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Alternative to GPS

Discussion in 'Bob's Track Builder' started by Kytt, Apr 27, 2009.

  1. Here is the way how i got my track altitude data. Maybe someone is interested.
    I was doing research how to get altitude data for my rallytrack when i started while back. As you know there are some problems with GPS accuracy, even more if you track is in the forest and blocks visibility to satellites.

    Alternative to GPS is barometric altimeter. I found particularly interesting http://www.microtim.com/index.htm digital altimeter which is very easy to use and the most importantly acceptable accuracy 1-2 feet, resolution is 1 foot which is about 30cm. This is more than enough. They use it mainly in airplanes to show altitude.

    This is more inconvenient way to get your data to PC but you spend more time on the track and getting to know it better. I chose nice sunny day to no big atmospheric pressure changes expected.
    First i printed out aerophoto (this is better than map because you know exactly were you are) of the track and went to track with bicycle. Set my altimeter to zero at the start of the track. Now i rode or walked through the track and marked altimeter changes on printed layout. Also marked some bumps, dips and other things what seemed important. Shortly said i marked all the changes on the road i saw. It took, if i remember correctly, 2 days to mark all my 20km long track. Afterwards i went back to the start and checked what my altimeter is showing and it showed zero. That confirmed my data correctness.
    Same aerophoto is my backround image in BTB. It is quite easy to look out marked altitude marks from printed photo what i used on the field and put them in BTB in the same spot.
    I'm pleased with the result as my track is relatively level. Didnt need to do much correcting after setting nodes Y positions. Dont know how is it working with lots of ups and downs on the track but i see no reason why it shouldnt.
     
  2. Thanks for the info... that's a very cool idea. Although I have to say the idea of manually entering all that data didn't sound all that appealing to me.

    This prompted a quick search for a digital version that supports data export and I found this:
    [ame]http://www.amazon.com/Garmin-Handheld-Barometric-Altimeter-Electronic/dp/B000CSQRYS[/ame]

    Doesn't seem much more expensive, and it seems that it will export the full GPS lat/lng data along with the accurate altitude (from the built-in barometric altimeter). Without trying it obviously I couldn't say for sure, but I'd be interested to know if anyone else might have tried something like this?

    (Whoa... that's pretty cool how the forum software automagically added in the thumbnail!!)
     
  3. My brother have same GPS as this one. I will give it a try for sure. :)
     
  4. Yes, this is better way for sure.
    If anyone could try that GPS out and give some results how good it is with altitude, thanks:)
     
  5. GlobalSat

    I have some expirience with GPS. I have tested Globalsat DG-100 GPS device. Forest sections and deep hole between downhill and uphill is place where altitude data goes unreal. I have hear that pressure altitudemeter is included about 300 (US dollar) GPS devices.

    I have thinking use some "degrees meter" that what is in some all-terrain vechiles. Middle of 90´s Mitsubishi Pajero for example. That is usefull creating the track cambers. But that is different feature.

    That ":plane: altimeter" is very indresting, hopefully someone would test it and write some evaluation in here.
     
  6. the barometric altimeter on my etrex was Way off of better quality data - so keep that in mind.