# LR-MPIBS: A LoRa-Based Maritime Position-Indicating Beacon System
###### Abstract  
Human marine activities are becoming increasingly frequent. The adverse marine environment has led to an increase in man overboard incidents, resulting in significant losses of life and property. After a drowning accident, the accurate location information of the drowning victim can help improve the success rate of rescue. In this paper, we explore a LoRa-based Maritime Position-Indicating Beacon System (LR-MPIBS). A low-power drowning detection circuit is designed in LR-MPIBS to detect drowning accidents in a timely manner after a person falls into the water. The instantaneous high current of the LoRa RF can lower the supply voltage and cause other modules to work abnormally. A fast current transient response circuit is proposed to solve the problem. LR-MPIBS includes a power ripple suppression circuit that can reduce the measurement errors and operational abnormalities caused by power ripple interference. We explore the impedance matching law of LoRa RF circuits through simulation experiments to improve the quality of LoRa communication. A data processing algorithm for personnel drift trajectory is proposed to alleviate the challenges caused by the raw positioning data with large deviations and high communication cost. The experimental results show that LR-MPIBS can automatically start and actively alarm within 3 s after a person falls into the water. The positioning cold start time is less than 50 s. The performance of communication distance is more than 5 km. The endurance of LR-MPIBS is 25 h (with a 30 s communication cycle). LoRa-based position-indicating beacon system; automatic detection of falling water; ship operators falling overboard; processing of positioning data for man overboard +
Footnote †: journal: Medicalintegrates On-Off Keying (OOK) technology and interferometer orientation technology [5], with a performance of orientation measurement accuracy within 10 degrees. Interferometer orientation technology was also used by the Royal Navy of the United Kingdom to design the Sea Marshall personnel search and positioning system. The developments based on wireless directional measurement technology have the problem of low measurement accuracy [6; 7], as wireless transmission at sea is subject to interference. With the vigorous development of satellite navigation technology, researchers integrate satellite navigation technology into the research of PIBS [8; 9; 10; 11]. [PERSON] designed a lifesaving terminal based on BeiDou positioning and BeiDou short message technology [12]. During emergency rescue, terminal equipment sends distress messages to nearby ships and coastal bases at regular intervals (1 min to 30 min). This utilizes Beidou short message technology to solve the problem of limited distance in commonly used communication methods, but due to the directional constraints of Beidou antenna communication, the communication success rate is relatively low. [PERSON] designed personal and maritime AIS-EPIRB, which combines AIS technology with satellite navigation technology [13]. This system can send the location information of a drowning person to ships or shore-based facilities equipped with AIS systems within a range of 5 nautical miles. The AIS system has not achieved full coverage of ships at sea, which limits the convenient deployment of the beacon system [14; 15; 16]. [PERSON] designed an automatic alarm system for falling into the sea, which integrates ShockBurst technology and BeiDou navigation technology [17], and provides a falling detection scheme. The system detects man overboard accidents by fusing data from three sensors: an acceleration sensor, a pressure sensor, and a humidity sensor. This method improves the accuracy of accident detection, but sacrifices the operational lifespan of the system. The beacon system designed with satellite navigation technology achieves a positioning accuracy better than 10 m. Nevertheless, the convenience of beacon system deployment and the endurance of the system still have substantial room for improvement.