Downhole Circuit Research Of Multilayered Well Tester Cable

High-speed remote transmission technology occupies an important position in oil well logging systems.High-speed,real-time data transmission is of utmost importance in well logging systems.With the continuous development of science and technology,well logging technology continues to advance,but the research and development of high-efficiency logging cable data transmission system is still a hot field in the field of well logging technology research in recent years.In view of the problems of cable transmission in our country,slow speed,signal attenuation,and serious distortion,this paper is based on the study of remote transmission technology at home and abroad,using ST's high-performance microcontroller(STM32F407)as the microprocessor and orthogonal frequency division multiplexing.(OFDM)technology is the core technology and researches on transmission systems.This dissertation firstly conducts in-depth theoretical research on cable transmission and OFDM technology,and earnestly learns the transmission characteristics of the cable and the key technologies of OFDM technology,which improves a good foundation for the design of the next system.Second,on the basis of theoretical knowledge,the overall design of the system was proposed.Takes OFDM technology as the core,adopts(2,1,3)convolutional code encoding,Viterbi decoding,16 QAM mapping reverse mapping,IFFT/FFT algorithm,and D/A conversion and A/D conversion to realize signal modulation and demodulation.Real-time transmission,while generating channel interference(ICI)due to channel multipath effects,requires insertion of a cyclic prefix.The hardware part is designed by using STM32F407 microprocessor,and some circuits include: power module,clock module,reset module and external interface circuit.Finally,the system is simulated and verified in MATLAB software environment.