Calibrating the 40T
relay in the seismometer, and 4 mm banana sockets for an external signal source.
As above, the equivalent input velocity for a sinusoidal calibration signal is given by
v
=
V
2
π
f R K
where
V
is the peak-to-peak voltage of the calibration signal,
f
is the signal
frequency,
R
is the magnitude of the calibration resistor and
K
is the feedback coil
constant.
R
and
K
are both given on the calibration sheet supplied with the 40T.
The calibration resistor is placed in series with the transducer. Depending on the
calibration signal source, and the sensitivity of your recording equipment, you may
need to increase
R
by adding further resistors to the circuit.
33
Issue F - June 2019
