Optimization of the periodogram average for the estimation of the power spectral density (PSD) of weak signals in the ELF band

•In the study of Schumann Resonances, averaged periodograms is used.•There isn’t an accurate theory for choosing the number of segments to be averaged.•Our aim is the optimization of the number of averaged periodograms.•This paper proposes a method to optimize the number of averaged periodograms.•A spectrogram of 24 h is shown as application of this method.

The frequencies between the ELF, ULF and VLF bands are widely used as indicators of the electrical activity in the atmosphere, as precursors of seismic activity and are of interest in the study of geophysical phenomena. These signal methods of analysis are varied, and among them, we find a method of averaged periodograms, which is based on the Fast Fourier Transform (FFT). In this type of analysis, the optimal number of segments to be averaged must be determined; however, there seems to be no satisfactory method for choosing them. In this paper, we provide a method that will allow us to select the optimal number of segments to be averaged.

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