been on trails that are far from straight or level, as they navigate some fairly rough terrain.

Thanks.

I'm happy to analyze one of your hikes where you've been disappointed with the results using UT if you'd like to send me one of your files! Hiking results would be different than running but is largely dependent on the accuracy of the accelerometer calibration. My running/walking cadence is quite different and certainly stride length also varies widely. I've got a lot of documented results but have never really publicized as it's incredibly boring, takes too much work and the audience who cares is very small.

Here's a trail run (single track, dense tree cover, varied elevation) comparing straight GPS (610 on left wrist) vs UT (Fenix 3 on right wrist).
GPS will deliver a complete track with all the twists and turns. Distance accumulation in these conditions in challenging for GPS devices however.
UT will deliver a choppy connected track that connects GPS points. While it's not going to produce as pretty a track, distance accumulation will be superior.
Again, while GPS is active it will use that as the data source. While GPS is inactive, the data source will switch to supplemental sensors (compass/accelerometer).
When GPS is reactivated, it will toggle back and use that as the data source. It WON'T advance distance or connect GPS points in any other way other than track position.
It doesn't make any difference how apart the GPS points are or how fast/slow you travel between these points.

GPS
UT

For reference, if I drop the UT file in a program that recalculates distance based on GPS track points I'll end up with a result of 4.12.
It loses two miles by missing all the traveled curves. Fortunately, that isn't how the watch works using UT.

Now on the Fenix 3 line, UT doesn't work very well if you're trying to navigate a course. You're basically off course whenever GPS goes silent.
The Fenix 5 adds in a gyroscope so that it can improve positional points and give you a cleaner track - this allows for navigational operation in UT mode.

As noted, a trail run would be much different that a trail hike. My accelerometer is calibrated for running and accuracy is roughly in the 97% range. When walking, that accuracy drops to about 90% (for me).

The twistier and snakier the trail is the more value I'll get from UT. Folks have a perception that it only works in straight lines as they believe it is connecting GPS points.
That isn't how it works!!

Well, I'm glad it is working for you. Maybe I will give it another shot without dense foliage, as part of the problem may be poor GPS fixes. I am curios it you are willing to share one of your hikes using Ultra so I can compare to mine. I have been on trails that are far from straight or level, as they navigate some fairly rough terrain.

Thanks.

Here's a run I did a while ago with Smart recording. https://connect.garmin.com/modern/activity/3194070370

If I ever had a track that looked anything like the one called UT that deeter26_2 posted earlier for a hike or a run, I wouldn't be happy either. Does your tracks look like that LiquidSquid?

I've tried both Smart and every second recording and don't see much difference between them, but a couple weeks ago I started using one second recording because, why not, not much difference for me as battery life is a non issue for me.

I am going to take a very simple hike late tonight with my coyote be good stick. I will give it another shot on the open driveway and road. To trails for this chicken shiz at 11PM. Too much work going on to get anything in the past few days worth a dang. Darned jobs.
But yes, my hike looked like Harold and the Purple Crayon on crack, though that was a while ago and on the 5S which I returned for poor battery life.

Clue is in the name: UltraTrak is designed to track "Ultras" (Ultra Marathons), basically running for a very long time. It's not designed for biking or any other sport where you would move faster than you could run through the woods.

I have used Ultratrac on my Fenix 5S plus on several hikes. When I look at my position on the map while walking I am usually off the hiking path by 50 meters or more. The recorded path is a weird Zigzag, way off where I walked. Ultratrac is simply useless, ridiculous. Switched back to normal GPS and that works.

This is a simple evening walk/hike down the road and back. It is "OK" for this I suppose, but surprised it isn't better on a more or less straight line. The distance is within 5% which is acceptable.

https://connect.garmin.com/modern/activity/3278789132

Interesting learning through:
1. Elevation is only captured periodically, and not nearly as frequently as GPS tracking, so there is elevation error (you can see step functions in the elevation data, at least on the F5, not so much on GC). GC seems to smooth it back out.
2. The auxiliary sensors are getting it more "wrong" than I would expect, and need continuous correction via the GPS fixes. You can see how the straight lines point away from the track, but quickly go back on track when GPS comes on line.
3. This tracking is perfectly acceptable for this type of activity.
4. The pace math is wonky. I never paused along the first 3/4 of the track, but there are several places where it claims I have, and jumps between two distinct value sets. The tail of the track should have several pauses as that's when I grabbed the dog for the final 1/2 mile and she pauses a lot.

To answer other questions, when I took a hike that had switchbacks up a steep incline, the tracking was terrible. Compounded by poor GPS visibility due to the valley I was coming up out of. It really isn't fair to bash Garmin on that one though as it really was a stress test.

The worst track ever was when I was in a gorge in Ithaca, NY. You cannot get a GPS fix in there to save your life. You may as well be in a cave. I was secretly hoping the F5 would get it sort of close by going to dead-reckoning, or pace counting, but I think it would fall back to whatever GPS it could get, which was NUTS. According to my F5 I have never run so fast in my life at times, and put in several miles for every one I actually hiked. I was disappointed is I could not figure out a mode to use under hiking where it would only use the step counter to estimate distance in cases where there was bad GPS visibility, like gorges. Indoor walk or GPS off apparently, but would prefer a little more automation.

I thought you had an Instinct LiquidSquid?

I've went back to Smart Recording as I really don't see any advantage using one second recording during my walking/hiking/running so far. This is on the Instinct which appears to operate different than the F5 series....