Experimental Research on a Pipeline Through-wall Communication System Based on Extremely Low Frequency

The traditional fixed-point operation robot of natural gas pipeline uses cable as the medium to realise the throughwall communication. However, with the increase of working distance, problems such as increasing cable weight or friction force with the pipeline wall will prevent the work from continuing and have a high potential risk. In order to solve this problem, this paper puts forward an overall design of the through-wall communication using the extremely low-frequency (ELF) electromagnetic wave with strong penetration ability. Firstly, a model of the solenoid transmitting coil is established using the Maxwell finite element simulation module to simulate the distribution of the extremely lowfrequency electromagnetic field. Then, the influence of different factors such as environment and medium on magnetic field intensity are analysed. With STM32F405 as the main control chip and AD9959 as the transmitting signal source, the hardware circuit of the communication system is built. At the same time, an experimental test of the ELF communication system is carried out and the experimental results show that the designed through-wall communication system can achieve good communication inside and outside the tube. The communication distance along the radial direction of the tube can reach 140 cm, which can meet the communication needs of fixed-point operation of the robot in the tube.