Whistler wave amplitudes during the first encounter of PSP (November 2018) from the DFB cross-spectral and BPF measurements compared to the background magnetic field from MAG. Right: 2D histogram of the waves relative amplitude and WNA from the BPF and cross-spectral measurements (8481 wave packets, that means BPF bins, in total). Left: relative amplitude of the magnetic fluctuations from the cross-spectra vs. the WNA for the whistlers (2701 wave packets in total).