可控震源的伪随机扫描与系统测试

Pseudorandom sweeping and system testing for seismic vibrator

为满足地震信号分辨率和信噪比的要求,针对地震勘探用可控震源的特点,对伪随机编码扫描方式进行了研究。讨论了二元伪随机扫描工作方式的特点,并提出了三元伪随机扫描工作方式。研究了伪随机码的原理,给出了伪随机码的生成方法,利用得到的伪随机码设计了实际应用的伪随机码序列。将所研制的三元伪随机编码扫描信号发生器嵌入到电磁驱动可控震源上,并进行了实际测试,测试结果显示调制频率对最终的相关结果有很大影响。对得到的自相关函数的分析表明,采用三元伪随机编码扫描方式得到的信噪比比采用二元伪随机编码扫描方式提高了9%,得到了适用于地震勘探的伪随机编码扫描信号。

To improve the resolution and Signal to Noise Ratio（SNR） of seismic signals, the sweeping mode of pseudo-random code of a seismic vibrator was investigated. The sweeping mode of binary pseudo-random code was discussed, then a new sweeping mode for ternary pseudo-random code was presented. The principle of the pseudo-random code was researched and how to generate the pseudo- random code was given. Based on the obtained pseudo-random code, a pseudo-random code sequence was designed for practical applications. Furthermore, a signal generator of ternary sweeping for the pseudo-random code was embedded into the vibrator, and tested results show that modulation fre quency has significant effects on the final self-correlation results. Analysis results on self-correlation function indicate that the SNR obtained from the sweeping mode of ternary pseudo-random code has been improved by 9% as compared with that of the sweeping mode of binary pseudo-random code, which means that obtained sweeping signals are suitable for the seismic exploration.