This radar data was collected by a system in Goose Bay, Labrador.  This

   system consists of a phased array of 16 high-frequency antennas with a

   total transmitted power on the order of 6.4 kilowatts.  See the paper

   for more details.  The targets were free electrons in the ionosphere.

   "Good" radar returns are those showing evidence of some type of structure 

   in the ionosphere.  "Bad" returns are those that do not; their signals pass

   through the ionosphere.