Complex sentence: The resulting pattern is proportional to the power density spectrum of the measured noise and it is then normalized by the duration of the finite-time sample and also by a numerical constant in the order of 1 to get its exact value.
Split into simpler sentences: The resulting pattern is proportional to the power-density spectrum of the measured noise. It is then normalized by the duration of the finite-time sample and also by a numerical constant in the order of 1 to get its exact value.