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Tony_P1 Occasional Visitor

Joined: Dec 30, 2008 Posts: 34
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Posted: Thu May 26, 2011 1:36 pm Post subject: Reducing number of data points collected? |
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Does anyone know if it's possible to reduce the number of data points that the Active 10 collects during a walk. I'm finding that a four hour walk is acquiring in excess of 10,000 points which seems rather excessive (looks like about one point per second). I am wondering if this frequent collection contributes to the overestimation of ascent and descent that many of us see. With so many points, a metre difference in height between points, due to the inherent inaccuracies of how height is estimated (either map or gps) would soon add up!
Thanks, Tony. |
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LostMike Frequent Visitor

Joined: Jan 17, 2008 Posts: 369 Location: Monmouthshire
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Posted: Thu May 26, 2011 3:06 pm Post subject: |
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Hi Tony_P1
I can't recall any way to alter the sampling rate. I am happy with the rate and cannot recall any others expressing concern. The raw gpx file contains all the detail but the .map file is a rounded and edited down version which should smooth out most problems and eradicate most silly readings thought it does not always.
As for the height gained readings, I think most of us find them excessive but they are far better than they were. I don't think it is the rate of readings that is the problem but how the device interprets them. If you are moving at walking speed you are unlikely to be changing altitude very rapidly (similarly but to a different degree with cycling) and the software should have a sensible algorithm to smooth out the changes. _________________ LostMike
Satmap A10. Platform 21
Software version 1.5.9193
Satsync 1.525 |
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Tony_P1 Occasional Visitor

Joined: Dec 30, 2008 Posts: 34
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Posted: Wed Jun 22, 2011 5:36 pm Post subject: |
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Thanks LostMike for confirming my belief that the rate of data collection is fixed.
I still find it sad that a trully excellent GPS (indeed the best) is, in my mind, spoilt by the ascent/descent calculation overestimating reality. I routinely take the altitude from the GPS signal as that is, in my hands, consistently more accurate than using the weighted map grid which I find poor in the hills. However, the ascent/descent quoted in the triplog appears to be calculted from the raw data with almost no smoothing. On looking at the raw data, I realise that just reducing the number of datapoints would not, as I had hoped, help me even if it were possible. Maybe smoothing will be improved in a future software update.
It's not a big deal to me though as I get the stats I want by copying the file to my PC and getting ascent/descent from Quo. Just thought I'd check that I hadn't missed something.
Thanks again.
Tony |
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davidor Regular Visitor

Joined: Nov 14, 2008 Posts: 117
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Posted: Sat Jun 25, 2011 12:09 pm Post subject: |
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I think the Satmap uses an OS grid for heights, based on a 100m grid. So if you are in steep terrain, but walking along the contour it can jump between height points even if you are walking along the level.
Walkingh along a cliff edge can really confuse it! |
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