The BIFI range is a shallow‐water acoustic range in Long Island Sound, about 19 miles long and 110 ft deep. Results of time‐smear and frequency‐smear studies made on this range are presented. It is shown how these results may be used to predict signal fluctuation. In time‐smear studies, the received signal is divided into a front, a main arrival, and a tail. The relative energies of the three sections of the signal are computed, and these results are used to predict the range of signal fluctuations. The above analysis and computation are easily carried out on a digital computer using, as input, data automatically punched on cards. Frequency smear is the Doppler shift undergone by a signal as a result of being reflected from a moving surface. Many frequency‐smear spectra were obtained for varying sea states, and, from these, dispersion as a function of sea state was calculated. The dispersion increased with sea state, in agreement with theory.