Ionosonde

An ionosonde, or chirpsounder, is a special radar for the examination of the ionosphere. An ionosonde consists of: The transmitter sweeps all or part of the HF frequency range, transmitting short pulses. These pulses are reflected at various layers of the ionosphere, at heights of 100–400 km, and their echos are received by the receiver and anal
Found on http://en.wikipedia.org/wiki/Ionosonde

ionosonde

radio equipment designed to carry out ionospheric soundings and to record the results
Found on http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=705-07-70

ionosonde

device for recording information about the ionosphere using echoes
Found on http://phrontistery.info/i.html
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