Guralp Systems CD1.1 - Manual (Page 77)

Operator's Guide
The CD1.1 calibration value for seismic sensors (including mass
position channels) should be in units of nm/count. To convert
from an acceleration gain to a dsiplaycement gain, it is
necessary to divide by (2πf)², or 4π²f². We also need to
introduce a scale factor of 1000, leading to:
C=1000
S
G
⋅ 4π²f² — CD1.1 calibration value for seismic sensor
with acceleration response, where C is the calibration value in
nm/count, S is the digitiser sensitivity in µV/count, G is the gain
of the instrument in V/m/s, and f is the frequency of the
calibration point in Hz.
12.3 Acoustic or infrasound sensors
For sensors which measure acoustic/infrasound responses, the
sensitivity (in units of V/Pa or VPa
-1 ) should be known. The
CD1.1 calibration value is expected to be in Pa/count, so to
convert:
C=g
S⋅10 − 6
G
— CD1.1 calibration for acoustic sensor, where C
is the calibration value in Pa/count, g is the gain of an optional
auxiliary signal conditioner (use 1 if no conditioner is present),
S is the digitiser sensitivity in µV/count and G is the gain of the
instrument in V/Pa.
12.4 Wind speed
For a wind speed sensor with an output that is given as V/m/s
(or Vm
-1 s), use:
C=g
S⋅10 − 6
G
— CD1.1 calibration for acoustic sensor, where C
is the calibration value in ms -1 /count, g is the gain of an
optional auxiliary signal conditioner (use 1 if no conditioner is
present), S is the digitiser sensitivity in µV/count and G is the
gain of the instrument in V/m/s.
12.5 Wind direction
For a wind direction sensor with an output that is given as V/°
(volts per degree), use:
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