GPS issue final state?

[Russell Sears]

Michael Shiloh wrote:
> Any advice appreciated.

I've been tricked a few times by what I think was lucky satellite 
positions (30-120 sec ttff one day, 20 minutes the next).

I don't know how long it typically takes the satellites to move from 
"lucky" to "unlucky", but that probably should be taken into account. 
Also, what about urban environments w/ more reflections, etc.  Should 
people report terrain type?