# LR-MPIBS: A LoRa-Based Maritime Position-Indicating Beacon System
## 4 Conclusions  
This paper describes in detail the design of a LoRa-based position-indicating beacon system with the objectives of rapid alarm, low power consumption, stable communication, and high reliability. The main results can be summarized as follows. 1. The design principles and methods of the falling water detection module are detailed, and the reliability of the circuit operation was tested. The FWD module can automatically detect and trigger startup after 3 s of falling into the water. Its current consumption during equipment shutdown is 10.1 mA, and its current consumption during water detection is less than 90 mA. 2. We analyzed the impact of the LoRa RF path impedance value on communication performance, and designed it to be 50 \(\Omega\) through software simulation. The LoRa wireless communication protocol was designed, which includes the rescue protocol of PIT and the response protocol of SMBS. This aims to achieve reliable communication between personnel in distress and rescue teams. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Institute** & **This Work** & **GD Panco Co, Ltd.** & **XING TU Co, Ltd.** & **Dalian Scientific** & **XIDIAN** & **NUC [3]** \\ \hline Communication/Positioning & LoRa/BDS & RSMC/BDS & RSMC/BDS & LoRa/BDS & AIS/GPS & GPRS/GPS \\ Methods & & & & & & \\ Startup Time For Man & 3 s & 5 s & 5 s & \textgreater{}60 s & - & 4–5 s \\ Overband Detection & & & & & & \\ RNNS Cold Start & 50 s\(\leq\) & 60 s\(\leq\) & 40 s\(\leq\) & - & 27 s\(\leq\) & 60 s\(\leq\) \\ Positioning Error & 10 m\(\leq\) & 5 m\(\leq\) & 5 m\(\leq\) & 10 m\(\leq\) & 10 m\(\leq\) & 10 m\(\leq\) \\ Rescue Information & & 30 s & 60 s & 60 s & 60 s & 300 s \\ Communication & & & & & & \\ Distance & \(\geq\)5 Km & & The Coverage Area Of BDS & \(\geq\)3 Km & \(\geq\)9 km & - \\ Communication & & & & & & \\ Success Rate & \(\geq\)89\% & \(\geq\)95\% & \(\geq\)95\% & - & - & \(\geq\)98\% \\ Key Information & & & & & & \\ Extraction & & & & & & \\ Of Drift Trajectory & & & & & & \\ Endurance & \(\geq\)25 H & \(\geq\)30 H & \(\geq\)17 H & - & \(\geq\)48 H & \(\geq\)8 H \\ Volume (mm) & 87 \(\times\) 60 \(\times\) 22 & 101 \(\times\) 62 \(\times\) 25 & 95 \(\times\) 59 \(\times\) 23 & - & - \\ ADDR & & Guangdong, China & Nanjing, China & Dalian, China & Xi’an, China & Shanxi, China \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Performance comparison of LR-MPIBS with MPIBS from existing products and research institutions. 3. The interference of power-supply ripple on RF was analyzed, along with the instabilities in the power-supply voltage caused by the sudden change in current during RF communication. In this study, we designed a power management module that can withstand a maximum transient current of 1 A, and its output voltage ripple is below 45 mV. 4. We designed positioning data processing algorithms, including those for verifying the effectiveness of positioning data, extracting key positioning data, and compressing key positioning data. The recognition rate of key positioning data was 97.67% and its compression rate was 50%. 5. The experimental results show that the system can automatically detect and sound the alarm for personnel drowning incidents. After the PIT is turned on, the search time for satellites does not exceed 50 s, the effective communication distance is no less than 5 km, and the battery life is 25 h during continuous operation. The experimental results are stable and reproducible. The marine comprehensive testing results of LR-MPIBS further demonstrate its practicality in the rescue process. Conceptualization, Z.L. and J.D. ; data curation, Z.L. and J.D. ; formal analysis, Z.L. and L.D. ; funding acquisition, Z.L. and L.D. ; investigation, Z.L. and J.D. ; methodology, Z.L., J.D. and L.D. ; project administration, Z.L. ; resources, Z.L. ; software, Z.L., J.D. and N.S. ; supervision, Z.L. and L.D. ; validation, Z.L., J.D. and Y.L. ; visualization, Z.L. and J.D. ; writing--original draft, Z.L. and J.D. ; writing--review and editing, Z.L. and J.D.