On Tue, 08 Jun 2010 14:59:52 -0700, Pietro rearranged some electrons to
say:

If this is the wrong group I'd appreciate a pointer to the right one!

I was wondering if it is possible to detect the presence of inactive
cell phones/wifi devices by detecting radio signals they emit. I figure
wifi would be the best bet because I guess cells dont broadcast all that
much when not in use, right?

Would there be enough output to find them? Would it be strong enough to
detect over a distance of say 100m? Could signals from multiple devices
be distinguished? Would the equipment be very expensive. Would I get
thrown in prison?

I am interested in triangulating and tracking the movement of phones
through a small area as a potential postgrad project.

Thanks.

The cell phone providers already track the phones, not sure that you
would be doing anything new.