Guralp Systems CMG-3ESPCD - Manual (Page 69)

CMG-3ESPCD Digital Broadband Seismometer Command line interface
number generator produces true white noise over the entire passband, as
shown in the power spectral density plot below:
The different coloured lines show the results of experiments which measure
the power spectral density over several frequency bands. Together, the results
show a flat noise level over the entire passband to within experimental error.
6.5.4 MINUTE
Syntax: duration MINUTE
Sets for how long the next SINEWAVE or RANDOMCAL calibration signal will be
injected, or the period of the next SQUAREWAVE calibration signal.
The argument duration is the desired interval, in minutes. If you now issue
a SINEWAVE or RANDOMCAL command, the calibration will last duration
minutes; if the next calibration command is SQUAREWAVE, a positive step of
duration minutes will be generated, followed by a negative step of a further
duration minutes.
If you do not issue MINUTE, calibration signals will default to 2 minutes. This
is to avoid the sensor and digitiser inadvertently being left in calibration
mode. Issuing, e.g., 5 MINUTE will cause the next calibration signal to last 5
minutes, but later calibration signals will revert to a duration of 2 minutes.
You will need to issue a MINUTE command before each injection.
MAN-C3E-0002 69 Issue B - November 2013