# Communication System Based on Magnetic Coils for Underwater Vehicles
## 6 Conclusions  
In the present work, a communication system based on magnetic coils of rectangular geometry was opened and implemented, and the electronic circuits necessary to transmit data of a serial communication protocol through water were designed. Several transmission tests were carried out while modifying the water temperature, varying the salinity concentration, and adding impurities such as cardboard, plastic, glass, and clay in different concentrations, and it was concluded that the aquatic environment does not present additional difficulties for data transmission. The proposed system has advantages over acoustic technology since it does not lose information due to the multipath effect, it is easier to identify the emitter, it is cheaper to implement, and it reaches higher data transmission speeds. It has advantages over systems based on radio frequency since it is not affected by the salinity level of the water, it uses less energy, and the dimensions of the transmitter and receiver coils are smaller, achieving greater versatility. The proposed system using magnetic fields is better than optical systems, because it is not affected by the turbidity of the water and can operate in water with different concentrations of clay. The proposed system has some advantages with respect to similar works (presented in Section 1.4): The communication system presented in [19] uses up to 7 A to power the emitter system, while our system is capable of operating with only 75 mA, achieving greater  
Figure 13: Data transmission in water with submarine. autonomy. It transmits information at higher speeds in the range of 9.6 kb/s to 115.2 kb/s compared to 21.64 kb/s or less reported in [20; 21]. Building the transmitter and receiver module is cheaper because it is made up of simpler components. Therefore, the proposed system can be consider as a viable option to be used in underwater vehicles for a wide range of applications in data transmission such as transferring information between a vehicle and an underwater station, accurate spacial localization, tracking trajectories, exploration and mapping of the seabed, induction of voltage to another vehicle to recharge its batteries, etc. In future work, we will try to use the data obtained with the underwater vehicle to carry out a mapping mission automatically, that is, use the transmitter system to send position and orientation data to the underwater vehicle, modify the programming so that these data are converted in reference signals, and make the robot know its position and manage to follow a programmed route. In order for the robot to move without a remote operator, it is essential to apply an automatic control law to control orientation and depth simultaneously and use artificial vision to be able to move faster towards the coverage area of the transmitter magnetic coil and avoid obstacles that could potentially damage or obstruct the path of the underwater vehicle. Hardware, data processing, investigation, and manuscript writing: G.C.-G.; conceptualization and visualization: [PERSON]-[PERSON] and N.J.-[PERSON]: writing--review, project coordination, and supervision: [PERSON]N., [PERSON]-Y. and R.S.N.-C. All authors have read and agreed to the published version of the manuscript. The construction of the underwater vehicle was partially financed by the Programa para el Desarrollo Professional Docente (PRODEP) number UPTLGO-PTC-081 and Programa de Emprendimiento e Innovacion para el Desarrollo de Prototiops (PROHINNOVA). Not applicable. Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. The results of the system design and the basic code of this work are available from the corresponding author on reasonable request. [PERSON] gives thanks to the Consejo Nacional de Ciencia y Tecnologia (CONACyT) with no. CVU 933175, [PERSON] gives thanks to the Consejo Nacional de Ciencia y Tecnologia (CONACyT) with no. CVU 933187, [PERSON] gives thanks to the Consejo Nacional de Ciencia y Tecnologia (CONACyT) with no. CVU 1000127.