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GEOPHONE DISTORTION OF SEISMIC PULSES AND ITS COMPENSATION *
Author(s) -
O'BRIEN P. N. S.
Publication year - 1965
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.1965.tb01935.x
Subject(s) - geophone , geology , distortion (music) , galvanometer , attenuation , phase distortion , vertical seismic profile , refraction , seismology , economic geology , acoustics , seismometer , phase (matter) , optics , physics , bandwidth (computing) , metamorphic petrology , telecommunications , engineering , amplifier , laser , quantum mechanics , tectonics
An electronic analogue was used to obtain geophone distortion of typical seismic pulses. Some of the results were checked by computation and in all cases agreement was extremely close. For late arrival events estimates of attenuation and phase shift may be made from the steady‐state response curves. It is explained why these curves are not applicable to the first peak, for which one must use the results in Table III. Ground‐geophone coupling introduces the same distortion as a very lightly damped galvanometer with a natural frequency usually in the range 100c/s—200c/s. In swampy terrain this frequency may reduce to 30c/s—40c/s and coupling effects may be severe. An electronic unit whose characteristics are the inverse of those of a geophone has been used to improve the first peak amplitude of a seismic refraction record. Since 1c/s geophones are often desirable in refraction survey it may well be more economic to use higher frequency geophones followed by their inverse filter.