It is strange a little bit...

Some time ago I have build device whitch measured speed and loged it. It was used in my car Nissan 100Nx. But in this car, sensor produced signal whitch frequency was proportional to speed. And even more - I can't remember exactly, but it was something like 10 pulses per 100 meter. so 1 pulse ~10 meters.

And I have found, that runing average filter was more then nesesary! Without filter speed was hoping ~5km/h or even more!

In my aplication I was counting pulses 0.5s and then passed it to filter, so, I had new speed every 0.5 seconds.

Have fun!