The Research On Signal Receiving Key Technology Of Through-the-earch Communication Based On Elastic Waves

In recent years, domestic and foreign scientists have been working to explore and research wireless communication system which is suitable for through-the-earth channels. Wireless communication system using high-frequency electromagnetic waves has big signal attenuation intensity, strong electromagnetic interference and transmitted power. In this paper, a modern signal detection technology based on the perfect characteristics of low-frequency elastic waves coupling with medium of the earth is adopted to discuss the related technologies of through-the-earth communications to improve receiver sensitivity.This paper is mainly composed of the following three parts:RAKE receiver related algorithm research, elastic wave signal detection algorithm research and the receiver hardware circuit and software design.Because of the inhomogeneity of the earth strata and the impact of topography, the received signal amplitude is affected by the multi-path effects and loss of absorption, the quality of through-the-earth communication system will be greatly lowered. In order to solve the receiving multi-path delay signals, time diversity of RAKE receiver technology and maximum ratio method for receiving signal merger are applied during multi-path diversity receiver design for through-the-earth communication system based on elastic wave, and simulation study is carried out about the anti-fading performance of multi-path diversity.In the research of elastic wave signal detection algorithm, a method based on adaptive wavelet analysis and segmentation threshold processing of the channel noise removal methods is suggested to overcome the effect of noise, which is produced by multi-path effect, reflection losses, absorption and scattering loss and loss of piezoelectric during the elastic wave in the transmission underground. The method helps to realize extraction and recovery of weak signal of elastic wave from the multi-path channel, and simulation study is carried out about wavelet de-noising effects of the elastic wave.The receiving scheme to the through-the-earth communication based on elastic wave introduced in this paper and the experimental methods of through-the-earth communication in the elastic wave test platform provides some experience for the follow-up of elastic waves through-the-earth communication system.