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调制技术决定了参量阵扬声器的性能。递归单边带调制由于失真小,所需带宽低等优点,被参量阵扬声器广泛采用。然而在递归单边带调制方法中,采样频率通常为超声载波的数倍,导致均衡滤波和希尔伯特滤波所需计算量较大。本文提出了一种新的参量阵扬声器调制技术。均衡滤波和希尔伯特滤波均在较低采样频率下进行;再通过升采样技术完成信号调制。实验表明,该方法可以在不降低系统性能情况下,减小实现所需计算量。
Modulation technology determines the performance of parametric array speakers. Recursive single-sideband modulation is widely used by parametric array loudspeakers because of its low distortion and low bandwidth required. However, in the recursive single-sideband modulation method, the sampling frequency is usually several times that of the ultrasonic carrier, resulting in a large amount of computation required for equalization filtering and Hilbert filtering. This paper presents a new parametric array speaker modulation technology. Equalization and Hilbert filtering are performed at lower sampling frequencies; signal modulation is then done by upsampling techniques. Experiments show that this method can reduce the computational cost without reducing system performance.