APPARATUS AND METHOD FOR ADJUSTING THE OUTPUT OF A PLURALITY OF GEOPHONES TO COMPENSATE THE EFFECT OF VARIATIONS IN THE NEAR SURFACE CHARACTER OF THE EARTH

摘要

1495767 Correcting geophone signals MARK PRODUCTS Inc 1 May 1975 18315/75 Heading G1G To compensate for lateral variations in the sound-conducting properties of the weathered earth layer below a geophone array and for individual geophone sensitivity differences the geophone signals produced by background seismic noise are compared with a reference signal, and subsequent signals from any geophone produced by desired seismic energy are subjected to a gain inversely proportional to the amplitude ratio of the respective noise signal to the reference signal. Thus the resulting signals with these gains will have matched amplitudes, enabling them to be composited for attenuating surface wave noise. In the embodiment shown, noise signals from geophone signal amplifiers 12, 13 pass through filters 16a, 18a to conditioning circuits 16, 18 in each of which the averaged, squared signal is formed and sampled. The sample is compared at 20, 21 with the reference signal from generator 23. The amplifier gains are set by the comparators in accordance with the above-mentioned ratios.