Why do you need an external GPS tracker? The Q500 records all data in the FlightLog. The FlightLog you can find at a SD-Card in the ST10. There should be one installed already behind the battery of the ST10. If you connect the ST30 via mirco USB to your PC you should see the fiole system at the SD card and you can copy the FlightLogs.Attached is my flight track of today, made directly from FlightLog. This is 'playable' in GoogleEarth. I think that is what you want. Accuracy should be better than 1m. With other word, I find my place exactly where I was.
And you see a lot more like voltage, GPS accuracy, speed, HW status and so on.
More info:
http://h-elsner.mooo.com/mydat/Q500log2kml_en.pdf
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