Force Balanced Medium Period Uniaxial Seismometer
Model SP-400-U

The SP-400-U instrument is designed as versatile, very rugged medium period seismic sensor. Unlike traditional seismometers, they are based on proprietary electrochemical transducer technology .

This instrument has many advantages over conventional electromechanical sensors. Force-balancing feedback provides for excellent response stability and linearity.

The SP-400-U sensor is offered in two application-dependent versions: a higher clip level SP-400-U/SM, and a reduced noise SP-400-U/RN. Both have the same dynamic range, which is shifted up by approximately 10db toward stronger ground motions in the SM version.

The SP-400-U has an exceptionally rugged design, does not require mass lock, mass centering over temperature changes, or special installation equipment or procedures and stays operational in any installation tilts.

This seismometer provides a low cost of ownership, requiring no maintenance over the life of the instrument. Borehole configurations including inclinometers are optional. Three and five-year extended warranties are available.

  • Horizontal/Vertical
  • Passband 0.06 Hz to 50 Hz,
  • Low Power
  • No Mass Centering or Mass Locks
  • High Sensitivity
  • 142dB Dynamic Range
  • Rugged
  • Maintenance Free
  • Waterproof
  • Force Balanced
  • OBS and Borehole Configurations
Operating principle: Electrochemical motion transducer with force-balancing feedback
Output signals: 1 horizontal or 1 vertical; velocity flat response
Output signal swing: 10 V single-ended; 20 V p-p 40V p-p differential
Dynamic Range: 142 dB
Bandwidth: 0.06 Hz - 50 Hz;
Self-noise: RN -160dB; SM -150dB on the USGS NLNM
Generator constant: Standard: 2000 V/m/s; Opt.: 350 - 20,000 V/m/s
Mass Centering: NONE REQUIRED
Maximum installation tilt Fully operational in any orientation
Mechanical resonance None
Waterproof: Submersible (1m)
Temperature range: Standard: -12 to + 55 C
Others optional
BasicSP-400 Configuration The standard configuration includes mating connector and calibration sheets
Sensitivity Option option -Sxxxxx
(x specifies sensitivity)
Low Power Option option -LP
Recorder Options DR-4000,
Supplies and Accessories Sensor Cable
General Spares None

S Printer Friendly Format For Specifications

Case diameter 137mm
Case height: 238mm
Weight ~6kg
Connector 14-pin circular
Power - Standard 3 - 15 Vdc; 12 Vdc nominal
Supply current Standard: 10 mA; LP version: 3 mA



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