Chapter 2. Introduction

The Güralp 5U sensor is a single-axis strong-motion force-feedback accelerometer in a sealed case, which can be used in either vertical or horizontal orientations. The sensor system is self-contained except for its 12 V DC power supply, which can be provided through the same cable as the analogue data. An internal DC–DC converter ensures that the sensor is completely isolated.

The 5U system combines low-noise components with high feedback loop gain to provide a linear, precision transducer with a very large dynamic range. In order to exploit the whole dynamic range two separate outputs are provided, with high and low gain. Nominally the high gain outputs are set to output a signal 10 times stronger than the low gain outputs.

The 5U sensor outputs are all differential with an output impedance of 47 Ω. A single signal ground line is provided as a return line for all the sensor outputs.

Full-scale low-gain sensitivity is available from 2.0 g down to 0.1 g. The standard frequency pass band is flat to acceleration from DC to 100 Hz. DC to 50 Hz and DC to 200 Hz variants are available.

Each seismometer is delivered with a calibration sheet showing its serial number and measured frequency response in both the long period and the short period sections of the seismic spectrum.