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