Neural Network Applications, The Seal Of Recognition

As we know, petroleum resource becomes the most vital energy resource in the world today and petroleum detection plays an important role in petroleum exploitation. After over 70 years' development, electric logging as one of the most popular well-logging approaches has become an independent subject. Recent years, induction logging develops rapidly and a series of apparatus are designed and manufactured successfully.Nowadays, only some famous oil companies of the USA and Russia in the world own advanced and commercial induction apparatus and explanation materials while the domestic oil companies depend on importation. The induction well-logging apparatus and explanation materials imported oversea are very expensive. Further more, domestic oil companies are blanked off technically to limit their exploitation oversea because of petroleum competition. Designing and developing induction well-logging apparatus with independent intellectual property rights is an urgent affair. In order to change this situation, COSL (Chinese Oilfield Services Limited) and UESTC(University of Electronic Science and Technology of China) began to work together to develop an original new induction logging apparatus named DFIT (Dual Frequency Induction Tool) which has independent intellectual property. It measures the phase different and the amplitude ratio in the same time.This dissertation mainly expatiates the design of the receiver of DFIT, including channel board and control board. The channel is designed to process the signal received by the receiving coil. For the precision requirement of subsequent processing, the signal is need to be processed. Because the signal received is only several mV in amplitude, it is need to be amplified. What's more, because it is restricted by the sampling frequency and amplitude range of A/D, the signal is multiplied and filtered. It is specially introduced that the magnitude of voltage affects capacitors in the dissertation. As a result the transfer function of filter is affected. It also introduces the design of a stable low band pass filter. The experiment result testifies the feasibility of this design. The whole system can achieve the requests of precision with this design. The main functions of the control board are decoding the commands from CPU, insuring the system works on the scheduling and generating the two local frequency signals. DDS (Direct Digital Frequency Synthesis) has a series of merits, such as high frequency resolution, fast frequency switching and low phase noise. FPGA (Field Programmable Gate Array) is high integrated, reliable and high-speed. Because of the advantages of DDS and FPGA, this design uses DDS to generate the local frequency signals and uses FPGA to accomplish the main functions of the control board. That makes the design more flexible.The experiment result testifies the feasibility of the design.