Using low light level television observations of the diffuse aurora, frequency spectra have been derived from time series data obtained by digitizing segments of a recorded video signal. The results suggest that temporal fluctuations having periods in the range 2-40 s are common to both quiescent and pulsating forms of the diffuse aurora and are the dominant fluctuation period. A representation of the data in the form of dynamic spectra, which shows the evolution of the temporal fluctuations at intervals of 20-30 s, has been derived by using maximum entropy spectral analysis. In one of the examples the 2 to 4-Hz modulation often observed during pulsating aurora is evident in the dynamic spectrum.