Guralp Systems CMG-3EX-EAM - Manual (Page 3)

Operator's Guide
1 Introduction
The CMG-3ESPCD is a full-featured three-axis digital seismometer
consisting of three sensors in a lightweight case, which can measure
the North/South, East/West and vertical components of ground motion
simultaneously, a built-in CMG-CD24 digitizer and a built-in CMG-
EAM embedded acquisition module.
Each sensor is sensitive to ground vibrations in the frequency range
120 seconds 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 seismometer unit is self-
contained apart from its 12 V power
supply. Once levelled and centred,
it will begin operating
automatically. Its output is
digitized within the sensor by the
internal CD24 digitizer, which
provides data streams to the
embedded acquisition module. The
instrument can be connected to a
PC over a serial port or Ethernet
network. The text- or web-based
configuration interface provides
complete control over the storage
and transmission of data, as well as
the instrument's centring and mass
locking processes. Data stored in
the internal memory can be written
to an external USB drive at the
touch of a button.
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.
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