Cross-term averaged FFT.

FD = ctafft(TD,Averages)
FD = ctafft(TD,Averages,N)

ctafft takes a time-domain signal TD as input and computes the cross-term averaged FFT. For this, ctafft computes the FFTs of TD(Averages(i):end) for all i and sums up their magnitudes. If Averages is a number, it is a shortcut for 1:Averages.

ctafft helps to get rid of dead-time artifacts in simple FFTs of ESEEM spectral data. The quality of the result can be very sensitive to Averages, so it is worthwhile to experiment a bit.

If N is given, all signals are zero-filled to length N before the FFT. If not given, N is set to the length of TD.

TD can be either a vector or a matrix. In the latter case, ctafft works along columns.

ctafft implements a procedure introduced in

• S. Van Doorslaer, G. A. Sierra, A. Schweiger, J. Magn. Reson. 136, 152 (1999).

fdaxis