R&D of an spread spectrum acoustic communication modem with ranging capability

With development of ocean exploitation, maritime rights protection, and other fields of marine information acquiring and processing, integrated underwater acoustic communication and ranging are extensively needed in applications such as underwater networking and AUV navigation and control. Because the traditional underwater ranging system usually uses a single frequency pulse signal, a conflict exists between range ambiguity and ranging accuracy. Moreover, as underwater acoustic channels pose multiple difficulties such as multipath, time-space selectivity, frequency dependent noise, and Doppler shifts, high precision ranging is a challenging mission. Considering that the spread spectrum technology features high reliability, strong anti-interference and anti-multipath capabilities and low probability of detection (LPD) capability, this paper introduces the application of the m-sequence spread spectrum technology into the integrated underwater acoustic communication and ranging function to develop a spread spectrum acoustic communication modem with ranging capability. Experimental results obtained in a physical shallow water channel demonstrate the proposed system's effectiveness.