Comment by Havoc

>you'd need tens of thousands of them per city

I was thinking more find a tall building and throw a single one there. Or maybe tallest 3.

As I understand it even a small number of extra satellites with line of sight can improve results a fair bit.

So aiming at low hanging fruit rather than blanket city

>very accurate atomic clock.

Indeed, but I'd think managing that on ground is easier than in space.