On-pulse averaged LRF spectra for two 512-pulse sequences (light colour, filled) together with the LRF spectra computed for the first and last 256 pulses of each pulse sequence (black, empty). Only the Fourier frequencies around the B-modefeature are shown. The pulse numbers in the legend are counted from the closest Q-to-B transition. Left: example of an LRF spectrum with two peaks that are resolved into a single peak that changes its position with time. All double features with clearly separated peaks were resolved in this way. Right: example of an LRF spectrum for a 512-pulse sequence that shows the peak offset from the peaks in the LRF spectra of the subsequences. This behaviour might be explained by phase jumps within the pulse sequence.