An Ionosonde is a swept frequency pulse, or Doppler chirp,  radar that measures 

radio frequency (RF) dependent characteristics of the Ionosphere. Usually operated in 

vertical incidence configuration the radio frequency range is normally between 

2MHz and 30MHz.



The audio sample here has seven Ionosonde sweeps pasted together. Usual sweep 

separation varies from several minutes to an hour depending upon the Ionosonde 

data use. An Ionosonde can be used simply as a data collection system or as part of a 

active Frequency Management System (FMS).



Reception of Ionosonde signals is extremely common as the number of FMS supporting

HF communications and/or HF Radars has grown significantly.