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Oct 2019
12:39pm, 3 Oct 2019
115,332 posts
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GregP
Top post larkim
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Oct 2019
12:47pm, 3 Oct 2019
11,413 posts
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Badger
+1.
The GPX precision is pointless. I'd have to check what FIT actually stores. I thought it was 32 bit which is nowhere near 27 dp. I remember it's basically fractions of a circumference rather than explicit lat/long.
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Oct 2019
1:58pm, 3 Oct 2019
11,414 posts
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Badger
It is 32 bit signed integer, which takes you just past the 7th decimal point in lat/long, so it's slightly excessive accuracy, but with word lengths of multiples of 8 bits it's the rational choice.
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Oct 2019
2:25pm, 3 Oct 2019
8,896 posts
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larkim
So the GPX/TCX outputs are just derived from those stored values, and the rounding of those creates a misleading impression of the precision of the stored coordinates then I presume? Does the FIT file integer imply a level of precision that the chip is writing to the FIT file then?
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Oct 2019
4:05pm, 3 Oct 2019
11,415 posts
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Badger
The FIT file integer gives exactly the precision that is written to the FIT file, in the sense of how precisely it's expressed as opposed to how accurately it matches your real world location. I don't know what the output from the chip is (I think I have a datasheet for that somewhere) but again I imagine it's enough bits that the error in the digitisation is small but not ridiculously small compared to the GPS location calculation error.
The conversion from the the FIT file value to latitude is val*180/2**32 (giving values between +/-90). The GPX/TCX output value looks as though somebody has done that calculation with a double or long double output, then formatted it with a stupidly large number of decimal places, so indeed it is misleading.
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Oct 2019
4:13pm, 3 Oct 2019
8,901 posts
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larkim
Makes sense, thanks!
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Oct 2019
4:15pm, 3 Oct 2019
268 posts
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Maccatheknacca
Thanks for the replies.
The “problem” run was a 41hr ultra, previously up to 36hrs has been ok so not an issue that’s going to occur very often hopefully. I guess I can reduce the GPS ping rate, set to ultratrac or just reduce the file post event, it just seems pointless creating/storing data that doesn’t mean anything.
The main concern was Garmin telling me to send them the watch back but it looks like it’s an issue generated on Garmin Connect which is reassuring as in all other respects the watch is great.
Larkim - setting aside the level of accuracy is totally spurious, if ever I’m racing through a lab and want to make sure I’ve not stepped on a particular atom 28 decimal places could be useful🤣
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Oct 2019
7:00pm, 3 Oct 2019
18,629 posts
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flanker
Macca, it'll come down to it being the easiest option - just store the value that comes out of the end of the sausage machine, rather than have to decide what degree of accuracy to store, how to round it, and then implementing this. Storage is cheap and almost unlimited these days, and the degrees of accuracy we're talking about meaningless, so the developers take the easy option.
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Dec 2019
6:30am, 12 Dec 2019
8,728 posts
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Son of a Pronator Man
My Fenix 5s will not charge.. I have tried different sockets and different cables but no joy.. I've tried switching it off an back on again.. Any other suggestions ? It's about 18 months old
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Dec 2019
6:59am, 12 Dec 2019
116,785 posts
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GregP
blow into the charging port and give it a gentle puggle with a cotton bud. Mine charges but it's a battle of wiggling things and blowing on things.
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Garmin
Jul 2025