Re: How do you measure SPEED on skates?

Eric Edwards wrote:
> If you do, you will find that speed is not so precise after all.  My

Well, while the GPS unit stays in touch with the satelites, the speed 
measurement is precise.

> experience is that GPS speed measurements are *on average* pretty good. 
> But individual samples can be crazy.  I use to skate to work with a
> Garmin GPS III.  Once or twice a week I would get a max speed
> measurement that clearly wrong.  Things like 60mph on skates on flat

If the unit looses the satelites and reconnects, then first positions are 
not precise and they tend to jump to the precise position. The speed 
computed from them is way off and that is causing the high max speed.

> ground.  The units can also lose contact with the satellites and importune
> times and neglect to take a measurement.  Like a friend of mine that
> wanted to get a good measurement of a favorite down hill run.  It's a
> 30mph run for the slackers and the GPS recorded only 17mph.  This
> happens just often enough to make me suspicious of any peek speed 
> measurement from GPS. 

Yes, peek speed is usually wrong but the average and the distance traveled is 
fine, if you put that GPS thing into the top end of a backpack.

_//__
ooooo - ing,
Michael,