Logging activities: A question of trust

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Jun 2012
3:41pm, 19 Jun 2012
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GregP
Hmm. I know (or am given to believe) strava are suffering server issues due to them being 'flavour of the month', so there may be something in that. Nice call.

I think sample rates effect device battery usage too?
Jun 2012
3:54pm, 19 Jun 2012
3,365 posts
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Badger
Garmins all sample once a second all the time, and then decide whether to save or prune each data point. Two thirds of a 910's power usage is GPS, no idea what fraction of that might be position computing as opposed to powering the receiver, but it's not something you can adjust anyway, so no telling!
Jun 2012
4:05pm, 19 Jun 2012
3,005 posts
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sprouty76
I don't know if the 310 is the same as the 910 in that regard, but if you have a power meter it forces it to record every second (I think the power calculations need a regular interval - autopause can throw it off too, I believe). I think in later firmwares you can force the 1 second recording on even if you don't have a power meter, so you can actually adjust it.
Jun 2012
4:21pm, 19 Jun 2012
3,366 posts
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Badger
But one second versus smart *recording* doesn't change how often the watch *samples" its position; only whether the watch bothers to record it or not. This is one of the reasons that the watch can record a different distance from software post-processing the watch data, actually, because the watch works out the distance based on one-second sampling, even if it doesn't keep every sample. You are right that both watches (with current firmware) let you choose one-second recording or smart recording. But all you're adjusting is whether it saves every sample or not, as it has to sample to decide whether the sample is worth saving or not :)
Jun 2012
4:24pm, 19 Jun 2012
3,006 posts
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sprouty76
Oh, yeah, I get that - but I was suggesting that as a way to see what impact the recording frequency alone has on battery life independently of the GPS being sampled. You're right that you can't control how much power gets used doing calculations of data that may or may not get discarded.
Jun 2012
4:25pm, 19 Jun 2012
3,367 posts
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Badger
Incidentally none of this thread makes me want to touch strava with a ten foot pole. You expect a percent or two of variation between different distance calculations depending on how agressively the data are smoothed or obvious outliers are pruned, but nothing anywhere near what people are reporting from there.
Jun 2012
4:29pm, 19 Jun 2012
3,368 posts
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Badger
Oh sorry, misinterpreted you. Yes I agree, it would use less power because you don't have to write to the flash memory as often. I suspect that the difference would be pretty tiny, though, wouldn't you reckon?
Jun 2012
4:37pm, 19 Jun 2012
60,838 posts
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GregP
This from Holly, who is (along with Fetch) joint Cleverest Person About This Stuff In The Whole World:

slodge
@GregP63 from your facebook post (when I found it) just looks like strava are ignoring pause time
Jun 2012
4:38pm, 19 Jun 2012
60,839 posts
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GregP
And I *love* Badger 3,367. Chapeau, that Fetchie.
Jun 2012
4:38pm, 19 Jun 2012
620 posts
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Pestomum
affect?

About This Thread

Maintained by GregP
A sort of 'Why FetchEveryone is better than STRAVA' wire.
----

Last Sunday I cycled to church.

My Fetch log, which I trust beyond all possibility of doubt, tells me this:

17.07 miles, 1h19m46s, max speed 30.3mph

Garmin Connect, which one assumes is closest to the raw data, tells me this:

17.07 miles, 1h19m46s, max speec 30.3mph

This makes me very happy.

Now, gentle Fetchies, you may have seen or read or experienced strava recently, and been tempted, as I was, to 'dabble' and see whether it might be fun. strava taking data from the same source (my Garmin EDGE 800) tells me this.

17.1 miles, 1h20m48s, max speed 31.9mph

Interesting, eh?

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