The measurement is a frequency analyser and shows the intermodulation and harmonics.(Plot from the Mag measure)To get the distortion there is to calculate the amplitude for following frequencies.Signal Fundamentalf1f2K2 K3 K4 IMD2f2-f1f2+f1IMD3f2+2f1IMD4f2+3f1RB low 180 360 540 720 54234 468 702 936 414 594 794RB mid 500 1,0k 1,5k 2,0k 150650 1,3k 1,95k 2,6k 1.15k 1,65k 2,15kRB high 1,5k 3,0k 4.5k 6,0k 4501,95 3,9k 5,85k 7,9k 3,45 4,95 7,95kThe first frequencies f1, f2 are the fundamentals, K2, K3 and K4 are the harmonics. To get thedistortion in dB there is the formulaAmplitude in dB of the fundamental – Amplitude in dB of the harmonic = distortion in –dB.To get the distortion in dB there is the formula2010dbWertDistortion in %-20dB = 10%-40dB = 1%-60dB = 0.1%25.3 THE DISTORTION MEASUREMENT79
