An experimental technique is described that will facilitate the acquisition and analysis of information from dynamic neutron physics experiments. The Fourier transform of a forced oscillating neutron field is determined on-line and presented in a visual display. Cross correlation is used to extract the information; the method is based on the utilization of detector pulses in weighting a correlative signal. The time of the measurement and data reduction is considerably reduced as compared with existing methods requiring a multichannel analyzer and a digital computer. Frequency measurements in the range of 10 kHz and above are feasible.