基于三元伪随机编码的冲击夯可控震源控制系统设计

Control system design of mini-SOSIE based on ternary pseudo random coding technique

冲击夯可控震源具有移动方便、质量轻、输出力大等优点,在城市工程勘察以及中浅层地震勘探等领域具有一定的应用前景.其激励信号主要基于二元伪随机编码技术,由于旁瓣效应导致相关干扰严重、地震记录信噪比低等问题,制约了冲击夯震源的推广应用.本文针对传统控制方法的不足,开展了基于三元伪随机的冲击夯可控震源编码技术和编码匹配控制方法研究,并在此基础上设计和实现了相应的控制系统.野外实验结果表明:相比于二元伪随机编码控制方法,三元伪随机编码控制方法得到的地震子波的主旁瓣比提高了4.04 dB;震源信号穿透力强,在测线远端处能量约为30磅锤击震源的100倍,约为二元伪随机方法的4倍;单炮地震记录中干扰抑制能力强,信噪比显著提升,子波频带宽,提高了分辨率,在一定程度上提高了地震勘探效果.

Mini-SOSIE is suitable for city engineering exploration and shallow geological exploration because it is easy to move, light quality and big output force. But its excitation signal is mainly based on binary pseudo random coding technology, and there is serious correlated interference and low SNR （Signal to noise ratio） of seismic data because of the side lobe effect, thus restricted its application. In this paper, a ternary pseudorandom control scheme of mini-SOSIE is proposed to solve these problems, and coding matching control method is analyzed in detail, and based on this we design and implement the control system. The results turn out to be that： compared with BPC-4 and TPC-4, the ratio between main lobe and side lobe, improved by 4.04 dB; the signal penetration is stronger, the energy of ternary pseudorandom method is about 100 times of the hammer, and 4 times of the binary pseudorandom method in the distance; and there is little interference in single shot seismic records, thus improved SNR. The frequency bandwidth of seismic wavelet is wider, and improved resolution, consequently improves the effect of seismic exploration.