Extending a Lippmann style seismometer's dynamic range by using a non-linear feedback circuit

Abstract

A Lippmann style seismometer (Lippmann and Gebrande, 1983) uses a single-coil velocity-feedback method in order to extend toward lower frequencies a geophone's frequency response. Strong seismic signals may saturate the electronics, sometimes clipping the signal or producing the characteristic whale-shaped recording. Adding a non linear feedback in the electronic circuit may avoid saturation, allowing the strong-motion use of the seismometer without affecting the usual performance. Such a seismometer will allow unsaturated data in epicentral area while offering nice low signal recording for far events.