伪随机信号电法仪的抗干扰参数

The instruments for electrical and electromagnetic prospecting using pseudo random signal have tried to Improve anti-interference ability for geting the earth frequency response or/and time response by means of correlation processing——to calculate the auto-correlation R_II(t) and cross-correlation R_IU(t) of the input signal (strength of supply current I(t)) and output signal (potential difference ΔU(t)). Previous research by the authers suggests that just in the condition of the offset time is litter than the bit width of the pseudo random signal, especially at the zero offset time, the function value of auto-correlation R_{I, I}(t) and cross-correlation R_{I, U}(t) are large, it has strong anti-interference ability; and when the offset time great than the bit width, the function value of auto-correlation R_{I, I}(t) and cross-correlation R_{I, U}(t) are very small, susceptible to interference and distortion. The anti-jamming capability of the "pseudo random correlation identification", which using the correlation function value of the whole cycle, to get the earth frequency response or/and time response, is clearly not ideal. In the condition of high electromagnetic interference or low SNR, can't get reliable data of earth frequency response or/and time response. Based on above-mentioned condition, this paper proposes to use only the function value of auto-correlation R_{I, I}(0) and cross-correlation R_{I, U}(0) at the zero offset time, to obtain conductive and IP parameters with high anti-interference performance. The concrete algorithm of these parameters and some simulation and field observation data, which proved actual anti-jamming ability of these parameters are given in this paper.