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Thread: Total ascent from GPS data

  1. #11
    Senior Member Brummy John's Avatar
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    Re: Total ascent from GPS data

    You can simply import the data directly from the GPS device to Sportracks and that gives you the time, ascent and distance as shown in the above sceenshot. It can even give you splits and loads of other stuff.
    Biriani for endurance, pathia for speed.

  2. #12
    Senior Member A.G's Avatar
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    Re: Total ascent from GPS data

    Quote Originally Posted by Brummy John View Post
    You can simply import the data directly from the GPS device to Sportracks and that gives you the time, ascent and distance as shown in the above sceenshot. It can even give you splits and loads of other stuff.
    It doesn't seem to work for PDAs....just Garmins and such like. Did 8.1 miles and ~1500 ft on the roads tonight. There was a 40ft difference between up and down on a looped course though!

  3. #13
    Senior Member Brummy John's Avatar
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    Re: Total ascent from GPS data

    Thats actually quite accurate for a GPS.

    Traingulating long and lat is accurate and only needs about 3 sats, the angles are big.

    But for altitude the angles are much more acute and you need at least 5 sats. A tiny difference in an angle on altitude can have a big effect on ascent.

    Then there is drift. If you look at this year's XC nationals you can see the route appearing to drift - which I reckon is the sattelite drifting. Same at Bury XC. That drift can make quite a difference when looking at small numbers like feet of ascent.
    Biriani for endurance, pathia for speed.

  4. #14
    Senior Member A.G's Avatar
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    Re: Total ascent from GPS data

    Quote Originally Posted by Brummy John View Post
    Thats actually quite accurate for a GPS.

    Traingulating long and lat is accurate and only needs about 3 sats, the angles are big.

    But for altitude the angles are much more acute and you need at least 5 sats. A tiny difference in an angle on altitude can have a big effect on ascent.

    Then there is drift. If you look at this year's XC nationals you can see the route appearing to drift - which I reckon is the sattelite drifting. Same at Bury XC. That drift can make quite a difference when looking at small numbers like feet of ascent.
    Are you sure....is it not just the fact that you chose slightly different race lines on each lap?

    BTW, know if I'd be able to get memory map to record points more frequently on my next run? Looks like it squares off a lot of the bends.

    The accurate altitude reading may be due to the fact that it probably had a better GPS chip than a lot of the sports specific ones. Its a Myo p560:

    http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=140156659036

    and has a 20 channel SiRFstarIII GPS Receiver if that means anything!
    Last edited by A.G; 10-03-2008 at 10:37 PM.

  5. #15
    Senior Member Brummy John's Avatar
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    Re: Total ascent from GPS data

    Ag,

    In MM try operations > convert to route, then highlight the route and right click > properties (see attached). This gives the OS ascent on a simplified version of the route.

    In this case:
    • mm OS map (using countours on simplified route instead of actual route and GPS)= 3024ft ascent
    • Sportracks with 25 sec intervals = 3625 ft ascent
    • Sportracks with 40 sec intervals = 3060 ft ascent
    • Sportracks with 5 sec intervals = 7225 ft ascent
    • Garmin Training Centre = 4575ft ascent
    Attached Images Attached Images
    Biriani for endurance, pathia for speed.

  6. #16
    Senior Member Brummy John's Avatar
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    Re: Total ascent from GPS data

    Incidentally the simplified route generated by MM to measure ascent using OS map countours was 1.2 miles shorter than the actual route (19.8m vs. actual of 20.95 miles)
    Biriani for endurance, pathia for speed.

  7. #17
    Senior Member A.G's Avatar
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    Re: Total ascent from GPS data

    Not sure how you can change the intervals in sports tracks?

    Attached are two GPX files of the same route ran two days apart.

    On the standard setting on sports Trax (as I don't know how to alter it) both distances are displayed as 8.1 miles.

    The ascent/descent of the first run is +1,477 / -1,534 ft

    The ascent/descent of the second run is +2,156 / -2,231 ft

    Both runs took about 63 mins (ignore the time logged on the files, the extra time was notched up either side of the run while the GPS was still recording).

    Not sure what the big difference was caused by. I'm not even sure how my GPS records altitude - by pressure variations or by satellite. As it's a PDA not a sports wrist watch type GPS, I suspect the latter.


    .....Sorry, won't seem to attach, but I can email them you if you PM your address...

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