An embodiment method includes identifying a set of targets within a field of view of a millimeter-wave radar sensor based on radar data received by the millimeter-wave radar sensor; capturing radar data corresponding to the set of targets across a macro-Doppler frame; performing macro-Doppler processing on the macro-Doppler frame and determining whether a macro-Doppler signal is present in the macro-Doppler frame based on the macro-Doppler processing; capturing radar data corresponding to the set of targets across a micro-Doppler frame, wherein the micro-Doppler frame has a duration equal to a first plurality of macro-Doppler frames; performing micro-Doppler processing on the micro-Doppler frame and determining whether a micro-Doppler signal is present in the micro-Doppler frame based on the micro-Doppler processing; and activating at least one range bin of a plurality of range bins in response to a determination that at least one of the macro-Doppler signal or the micro-Doppler signal is present.