Guralp-systems CMG-3ESPCD Manuel d'utilisateur télécharger pdf (Page 37)

CMG-3ESPCD Digital Broadband Seismometer Calibrating the 3ESPCD

The bbnoisecal script automatically performs appropriate averaging

to reduce the effects of aliasing and cultural noise.

4.3.1 Sensor response codes

Sensor Sensor type code Units

(V/A)

CMG-3T or 3ESP, 30 s – 50 Hz response

CMG-3_30S_50HZ

CMG-3T or 3ESP, 60 s – 50 Hz response

CMG-3_60S_50HZ

CMG-3T or 3ESP, 100 s – 50 Hz response

CMG-3_100S_50HZ

CMG-3T or 3ESP, 120 s – 50 Hz response

CMG-3_120S_50HZ

CMG-3T or 3ESP, 360 s – 50 Hz response

CMG-3_360S_50HZ

CMG-3TB/3V/3ESP borehole, 30 s – 50 Hz

CMG-3B_30S_50HZ

CMG-3TB/3V/3ESP borehole, 100 s – 50 Hz

CMG3B_100S_50HZ

CMG-3TB/3V/3ESP borehole, 120 s – 50 Hz

CMG3B_120S_50HZ

4.4 The coil constant

The feedback coil constant K is measured at the time of manufacture, and

printed on the calibration sheet. Using this value will give good results at the

time of installation. However, it may change over time. The coil constant can

be determined by tilting the instrument and measuring its response to gravity.

To do this, you will need apparatus for measuring tilt angles accurately.

1. Measure the acceleration due to gravity, g, at your location.

2. Tilt the instrument slightly, and measure its attitude and the gain of the

mass position output for the component you wish to calibrate.

MAN-C3E-0002 37 Issue B - November 2013

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Guralp-systems CMG-3ESPCD Manuel d'utilisateur Page 37