An experiment in high rate underwater telemetry

A project is described which explores the feasibility of high rate telemetry over the short range (< 10 km) underwater acoustic channel. An experimental digital signal generator was constructed to provide a variety of modulations for evaluation. A frequency-hopping signalling format of 2.5 kHz bandwidth was chosen with simultaneous FSK and PSK modulation. Several operating modes with transmission rates from 138 to 1640 bits/s were tested at sea. Analysis of the sea test data to date has shown both the FSK and the PSK modulations to be readable, indicating that high rate telemetry can be realized with this signalling format.