Reproducibility of signal transmissions in the ocean

Repeated transmissions of acoustical signals were made over a distance of 20 nm. One transmission was compared with succeeding transmissions with the matched signal technique. The experiments showed 10 average arrivals added coherently. The signal is matched for particular source and receiver positions. Displacement of the source or receiver from these positions reduces the coherent addition of arrivals. The sensitivity to small displacements also depends upon the signal bandwidth. These experiments were done at 400 c/s with a bandwidth of 100 c/s. A displacement of the source of about 0.1 nm decreased the peak of the coherently added arrivals to about 60 %.