A digital beamsteerer for difference frequency in a parametric array

A steerable audio system can be realized using parametric array. However, the available steerable angle is often limited by the sampling interval used in the digital system. As such, the smallest steerable angle is large (∼ 26°) for several hundred kilohertz of sampling frequency. Although there arc some fractional delay or frequency domain algorithms can be used to improve the steering angle, most of the algorithms arc either computational intensive or introduce error during the process. In this paper, an algorithm is proposed to rectify this problem by applying separate delays to the carrier and sideband frequencies. Different weighting functions also added to the carrier and side-band frequencies to control the difference frequency's beamwidth and sidelobe. Most importantly, the proposed system can steer the difference frequency to a small angle with minimal computation.