Experimental reference filtering.

experimental_filtering.py

def remove_reference_signal_with_experimental_reference_method_with_extended_FFT(
                                                  signal,
                                                  reference,
                                                  optical_delay_spacing,
                                                  ref_calibration=None):
    """Removes reference signal using extended FFT method."""
    # transform reference signal to frequency domain
    t_points = reference.shape[0]
    ref_spec = np.fft.rfft(reference, reference.shape[0]*2)
    signal_spec = np.fft.rfft(signal, signal.shape[0]*2)
    freq = freq_from_optical_delay(optical_delay_spacing, len(ref_spec))

    # apply filter in frequency domain
    deconv_spec = signal_spec / ref_spec

    # ref_calibration is a data array or None (i.e. Python null data type)
    print('Removing reference signal with reference...')
    if ref_calibration is not None and len(ref_calibration) > 1:
        # Get the y axis
        cal = ref_calibration['spec']
        # Interpolate the real data from cal onto the current frequency domain grid
        real_cal = np.interp(freq,
                             ref_calibration['freq'],
                             cal.real,
                             cal[0].real,
                             cal[-1].real)
        # Interpolate the imag data from cal onto the current frequency domain grid
        imag_cal = np.interp(freq,
                             ref_calibration['freq'],
                             cal.imag,
                             cal[0].imag,
                             cal[-1].imag)
        # Apply calibration by multiplication with the interpolated complex array
        deconv_spec *= (real_cal + 1j*imag_cal)

    # Rather than apply filtering parameter here we
    # using the reference signal as the filter.
    deconv_spec *= ref_spec
    deconv_spec[0] = 0
    deconv = np.fft.irfft(deconv_spec, 2*t_points)
    deconv = deconv[0:t_points]
    return deconv