Weird deviations/spikes on self-created track

[Dvinis]

Hello!
First of all i wanted to thank you for great and easy-to-use application.
I downloaded this app to use it on Bikernieki track in Riga, Latvia, but since its not included in default track list, my only option left was to "create" this track by my own.
I followed your instructions on website and created the Start/Finish trigger, by placing it right in the middle of finish line.
The first drive session went well, app recorder laptimes. After the session i could see each lap layout, times, speeds acceleration, braking zones etc.
But then at home i wanted to analyse acuired data, and then, using Google maps, i noticed that on each lap there are atleast three deviations or "spikes" from track:
One lap of recorded track:

Deviations1:

Deviations2:

My question is, what could be the reason for these "spikes" and how can i repair them?
Thanks in advance!
P.s. I also attached link to all database files of my driving session:
http://www.4shared.com/rar/-2eaCiqW/Lap ... 2-145.html

[Harry]

Hi,

These deviations appear when GPS does not have enough satellite locks - i.e. when GPS accuracy is not stable. If you look at some of the examples you have sent, you will see bigger blue bubbles - which is lower accuracy again. The only thing you can do against this is placing the device in an (even) better position, or go for an external solution like described here: http://www.gps-laptimer.de/Compatibility.html

Please note even with high quality receivers like the Dual or the Emprum, you will have these effects from time to time.

- Harry