Frequency of optimum transmission

Propagation too low (red) and too high frequencies (blue)

The Frequency of Optimum Transmission ( FOT , French fréquence optimal de travail ) is the optimal frequency for a radio link on shortwave .

It is defined as 85% of the Maximum Usable Frequency . The FOT guarantees a reliable radio connection 90% of the time. Lower frequencies are more attenuated in the ionosphere , higher frequencies may no longer be reflected.

literature

• Kenneth Davies: Ionospheric Radio. Peregrinus, London 1990, 180.

Web links

• Improved radio weather forecast through the use of effective or equivalent sunspot relative numbers