> Could you use the regularity of the window spacing on the
> train carriages to measure speed by detecting variations in
> reflected light?

I was just thinking the very same, using a low-power IR laser
perhaps so as to not startle passengers

*
*
**********
Quality PIC programmers
http://www.embedinc.com/products/index.htm
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.