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Old 06-15-2009, 11:48 AM   #6 (permalink)
emacf1
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I just stumbled over this issue myself... I received a GPSLogger log file from a skydiver... well and apparently the data recording said, that he went 4500 m below "sea level" just to reach to surface after a couple of minutes...

Since I am living in quite a flat area it was quite difficult for me to understand the problem - since there are other GPSLogger users who does not encounter this problem (I have also logs that where taken during flights with commercial air liners)...

First of all you have to know, that the altitude is provided in WGS84 - this means, that depending on your location on earth there could be negative values! (since the earth is not an ellipsoid)... but for sure values smaller then -500 are far off the possibilities...

A typical GPS device sends the data in so called NMEA sentence - and on my Storm (and I assume also on a Bold) the $GPGGA NMEA sentence only contains negative values for the altitude - that's quite odd - but there is nothing that a software developer who is working with the RIM API can do about it...

All what can be done (and that will be in the next release of my GPSLogger) - to include an option to use only "absolute Elevation" values... It's correct, that this will not be correct in areas where the WGS84 will be indeed negative - but that will be not too many places...

So for your TrakBuddy problem you can kindly ask the developer if he might can consider a similar option in his application (to fix the problem for Bold & Storm users)... if you like you can additionally suggest the developer can contact me in order to get further details about this problem.

Matthias

Last edited by emacf1 : 06-15-2009 at 11:50 AM.
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