Guralp Systems CMG-1T User Manual
Page 21
Operator’s Guide CMG-1T Ocean Bottom
Seismometer
September, 1999, Issue C Section 4,
Page 1
4.
THE FORCE TRANSDUCER
Force feedback seismometers which use a coil and magnet system to generate
the restoring feedback force are inherently dependent on the constancy of the
field strength produced in the force transducer. The design of the magnetic
circuit and the magnet/pole assembly is such that the field strength from the
feedback transducer is constant over large deflections and current levels.
Tests have shown that the mechanical suspension system and the electronics of
the CMG-3NSN is linear to better than 107 db (measured at ASL during USGS
National Network evaluation in 1989).