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UXO Detection

LE-3D/20s Seismometer Sensor

This is the latest addition to the product line, further boosting low frequency response down to 20 seconds.  For those interested in "classical" regional earthquake seismology, or in the low frequency grumbling of volcanoes, this instruments fills a niche between short period and "real broadband".

While physically identical to LE-3D/5s (except for the different paint color), it is a fundamentally different instrument under the hood.  In order to bring a physical 2 Hz electrodynamic geophone to behave like a 20 sec seismometer (remember those clumsy yet delicate beasts?  You barely touched them, and the mass would shift out of whack!), considerable electronic wizardry needs to be applied.  To some extent, this comes at a price - increased power (but still within very reasonable limits).  However, many of the qualities that have made these seismometers the practitioner's favorites for more than a decade are present in this instrument.  Compared to "true broadband" sensors, the most salient advantages are much faster startup time (the instrument will output meaningful results in less than a minute after power-up!) and drastically reduced sensitivity to temperature or pressure fluctuations.  Since there is no physical long-period element inside, nothing will respond to daily temperature drift, or to the sudden air draught of a door being shut.

Technical Details



Power Supply

10...16V DC, unstabilised

Power Consumption

approx. 50mA @ 12 V DC, max.  100 mA (when full scale output is present)

Output Voltage

1000 V/m/s, precisely adjusted on all components


0.707 critical (internal damping; independent of datalogger input resistance)


195 mm diameter
165 mm height

Weight, including 1.5 m cable and Cannon KPT connector)

6.5 kg

Temperature range


Optional temperature range (specify when ordering)



Painted aluminum, splash proof, with level adjustment feet and water bubble level control


0.05 Hz

Upper corner frequency

> 40 Hz

RMS noise at 1 Hz

< 2 nm/s