I tried the RaceChrono app for Android using the internal GPS for a few karting runs, but it turned out to be totally unusable due to the low GPS accuracy with constants jumps in position, crossing the path itself, etc . I had the phone attached to my chest with a "harness".
Is it normal this low accuracy using the internal GPS? Could it be the position of the phone (attached to my chest) a reason for it?
In case of buying an external GPS what would be the cheapest but still reliable option for karting? I have read good reviews about Garmin Glo, but although in the specifications it is said that supports 10Hz, seems that it is not working at 10Hz with this app, is there any reason for this? And what about the Qstarz BT-Q818XT?