Guralp Systems CMG-3T - Manual (Page 45)

Operator's guide
The conventional-response feedback system has an additional parallel
feedback circuit, consisting of a non-inverting integrator in series with
a resistor. This arrangement results in two poles at specified
frequencies. The velocity response of a conventional-response system
is defined by a transfer function identical to that of a conventional
long-period sensor with a damping constant of 0.707 (1/√2) ζ
The seismometer can be supplied with an equivalent resonant
frequency of 0.033 Hz (30 seconds), 0.01 Hz (100 seconds) or 0.0083
Hz (120 seconds) as required. An active low-pass filter provides a high-
frequency cut-off point at a frequency you specify.
Comparisons
The figures below plot the comparative response of a conventional
velocity output broadband sensor and a hybrid output broadband
sensor. The first graph shows the response in terms of output against
input acceleration in units of V/m/s², whilst the second is plotted in
terms of output against input velocity, in V/m/s.
July 2009 45