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LE-3D/5s Seismometer Sensor
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This instrument is the runner-up in terms of popularity - it provides flat velocity response down to 5 seconds while still preserving basic fieldworthy qualities such as ruggedness and portability.  After its introduction in late 1990, it quickly gained acceptance among those requiring a little bit of extra low frequency response.

LE-3D/5s is the sensor of choice for a wide variety of field and observatory tasks - being still portable, it will allow you to go places where a broadband sensor just won't do the job.  If space and weight constraints prevail, LE-3D/5s will help you meet them.  It is not only the dimensions and weight of the sensor proper that count - do not forget to take power requirements into account.  In this department, the LE-3D/5s leaves broadband seismometers in the dust.  At only 100mW, LE-3D/5s won't require its own truck battery even for a long-term deployment.  As an example, a 20 Ah battery (which is still easily handled) will last up to 100 days!

But do not believe that this noteworthy power consciousness will incur a significant performance penalty - the noise level of this sensor (approx. 1 nm/s RMS at 1 Hz) is such that it can be used in most low-noise sites without problems.

Most of the salient points in favor of the 1 Hz seismometers are equally applicable here:

  • Compact and lightweight
  • Rugged
  • Sheer simplicity; true plug-and play operation
  • All sensors calibrated to identical output voltages; no need to keep records of which sensor has been connected to which datalogger
  • Low noise, low power (typically 3 mA per component @ 12 V DC)
  • Dynamic range > 120 dB
  • Comparatively insensitive to improper leveling
  • No mass lock, mass center, control box, or other contraption required; can be transported in any orientation
  • Proven long-term stability; well over ten years of field experience
Technical Details
  LE-3D/5s
Power Supply 10...16V DC, unstabilised
Power Consumption approx. 10mA @ 12 V DC
Output Voltage 400 V/m/s, precisely adjusted
Damping 0.707 critical (internal damping; independent of datalogger input resistance)
Dimensions 195 mm diameter
165 mm height
Weight, including 1.5 m cable and Cannon KPT connector) 6.5 kg
Temperature range -15...+35C
Optional temperature range (specify when ordering) 0...+50C
Housing Painted aluminum, splash proof, with level adjustment feet and water bubble level control
Eigenfrequency 0.2 Hz
Upper corner frequency > 40 Hz
RMS noise at 1 Hz < 1 nm/s