CAJ | 학술논문

针对近地表频率域电磁探测对发射信号的要求，以直接数字频率合成技术为理论基础，利用单片机与可编程数字逻辑器件FPGA构建硬件控制平台，设计具有通用性的多频信号产生系统，实现单频及多频（双频、三频等）正弦信号的产生。经验证，该方法产生的波形可控性强、谐波失真低、分辨率高，克服了位流法对线圈负载稳定性要求高，伪随机法不能任意设定频率并且THD （总谐波失真）高的缺点。
침대근지표빈솔역전자탐측대발사신호적요구，이직접수자빈솔합성기술위이론기출，이용단편궤여가편정수자라집기건FPGA구건경건공제평태，설계구유통용성적다빈신호산생계통，실현단빈급다빈（쌍빈、삼빈등）정현신호적산생。경험증，해방법산생적파형가공성강、해파실진저、분변솔고，극복료위류법대선권부재은정성요구고，위수궤법불능임의설정빈솔병차THD （총해파실진）고적결점。
In this paper, in order to meet the requirements of the transmitting signal in shallow surface FEM do-main, based on the DDS theory, using single-chip microcomputer and programmable logic device as the hardware control platform, the universal multi-frequency signal generating system is realized. A single frequency, multi-fre-quency (dual-band, tri-band) sine signal can be produced in this system. The experiment results show that, wave-forms produced in this way have good quality, pure frequency spectrum and high resolution. Some other methods’ defects can be overcome, such as the high requirement of stream method to the stability of coil load and the pseu-do-random method which cannot arbitrarily set the frequency and the higher THD (total harmonic distortion) . Theoretical simulation and experimental results verify the effectiveness of the method.