Digital transmission in water

An ultrasonic radiator has been developed to transmit data in water. The radiator consists of a thin rectangular blade and is excited by an AC signal applied to a pair of PET ceramic bars mounted on either side of the blade to develop flexural vibrations. The important feature of the system is the impedance mismatch between the material of the blade and water to which it is coupled. Direction of propagation is dictated by the wavelength coincidence condition. TCM (trellis coded modulation) coding and modulation has been applied using the operational frequency of the radiator as the carrier signal. This process which is the combination of coding and modulation of the signal has demonstrated the capabilities of a new underwater transmission system. A narrow beamwidth is the condition to obtain optimal power and performance. Simulation of the above system has been developed for the purpose of data telemetry in acoustic channels