## 3 Experimental Results, Verification, and Discussion
According to Figure 5(a2,b2), which show the zoomed-in raw data collected during the first 40 ns with more detailed information, we can find that the peak jitter of channel 2 is greater than that of channel 1, and the peak-to-peak value collected by channel 1 is greater, which means that the signal power of the same signal collected through two channels is inconsistent. In fact, as the average power consistency \begin{table}
\begin{tabular}{c c c c c} \hline \hline \(f\) (MHz) & \(k_{\mathrm{f}}\) & MRMSE\_f & \(k_{\mathrm{b}}\) & MRMSE\_b \\ \hline
100 & 12 & 44.4174 & \(-\)40 & 45.3537 \\
200 & 12 & 28.9738 & \(-\)14 & 30.6193 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Measured MRMSEs and corresponding shift amounts of two detection RF signals. of the two channels has been modulated through the TFOA, the inconsistency here is caused by the instantaneity of signal acquisition and accidental jitter during photoelectric conversion by the PD. Figure 5(a3,b3) show the raw data collected during the first 400 ns and the corresponding fitted signals, depicted by solid blue dots and solid red lines [26]. By comparing the raw data with the fitted signal, it can be observed that the peak noise in channel 2 is actually higher. Figure 5: Two channel signals of 100 MHz collected by the PADC system. (**a**) Data of channel 1; (**b**) data of channel 2; 1–6: raw data, zoom-in data of first 40 ns, raw data and fitted signal of first 400 ns, peak-limited and normalized raw data and fitted signal of first 400 ns, zoom-in raw data and fitted signal of first 40 ns after the PLM and normalization, and normalized power spectrum. In order to reduce the impact of peak jitter, we assign the collected signal values that exceed or fall below the maximum and minimum values of the fitted signal as the maximum and minimum values of the fitted signal, referred to as the peak limit method (PLM). Then, we normalize the signal to reduce the impact of inconsistent signal power between the two channels. Figure 5(a4,b4) depict the raw data and corresponding fitted triangular signal within the first 400 ns after applying the PLM and normalization processing. It can be observed that the signal peak jitter and power inconsistency between the two channels have been significantly reduced. Based on our calculations, the ENOBs of the two processed channels are 4.9241 and 4.3534 bits, respectively, which are higher than the original data values, and the ENOB of channel 2 has improved more significantly. Figure 5(a5,b5) show the normalized data and fitted signals for the first 40 ns, represented by solid blue dots and solid red lines. It can be observed that the intensity consistency of the two channels has been significantly improved, and the data from channel 1 match the fitted signal very well. However, the data from channel 2 not only experience significant jitter near the peak, but also have a poorer consistency with the fitted signal compared to channel 1, resulting in a lower ENOB. Figure 5(a6,b6) show the normalized power spectrum information. The top three frequencies and power information with the strongest power are marked in the figures. It can be observed that the strongest frequency component in both channels is 100 MHz, which is consistent with the detection signal frequency (which is the main frequency), and the second strongest frequencies are both 300 MHz. The mutual power difference of 100 MHz in both channels is 0.0263 dB and is \(-\)0.38 dB for 300 MHz, and the differences are all small. The main difference lies in the power of the third strongest frequency, with a difference of \(-\)4.74 dB. Except for the main frequency, the lower the power of the other frequencies, the smaller the nonlinear distortion, indicating a relatively large distortion in channel 2. In addition, the blue solid horizontal line in the figure indicates the average peak value of the noise base, which is about \(-\)73 dB and \(-\)67 dB, respectively, indicating that the noise in channel 2 is relatively large.