Processing And Realizing With DSP Technology Of Measurement While Drilling Mud Signal

In the process of drilling, Measurement While Drilling measures the geological androck physical parameters of stratum, basically have resistivity, radioactive, acoustic waveand nuclear magnetism. Limited by drilling conditions, it’s difficult to transmit signalbetween ground and down-hole by wire, wireless transmission style is used in practice. Inthe wireless measurement while drilling telemetry, the transmission style of signal mainlyhas the follow2kinds: Electromagnetic Wave and Mud Pulse. At present, the mud pulsesignal transmission is the most common and most widely applied in the wirelesstransmission.while the mud pulse transmission includes the positive pulse, the negativepulse and the continuous wave. The underground instruments modulate the measuredmessages, and transfer them to the ground with the form of the mud pulse. Then the groundsystems receive the signal by sampling with the pressure sensor, filter and detect andidentify the signal, and finally the systems get the underground measured information.In the process of transferring signals, due to pump noise and mechanical vibration noisein channel have serious effect on signal transmission and identification. The model ofwireless communication by mud pulse and the characteristics of noise were analyzed in thispaper. And then the FIR filter, linear filtering method, nonlinear filtering method,multi-scale analysis method and the adaptive filter were applied to the sampled mud signalprocessing. Considering the characteristics of the noise, the combined use of FIR filter andadaptive filter has obvious effect in the real time processing after comprehensivecomparison of various methods.The technology of DSP is being applied to much field, such as communicationtechnology, electronics technology, computer technology and signal processing, etc. Thereis very important significance to improve the Measurement While Drilling System. In this paper we used TMS320VC5509A DSP to process the signals, and at the same time a C#upper interface software had been designed. With the software, we can identify and decodethe signals which were filtered by DSP and then display the well bottom parametersinformation real time. Test results show that the research is expected to the target.