1.Digital fidelity While the response of geophones is damped below their natural frequency and distorted above their spurious frequency,MEMS sensors offer linear and flat amplitude and phase responses from DC to 800 Hz in the acceleration domain.Their specifications are not affected by temperature,ageing or manufacturing tolerances,making the signal recorded accurate in phase and amplitude on the entire seismic bandwidth of interest.The preservation of amplitudes has been recognised for amplitude versus offset applications.The coil-free design makes the sensor insensitive to electromagnetic noise,and the sensor distortion is much lower than that of geophones.It has been 20 years since digital seismic sensors based on microelectromechanical systems(MEMS) accelerometers were launched,replacing analogue.Here are five drivers behind the migration from analogue to digital technology.By Nicolas Tellier,chief geophysicist,Sercel.
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