Accelerometer

Instrument to measure seismic acceleration

The Accelerometer can be of two types:

analog instrument: ground acceleration is reproduced by a mechanical instrument on a physical support, typically paper or photographic film, and it is digitized at a later stage.

digital instrument: it is typically based on either electro-magnetic or force-balance transducers. The electric signal is then properly conditioned, sampled and digitized. The digital instruments are operating from about the mid-80s.

The most representative parameters defining the characteristics of the recording instrument response are as follows:

- sensor undamped natural vibration frequency (frequency);

- sensor damping coefficient with respect to critical (damping);

- frequency band for which the sensor gives a flat response (frequency band);

- generator constant of the sensor (gain);

- smallest signal that can be resolved by the sensor (sensitivity);

- maximum signal that can be resolved by the sensor (full scale);

- number of bits of the recorder (number of bits).