Revised 2D fast fourier transform

It is assumed here, that some signal samples in the respective period, available for processing digitally by the fast Fourier transform (FFT) procedure for determining spectra of two-dimensional (2D) signals, are updated by a sensor in real time. It is urgent for each new sample that emerges to have a new 2D spectrum. The idea is that the 2D FFT procedure should not be repeated for each new sample. It is needed just to modify the procedure when the new sample emerges and replaces the previous one. The recursive formulas for FFT algorithms that refer to the modification and on-line calculation of 2D spectrum samples are obtained. Simulation results are presented here, too (see table, Figures 1 - 3).