Implementation of a micro-modem for underwater wireless sensor networks

Recently, underwater wireless sensor network (UWSN) has been emerged as one of interesting research topics. For UWSN, each sensor node should be equipped with acoustic communication modem which has the properties of low-power consumption, small size, low cost, moderate communication distance and data rate. In this paper, We design and implement a micro-modem conforming to the requirements for UWSN and make experiments in a water tank and a pond to verify the performance of the developed modem. According to analysis and experiments, the output voltage of the transducer at receiver is directly proportional to the input voltage supplied to the transducer at transmitter and inversely proportional to communication distance between transmitter and receiver if the distance is small enough. We also measure the bit error rate of the modem depending on input voltage, distance and data rate. Since the developed modem supports the characteristics for the use of UWSN, it is expected that the micro-modem could be utilized for various applications in UWSN.