Although various wired or wireless communication facilities play a significant role in underground mine production monitoring and disaster warning, some communication nodes will be damaged when an accident occurs, resulting in unreliable emergency communications. Due to the excellent transmission characteristics of seismic waves in the earth channel, there is no need for the seismic wave communication system to set up relay nodes. Since seismic waves are not easily disturbed by the external environment, they can be used as a new type of emergency communication carrier to realize information transmission. However, under strong background noise interference in a real environment, the feasibility of seismic wave communication using an electromagnetic vibrator is not yet known. Therefore, a field experiment research on electromagnetic vibrator seismic wave communication was conducted. First, the model of electromagnetic vibrator seismic wave communication was established. In addition, the on–off keying modulation method, the cross-correlation segment threshold demodulation method, and the noise suppression method based on the time–frequency characteristics of the carrier were introduced. Finally, an electromagnetic vibrator seismic wave communication system was built, and binary data communication up to 72 m without deploying additional relay nodes was achieved successfully. The experimental results illustrate the feasibility of the electromagnetic vibrator seismic wave communication under strong background noise interference in a real environment. Furthermore, combined with the characteristics of the seismic wave, the time–frequency slice filtering can significantly improve the signal-to-noise ratio of the seismic wave and can further increase the communication distance with respect to the traditional methods.

This paper points out a critical issue in the study of estimating the azimuth of ground sources by using the polarization characteristics of Rayleigh waves: even if the signal quality is good, the degree of polarization of Rayleigh waves varies across different frequency bands, and the band with the strongest energy is not the one with the lowest azimuth error. A direction of arrival estimation method for ground sources based on optimally polarized Rayleigh waves using a single three-component geophone is presented in this paper. First, the reciprocal ellipse rate, flatness coefficient, and the angle between the semi-minor axes and the horizontal plane are selected as the polarization parameters of this method according to two quantitative principles. Then the frequency band range of the optimal polarization Rayleigh wave is determined by analyzing the sum of the weights of the three polarization parameters in different frequency bands. After filtering and combining with the existing surface wave analysis method, the actual data bearing estimation result with an average error of only 4.95 degrees and a standard deviation of only 1.82 degrees is obtained. It is also found that the signal-to-noise ratio approximates the exponential decay of the direction of arrival error obtained by this method.

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