# Functionality of the Search and Rescue Transponder (SART) in Maritime Search and Rescue Actions
## 2 Materials and Methods

Table 3: Assessment of radar image features. where,  
\(S\)--corrected sweep width;  
\(S_{u}\)--recommended track spacing;  
\(f_{w}\)--weather factor. For a six-person raft, the track spacing of 2.5-6.9 Nm is recommended, depending on the meteorological visibility in the area (3-20 Nm). This applies if the wave height does not exceed 1 m. For wave heights of 1-1.5 m, these figures should be reduced by a weather coefficient of 0.9. If the wave height exceeds 1.5 m, it is recommended to reduce the spacing by a factor of 0.6. This gives a corrected sweep width of 1.5-4.1 Nm (depending on the meteorological visibility in the area in the range of 3-20 Nm). All these guidelines, however, do not take into account the height of the observer's eyes. The size of the vessel and the height of its superstructure determine the position of the observer. On boats, this elevation is about 1-2 m above the sea surface. On small vessels, it is usually 3-10 m. On large vessels, it is even above 50 m. The elevation of the observer's eyes is an important aspect affecting the effectiveness of the search action, according to the authors. Figure 7 shows a plot of the corrected sweep width for two objects: a man overboard (MOB) on the water surface and a six-person raft. The variable factors are the weather factor \(f_{w}\), expressed by wave height in meters, and the visibility range, expressed in nautical miles. The track spacing for searching for a person in the water ranges from 0.4-0.7 Nm for wave heights below 1 m, and from 0.1-0.2 Nm for wave heights above 1.5 m. In this case, more restrictive weather coefficients are applied (0.5 and 0.25, respectively). Spotting a small object, such as a person (usually only part of the body is visible above the water surface, e.g., the head or chest), is typically very difficult for the observer. Therefore, the use of a device to support tracking and locating is crucial, especially in conditions of reduced visibility. Table 4 presents the technical data of the SART device used [23]. \begin{table}
\begin{tabular}{l l l} \hline
**Item** & **Details** & \\ \hline Frequency & 9.2–9.5 GHz & \\ Polarization & Horizontal & \\ Sweep rate & 5 \(\upmu\)s per 2000 MHz nominal & \\ Response signal & 12 sweeps & \\ Form of sweep & Forward & 7.5 \(\upmu\)s \(\pm\) 1 \(\upmu\)s \\ Pulse emission & 100 \(\upmu\)s nominal & \\ Effective Isotropic & & \\ Radiated Power (EIRP) & \textgreater{}400 mW (+26 dBm) & \\ RX sensitivity & Better than \(-\)50 dBm (0.1 mW/m) & \\  & 96 h in stand-by condition followed by a minimum of 8 h & \\ Duration & of transmission while being continuously interrogated & \\  & with a pulse repetition of 1 kHz & \\ Temperature range & Operating: \(-\)20 \({}^{\circ}\)C to +55 \({}^{\circ}\)C & \\ Recovery time & Following excitation 10 \(\upmu\)s or less & \\ Antenna height & Greater or equal to 1 m & \\ Response delay & 0.5 \(\upmu\)s or less & \\ Antenna beam & Vertical: \(\pm\)12.5 degrees & \\  & Azimuth: Omnidirectional to \(\pm\)2 dB & \\ Weight & SART complete: 530 g & \\ Buoyancy & Buoyant & \\ \hline \end{tabular}
\end{table} 
Table 4: Technical specification of SART used for research.