[OSM-talk] fwd: Two thirds of mobile users want driving ANDwalking navigation
edodd at billiau.net
Tue Feb 16 19:51:46 GMT 2010
On Wed, 17 Feb 2010, Dave F. wrote:
> > It has little to do with the material it's made of, it's all about how
> > much mass an object has, the more mass the more it will absorb RF.
> Is this correct?
> I assumed the reason I had trouble getting reception on board trains
> because of what their roofs were screened with.
> I can't believe they'd put much mass up there.
the signals are simply radio signals
they are also blocked by metal mesh like structure when the size of the mesh
is smaller than the wavelength of the signal
Inside the building multipath is another problem - reflected signals coming to
the unit at a later time than the non-reflected signals.
Have a look at a trace inside a building and see how much it jumps around and
you will realise that you won't get much useful information from one inside a
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