Overview

Chapter 2 described the transducer characteristics that are determined while the transducer is measuring a non time varying or static signal. One of the most important characteristics of a transducer is its ability to provide an accurate measurement even when the input is changing rapidly. During rifle testing, for example, we may want to measure the pressure exerted by the explosive charge so we can calculate stresses on the rifle barrel. The pressure transducer must be capable of responding quickly to the sudden increase in pressure and providing an accurate measurement of the pressure change. Similarly, while conducting crash tests of automobiles we may want to measure the motion of crash-test dummies as the automobile is run into a solid object. The velocity of the automobile changes instantaneously from its initial speed of 60 mph to a speed of 0 mph as it impacts the solid object. The car is designed so that components and materials crumple on impact so energy is absorbed and the rate of change of velocity (acceleration) is reduced. Air bags are deployed at a certain deceleration value in order to protect the occupants. The transducers that are used to measure these changes in velocity, acceleration, and motion must be able to accurately measure changes that occur within milliseconds of the time of impact.

Each transducer system has some limit on the rate of change in input to which it can respond. This limit is determined by the transducer's design, materials used, and the capabilities of...