Amit Ray
This chapter covers the challenges and developments in underwater communication, which is critical for all types of operations. The communication modalities used underwater are acoustic, optical, and electromagnetic. For each of these three modes, this chapter discusses the characteristics (frequency range, modulation techniques), performance metrics (range, bandwidth, and latency), and current applications (naval, scientific, and industrial). Techniques and measures are suggested, based on practical experience and physical understanding of concepts, for ensuring reliable acoustic communications in real-world conditions.