Coupling methods

ppc_constant_phase_shift(waveform, sfreq, ...)	Generate a time series that is phase coupled to the input time series with a constant phase lag.
ppc_von_mises(waveform, sfreq, phase_lag, ...)	Generate a time series that is phase coupled to the input time series with a probabilistic phase lag based on the von Mises distribution.
ppc_shifted_copy_with_noise(waveform, sfreq, ...)	Generate a time series with desired level of coherence with the provided waveform in a frequency band of interest.