On joint acoustic communication and positioning through MFSK-modulated signals and Costas arrays

The underwater positioning applications with ultra-short base line (USBL) antenna have expanded significantly over last decades. Their principles are based on the geographical positioning of transponders emitting deterministic waveform such as Costas arrays from a receiving antenna composed of several acoustic transducers. Recovering from the transponder of external information such as immersion can increase accuracy of USBL positioning system. Jointly achieving a digital positioning and communication in a shallow water channel requires a careful design of the algorithms to get acceptable performance at limited complexity. This issue is investigated in the present paper. A processing chain design combining underwater acoustic communication and positioning through BFSK modulation of the data over Costas arrays is proposed, discussed and evaluated. Results show that the developed communication method is an efficient tradeoff between simultaneous transmission of telemetry data and positioning signal at a limited complexity. An experiment at sea will be conducted by IXSEA soon to confirm these first lab results.