No abstract

The use of acoustic communications in any number of projected applications requires trade-offs within the realm of technologies currently available and those projected for the future. Analyses must be performed to predict the performance, strengths, and limitations of competing approaches. Because underwater acoustic data telemetry can be viewed as a union of sonar and communications, it suffers from the same environmental degradation as sonar and communications systems. Efforts undertaken to date have shown that system performance is dictated by received signal-to-noise ratio and multipath complexity, spread, and rate-of-change. Comparisons between different signaling technologies can be made using a variety of measures of effectiveness. These metrics provide a detailed structure for the evaluation of the performance envelope as a function of environmental and platform conditions. We have compiled published results on a large selection of modems in terms of range-rate product, bandwidth efficiency, range, frequency, and power. Based on these compiled results and on simple physical models, design rules-of-thumb have been derived to ensure that proposed system designs have communication requirements that are reasonable and robust. While these rules may seem somewhat conservative, the sample points reported in the literature may not have been achieved reliably or more than once.