Propagation time estimation between underwater acoustic modems during data exchange via synchronous instant messages

Modern underwater acoustic modems, besides transmitting and receiving data, are capable for measuring signal propagation time and thus also for evaluation of the distance between the transmitter and the receiver. Such capabilities can be exploited for synchronization of underwater acoustic sensor networks, where sensing and actuation must be coordinated across multiple nodes. However such problem, as accuracy of propagation time measurement, especially in reverberant environments, have been investigated rather poorly. Main objectives of this paper consist in analytical and experimental evaluation of the accuracy of propagation time measurements during bidirectional data exchange between underwater acoustic modems via synchronous instant messages.