基于逆重复m序列的地电系统相关辨识

【作者】 李飞；

【导师】 汤井田；

【作者基本信息】 中南大学 ， 地球探测与信息技术， 2007， 硕士

【摘要】 阶跃法和频率法是辨识地电系统脉冲响应和频率特性的传统方法，但精度差、抗干扰能力弱。伪随机相关辨识已在众多领域得到广泛应用。本论文针对目前频率域电磁法观测方案的不足，分析了变频法和2~n系列伪随机电磁法的技术特点，较详细地分析了逆重复m序列的波形特征、相关函数及频谱特性；介绍了伪随机相关辨识系统原理，讨论了影响测量精度与勘探分辨率的参数设计原则；讨论了对各种干扰的压制方法，并设计了基于逆重复m序列的地电辨识系统，提出了基于相关辨识的逆重复m序列伪随机信号电磁法。逆重复m序列伪随机信号具有与白噪声类似的相关函数，在频带内，频谱等间距均匀分布。理论证明，合理地选择产生逆重复m序列的几个参数可以很好地压制各种干扰，高精度地辨识大地系统。本论文还进行一个多功能电法发送机的设计，主要是基于伪随机相关辨识原理，用逆重复m序列伪随机信号作为场源信号，基于CPLD开发设计了信号发生单元；加入了GPS同步模块，设计了基于80c51的硬件结构和软件流程，用来实现发送机和接收机的同步。发送机能开展多种物探方法，如多频SIP、多频CSAMT、电阻率法、TDIP、FDIP、TEM、CSEM等，真正达到多功能。密频比设计可有效地提高对目标体的分辨力。更多还原

【Abstract】 Skip method and frequency method are the traditional methods in earth-electricity system identification, whose main aim is finding pulse response and frequency response. But earth-electricity system identification has a low precision and a weak anti-jamming capability. Now the pseudo-random correlation identification is widely used. In this paper, by pointing out the deficiency in the observation means of frequency electromagnetic method and the specialities of frequency-varying method and 2" -series pseudorandom signal, and primarily by analyzing the wave-form characters, correlation function and spectrum specialities of invert-repeated m-sequence in detail, the pseudorandom correlation identification theory is introduced and the principle of parameters design which influences the measurement precision and the prospecting resolution is discussed. Then several methods suppressing interference are discussed, the earth-electricity system identification based on invert-repeated m-sequence pseudorandom signal (IRmPRBS) is designed, and accordingly pseudorandom signal electromagnetic method found on IRmPRBS is put forward. So, it is proved that properly selecting the parameters which include the length of sequence, clock frequency, and so on, for the generation of IRmPRBS, can resultes in a better interference suppressing and a higher resolution in earth-electricity system identification than before.In addition, based on pseudorandom correlation identification theory a multifunctional electrical method transmitter is designed. In this design, by using IRmPRBS as the transmitte signal a signal generation unit is designed on CPLD device LC4256V-100T. In order to realize the synchronization between the transmitter and the receiver, a GPS module is joined into the transmitter, relating to the hardware architecture and the software flow based on 80c51. Using this transmitter we can carry through many prospecting methods including SIP, multi-frequency CSAMT, resistance method, TDIP, FDIP, TEM, CSEM, and so on. The dense frequency design can effectively enhance the resolution to all sorts of objectives.更多还原