Description:
<jats:p>Properties of simple mechanical and electrical systems are summarized, with special reference to certain ones useful in vibration measurement. It is shown that several physical systems, including the mechanical “seismographic” system used in vibration pick-ups and the electrical circuit of the resistance coupled amplifier, are governed essentially by a single analytical expression. Information is presented in the two equivalent forms: frequency characteristics of amplitude and of phase time (converted from phase angle); and indicial response, i.e., the response to forcing by a step function. These results are discussed in relation to the fundamental possibilities of vibration measurement by the seismographic method and to the determination of the parameters of particular instruments. The concepts of instrument element and instrument sensitivity, as used in the instrumentation courses at M. I. T., are introduced to systematize the discussion.</jats:p>