## 4 EMC Evaluation Method for Communication Receiver
The evaluation results are shown in Tables 1 and 2. The experiment layout for EMC evaluation of BDS is shown in \[P_{e}=Q(\sqrt{4\frac{W_{L}/R}{P_{j}/P_{av}}})=Q(\sqrt{4\frac{W_{L}}{R\times SIR }}) \tag{26}\]0 In this experiment, the SIR is the actual measured value, which is 46.5 dB, and the pulse signal duty cycle is 50%. SIR and pulse signal duty cycle remains unchanged during this experiment. Change the pulse width \(W\), thereby the BER value varies. The experimental results are shown in \[P_{e}=Q(\sqrt{4\frac{W_{L}/R}{P_{j}/P_{av}}})=Q(\sqrt{4\frac{W_{L}}{R\times SIR }}) \tag{26}\]1 It can be read from Table 1 that when no interference is predicted, the number of satellites remains unchanged at 10 satellites. When the predicted interference occurs, the number of satellites gradually decreases, and when the navigation receiver is predicted to stop working, the number of satellites becomes zero. Similarly, keep the SIR of the receiver at 46.5 dB and the pulse width \(W=10\) us, the pulse signal duty cycle is 50%. By changing the repetition period \(T_{PRP}\), the value of BER is affected. The experimental results are shown in \[P_{e}=Q(\sqrt{4\frac{W_{L}/R}{P_{j}/P_{av}}})=Q(\sqrt{4\frac{W_{L}}{R\times SIR }}) \tag{26}\]2 It can be read from Table 2 that when no interference is predicted, the number of satellites remains unchanged at 10 satellites. When the predicted interference occurs, the number of satellites gradually decreases, and when the navigation receiver is predicted to stop working, the number of satellites becomes zero. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**SIR (dB)**} & \multirow{2}{*}{\
\begin{tabular}{c} **Duty** \\ **Cycle** \\ \end{tabular} } & \multirow{2}{*}{\(W\) (us)} & \(\frac{T_{dup}+W}{T_{PRP}}\) & \multirow{2}{*}{**BER**} & \multirow{2}{*}{**Evaluation**} &
\begin{tabular}{c} **Number of** \\ **Satellites** \\ \end{tabular} \\ \hline \multirow{4}{*}{46.5} & \multirow{4}{*}{50\%} & 10 & 0.0015 & 2.03 \(\times\) 10\({}^{-6}\) & No interference & 10 \\  & & 10 & 0.0105 & 1.42 \(\times\) 10\({}^{-5}\) & Interference & 9 \\  & & 100 & 0.1005 & 1.36 \(\times\) 10\({}^{-4}\) & Interference & 7 \\  & & 500 & 0.5005 & 6.76 \(\times\) 10\({}^{-4}\) & Interference & 5 \\  & & 1000 & 1 & 1.35 \(\times\) 10\({}^{-3}\) & Stop working & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: EMC evaluation experiment results of BDS when changing pulse width. Figure 15: Experiment layout for EMC evaluation of BDS. It can be seen that in this experiment, the interference phenomenon of the BDS receiver is accurately evaluated by estimating the BER of the receiver. When the evaluation result is \"no interference\", the measured number of satellites is 10, indicating that there is no obvious interference. When the evaluation result is \"interference\", the number of measured satellites decreases significantly, and the higher the BER, the fewer the number of measured satellites, and the more apparent the interference phenomenon. When the evaluation result is \"stop working\", the upper computer displays that the number of satellites is zero, and the BDS receiver stops working. Through experimental verification, the evaluation results are in good agreement with the measured interference phenomenon of BDS receiver, which verifies the effectiveness of the evaluation method proposed in this paper.