My SatNav sends its message out
to satellites in the sky,
and they can tell, without a doubt,
its source, as overhead they fly.
They then ‘speak’ back to the GPS
to say where my car is now
upon its map, to help it to assess
the way that I will have to go –
– compare my stated destination
with the present pinpointed location,
and for the route’s continuation
then ‘voice’ the needed next instruction.