## 4 Effect Evaluation of Electromagnetic Environment on Equipment
### Effects Mechanism Methods
#### 4.2.2 Evaluation Models  
Figure 7 demonstrates the research process of the evaluation models based on the effect mechanism method. In the first stage, we only tackled the essential effect evaluation issues, such as the intermodulation and non-intermodulation blocking effects, separately. However, with the deepening of the research process, we are encountering or will encounter new interference effects in the second stage. Therefore, we need to construct models to solve the new problems of effect evaluation. In our current research, we have established more than one model to solve various effect evaluation problems. However, some of the equipment may have multiple effects. In this case, using different effect evaluation models on the same equipment will lead to inconsistency in the evaluation results and a cumbersome evaluation. We should simplify the evaluation models in the following studies. In other words, we expect to obtain a new model involving more interference effects, such as multi-frequency interference, intermodulation interference, and noise interference. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Test Equipment**} & \multirow{2}{*}{**Sensitivity Criteria**} & \multicolumn{2}{c}{**Interference Signal**} & \multicolumn{2}{c}{**Test Method**} & \multirow{2}{*}{**Error**} \\ \cline{3-4} \cline{6-7}  & & **Single-Frequency** & & & **Injection** & **Radiation** & \\  & & **Continuous Wave** & & & **Method** & **Method** & \\ \hline Voice & & & & & & \\ communication & & & & & & \\ radio [69] & Work-break level & \(\surd\) & - & - & \(\surd\) & \(<\)1 dB \\ \hline Digital & & & & & & \\ communication & & & & & & \\ radio [69] & Bit Error Rate of 10\% & \(\surd\) & - & \(\surd\) & - & \(<\)1 dB \\ \hline Digital & & & & & & \\ communication & & & & & & \\ radio [70] & The relationship between & & & & & \\ communication & & & & & & \\ radio [70] & & repetition & & & & \\ \hline Radar [71] & Peak echo level & \(\surd\) & - & - & \(\surd\) & - \\  & compression & & & & & \\ \hline Radar [72] & Effective jamming & & & & & \\ probability of 40–60\% & \(\surd\) & - & - & \(\surd\) & \(<\)1 dB \\ \hline Navigation & & & & & & \\ receiver [73] & CNR of 30 dB-Hz & \(\surd\) & - & \(\surd\) & - & - \\ \hline Navigation & & & & & & \\ receiver [74] & Loss of positioning & & & & & \\ receiver [74] & within 4 s and lasts 30 s & \(\surd\) & - & - & \(\surd\) & - \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The sensitivity criterion research on equipment. Based on previous studies, a large amount of research has been carried out in recent years. [PERSON] et al. [75] found that the blocking interference phenomena of radio stations can be divided into two categories through the electromagnetic environmental effects experiment. Based on the third-order power series expansion analysis, they built two different effects evaluation models: the RMS (Root Mean Square) sensitive model and the peak-level sensitive model. They did so by analyzing the blocking interference mechanisms of equipment radio frequencies. They accurately evaluated the effect of in-band blocking interference of communication stations. According to the literature [75], [PERSON] et al. [76] mainly assessed the effects of out-of-band blocking interference from radio stations. They found that the effect evaluation models of in-band blocking interference are also applicable to out-of-band blocking interference, which indicates that the non-intermodulation interference mechanism of out-of-band is the same as that of in-band. However, a completely different phenomenon was found in the out-of-band interference in the electromagnetic environmental effect test. Researchers confirmed that it belongs to intermodulation interference through experiments and theoretical analysis. Subsequently, they built the second-order [77] and third-order [78] intermodulation effect evaluation models, respectively. The reliability of their models is verified, and their mechanism is also illustrated.