The disclosure provides an electronic device including a coupler, a transceiver, and a control circuit. The coupler generates a coupled downlink signal according to a downlink signal from a head-end unit. The transceiver switches between the transmission of a downlink signal and the reception of an uplink signal according to a control signal. The control circuit receives the coupled downlink signal, generates a status counting signal according to the power status of the coupled downlink signal, and generates the control signal according to the status counting signal. Only when the level of the coupled downlink signal is lower than an amplitude threshold level with a duration longer than a status counting time, the control circuit converts the status counting signal from a first logic level to a second logic level opposite to the first logic level. Otherwise, the control circuit maintains the status counting signal on the first logic level.