STUDY FOR ACOUSTIC CHARACTERISTIC WITH DIGITAL SPEAKER
武道 石川, Takemichi Ishikawa · Medical Entomology and Zoology · 2015
The paper proposes a novel directive control method with amplitude-phase control and using mismatch shapers in the time domain for a beamforming speaker by using a digitally direct-driven system with an array loudspeaker. This system can achieve high directivity and control side-lobe attenuation with the amplitude-phase control. The output pulse width is controlled using pulse width modulation for changing the amplitude and phase by using several 1-bit D flip-flops because the sub-loudspeakers are driven by 1-bit digital signals without digital-to-analog converters and amplifiers. A segmented noise shaping dynamic element matching (S-NSDEM) method is used to reduce the noise generated by the mismatch of sub-loudspeakers and a time domain noise shaping dynamic element matching (TD-NSDEM) method is contributed to reducing humming noise in the full scale input, which degrades the signal-to-noise ratio.