In the following diagrams, the effect of the measuring time on the course of the spectrum is shown in comparison for a random modulation (super-soft) and a triangular modulation. The measuring time is to be seen as the time window for FFT computation. This is somewhat analogous to the measuring time of a detector circuit inside an EMI-receiver.

A priori, one would guess more likely a significant influence of the measuring time for the random modulation - in contrast to a periodically repeating time function (such as the triangular modulation), the stochastic random function has exactly no predictable repetition. The random function corresponds the more to an ideal random distribution, the longer the observation period (the measurement window) lasts.