def welch(timeseries, segmentlength, noverlap=None, window=None, plan=None):
return _lal_spectrum(timeseries, segmentlength, noverlap=noverlap,<EOL>method='<STR_LIT>', window=window, plan=plan)<EOL>
Calculate an PSD of this `TimeSeries` using Welch's method

    Parameters
    ----------
    timeseries : `~gwpy.timeseries.TimeSeries`
        input `TimeSeries` data.

    segmentlength : `int`
        number of samples in single average.

    noverlap : `int`
        number of samples to overlap between segments, defaults to 50%.

    window : `tuple`, `str`, optional
        window parameters to apply to timeseries prior to FFT

    plan : `REAL8FFTPlan`, optional
        LAL FFT plan to use when generating average spectrum

    Returns
    -------
    spectrum : `~gwpy.frequencyseries.FrequencySeries`
        average power `FrequencySeries`

    See also
    --------
    lal.REAL8AverageSpectrumWelch