Multiple input single output magnetic induction through-the-earth communication for emergency rescue

In order to improve transmission performance and increase transmission distance of magnetic induction through-the-earth communication system, multiple input single output (MISO) magnetic induction through-the-earth communication system was studied. A MISO model was established and KCL equations were built according to Kirchhoff law, so as to get transmitting and receiving power. Path loss of MISO magnetic induction through-the-earth communication system was analyzed. Magnetic induction density of MISO model was researched and signal transmission characteristics of MISO magnetic induction through-the-earth communication system were obtained. The results show that: When transmitting coils have the same current, path loss of MISO model is significantly lower than that of single input single output (SISO) model.The more transmitting coils there are, the smaller the path loss will be. When transmitting power is the same, receiving power is proportional to the number of transmitting coils, and magnetic induction density at receiving end increases with the number of transmitting coils increases. The MISO model can effectively increase transmission distance of magnetic induction through-the-earth communication system. When all transmitting coils have the same current, transmission distance of MISO(1,2) model is about 1.11 times than that of the SISO model, and the transmission distance of MISO(2,2) model is about 1.26 times than that of the SISO model.