## 3 Experimental Setup and Results
### Measurement System
#### 3.1.5 Supervisory Application for PD Monitoring
The performance of the algorithms was evaluated in terms of localization error and optimized values of the path loss exponent in two field-trial scenarios. The least squares algorithm is quite simple and does not optimize the path loss exponent. The proposed algorithm and ratio and search algorithms both optimize the value of path loss exponent within a given range. When seven measurement nodes were used, the comparison of true versus estimated locations between the three algorithms is shown in Table 5.  
Estimated location values shown in Table 5 above are rounded to two decimal places. Comparing the true versus estimated locations, it is evident that all three algorithms estimate the coordinates of the source within reasonable accuracy. For the majority of the locations, the estimated versus the true locations seem reasonably close. A comparison of error calculation and PLE for each position when seven measurement sensors are used is shown in Table 6.  
Table 6 shows the error comparison for each position as well as the optimized value of the PLE. The results show that for the majority of the positions, the proposed algorithm offers better accuracy and lower mean error. An error comparison between the algorithms can be seen in Figure 11, where seven measurement sensors were used. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Source Position** & **LS Error (m)** & **LS PLE** & **R\&S Error (m)** & **R\& PLE** & **Proposed Algorithm Error (m)** & **Proposed Algorithm PLE** \\ \hline Position 1 & \(1.65\) & 2 & \(1.45\) & \(1.65\) & \(1.13\) & \(1.75\) \\ Position 2 & \(1.26\) & 2 & \(1.32\) & \(2.15\) & \(1.57\) & \(2.15\) \\ Position 3 & \(2.70\) & 2 & \(1.38\) & \(3.2\) & \(0.94\) & \(3.45\) \\ Position 4 & \(0.94\) & 2 & \(2.15\) & \(1.50\) & \(3.23\) & \(4.25\) \\ Position 5 & \(2.97\) & 2 & \(3.91\) & \(1.50\) & \(2.81\) & \(1.60\) \\ Position 6 & \(0.78\) & 2 & \(1.95\) & \(2.50\) & \(0.78\) & \(2.05\) \\ Position 7 & \(3.66\) & 2 & \(2.60\) & \(3.20\) & \(1.90\) & \(3.30\) \\ Position 8 & \(2.18\) & 2 & \(2.38\) & \(2.80\) & \(1.45\) & \(2.60\) \\ Position 9 & \(2.34\) & 2 & \(1.37\) & \(2.80\) & \(2.36\) & \(2.75\) \\ Mean Error & \(2.05\) & & \(2.06\) & & \(1.80\) & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Error comparison for seven measurement sensors. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Source Position**} & \multicolumn{2}{c}{**Actual Locations**} & \multicolumn{2}{c}{**LS Estimated Locations**} & \multicolumn{2}{c}{**R\&S Estimated Locations**} & \multicolumn{2}{c}{**Proposed Algorithm Estimated Locations**} \\ \cline{2-9}  & \(\mathbf{X}\) **(m)** & \(\mathbf{Y}\) **(m)** & \(\mathbf{X}\) **(m)** & \(\mathbf{Y}\) **(m)** & \(\mathbf{X}\) **(m)** & \(\mathbf{Y}\) **(m)** & \(\mathbf{X}\) **(m)** & \(\mathbf{Y}\) **(m)** \\ \hline Position 1 & \(13.50\) & \(4.50\) & \(11.88\) & \(4.77\) & \(12. From the above comparison, it is evident that the proposed algorithm offers the least error when compared with the other algorithms and that the path loss exponent estimation accuracy has also improved for nearly all positions. Performance Evaluation of the Proposed Algorithm in Terms of Localization Error and PLE Optimization When Eight Measurement Sensors were Used  
To evaluate the performance of the proposed algorithm further, a node is added in the receiving system, and this time eight measurement sensors are used. A comparison between the estimated and true locations has been made and error is computed for each position as well as the optimized PLE. When eight measurement sensors are used, the comparison between the true and estimated locations for each algorithm is shown in Table 7.  
Table 7 results are based on eight receiving nodes. With the addition of a single node to the receiving system, the source location estimations have improved for the majority of positions for the ratio and search and the proposed algorithms. A comparison of error calculation and PLE for each position when eight measurement sensors are used is shown in Table 8.