Study On Multifunction Electromagnetic Transmitter

Since 1950s, a great amount of work has been done from theory to practice in the field of electrical prospecting. Good result has been achieved in search for metal mine and groundwater, also in exploring engineering geology and oil gas. Its theory and instrument are improved and innovated continally, the precision and effect of the geological interpretation are improved continuously. To design a transmitter that has multiple functions and can be used in different probing field is becomes more important. Basing on the conventional transient electromagnetic transmitter and combining the technology of direct digital synthesizer, the control system of the multi-function electromagnetic transmitter was designed, and the tests were performed in this paper. This paper includes the following works:①By studying the development condition of the electromagnetic transmitter at home and abroad, analyzing the constitution principle and modular circuit of the control system of the transmitter, combining the existing design idea of the electromagnetic transmitter, a new design idea of the multi-function electromagnetic transmitter is developed: To adopt CPLD and singlechip as the controll core and external circuits include real-time clock circuit, memory circuit, LCD display circuit, communication circuit, drive circuit, testing circuit and so on. The PCB was made and the tests were performed.②On account of almost transient electromagnetic transmitter has only a few of frequency points, divided frequency technology and direct digital frequency synthesis technology are used in this paper to produce muliti frequency points, the fundamental frequency is from TCXO that the precision is±3ppm, by whose transmitter can produce many frequency points from 0.0625 to 69500Hz, and some dutyfactor can be regulated. By programming with VHDL and simulating with QuartusⅡ7.2, this design idea is supported by the experiments.③The IGBT driver circuit of main circuit is designed. To avoid vibration of driving signal near the set value, the clamped constant pressure controlling switch drivered circuit is inproved,and Schmidt circuit is used , by this, the controlling switch malfunction is decreased.④The control program flowchart of electromagnetic transmitter has been drawn. The program include monitor program and function program. The monitor program is composed of keyboard program, alarm program, interrupt program and so on. The function program is composed of LED display program, EEPROM stored program, communication program and data acquisition and handle program.