Periodogram.flatten(method='logmedian', filter_width=0.01, return_trend=False)[source]

Estimates the Signal-To-Noise (SNR) spectrum by dividing out an estimate of the noise background.

This method divides the power spectrum by a background estimated using a moving filter in log10 space by default. For details on the method and filter_width parameters, see Periodogram.smooth()

Dividing the power through by the noise background produces a spectrum with no units of power. Since the signal is divided through by a measure of the noise, we refer to this as a Signal-To-Noise spectrum.

methodstr, one of ‘boxkernel’ or ‘logmedian’

Background estimation method passed on to Periodogram.smooth(). Defaults to ‘logmedian’.


If method = ‘boxkernel’, this is the width of the smoothing filter in units of frequency. If method = logmedian, this is the width of the smoothing filter in log10(frequency) space.


If True, then the background estimate, alongside the SNR spectrum, will be returned.

snr_spectrumPeriodogram object

Returns a periodogram object where the power is an estimate of the signal-to-noise of the spectrum, creating by dividing the powers with a simple estimate of the noise background using a smoothing filter.

bkgPeriodogram object

The estimated power spectrum of the background noise. This is only returned if return_trend = True.