III. FEATURE REPRESENTATION FOR PD SIGNALS
For PD signals from the PD sensors such as, UHF or HCFT,
we generally represent them in two different patterns, namely
time-resolved patterns and phase-resolved patterns as shown in
Figure 2. Figure 2(A) shows a time-resolved pattern, i.e., a q−t
waveform, where q is the amplitude (i.e., the apparent charge
or discharge voltage) and t shows the time information. Figure
2(B) demonstrates a phase-resolved pattern (PR pattern), i.e.,
a φ − q − n pattern, where φ is the phase angle for the PD
pulse, q also refers to the apparent charge or discharge voltage
and n is the number of pulses.
In Figure 2(A), the waveform shows a single PD pulse,
which appears at the time point t = 2μs, and the whole
signal lasts 10μs with 1000 data points (i.e., the sampling