Design of a high-order FIR digital filtering and variable gain ranging seismic data acquisition system

A new approach to designing an embedded microcomputer seismic data acquisition system to record high-quality seismic data is discussed. The seismic signal is sampled at a rate 10 times higher than the desired rate to avoid aliasing. The noise in the digitized seismic signal is filtered by a high-order finite impulse response (FIR) digital filter implemented in the microcomputer system. During filtering, excess samples are decimated to yield the required sampling rate. To avoid saturation, variable gain amplifiers (VGAs) were deployed in the design. A 16-b high-resolution analog-to-digital (A/D) converter helps to achieve a large dynamic range (120 dB) of the system and reduce the number of VGA gain ranges. Both computer simulation and experimental results confirm the validity of the design