the depth to the centroid of the anomaly source after Spector and Grant (1970). They aim to
decompose the signal to its constitutive sources in the frequency domain. The power
spectral density of a potential field decreases exponentially in function of the depth to the
source and the wavelength. Hence, we usually relate deep sources to strong spectrum at
long wavelength which decays rapidly. However, to estimate the depth to the source is not …