Data Transmission Technology Research Of The Joint In The Wireless MWD System

MWD and LWD technology has assumed an increasingly important role in thedrilling industry, as technology evolves, more and more devices sensor is installedclose to the location of the drill in order to obtain a more comprehensive andaccuratethe downhole data on a drill string is attached to the short section of a varietyof functions, and a short section of drill pipe in turn separated open, so that thetransmission of data into a technical difficulty. Relative to the high cost of cabletransmission, easy to wear and tear and other shortcomings, the wireless transmissionis the focus of current research. How to achieve due to the special environment ofhigh temperature and high pressure underground, choose what way to the wirelesstransmission, data transmission has become the focus of study and discussion in thispaper.First, the paper have a brief introduction of several commonly which used athome and abroad with measurement-while-drilling, comparison of the advantages anddisadvantages of the various methods of measurement, the application of the principleof electromagnetic induction to achieve wireless data transmission technologyresearch.Secondly, Learning Theory through electromagnetic induction, electromagneticinduction signal transmission principle, the establishment of signal couplingequivalent model of the signal transmission characteristics, according to the law of themagnetization of the magnetic material and the loss characteristics of the ferritemagnetic material is selected asthe coil core of the transmission system, and in orderto achieve optimum transmission effect, so that the coil within the desired frequencyband having a maximum sensitivity and signal-to-noise ratio, the transceiver coildesign suitable for the transmission system Again, the study of the signal modulation and demodulation principle, themodulation and demodulation of the FSK signal is selected by comparing threecommon modulation and demodulation, a detailed description of the basic principlesof FSK, signal modulation and demodulation,method, in order to reach the circuit issimple and practical, the use of dedicated modulation chip XR2206FSK modulation,and apply the corresponding demodulator chip XR2211achieved through theamplification and filtering of the signal after demodulation.Finally, the use of the Systemview the modulation and demodulation simulation,Multisim circuit simulation. Through the analysis of simulation results prove thefeasibility of the system theoretically, followed by a ground simulation test,Validtransmission data can be obtained within a short distance.