Abstract :
The width of frequency-spreading (Δff) on ionograms was shown (Wright, et al., 1977, by comparison with OGO-6 Satellite observations) to be proportional to ΔNN near and above the F-region peak. Thus, even classical analog ionograms using logarithmic frequency scales were direct reading for this important parameter, although little use has been made of this fact. How can modern digital ionosondes produce (by automated methods) a comparable parameter? This paper provides an answer to the question, as the first of a series of steps aimed at exploiting the full capability of HF sounding to understand the distinctive phenomenon of Spread F.
