Binary telemetry in a high doppler underwater acoustic channel

Communication of data to or from a moving underwater vehicle presents unique problems due to the low ratio of acoustic propagation velocity to potential vehicle speeds. Several binary telemetry methods are examined for performance in a noisy channel at Doppler values up to ±3 percent. Carrier frequencies of above 10 kHz are assumed and channel interference is Gaussian noise and multipath fading. It is shown that the best performance is obtained with phase shift keyed modulation and that the optimum detector employs a hybrid tracking loop which combines fast acquisition of a data burst and near-coherent detection of the acquired message. Low false alarm rates are possible by using phase lock indication as a necessary precursor to a valid message.