The Development For Broadband Frequency_domain EMI Digital System Based On DSK6713

With the accelerated development of global industry and rapid increment of population , geological disasters are becoming severer , the safety of large-scale construction more important and the environment pollution induced by rejectamenta emission as well as extra exploitation of water resource more exacerbated . The problems of engineering and environment are so widely focused that people begin to attach importance to the detection of geologic surface . In all survey methods , the broadband EMI detection working in 100-100kHz can obtain underground information from several meters to tens of meters , which cover the depth range concern by those problems . There're a series of instruments , such as GEM-2 detector from Geophex corporation in USA, NaoTEM from Zonge corporation and so on . However, the domestic EMI detectors are just on the commencement .We can get multi-frequency results through transmitting multi-frequency EM waves on the same time meanwhile the subterranean information of different deepness is obtained according to the relationship between frequency and depth so that the steps of EMI survey is simplified . The digital system of broadband frequency domain EMI detector is discussed in this paper.The basic principle and the design of digital system based on the requirement of theory are described in this paper. The precision of collected datas and the speed of realtime data-processing are the main characteristic of this system . 24-bit A/D CS5360 , whose sample rate is 48kHz, is adopted in order to promote the datas' precision and DSP TMS320C6713 , which is a float digital signal processor, is adopted for the sake of computing In-phase and Quadrature of primary signals and secondary signals and then getting the value of PPM .One key to this system is the design of data acquisition circuit . The datas collected by A/D5360 are carried into C6713 through Multi-channel Buffered Serial Port. An external analog circuit which is a full-differential input buffer circuit with an inverted-amp is required . Furthermore , the settings of McBSP registers are based on the timing sequences of A/D and the format of left-channel data as well as right-channel data.Another key to this system is realtime data-processing which is based on lock-in amplification detection technique . In the lock-in detection full period...