| 摘要 |
In an apparatus having at least one detection coil (1) for the detection of nuclear magnetic resonance (NMR) from a sensitivity region of the detection coil (1) in the ground, whereby nuclear spins within the sensitivity region are excited by repeated coherent excitation, in each case, to precess in the earth's field and produce a small NMR induction voltage in the detection coil (1) which is introduced to a first amplifier (7), the detection coil (1) consists of at least two oppositely wound partial coils (2, 3) having parallel coil axes which are connected electrically in series and at least one compensation coil (8, 9, 10) is provided for additional compensation of spatially inhomogeneous interfering fields whose induction signal is introduced to a second amplifier (18, 19, 20) having adjustable amplification. In this fashion, in addition to the homogeneous portion, an inhomogeneous portion due to distant disturbances can be eliminated from the measured signal.
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