Maximum usable frequency

Maximum usable frequency (MUF) describes, in radio transmission, using reflection from the regular ionized layers of the ionosphere, the upper frequency limit that can be used for transmission between two points at a specified time, independent of transmitter power. This index is especially useful in regard to shortwave transmissions.

MUF is a median frequency applicable to 50% of the days of a month, as opposed to 90% cited for the lowest usable high frequency (LUF) and the Frequency of optimum transmission (FOT).

Typically the MUF is a predicted number. Given the maximum observed frequency (MOF) for a mode on each day of the month at a given hour, the MUF is the highest frequency for which an ionospheric communications path is predicted on 50% of the days of the month.

On a given day, communications may or may not succeed at the MUF. Commonly, the optimal operating frequency for a given path is estimated at 80 to 90% of the MUF.

See also

• Radio propagation
• MW DX
• TV-FM DX
• DX communication
• Near Vertical Incidence Skywave
• E-skip
• E-layer
• F-layer
• List of telecommunications transmission terms

Sources

 This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).

External links

• MUF Basics
• Real-Time Predicted Maximum Usable Frequency Conditions World-Wide

This article related to telecommunications is a stub. You can help Wikipedia by expanding it.