AbstractThe differential equation for cup and vane anemometers, developed earlier (Ramachandran 1969) is checked by comparing the computed overestimations of mean values in sinusoidally fluctuating winds with the experimental results of Deacon (1951). The equation predicts an overestimation of low frequency components in winds containing more than one sinusoidal component.Results from direct measurements are compared with those obtained from compensated data, using an approximate compensation technique.The logarithmic power spectra obtained from compensated data show peaked shapes arising out of the removal of the nonlinear overestimation of response at the low frequencies.