In a truck the propeller speed starts to oscillate under certain conditions. Scania would like to find a method to estimate the powertrain oscillation. The objective of this master thesis was to find a method which can perform the estimation in a micro-controller in real-time. This master thesis discuss three different methods of estimating a powertrain oscillation. - Linear search. - Differentiation of the propeller speed. - Fast Fourier Transform, FFT. The last method was found to estimate the oscillation best. Unfortunately it is not able to run in real-time with the available computation capacity of today. Then a method was developed which made an approximation of the amplitude of the oscillation, which was able to run in real-time in the microcontroller. Finally Scania is recommended to use the FFT to make the estimations since it is the most robust method, when the power of the microcontrollers has improved.