# Detection of Quasi-Static Trapped Human Being Using Mono-Static UWB Life-Detection Radar
## 3 Experimental Results
### Experimental Results for Scanning Operating Mode
#### 3.2.2 The Type-II Experiment  
To study the influence of the angle between people and radar on the observation results, we designed the type-II experiment including three measurements of A, B and C, which were carried out in our institute's stadium. The experimental setup is shown in Figure 12, and the two radars were placed on the same side of a 37 cm brick wall, 1.8 m apart. In the measurement A, the person under test stays still and breathes normally, standing 22 m behind the wall and at the center of the horizontal line of the two radars. Define the center of the horizontal line of the two radars as the center of the system. The center of the system and the subject are on the same horizontal line, so the angle between people and  
Figure 11: The summarization of the type-I experiment. (**a**) The detection errors of No.1 radar. (**b**) The detection errors of No.2 radar  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & & & & & & & & & \\ \multirow{2}{*}{**Measurement**} & \multirow{2}{*}{ \begin{tabular}{c} **The Actual Distance** \\ **between No. 1 Radar** \\ **and Target** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **The Actual Distance** \\ **between No. 2 Radar** \\ **and Target** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **FFT*-Based** \\ **Respiration** \\ **Detection Method** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Measuring Error** \\ **of Table Method** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Scanning Operating** \\ **of Table Method** \\ \end{tabular}  } & \multirow{2}{*}{\ \begin{tabular}{c} **Scanning Operating** \\ **of Table Method** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Measuring Error** \\ **of Table Method** \\ \end{tabular}  } \\
**No. ** & & & & & & & & & & \\ \multirow{2}{*}{\ \begin{tabular}{c} 1 \\ 2 \\ 3 \\ 4 \\ 5 \\ 6 \\ 7 \\ 8 \\ 9 \\ 10 \\ 11 \\ 22 \\ 27 \\ 13 \\ 14 \\ 15 \\ 33 \\ 16 \\ 16 \\ 17 \\ 37 \\ 18 \\ 19 \\ 41 \\ 41 \\ 20 \\ 20 \\ 21 \\ 22 \\ 23 \\ 24 \\ 24 \\ \end{tabular}  } & \multirow{2}{*}{
\begin{tabular}{c} **No. 1** & **No. 2** & **No. 1** & **No. 2** & **No. 1** & **No. 2** \\ **of Table Radar** & **Radar** & **Radar** &  
radars is 0\({}^{\circ}\). The \"scanning operating mode\" is used to detect the vital signal, combining the data from two radars. Figure 13a,b shows the output range-frequency images of the normal FFT-based respiration detection methods using the echoes from a single radar. Due to the low SNR in this experimental scene, the output range-frequency images are too noisy to distinguish the vital sign feature (VSF). Figure 12: The type-II experimental setup. Figure 13: The experiment A result. (**a,b**) The output range-frequency images using the normal FFT-based respiration detection methods using the echoes from a single radar. (**c**) The output two-dimensional (2D) slice (range \(\times\) range) image for the specific respiration frequency. (**d**) The positioning result calculated by the radar system is compared with the actual position of the person. According to our proposed \"scanning operating mode\", the cross-correlated range \(\times\) range two-dimensional (2D) image is shown in Figure 13c, and the VSF is remarkable. In Figure 13d, the positioning result calculated by the radar system is compared with the actual position of the person. The red circle represents the actual position of the person, the blue \(\times\) represents the estimated location through the \"scanning operating mode\" and the positioning error is 46 cm. In the measurement B, the tested person with static state and normal breathing stands 22 m behind the wall and moves horizontally to the left by 3 m. The angle between people and radars is 7.84\({}^{\circ}\). Figure 14a,b shows the output range-frequency images of the normal FFT-based respiration detection methods using the echoes from a single radar. Similarly, they are too noisy to distinguish the VSF.