Amplitude fluctuations of signals received from cw sources towed at long ranges in the deep ocean

In April 1974, three cw sources (9.807, 110, and 262 Hz) were towed for 16 days in the Atlantic along a track from Antigua to the Grand Banks of Newfoundland. Data from these sources were recorded near Bermuda, Puerto Rico, and Antigua on both bottom and suspended hydrophones. A 3-h running average was subtracted from the amplitude data in order to remove long-term deterministic trends. The remaining fluctuations were analyzed in fixed time segments to determine the correlation time, the density function and the associated first four moments. The variate difference technique was used to estimate the degree of randomness of the fluctuations. Finally, the effects of range, range-rate, source frequency, and environment on the fluctuation statistics are discussed.