Two-stage Long-correlation Signal Acquisition Method for Through-the-earth Communication of the Ground Electrode Current Field
Wireless through-the-earth communication provides a solution for information transmission in heavily shielded space.The received current field signal has low Signal-to-Noise Ratio(SNR),is easily distorted,and is greatly affected by carrier frequency offset,making signal acquisition difficult.In this paper,a long synchronization signal frame structure is designed and a two-stage long correlation signal acquisition algorithm is proposed that combines coarse and fine frequency offset estimation.In the first stage,the training symbols in the received time-domain signal are used for coarse estimation of sampling interval deviation based on the maximum likelihood algorithm,and the coarse estimation value of the sampling point compensation interval is calculated.In the second stage,the coarse estimation value and the received SNR are combined to determine the traversal range of the fine estimation value of the sampling point compensation interval.A long correlation template signal with local compensation is designed to achieve accurate acquisition of the current field signal.The algorithm's performance is verified in a heavily shielded space located 30.26 m below the ground.Experimental results show that compared to traditional sliding correlation algorithms,the proposed algorithm has a higher acquisition success probability.
万方数据
维普
