Relative phase of the Saturn radio emissions. Panel a: Cassini RPWS wave electric field spectrogram. The horizontal white dashed lines mark the frequencies of 71.2 kHz (corresponding to SKR), 15 kHz (corresponding to 20 kHz NB), and 5.1 kHz (corresponding to 5 kHz NB), which are used in the following panels to plot the frequency intensity versus time variation. The blue, pink, and black arrows in panel a indicate the three radio emissions. Panels b–d: spectral density in units of dB above the background. The oblique red dashed lines depict the rough phase relation between the three radio emissions. The peaks marked by the oblique red dashed lines correspond to the blue, pink, and black arrows in panel a, which correspond to the main emissions of SKR, 5 kHz NB, and 20 kHz NB. The black shaded regions in panels b–d indicate the regions that are polluted by the low-frequency extensions of SKR. The relatively constant relations shown suggest a phase-lock situation.