GPS question

Discussion in 'Weapons, Equipment & Rations' started by bibo_boy, Oct 28, 2005.

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  1. I was out last night checking the distance on some running/tabbing routes with my Garmin Etrex GPS and as per usual, every now and then it would read "weak gps signal" then kick back in and carry on measuring distance etc....

    What i want to know is whislt it has a weak signal, does the unit still know how long I've walked? If this happens a few times during a long trip, will the distance be wrong?

    Logic says it will be out, but thought I'd ask?

    Cheers.....
     
  2. Weak signal usually means it will go into 2D mode (ie no altitude and it usually looks for another sat quite quickly). I would agree that it seems logical its out but as long as it says weak signal and doesn't slip into No GPS coverage mode then it will be as accurate as usual - at the very worst it will cut corners and measure form A to C and not add in the little curve via B.

    If tracking 7+ sats it will be more accurate than when tracking 3 so accuracy varies even with full coverage shown. The GPS needs to 'see' the sat so avoid dense tree cover and built up areas if you can.
     
  3. If your Etrex is one of the following;
    then the Sport Tracks free programme will work for you. It pulls maps from google allowing you to edit out GPS errors. It's the ideal programme for a running log; even pulls the current weather for you.
     
  4. Mine's the Camo I think? It the one in Mils in Real tree cam?

    I was running with the unit in my hand but only running through streets only under the occasional tree, should it keep loosing signal?
     
  5. Use a map you kn*b.....they are never wrong.....GPS is for lazy, stupid people who shouldnt be able to pass basic training.....you have more money than sense....cider is expensive enough so why waste valuable fermented apple vouchers on cr*p! Spleen vented!
     
  6. I have got a headache now! and its not loopjiuce induced either!
     
  7. Cheers for the comments :)

    FYI, I have passed "basic" And I'm up to speed with Map reading.

    Not even going to waste time biting.......
     
  8. too late bibo!!!
     
  9. I hate it when that happens :)
     
  10. GPS isn't a good tool for getting stats while running. If you check the max speed achieved, this can sometimes be quite incredible - I've had 40mph - as it measures the movement of your hand during the arm swing rather than your body speed. Problems with weak signals are caused by your body shielding the GPS's view of the satellites, so unless you run with your arm held out in front of you....

    You could tape it onto your head - but then you wouldn't see the display.
     
  11. This all adds up.... cheers..... I might just stick it Memorymap?

    Or are these pedometers any good?
     
  12. No, pedometers are for chavs - they measure number of strides but not stride length, hence are a waste of space. Just pick a route, measure it and use a watch. If you complete the route in less time than previously you're improving. If you vary the routes, you're up the Swannee anyway as different inclines will result in different stride lengths and different times, so you can't compare.

    Edited after a thought to include:

    Pedometers may have a use for night navigation limited to metalled roads in Holland provided you march at constant speed.
     
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  14. The reason for mental speed variations using GPS is nothing to do with your arm swinging. The unit only checks it's position every 10 seconds or so and if it loses the signal for a bit will extrapolate the distance and unfortunately the time, hence you just ran at 40Kph or whatever. That's the reason I bought Garmin Foretrex instead of the Forerunner as the latter's virtual partner doesn't work well. The Sport Tracks programme will smooth out stuff like that including "Stopped Time", ie while the unit is warming up on the window sill. Remember most units have various timers, so stick with the trip odometer reading.
    GPS is a bit dodgy when running in forests etc and combine this with heavy cloud cover and you can forget it. I remember using pedometers and driving the route to calculate a run. Now I can scan a map into something like Easy GPS and plan the run from the computer screen.
     
  15. Cheers ojg