@macle Hi. I don’t have the AtomicGPS, but I did some digging around to try to understand the speed measurement within the GPSAnalyse.cpp file. I see this in that file relating to speed: _s_GNRMC.TrackSpeed = _s_GNRMC.pamstr[7].toFloat(); Doing a quick google search on “GNRMC speed” I found this source that says GNRMC ground speed is in knots. Doing the conversion between knots and kph (1 knot = 1.852 kilometers per hour), it seems about right that the GPS is reporting a speed measurement that is roughly half of your vehicle speed in kph (0.54 to be exact!). Hope this helps!