SOG Units and Calculation

RaceQs Community:

Nice software!

I’m looking for confirmation that the SOG displayed in race replay is in units of nautical miles per hour (knots), and not some other unit e.g. mph. On the phone app, all the speed fields seem to be in units of knots and I don’t see any way to change that (not that I want to).

Also can anyone confirm how the phone app calculates SOG? By that I mean confirm the algorithm? I assume the app samples the phone’s GPS position at some frequency, then computes the difference in position between samples, and divides that difference by the amount of time between samples to yield a distance over time (i.e. speed) measure, then does unit conversion to express that speed in nautical miles per hour. Can anyone confirm? What is the sampling frequency?

Thank You,
Randy Stafford
S/V Grenadine
C&C 30-1 #7
Ken Caryl, CO

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