External GPS antenna question

[Ben Wong]

> and if you are carrying the FR in a pocket, yes it gets a lock most of
> the time, but the track wobbles all over the place - up to a hundred
> meters.  And if driving through an "urban canyon", similar track errors
> can occur.  Ive wanted a small external powered antenna for some time to
> improve this.

I've noticed the same wobbles, but only when I'm not moving very
quickly.  Does anybody know if setting the GPS to "Pedestrian" instead
of "Car" mode helps?  Or is an antenna the only solution?

--Ben