CMG-3T (120 sec) weak motion broadband seismometer



  The CMG-3T is a compact three-component broadband sensor, suitable for surface vault (observatory), subsurface vault and pesthole installations.

 







  Features


  • True broadband force-feedback instrument
  • overs the complete seismic spectrum with a single transfer function
  • Response from 1 - 360 s to 50 - 200 Hz H (120 s - 50 Hz standard)
  • Tru ly portable with lifting handle and convenient access to connectors
  • High linearity: >107 dB horizontal, llldB vertical (USGS figures)
  • Over 140 dB dynamic range over the entire passband (USGS figure)
  • Cross-axis rejection over 65 dB
  • Sensor axes orthogonal to within 0.1 *
  • Remote electronic mass locking, unlocking and centring
  • Adjustable feet allow for up to 5 . tilt
  • Low power consumption (750 mW from 10 - 30 V input power)
  • CMG-3TD fully digital instrument available, combining the CMG-3T with our low-noise DM24 digitizer in a single package


 

  Specifications

Standard velocity output band

120 s -50 Hz'

Mass position output band

DC - 120 s

Output sensitivity

2 * 1000 V/m/s**
Peak output ±10 V differential
Lowest spurious resonance >  140 Hz (vertical)
Linearity, vertical (USGS) >  111 dB
Linearity, horizontal (USGS) >  107 dB
Cross-axis rejection >62dB

Remote control

Lock, unlock, centre
Operating temperature -20 to+75 °C (-55 °C optional)
Temperature sensitivity < 0.6 V per 10 °C
Mass recentring range ± 2.5 ° from horizontal
Materials Stainless steel case
Mil-spec connector (1500 psi waterproof connector or user connector optional)
Case diameter 168 mm
Case height (with handle) 344 mm

Case height (sensor only)

274 mm

Isolating power supply

10 - 36 V DC
Optional low power sensor 5 V DC supply (output ±4.5 V)
Current at 12 V DC 75 mA
Calibration controls Independent signal & enable lines exposed on sensor connector

Optional low pass corner

50 Hz, 100 Hz or 200 Hz