# Timing Performance Testing and Regularity Analysis of eLoran System
## 4 Testing and Analysis
### Receiver Signal Source: Long-Wave Signal from Analogue Source
#### 4.1.4 Ability of Receiver 2 to Accurately Measure 1 PPS Source  
To further explore the actual timing accuracy of the domestic receiver, a long-wave analogue source was used to generate signals from each station to measure the 1 PPS accuracy of Receiver 2. The test results are presented in Tables 4-6. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Receiver** & **Station** &
\begin{tabular}{c} **Receiver Field** \\ **Strength (dB\(\upmu\)V/m)** \\ \end{tabular} & **Receiver SNR (db)** \\ \hline  & 8390M & 3.72 & –2.56 \\
1 & 8390X & 8.28 & 2.65 \\  & 8390Y & 7.20 & 2.16 \\  & 8390M & 18.6 & –9.75 \\
2 & 8390X & 18.9 & –5.08 \\  & 8390M & 3.72 & –2.56 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Indicators for each receiver after an analogue source origination time difference. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Analogue Source Signal** & \ \begin{tabular}{c} **Maximum Value of** \\ **Tining Deviation (ns)** \\ \end{tabular}  & \begin{tabular}{c} **Minimum Value of** \\ **Timing Deviation (ns)** \\ \end{tabular}  & **Timing Accuracy (ns)** & **Timing Stability (ns)** \\ \hline
118 & 1018.9 & 768.9 & 865.5 & 60.3 \\
114 & 938.8 & 698.4 & 777.5 & 49.9 \\
100 & 936.9 & 636.3 & 754.3 & 54.2 \\
90 & 1143.2 & 861.9 & 995.1 & 57.9 \\
80 & 1142  
Figure 7 indicates that the timing accuracy and stability of the domestic receiver at the source stations were generally consistent, with the timing stability fluctuations being within hundreds of nanoseconds. The difference in accuracy between the two tests remained stable for 30 ns. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Station** & **Difference in Accuracy between** & **Difference in Stability between** \\  & **Two Tests (ns)** & **Two Tests (ns)** \\ \hline
6000M & –26.8 & \(\pm\)13.1 \\
6780M & –17.5 & \(\pm\)9.8 \\
7430M & 11.1 & \(\pm\)15.7 \\
8390M & 2.8 & \(\pm\)24.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of the accuracy of two 1 PPS measurements (analogue sources). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Station** & **Timing Accuracy (ns)** & **Timing Stability (ns)** \\ \hline
8390M & 890.8 & 72.7 \\
7430M & 837.3 & 92.7 \\
6780M & 849.5 & 88.6 \\
6000M & 889.7 & 103.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Receiver 2’s 1 PPS measurement accuracy (first time for analogue sources). Figure 7: Receiver 2’s 1 PPS output measurement (analogue source). A comprehensive comparison of the actual test results and the simulation results shows that they are basically the same. Specifically, the actual results are slightly higher in some cases, which may be caused by the fact that certain environmental factors and disturbances were not fully considered in the simulation. As indicated in Figure 8 and Tables 7-9, we analysed in detail the reasons that the eLoran receiver has basically the same timing accuracy in the morning, midday, and evening time slots and found that the following factors may play a role:  
1. Signal stability: the eLoran system has high signal stability and an anti-interference capability, which enables it to maintain consistent timing accuracy in different time periods. 2. Environmental conditions: although there may be variations in environmental interference from one time period to the next, the overall environment at the receiver's location is relatively stable, with no significant changes in signal propagation paths or conditions, so timing accuracy remains consistent. 3. Equipment performance: eLoran receivers are equipped with high-performance equipment and antennas that can effectively capture and process signals to maintain high timing accuracy even in different time periods. For both tested receivers, the test site environments were the same, but Receiver 1 outperformed Receiver 2 in terms of timing accuracy and stability. This may be caused by the fact that Receiver 1 may be equipped with higher performance antennas and boards that are able to capture and process eLoran signals more efficiently.