An electronic device including a signal unit configured to emit a first radiated signal to a subject; a signal receiving unit configured to detect a reflected signal of the first radiated signal from the subject; and a controller configured to determine whether a distance to the subject is calculated based on the reflected signal of the first radiated signal, change a waveform of the first radiated signal when the distance is not calculated, cause the signal output unit to emit a second radiated signal with the changed waveform, detect, via the signal receiving unit, a reflected signal of the second radiated signal from the subject, and calculate the distance to the subject based on the reflected signal of the second radiated signal.