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Differences in distance on two phones

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roadcone

Differences in distance on two phones

Post by roadcone »

Two phones, both Android, same map, same version of Alpine Quest, two owners walking the same walk. Track logging enabled - one phone reports distance as 14.57m, the other as 15.5m. Others who are also logging get 14.5/14.7m.

Exported both as gpx - one reports 14.6m, the other as14.7m. The gpx files are of similar size and number of lines - 3.5% difference, but one was logging for a slightly longer time.

The gpx differences are trivial but the Alpine Quest 1m in 15m is not. Any ideas from anyone please?

Clive
suntalla

Re: Differences in distance on two phones

Post by suntalla »

Hi,
The longer the distance the smaller the % difference? The more unimportant? Or allways high % difference? I am curious.
Friendly greetings
Jos
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Re: Differences in distance on two phones

Post by Psyberia-Support »

Hi roadcone,
I don't really know what you expect I tell you, except that different devices produce different tracks (see here).
The application does with what the GPS chip gives... If you compare the displayed tracks on both phones, you should see where are the differences.
You can also email me both tracks so I can give you a more detailed answer on what's happening.
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Roadcone

Re: Differences in distance on two phones

Post by Roadcone »

Sorry for not replying but I was expecting to see an email alert.

I can fully accept that different chips might produce different results but I can't see how that is the case here. Thought process: We have a long chip and a short chip so expect to two route lengths. In that case, both AQ phones and the exported gpx tracks will be different - but that is not the case. At the end of the walk, AQ's track info reports 14.4m in my case and 15.5m on the other. Then, on each phone, we export from AQ as gpx and email them to me. I load both into Memory Map on Windows and they are within 0.2m (essentially the same distance). So ... AQ screen reports a 1.1m difference whereas the exported files are only 0.2m different.
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Re: Differences in distance on two phones

Post by Psyberia-Support »

Here is also what can impact length:
- If you have multiple legs (path segments, when you stop then restart the track recorder), there is a setting to take into account (or not) length between them, check if they are set the same on both devices (setting 5 here).
- Changes of elevation also impact overall length, you can compare the flat lengths: display the stats, tap "More" and see the values on the "Length" line: first value (bold) is overall distance, second value is "flat" distance, and third one is length added due to elevations.
Other than that I'll need access to both tracks.

Note that you don't need to stop the record when you stop (for eating), the app will detect stops and handle this correctly.
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Roadcone

Re: Differences in distance on two phones

Post by Roadcone »

Thank you for the guidance - good timing as we are walking tomorrow (Monday) so can compare the points you suggest. I'll get back once we have done that.

Clive
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Re: Differences in distance on two phones

Post by Psyberia-Support »

You can compare for your previous tracks too, this setting applies when displaying stats, not when recording.
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roadcone

Re: Differences in distance on two phones

Post by roadcone »

We are back from another 15 mile walk and have some information. First of all, thank you for directing me to the detailed statistics page and your explanation - that has highlighted what appears to be the source, but not the reason.

Both phones show a flat distance that is within 0.1 mile of each other. The distance that takes account of elevation is 1.1 mile higher on the one phone. The third figure - my phone shows that 774 ft has been added to distance for elevations but the other phone shows 1.1 mile. I looked further down at the Elevations Gain/Loss - my phone shows around 2,600 ft whereas the other phone shows around 12,500 ft. It was a walk in the flat lands of the UK Midlands and that sort of gain / loss is inconceivable in a 15 mile walk.

I checked the AQ settings on the two phones during the lunch stop and as far as I can tell, they are identical, with the exception of a few of the screen interface options (pinch, two-finger swipe etc).

Regards

Clive
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Re: Differences in distance on two phones

Post by Psyberia-Support »

Hi again,
You can have a look at the elevation profile, it gives you a visual feedback from where comes the cumulative gain computed by the app.
If you see too much sawtooth (GPS inaccuracies) on your profile, you can increase the error reduction setting (2) here: https://www.alpinequest.net/en/help/v2/ ... s_settings
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Roadcone

Re: Differences in distance on two phones

Post by Roadcone »

Thank you fir the response and guidance. There will be a slight delay until the next walk - maybe Sunday. I'll check out the settings then.

Clive
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Re: Differences in distance on two phones

Post by Psyberia-Support »

As said previously, the stats settings are used when you display the stats, not when your record a track.
So you can get the stats with the new settings on the tracks you've recorded previously.
Do you like AlpineQuest ? Leave a small comment on Google Play !
Roadcone

Re: Differences in distance on two phones

Post by Roadcone »

Hello again,

The setting on the problem phone was 'none' so I changed it to medium/default and it made all the difference. On yesterday's 15-mile walk (cold, biting wind and very wet later) the tracks recorded on the two phones were within 0.2 miles. Thank you very much for your help, explanations and guidance - it is appreciated.

Clive
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Re: Differences in distance on two phones

Post by Psyberia-Support »

Thank you for the update.
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