针对瞬变电磁信号具有早期幅值大、衰减快,晚期信号微弱、衰减缓慢的特点,设计了高速12位A/D和高分辨率16位A/D分段采集的瞬变电磁接收机,解决了以往单A/D采样速率与动态范围不能同时兼顾,无法同时精确记录瞬变电磁早期信号和晚期信号的问题。接收机具有2个并行的采集通道,最高采样率为1MS/s,并采用了浮点放大技术,使探测的有效信号动态范围达到153dB。
Transient electromagnetic signal is large and quickly attenuates in the early stage, however, it is weak and slowly attenuates in middle and late stage. For the characteristics of transient signal, the transient electromagnetic receiver utilized a 12bit A/D with high speed and 16bit A/D with high resolution to record the transient electromagnetic signal in sequent stage. Double A/Ds technique solves contradiction between high sampling rate and large dynamic range, which is difficult for single A/D. The transient electromagnetic receiver has two parallel sampling channels with the highest sampling rate of 1 MS/s. Floating point amplifying technique was also used to enhance the sampling dynamic range to 153dB.