This paper presents the design, development and tests of a prototype of a seismograph system for seismic studies applied to engineering, hydrogeology and environmental problems. The system is based on the in board electronic of an IBM-PC type microcomputer. Piezoelectric accelerometers, as well as the amplifiers and filters were specially designed to be used in seismography. The interfacing with the microcomputer is accomplished by an A/D (analog to digital) converter board. The acquisition velocity to record high frequencies was obtained by using the DMA (direct memory access) available in the microcomputer. Control software was developed to allow the use of the DMA and to simulate the normal functions of a standard digital seismograph. In laboratory tests the accelerometers showed a linear behavior (± 0.5 dB, between 10 Hz and 2000 Hz), and the amplifiers and filters exhibit the same linearity between 20 Hz and 1000 Hz. Field tests have shown the system to be operational. Thus, the system proposed and developed is feasible, relatively cheap, and suitable for the objectives of seismic work applied to engineering, hydrogeology and environmental problems. It is also suggested that the same architecture can be used in other geophysical instruments.
