As radar transmits coherent pulses with a certain pulse repetition frequency (PRF), the doppler processing technique is applied. A Power spectrum can be calculated from a sequence of formula_25 components in the following way. In every range gate the FFT algorithm is applied to the serie of formula_26 IQ signals, where formula_26 is the number of FFT points used in the FFT. The result of the FFT is a complex spectrum formula_28 where formula_29 is the Doppler frequency. The power spectra is then easily estimated by