Improvement The Electromagnetic Compatibility Of Transient Electromagnetic Method Transmitter

Time domain electromagnetic methods, or which called transient electromagnetic methods (TEM), are some kind of electrical discrepancy based on target. It utilizes re-line untouched to ground or re-line touched to ground to transmit once pulse magnetic field toward the underground. In the period of the first field's intermission, measures the induced electromagnetic field (the second field) changed with time which is created by underground substance. So it can measure the position of underground inhomogeneous substance and estimate its scale and electricity capability. This method can be applied in mineral resources exploration. But in working circumstance exiting strong radiation noise, the detecting depth markedly reduced. So we bring forward to make strong field source TEM instrument system to increase the detecting depth. The strong field source TEM instrument system uses a key technologies (large power switch) to suppress noise, improves incept signal-to-noise ratio and increase the detecting depth.The strong field source TEM system suppresses noise by means of increasing eradiate field, while to increase eradiate field is hard, and it will bring boundary phenomenon. The sensitivity of the instrument increase with the eradiate electric current, but the bigger the electric current is, the poorer the improvement of the sensitivity is. So it is necessary to search for other methods to enhance the detection depth. The main performance index of transient electromagnetic transmitter is the electromagnetic compatibility and the stability. Enhance the electromagnetic compatibility and the stability of the TEM transmitter, may enhance the detection depth of the instrument with the same eradiate field. In view of the character of the signal, the paper puts forward the electromagnetic compatibility technology to improve the detection depth of the TEM instrument. The main content of the paper is improvement the electromagnetic compatibility of transient electromagnetic method transmitter.Improvement the electromagnetic compatibility of transient electromagnetic method transmitter main contains three parts, interferential analysis, conductive restrain and radiant restrain.The key technology of design is to ensure the interferential source. The analysis part is to analyze the interferential reasons when work for a long time and high power. Make use of EMSCAN system to measure electromagnetic information of PCB, catch the instant interference and confirm the interferential source. Interferential analysis contains the frequency scan, space scan and frequency/space scan. The main function of frequency scan is to estimate the range of interferential frequency and make sure the frequency points with strong interference. The main function of the space scan is to scan the electromagnetism and make sure the interferential source. The main function of the frequency/space scan is to examine radiation within the all frequency; combine frequency information and space interference to detail analyze the reasons of interference.The conductive restrain is based on conductive theory, complete from selecting devices, routing, filtering and so on, in order to restrain conductive interference. Use complex programmable logic device to replace dual in-line package, in order to eliminate bottom interference. Restrain differential mode radiation and reduce influence to each other, reduce return current of signals at the same time. The filer is to deal with noise of the current and noise of the voltage, assure circuit and device to reliable work.The radiant restrain is based on analytic theory of the differential mode and the common mode radiation, finish grounding, polygon and shield to restrain radiant interference. Grounding is the main technology to restrain noise, remove noise voltage when current is flow through the common ground. The polygon and shield are to depress ground impedance and reduce impulse current in digital circuit.Finally, shows the performance test and experiment results. It includes performance index and frequency experiment. The performance test includes frequency scan, space scan and frequency/space scan and so on. The frequency experiment includes scan results, analyze of experiment results and error. The results indicate that the equipment has the good stability and the usability. The paper is completes analyzing of electromagnetism interference, researching of key technology, circuit design and the construction design of transmitter with EMC, validate the feasibility of utilizing EMC to improve detection.