A Simple Time Synchronization Method for Underwater Communication Receivers

A method is developed for acoustic time synchronization/pulse acquisition suitable for use in reverberant multipath environments. This scheme uses two identical broadband synchronization pulses for the acquisition, and it is motivated by passive phase conjugation. The first pulse is used as a preamble pulse and replaces the replica signal later to correlate with the second pulse. Within the coherent time interval, a fixed threshold is used to measure the correlation coefficient between the first pulse and the second one, so it is easy and robust for the receiver to make a decision in synchronization. The method overcomes the difficulties of presetting a threshold for receivers to acquire synchronization automatically.