Ionosonde

The basic ionosonde technology was invented in 1925 by Gregory Breit and Merle A. Tuve[1] and further developed in the late 1920s by a number of prominent physicists, including Edward Victor Appleton.

An ionosonde consists of: The transmitter sweeps all or part of the HF frequency range, transmitting short pulses.

The result is displayed in the form of an ionogram, a graph of reflection height (actually time between transmission and reception of pulse) versus carrier frequency.

ARTIST is the software program used to "scale" (deduce or calculate) the characteristic parameter values shown in the table on the left.

If one is monitoring a specific frequency, then a chirp is heard (in CW or SSB mode) when the signal passes through.

Typical ionogram indicating an F2 layer critical frequency (foF2) of approximately 5.45 MHz.
An example of an ionosonde system displaying an ionogram