Fade slope estimations extensively depends on the rain type (convective/stratiform), drop size distribution and the melting layer (bright band) height. Tropics show unusual changes in these parameters due to occasional severe thunderstorms, cyclones and seasonal monsoon (SW and NE) currents. An ITU-R prediction based on temperate climatic conditions often fails to estimate accurately rain attenuation and rain fade slopes. Hence, precise experiments and data processing techniques in tropics are quite required to compare the ITU-R results. In this paper we have taken up fade slope estimations over an operational Ku band link in southern India using different signal processing techniques viz., time domain, frequency domain and wavelet domain. For the first time biorthogonal spline wavelets are used to differentiate rain fades to estimate the rain fade slopes. The results are significantly different from ITU-R predictions.