ANALOG-TO-DIGITAL CONVERTERS FOR SEISMOMETERS

摘要

The analog output signal of a seismometer SM is compared in a comparator COMP with the output of a ramp signal generator RG to produce pulses of width proportional to the instantaneous amplitude of the output signal as determined by pulses from a clock CK via a gate G. The number of clock pulses, as counted by a multi-bit counter CT, provides a digital output signal. The variable-width pulse from comparator COMP is also applied to a converter PC to switch positive and negative precision voltage sources (PVS1) and (PVS2) (Fig. 3) into a low-pass filter which thereby provides an analogue feedback signal to the seismometer SM.