Spatial distribution of signals emitted by a sigma-delta modulation-driven linear digital transducer array

Digital transducer array (DTA) has the advantages of greater integration scale, smaller size, lower cost, and possibly improved electroacoustic efficiency over existing analog systems. The original DTA is realized using pulse code modulation (PCM) technique, where a large number of loudspeaker elements are needed to map PCM audio signals to the transducers. Recently, sigma-delta modulation (SDM) driven DTA was proposed, which can achieve a satisfactory performance with only a few transducer elements. In this report the quantization noise and harmonic distortion of multibit SDM-driven DTA in each channel are investigated. The spatial distribution of signals emitted by multibit SDM-driven DTA is then derived. To confirm the analysis, a four-bit SDM-driven DTA system is constructed based on field-programmable gate array.