Guralp Systems CMG-3TB - Manual (Page 4)

CMG-3TB
1 Introduction
The CMG-3TB is a three-axis seismometer consisting of three sensors
stacked vertically in a sealed borehole sonde, designed for use in cased
boreholes with diameters between 5” / 89 mm and 9” / 229 mm.
The seismometer system is self-contained except for its 12 – 30 V
power supply, which is provided through the same cable as the
analogue data. Sensor functions such as levelling and mass locking are
carried out through a surface control box.
The 3TB's sensors are sensitive to ground vibrations in the frequency
range 0.0027 – 50 Hz. It outputs analogue voltage representing ground
velocity on balanced differential lines. Each seismometer is delivered
with a detailed calibration sheet showing its serial number, measured
frequency response in both long and short period sections of the
seismic spectrum, sensor DC calibration levels, and the transfer
function in poles/zeros notation.
4 Issue C