The SP400 Medium period sensor is designed as a versatile, rugged, extended band short period active seismic sensor. They consume very low power and are packaged in compact, lightweight heavy-duty PVC cases.
Unlike traditional short period seismometers, they are based on proprietary electrochemical transducer technology MET. These transducers have many advantages over conventional electromechanical sensors. All three sensors in the SP400 are equipped with a force-balancing feedback and its noise is reduced by an additional 10dB.
The SP400 sensors are offered in two application-dependent versions: a higher clip level SP400SM, and a reduced noise SP400RN. Both have the same dynamic range, which is shifted by approximately 10db up toward stronger ground motions in the SM version.