Design Of Underground Coal Mine Broadcasting System Based On CAN Bus

The voice broadcasting system of coal mine has the functions of directing daily production activities and early warning and emergency communication in coal mine disaster period.Daily production activities include regular broadcasting,safety publicity,music broadcasting,guidance of coal mine production operations,equipment installation and other functions.The real time,reliability and received quality of voice transmission are important factors for the safety and reliability of broadcast system.Aiming at the influence of the adverse electromagnetic interference and noise environment on the audio transmission function of the mine broadcasting system,it is of great significance to study the safety and reliability of the mine broadcasting system and the method of speech enhancement.The main research contents of this paper are two-channel CAN design and noise power density(PSD)estimation.The underground broadcasting system of coal mine is composed of two layers of equipment: the audio server of the upper computer on the ground,the broadcasting master station and the broadcasting terminal.Ethernet and dual-channel CAN bus network transmission mode are adopted,and the ground and underground equipment realize data transmission through the mutual conversion of CAN bus and Ethernet protocol.When the downhole cable transmission cable fails,the single point failure failure mode of CAN bus leads to the communication failure between downhole node and ground.The hardware design of underground mine broadcasting system is based on ARM,which includes peripheral circuits such as the local safety power module,dual-channel CAN bus module,audio acquisition module circuit,etc.Based on the hardware platform of embedded Linux system,the dual-channel CAN module,audio acquisition module and CAN sleep wake software are designed.According to the characteristics of non-stationary noise,low SNR,single channel characteristic and poor quality of received speech,a noise PSD estimation algorithm based on statistical model was proposed to restore the purespeech information.Through MATLAB simulation,the tracking delay time,itakura-saito(IS)speech distortion measurement,accuracy and other evaluation indexes of other algorithms were compared,and the PSD estimation of statistical model noise was verified to be more suitable for underground coal mine noise.PSD estimation algorithm based on statistical model noise was applied to MMSE-LSA speech enhancement algorithm with prior information.MATLAB simulation analysis and comparison of speech enhancement performance of other algorithms.The reliability of dual-channel CAN bus design is verified by systematic test on the real-time performance and bus load rate of the broadcasting system in coal mine.Simulation verifies that the statistical model noise PSD estimation algorithm is more suitable for the non-stationary noise environment with low SNR,which can effectively improve the accuracy of the voice signal in the broadcasting system of coal mine.