Development of Decibel Stepped Attenuator for Automated Sound Level Meter Calibration

摘要

Parameter testing in the sound level meter calibration, such as frequency weighting and linearity, needs precise adjustment of sound level in the decibel (dB) unit. In the previous calibration setup, a hardware-based sound attenuator instrument was used as the complementary to a signal generator instrument system where the adjustment of sound using the attenuator was performed manually by the operator. By this manual adjustment, frequency weighting and linearity parameter testing need a sufficiently long time to finish. This paper presents the development of software for an attenuator system and the automation of frequency weighting and linearity parameter testing process without additional hardware-based attenuator instrument in the calibration setup. The developed software attenuator system has attenuation range from 0 to 99 dB and a resolution of 0.01 dB. The calibration time efficiency can be improved by the automation of frequency weighting and the linearity testing process built within the software.