Research On Anti-interference Modulation Method Of Multi-point Ectopic Emergency Seismic Wave Communication

In recent years,the frequent occurrence of mine accidents at home and abroad has brought great loss of life and property to the country and people.The effectiveness of mine rescue operations depends on what the ground command knows about the men trapped underground.However,mine accidents will lead to the destruction of conventional communication facilities.The rescue workers cannot know the location of underground trapped miners and casualties.They can only use drilling,drilling,wire rope to pass paper and other ways to rescue and communication.However,drilling holes into the ground is somewhat blind,and the method of passing paper is relatively inefficient,greatly delaying the progress of the rescue.Therefore,it is urgent to study a safe and reliable mine emergency communication technology,which is of great significance for ensuring the life safety of trapped miners and improving the speed and effect of mine accident emergency treatment.In fact,seismic wave has good carrier characteristics in earth channel.In order to meet the needs of mine emergency communication,this paper tries to study the electromagnetic vibrator seismic wave as the means of communication.Mine tunnels are located hundreds to thousands of meters underground,so the seismic wave communication distance needs to be longer than the mine depth.Due to the collapse and collapse of underground mines,the construction of rescue site vehicles and some other noise interference,the surface received emergency communication information will be weak,so it is necessary to study the seismic wave anti-jamming detection technology.Due to the complex distribution of underground tunnels,the distress signals sent by trapped miners in different positions are random,concurrent and asynchronous.This scenario is defined as "multi-point ectopic seismic wave communication".For small mines in the early stage of construction,only a single roadway needs to communicate with the surface,which is defined as "single point seismic wave communication".The crosstalk problem of multiple sources communicating at the same time is not considered in the existing seismic wave communication technologies.Therefore,it is necessary to study the source control methods and multi-point ectopic communication anti-interference methods.In order to solve the above problems existing in seismic wave communication,this paper combined with the characteristics of electromagnetic vibrator to stimulate seismic waves,carried out research from three aspects,including the improvement of anti-interference detection ability of single point communication,the design of new modulation and demodulation methods,and support for multi-point ectopic communication,and combined with numerical simulation and field experiments,proved the effectiveness and feasibility of the proposed method.The main contents are as follows:Aiming at the problem of short transmission distance of existing seismic wave communication,a single point seismic wave communication anti-interference detection method based on Short-Time Fourier Transform(STFT)is proposed from the perspective of seismic signal detection at the receiving end.In order to carry out seismic wave communication experiment,a high-speed seismic wave data acquisition system based on Compact RIO is designed.Finally,field experiment results show that the detection method can increase the communication distance of seismic wave by 50% compared with the conventional method under the interference of strong ambient noise.Combined with the difference of correlation between seismic wave Signal and environmental noise,this paper studied from the perspective of source transmitted signal design,proposed the anti-interference time-frequency slice modulation method of single point seismic wave communication based on the Vibrator Control Signal(VCS),and designed a source coding controller capable of generating time-slice modulated signals.Considering the actual application environment,the numerical simulation is carried out by adding different intensity of environmental noise to the simulation signal.The results show that the proposed method has stronger anti-noise interference ability and lower bit error rate than other seismic wave communication methods.Finally,the experiment of time and frequency slice modulation for single point seismic wave communication is carried out,and the experimental results further prove the feasibility of the proposed method.Aiming at the problem of location dispersion of trapped absenteeism during the accident,by referring to the idea of multi-source parallel excitation technology,a multi-point ectopic seismic wave communication method based on the Anti-interference Time-frequency Slice Modulating On-Off Keying(ATSM-OOK)is proposed.The results of numerical simulation and field experiment show that the different modulation signals designed by ATSM-OOK method are independent and do not interfere with each other,which solves the problem of mutual interference when multiple sources communicate at the same time.Based on the exponential attenuation model of seismic waves,it is estimated that 48 m communication on the surface with a 300 N small source is equivalent to 753 m long distance information transmission underground with a 50 k N source.