Pulse Width Encoder

In AUTD3, the output sound pressure is controlled by PWM (Pulse Width Modulation). In PWM, the relationship between the pulse width and the output sound pressure is theoretically expressed as follows.

By default, the settings are such that the intensity parameter and the output sound pressure are theoretically linearly proportional. Specifically, the pulse width is converted from the intensity parameter (8 bit) as follows.

However, note that in practice, due to individual differences between transducers and deviations from the theoretical value, the relationship is not necessarily linearly proportional. Even so, the output sound pressure can be assumed to increase monotonically with respect to the intensity parameter.

Note that this conversion is performed by a lookup table keyed on intensity, and this table can be changed. For details, refer to SetPulseWidthTable.