## 4 Results and Discussion
### Analysis of Multiple Stations  
In this section, to expand data coverage, we analyze additional three typical intense L-band SRB events. For each event, seven stations close to the subsolar point are selected. Table 5 lists the detailed information for each SRB event, including the period when the SRB occurred, the RSTN stations, the time of the peak of flux density, the IGS stations and the solar incident angle. Due to the incompleteness of the RSTN and IGS data, it is impossible to guarantee that the flux density data for different events are from the same RSTN station and that all seven stations are the stations closest to the subsolar point. For each SRB event, the valley period common to at least \(N_{station}\) stations is judged as the final detection result. In addition, for each station, we take the value \(N_{sat}\) = 3 from the optimization in Section 4.1. Figure 6 presents the results corresponding to different values of \(N_{station}\) for GPS. In addition to the time when the SRB occurred, the period detected in this experiment includes normal conditions. We can effectively test the false alarm rate based on the 2589 samples in the range of 0-100 SFU. Generally, the number of samples gradually decreases with increasing solar radio flow. The range of \(\geq\)10 kSFU is not further divided, as a flux density of more than 10 kSFU is quite easy to be detected. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Date**} & \multirow{2}{*}{**Period**} & \multirow{2}{*}{
\begin{tabular}{c} **RSTN** \\ **Station** \\ \end{tabular} } & \multirow{2}{*}{**Peak Time**} & \multicolumn{6}{c}{**IGS Station ID and Solar Incident Angle/(\({}^{\circ}\))**} \\ \cline{4-9}  & & & & & & & & & \\ \hline
06.12.06 & 12:11–20:24 & \begin{tabular}{c} Sagamore- \\ Hill \\ \end{tabular} & 19:30 & ISPA: 83.5 & \begin{tabular}{c} AREQ- \\ 58.3 \\ \end{tabular} & \begin{tabular}{c} BOGT: \\ 50.6 \\ \end{tabular} & \begin{tabular}{c} MDO1: \\ 37.6 \\ \end{tabular} & \begin{tabular}{c} CHPI: \\ 34.8 \\ \end{tabular} & \
\begin{tabular}{c} CRO1: \\ 34.5 \\ \end{tabular} &
\begin{tabular}{c} KOUR: \\ 32.3 \\ \end{tabular} \\
13.12.06 & 00:00–10:00 & Learmonth & 03:30 & 77.1 & 76.3 & 66.6 & 68.5 & 52.4 & 38.0 & 36.0 \\
15.02.11 & 02:04–10:45 & Learmonth & 03:00 & \begin{tabular}{c} PIMO: \\ 75.8 \\ \end{tabular} & \begin{tabular}{c} GUAM: \\ 80.0 \\ \end{tabular} & \begin{tabular}{c} USUD: \\ 72.6 \\ \end{tabular} & \begin{tabular}{c} TXRB: \\ 72.2 \\ \end{tabular} & \begin{tabular}{c} DARW: \\ 59.0 \\ \end{tabular} & \
\begin{tabular}{c} KUMN: \\ 58.8 \\ \end{tabular} &
\begin{tabular}{c} TOUW2: \\ 50.4 \\ \end{tabular} \\
24.09.11 & 11:00–22:00 & \begin{tabular}{c} Sagamore- \\ Hill \\ \end{tabular} & 13:00 & \begin{tabular}{c} RABT: \\ 56.2 \\ \end{tabular} & \begin{tabular}{c} MAS1: \\ 63.0 \\ \end{tabular} & \begin{tabular}{c} CHPI: \\ 63.0 \\ \end{tabular} & \begin{tabular}{c} SFER: \\ 53.4 \\ \end{tabular} & \
\begin{tabular}{c} KOUR: \\ 53.2 \\ \end{tabular} &
\begin{tabular}{c} YEBE: \\ 51.7 \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Information on four intense L-band SRBs. The solar radio emission power is obtained from different RSTN stations due to the incompleteness of the RSTN data. With increasing \(N_{station}\), the detection rates of both frequencies gradually decrease and reach approximately 0% in the range of 0.1-1 kSFU, proving that the proposed method has a low false alarm rate and high reliability. Furthermore, the low false alarm rate indicates that the proposed method can avoid the impact of multipath to some extent. In other words, if multipath interference is detected as SRB by mistake, the predicted samples are distributed in each flux range instead of most being in the ranges above 100 SFU. The detection rate at GPS L2 is much higher than that at GPS L1, which is consistent with Figure 5. For GPS L1, there are a small number of flux ranges with a detection rate of 80%.