Device for digital measurement of the change in physical variables

摘要

The device according to the invention determines length or separation changes which are caused by changes in physical variables such as temperature and pressure, by means of propagation time measurement (delay time measurement) of electrical signals in an optical waveguide (LWL) which is subjected to the physical variable. Signals are fed into the optical waveguide via an optical multivibrator (S, SE, E, EA). In this case, the total propagation time of a plurality of pulses is determined via a high-frequency counter. The deviation of the actually determined counter result from a normal counter result is determined by comparison with said normal counter result, this deviation is used to determine the length or separation distance which has occurred, and this length or separation difference is converted into the physical variable to be determined. The device requires only a small number of cost-effective and proven components and permits highly accurate determination of the physical variables to be evaluated. <IMAGE>