On a Newly Devised Frequency Response Recorder

Abstract

In order to facilitate the measurement of frequency response, a frequency response recorder was newly devised. This recorder is constituted of two parts, one is a sine wave generator which is used to impose the input signal X sin ωt being accomplished with an eccentric disc rotating at the angular velocity ω ; another part is a rotating table at the same angular velocity ω on which the output signal of the system is recorded with a pen. If the output signal is a theoretically perfect linear simple harmonic oscillation whose neutral point corresponds to the center of rotation of the table C, the record on the table becomes a circle passing through C, then, the diameter and the position of the center of the circle indicate the amplitude of the output signal and phase lag angle with respect to the input signal, respectively.