The Circuit Design Of The Multi-frequency Transmitter And Receiver System Of An Array Induction Logging Tool

Oil is a kind of important strategic resource,while logging technology is one of thehighest-tech sectors.Due to the use of the advancing digital processing method andprooviding a lot of data,it becomes more and more important.what important is the designof multi-frequency transmitter and receiver system circuit.Firstly, this paper introduces the background,significance and the theory of arrayinduction logging.it introduces the development status of array induction logging,the theoryof dual coil induction logging,the theory of three-coil induction logging,the struction ofcoil and the transmitted waveform.By verifying the three step-wave signal’s Fourierexpansion, we show that the three step-wave signal contains all harmonics besides the 3octave.And by it,we clear the direction of design.Then,we design the hardware and software of multi-frequency transmitter andreceiver circuit.The transmitter circuit consists of amplitude amplification circuit,shapingcircuit,power amplification circuit and switching circuit.It builds the three step-wave signalto drive transmitter coil.The receiver consists of the primary and secondary amplification,low-pass filter, voltage follower, and the AD conversion circuit.It can receive smallmillivolt signal.In addition,we design the Blackfin 592 DSP system and softwareprogramming,according to the functional requirements of the circuit.Subsequently, using the Lab VIEW tools we simulate the character of multi-frequencytransmitter and receiver.At the free noise, the characteristic of transmitting and receiving ofthe three step-wave signal which is composited by eight term harmonics are simulated.What have done illustrates that the even harmonic is closer to the ideal three step-wavesignal than the odd one in transmitter wave. The receiver wave is not the three step-wave,but it has some important peak features to obtain fundamental frequency of the three step-wave signal. The characteristic of transmitting and receiving is simulated when it has30%’s Random Gauss white noise. It validates that the ability of detecting the weak signalcan be improved and the random noise can be removed by the stack technology and Fouriertransform.Finally,we degug the transmitter and receiver circuit,and test the whole circuit.Theactual results and simulation resultsare similar.It verifys the reasonableness of thedesign.What we do provide a kind of new array induction tool model and have importantparctical significance.