[FOSS-GPS] Introduction

Oliver Eichler oliver.eichler at gmx.de
Sat Sep 20 05:35:03 EDT 2008

> Of course you want to use the velocity only if it is accurate enough.
> Some receiver like the ublox gives accuracy indicator for velocity too.
> You might also want to apply a low band filter on the velocity before
> using it; the cut frequency would be a function of the use case

You can use a similar function for that (recursive lowpass filter):

avgspeed0 = A * speed + (1.0 - A) * avgspeed1;
avgspeed1 = avgspeed0;

speed     := current speed
avgspeed1 := avgspeed[n-1]
avgspeed0 := avgspeed[n]

with A = e^(1/t) - 1
t = number of samples to average

Thus if you want to get the average over ~ 5 samples A = 0.22140.


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