Examining the Time Domain image can also be of help. In the case of Corona, you will have a uniform band of signal with very few peaks that extend above the average “band”. With Tracking, you will begin to see the peaks created by the discharges extend above the average “band”. With Arcing, you will see several “bursts” of energy, which correspond with the discharges. In all cases, both the Spectrum and the Time Domain should be examined before the final determination is made.