Identification, Based On The Inverse Repeat M Sequence Ground System

Skip method and frequency method are the traditional methods in earth-electricity system identification, whose main aim is finding pulse response and frequency response. But earth-electricity system identification has a low precision and a weak anti-jamming capability. Now the pseudo-random correlation identification is widely used. In this paper, by pointing out the deficiency in the observation means of frequency electromagnetic method and the specialities of frequency-varying method and 2" -series pseudorandom signal, and primarily by analyzing the wave-form characters, correlation function and spectrum specialities of invert-repeated m-sequence in detail, the pseudorandom correlation identification theory is introduced and the principle of parameters design which influences the measurement precision and the prospecting resolution is discussed. Then several methods suppressing interference are discussed, the earth-electricity system identification based on invert-repeated m-sequence pseudorandom signal (IRmPRBS) is designed, and accordingly pseudorandom signal electromagnetic method found on IRmPRBS is put forward. So, it is proved that properly selecting the parameters which include the length of sequence, clock frequency, and so on, for the generation of IRmPRBS, can resultes in a better interference suppressing and a higher resolution in earth-electricity system identification than before.In addition, based on pseudorandom correlation identification theory a multifunctional electrical method transmitter is designed. In this design, by using IRmPRBS as the transmitte signal a signal generation unit is designed on CPLD device LC4256V-100T. In order to realize the synchronization between the transmitter and the receiver, a GPS module is joined into the transmitter, relating to the hardware architecture and the software flow based on 80c51. Using this transmitter we can carry through many prospecting methods including SIP, multi-frequency CSAMT, resistance method, TDIP, FDIP, TEM, CSEM, and so on. The dense frequency design can effectively enhance the resolution to all sorts of objectives.