Technology for a repeater is disclosed. The repeater can include a narrowband detector configured to detect one or more power levels that correspond to one or more signals communicated in one or more sub-bands of a selected band. The repeater can include a controller. The controller can select a signal from the one or more signals based on a power level of the selected signal. The controller can adjust a gain or output power of the repeater based on the power level of the selected signal communicated in the one or more sub-bands of the selected band.