## 6 Validation in Real PR Trials
### PR Trials Results
The following targets were checked by video ground truth (Figure 17a):  
* **Moving away** from nearer to further from the PR: a car probably out of the main beam, two vehicles at range bins about \(\sim\)150 and \(\sim\)200 and \(f_{D}\sim-1700\) Hz (Figure 17b) and another set of 2 cars, one of which appears at range bin \(\sim\)300 and \(f_{D}\simeq-1300\) Hz;
* **Approaching:** A concrete truck, at range bin \(\sim\)330 and \(f_{D}\simeq 1100\) Hz, followed by a car that is not appreciated in the RD map. Table 3 summarizes the quantitative results, in terms of probability of detection \(P_{D}\) and maximum detected range bin, for acquisition in scenario 2. Target T1 has a high probability of detection (95.71%) up to maximum range bin 305, when acquisition finished, which translates into a distance of 510 m relative to the PR. The maximum detected range corresponds to target T2 which is detected at a maximum distance of 615 m from the PR. The \(P_{D}\) of targets T2-T4 is lower, probably because they are masked in several points, due to the geometry of the area of interest, by target T1, which is nearer at the start of the acquisition. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Parabolic Dish**} & \multicolumn{3}{c}{**Reflectarray**} \\ \cline{2-7}
**Direction** & **Target** & \(P_{D}\) & \begin{tabular}{c} **Max.** \\ **Range** \\ \end{tabular} & **Target** & \(P_{D}\) & \begin{tabular}{c} **Max.** \\ **Range** \\ \end{tabular} \\ \hline Moving away & Car & 59.72\% & 144 & \begin{tabular}{c} Car (T1) \\ \end{tabular} & 82.67\% & 151 \\ \cline{3-7}  & & & \begin{tabular}{c} Car (T3) \\ \end{tabular} & 100\% & 86 \\ \hline Approaching & Bus & 79.75\% & 166 & \
\begin{tabular}{c} Car (T2) \\ \end{tabular} & 68\% & 102 \\ \cline{3-7}  & & &
\begin{tabular}{c} Car (T4) \\ \end{tabular} & 83.3\% & 112 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Probability of detection of targets in scenario 1 employing the designed reflectarray and a parabolic dish as surveillance antenna. T1–T4 refers to the tracks represented in Figure 18a. Figure 16: Cumulative RD maxima from results of trials in scenario 1 employing the designed reflectarray and commercial parabolic dish antenna in the surveillance channel. Accumulated detection matrices generated from the 75 CPIs for both scenario trials are presented in Figure 18 with the estimated tracks and the associated detections in black, the false alarms in grey. For scenario 1, the GPS ground truth for both targets is also represented. In both cases, the number of generated target tracks equals the number of vehicles in the area of interest. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Direction**} & \multicolumn{3}{c}{**Reflectarray**} \\ \cline{2-4}  & **Target** & \(\mathbf{P_{D}}\) & **Max. Range [bin]** \\ \hline \multirow{4}{*}{Moving away} & Car (T1) & 95.71\% & 305 \\ \cline{2-4}  & Car (T2) & 52.46\% & 369 \\ \cline{2-4}  & Car (T3) & 66.67\% & 348 \\ \cline{2-4}  & Car (T4) & 75\% & 267 \\ \hline Approaching & Concrete truck (T5) & 65.12\% & 335 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Probability of detection of targets in scenario 2 employing the designed reflectarray as surveillance antenna. T1–T5 refers to the tracks represented in Figure 18b. Figure 17: Video ground truth of an instant of the measurement in scenario 2, its corresponding RD map and the cumulative of RD maxima.