Guralp Systems CMG-3TB - Manual (Page 72)

CMG-3TB
Conventional-response feedback
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 s), 0.01 Hz (100 s) or 0.0083 Hz (120 s) as
required. An active low-pass filter provides a high-frequency cutoff
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 left-hand graph shows the response in terms of output
against input acceleration in units of V/m/s
2 , whilst the right-hand
graph is plotted in terms of output against input velocity, in V/m/s.
72 Issue C