Research On The Down-hole AMI Manchester Codec System Based On PIC Microcontroller

The main work of this paper is to research the signal transmission of AMIManchester coding technology which applied to the well logging system of void fraction.The purpose is to elevate the transmission rate on a single-core cable by using that codingtechnology. The way that down-hole instrument upload the well logging signal by codingtechnology is widely used. But the well logging system of void fraction use single-corecable as transmission medium for AMI Manchester coding technology is relatively rare. Inresponse to this situation, this paper designs a well logging system of void fraction whichbased on PIC microcontroller.Firstly, this paper designs a configuration diagram of the system by reference to theactual workflow of well logging of Numerical Control. After a comparison of severalcommonly used encoding technologies, we chose AMI Manchester encoding.Secondly, combined with the expected target of the system, the design is divided intodifferent circuit function module based on PIC18F2550, which include the signalamplification processing, the serial signal conversion, the signal A/D conversion, the AMIManchester code generation, and a power connection module, thus completes the circuitdesign of the hardware encoding. Then, the paper introduces the way of writing Assemblyprogram which can control the coded process of the microcontroller.Again, the paper design the corresponding PC software system, which is a run file，developed by the Visual C++6.0tools and Windows MFC class library. At the core ofUSB data acquisition card, the software designs different function, which include thesignal decoding, the estimation of void fraction, the graphic display, the data storage andthe playback function. The purpose is to simplify the hardware design of code circuit bydecoding the encoded data in the software system. And decoding process can be optimizedthrough different programming ideas to improve the signal transmission rate.Finally，in order to test the hardware and software parts of the system the paper buildthe related test platform. By observing the test results, the hardware circuit part of the system achieve to encode the data signal AMI Manchester code and the software partachieve the function of decoding the data and so all. Furthermore, by comparing differentdecoding schemes optimizes the decoding process of PC software. Basically we achievesthe purpose of designed this system.