Distance calculation and inaccuracy on Edge 1030 Plus during a slow speed activity (walk, run)

I think the firmware of bike computers is not optimized for slower speed activities 

You‘re not allone.

https://forums.garmin.com/sports-fitness/cycling/f/edge-1030/246212/edge-800-vs-1030-while-walking?ReplySortBy=CreatedDate&ReplySortOrder=Ascending

I looked at your 1030 gpx file and noticed: the total distance calculated by GPS trackpoints is correct: 30.02 km.

There could be an approximation specially designed for bikes, like it will ignore reverse movements, but the strange thing is that only edge1030 (or maybe 530/830 sharing the same code) are affected. So maybe they integrated a super feature that makes Edge unusable for other slow activities.

Obviously, people want to get maximum from their devices so they use them for all other activities. But with Edge it is not possible - only bike profiles are possible. On the other hand we have bike computers from Polar where you can select any sport - Basically it is changing just one field in fit/gpx file, so it is not a big deal...

Both Garmin devices have different distance than GPS Distance. When I compare it with the other Suunto devices, where you will get the same distance on device itself and calculated by fit/gpx library, so it must be something wrong with the internal distance calculation.

For me, the main question is:
when walking - using no speedsensor (of course): there is nothing but GPS data available to calculate distance and speed - at least that's what I think.

Why does the Edge not calculate the distance correctly using GPS?
How on earth does the Edge calculate the distance if there is no speed sensor?

See picture below recorded on Edge 1030 on a walk - blue
(GPS based distances calculated by Fitfile Repairtool - yellow):

And as you can see: GPS recording was well done by Edge:

I believe the smart recording gives us really bad results and since sensor data are stored only together with position data, it will drop a loot of values. But yes, the distance calculation is really strange.

Of course it's using GPS for speed and distance.  But the antenna and filtering and error correction software is going to be designed for a relatively flat and consistent orientation.

There is so much black magic going on with converting incredibly weak directional radio signals from hundreds of miles above into locations, it's surprising this stuff works at all.

While Garmin was able to fit a good ceramic antenna to Foretrex 401 (ha ha, it is still available :D), why they don't do the same with other bigger devices? THey rather use pcb or flex antennas glued to case.

But the question is why the other wrist wearable devices that are receiving mainly reflected signals are giving us a relative good output and the big one is not? During the test my edge 1030+ was in front pocket on my inov-8 race vest, so it was in a stable and theoretically ideal position. Not exactly like on a bike, but it was in more stable position than Fr935 on my wrist.

From my point of view:
it is not a question of poor antenna and it is not a question of a poor GPS signal.
Look at my above picture of the recorded GPS track - it is a perfectly recorded track for walking!

It is the question, why does the device not calculate the right distance out of the well recorded GPS trackpoints!

For example:
look at the first 30 sec (half minute) of my walk in the excel sheet above:
GPS coordinates say, I have walked about 25 m - that‘s about 3 km/h and that‘s correct.
Edge calculation for that half minute says I have walked 1 m. That‘s ridiculous and has nothing to do with bad GPS reception.