## 3 Experimental Results, Verification, and Discussion
Overall, through the PLM and normalization processing, the signal peak jitter and inconsistent power between the two channels can be reduced. Moreover, the nonlinear distortion and noise of the signals collected from channel 2 are relatively large. Figure 6 shows the signals from the direct synthesis and shift synthesis of the two channels' data. Figure 6(a1) shows the signal synthesized directly within the first 40 ns of the two channels, and a significant intensity non-uniformity can be observed. Figure 6(a2) shows the result of the two channel signals being synthesized after the PLM and normalization processing, and it can be observed that their intensity non-uniformity has been significantly improved. Figure 6(a3) depicts the fitted signal according to the data in Figure 6(a2) by the main frequency of 100 MHz. The solid blue dots represent the directly synthesized data, and the solid red lines represent the fitted signal. It can be found that the collected data do not match the fitted signal very well, and the calculated ENOB is only \(-\)0.1051 bits. Figure 6(a4) illuminates the power spectrum information of the directly synthesized signal. The top four frequencies and corresponding power information with the strongest power are marked in the figure. Among them, 100 MHz and 5.1 GHz have the highest power, and the difference in power is not significant, so there will be two main frequencies. The next ones with higher power are 4.9 GHz and 300 MHz, so the nonlinear distortion of the directly synthesized signal is significant. In addition, it can be observed that the average peak value of the noise base is approximately \(-\)70 dB, which is the average value of the peaks of the noise base of the two channels. The result of synthesizing the data of channel 1 and that of channel 2 after shifting forward by 12 positions is shown in Figure 6(b1). It can be clearly seen from the time domain that it is a 100 MHz signal, and its ENOB is calculated to be 4.0136 bits. Compared with Figure 6(a1), it further verifies the effectiveness of using shift synthesis to recover the signal to be tested. Figure 6(b2) presents the synthesized result of the two channel signals being processed by the PLM and normalization, and then shifted. By comparison, it can be found that the processed signal has fewer peak spikes and smoother curves. Based on our calculation, its ENOB  
reached 4.5668 bits, which is significantly higher than that in Figure 6(b1). The signal quality has been significantly improved, further verifying the effectiveness of the PLM and normalization, which will be directly used in the subsequent signal processing. Figure 6(b3) shows the shift synthesized signal and corresponding fitted signal after applying the PLM and normalization processing, and it can be found that the processed data match the fitted signal very well. Figure 6(b4) shows the power spectrum information of the normalized shift synthesized signal. It can be observed that the Nyquist frequency has changed from a single channel 2.6 GHz to a dual channel synthesized 5.2 GHz. The figure indicates the top four frequencies with the strongest power and corresponding power information, with the highest power being the 100 MHz frequency, which is 36.66 dB higher than the three other frequencies, meaning there is only one main frequency. Therefore, the nonlinear distortion of the shift synthesized signal is small and can effectively recover the testing signal. In addition, the average peak noise level of the synthesized signal is also about \(-\)70 dB, which is related to the noise of the two channels. Figure 7 depicts the results of the PADC system collecting two channel signals at 200 MHz and synthesizing them directly and after the shift correction. Figure 7(a1,b1) display 35 K of raw data collected by two channels of EADCs. Overall, the signal peak jitter collected by channel 2 is relatively large.