Medium Frequency Repeater

The DRUM® 100R Analog Repeater is a dual-band radio, where one of the front ends operates at medium frequency and the other front end operates at either VHF or UHF. The analog repeater continually listens to both frequencies. When one of the front ends detects an incoming signal, the analog repeater shifts the signal and retransmits it on the other front end. Tone squelch is used to indicate the presence of a valid signal.
Under normal operating conditions, signals can be relied on to propagate many miles between the sending radio and any receiving radios with little attenuation. In post-incident emergency circumstances, when conductive infrastructure has been altered or damaged, the units can be moved to propagate their signals on surviving conductive infrastructure, forming a survivable redundant communication path.