Bad distance measurement when recording hiking

subra said:

The difference in distance may be due to GPS drift.

No, it is not this case. The same track shows a different distance after reimport, while keeping identical coordinates of all keypoints. It imports with the correct total distance if imported from a GPX file (not containing distances, just coordinates), while it shows a significatly shorter distance when imported in the original format (FIT) - that tile format includes also redundant keypoint distances in addition to the GPS keypoint coordinates. It means the watch records wrong distance between keypoints, despite that the pace is above the critical threshold, and despite that GPS works correctly without any drifts.

• Hi, I have auto pause switch on. some time I make foto, that auto pause is ready do. But my pause of hiking is only a few second or minute. This is a very big difference between gxp and value from garmin instinct.

trux said:

It imports with the correct total distance if imported from a GPX file (not containing distances, just coordinates), while it shows a significatly shorter distance when imported in the original format (FIT)

Maybe it's a question of extrapolation and smoothing of the GPS lat/lon's. Garmin also uses a qualifier for the GPS signal that ranges from "good" to "poor". and in the FIT is also stored the distance, that may not match with the distance calculated with another SW.

Olda said:

exported gpx and imported it into map data on the Internet, the data differed by several kilometers.

@Olda: Do you've graphically compared the routes from GC and the other SW at the internet? There must be a difference.

Calculating the distance for slow paces is a basic problem.

According to Garmin, the GPS position error with strong GPS signal is about 3m, i.e. a circle with radius 3m around of the position. Hence the total error is the diameter of the circle, that is 6m. Assuming the watch records the GPS signals every second. Then, if you move with a pace <6m/s, many GPS locations are inside the position error, and may be the same for 2s or more. With this it's not possible to calculate the direction, distance and speed of moving. Of course, Garmin tries to enhance the accuracy with extrapolations, smoothings and take into account HR, cadence, ... But generally moving with slow speed is afflicted with position errors.

In contrast with this the routes, speed, etc. are much more correct with cycling.

Other question, do you've a clue what distance is correct, Garmin's or the other SW's, i.e. what distance coincides mostly with the real distance, you've hiked.

O. K. I understand but when I wrote that friday hiking a went with my friend Tom and he have more cheaper smart clock from shaomi and his data is beter to value from gpx from my instinct. But I don't understand why the values ​​from the watch are shown by garmin connect other than exporting gpx also from garmin connect. Gpx from connect are similar to Tom's data and when importing gpx into map data on the internet they are more in agreement with reality

subra said:

But generally moving with slow speed is afflicted with position errors.

There are no position errors on his track. All keypoints are recorded with correct coordinates. And when you check the distance between two keypoinfs on the map, then the topographical distance is significantly bigger than the distance reported by the activity (at the first activity it is reduced exactly by the ratio of 1 mile to 1 km, hence the suspiction of a units mixup).

And when you take the activity, export it as GPX file and then import back, it fixes the distances (i.e. showing the total distance of 4.4km instead of the wrong 2.7km), while keeping the coordinates of all keypoints intact. It is sure that the distance 4.4 km is correct.

Ahoj Oldo,

ono se to dost liší nejen FW, ale i dobou používání hodinek. V návodu je, že ikdyž si zadáš délku kroku, tak se to vyladí pak dle GPS a optimalizuje. Loni jsem to dost zkoumal, protože mě hodně mrzelo, že Instinct neumí měřit dle krokomeru sporty jako badmington, hohejbal, volejbal atd.. jelikož nemá gyroskop ale jen akcelerometr.

Což se moc v návodu nedočteš na první dobrou... JInak mně souhlasila vzdálenost, když jsem šl trasu 5 km bez gps jako aktivita chůze a pak hned s gps jako aktivita chuze, ale s gps. Možná to chce jen čas...Instinct si to přepočítá. Ale je fakt, že nejaky FW cosi pridá, ale naseká chyby kde nebyly. Mně už opet nefunguje treba DEM... ale to je trochu OT.