System design aspects of a steerable directional acoustic communications transducer for autonomous undersea systems

The U.S. Navy is developing deployable networks of autonomous sensors, sources, and vehicles for littoral operations. Reliable and secure wireless acoustic communication among network nodes is essential for this concept to be viable, and depends critically on the modem and acoustic transducer. A transducer with azimuthal directivity will reduce power budget and vulnerability to intercept, increasing battery operated lifetime, signal-to-noise ratio, and asynchronous multi-user transmission channel accessibility. To gain these advantages requires innovative solutions to such problems as increased driver electronics complexity, and sensitivity to mechanical transducer movement. This paper reports on research efforts that involved modeling and dynamic analysis of a piezopolymer-based transducer array, along with development, testing, and analysis of a low cost microcontroller-based orientation sensor system. A new auto-calibration algorithm significantly improves the precision of the low-cost sensor elements.