2introduction – Guralp Systems CMG-6TD User Manual
Page 7
Introduction
2
Introduction
The CMG-6TD is an ultra-lightweight digital
three-axis seismometer consisting of three
sensors in a sealed case, which can measure
the north/south, east/west and vertical
components of ground motion
simultaneously. Each sensor is sensitive to
ground vibrations over a wide frequency
range (0.033 – 50 Hertz as standard). This
frequency response is made possible by
advanced
force-balance
feedback
electronics. A built-in 24-bit digitiser
converts ground movements to digital data
at source with maximum fidelity.
The 6TD has a rugged, waterproof design for
ease of installation, and requires no
levelling or centring as long as its base is
within 3 ° from the horizontal. For the best
results, however, you should install where
possible on a hard, near-horizontal surface
well coupled to the bedrock.
Once it is provided with 10 – 28 V power the 6TD will begin operating
automatically, measuring and digitizing ground movements and either
outputting them to your own recording system, or saving them into internal
Flash memory. Accurate timing information can be taken from a GPS unit
connected to the 6TD through a breakout box. Both breakout box and GPS are
normally supplied with the instrument.
Each seismometer is
delivered with a detailed
calibration sheet showing
its serial number,
measured
frequency
response in both the long
period and the short period
sections of the seismic
spectrum, sensor DC
calibration levels, and the
transfer function in
poles/zeros notation.
6TD sensors can be delivered in sets of 5 with GPS and cabling included.
Each set is supplied in a “smart” case allowing you to huddle-test the sensors
without needing to unpack them.
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Issue F - February 2014