Guralp Systems CMG-3ESPCD - Manual (Page 6)

CMG-3ESPCD Digital Broadband Seismometer Introduction
2 Introduction
The CMG-3ESPCD is a full-featured three-axis digital seismometer consisting
of three sensors in an ultra-lightweight case, which can measure the
north/south, east/west and vertical components of ground motion
simultaneously, and a built-in DM24 digitiser.
Each sensor is sensitive to ground vibrations in the frequency range 0.003 Hz
to 50 Hz, a broadband frequency response made possible by advanced
force-balance feedback electronics. Because of this wide response range, the
3ESPCD can replace many of the instruments conventionally used in a
seismic observatory; it also produces true pulse-shape records suitable for
modern earthquake mechanism analysis. Its small size and low weight make
it an ideal choice for rapid deployment of low-noise installations.
The 3ESPCD will produce the best results if it is mounted on a hard,
near-horizontal surface well coupled to the bedrock. After levelling and
orienting the case, you can perform accurate adjustments internally by
sending the instrument control signals. These electronics allow it to
compensate for a tilt of up to 3° from horizontal.
The seismometer unit is self-contained apart from its 12 V power supply.
Once levelled and centred, it will begin operating automatically. Its output is
digitised within the sensor by the internal DM24 digitiser, which provides
data streams in GCF format. The instrument can be connected to a PC's serial
MAN-C3E-0002 6 Issue B - November 2013