Acoustic velocity sensors with programmable directivity

A directional acoustical sensor with programmable axis of maximum sensitivity is described. The sensor is based on a combination of two orthogonal acoustical particle velocity (APV) sensors, integrated on the same chip. The APV sensors are based on a thermal transduction principle. Differently from former implementations, the proposed devices are fully CMOS compatible. Rotation of the sensitivity axis is obtained by combining the output of the two APV sensors properly weighted with programmable coefficients. This operation is performed using a microcontroller ADuC842 (Analog Devices) equipped with 12 bit, 400 kS ADCs.