The THD measurements at distance of 315 mm and voltage levels 2.83 - 4 Volt were carried out with High Pass Filter "on" (2nd order Butterworth type, 300 Hz cutoff, HPF2-300)
The THD measurements at distance of 315 mm and voltage levels 5.6 - 8 Volt were carried out with High Pass Filter "on" (2nd order Butterworth type, 500 Hz cutoff, HPF2-500