Design of Quasi-Logarithmic Multisine Excitations for Robust Broad Frequency Band Measurements

The logarithmic distribution of spectral lines in excitation signals is widely used to measure the transfer functions of dynamic systems over a wide frequency band, covering several decades. Periodic signals are very popular in many advanced dynamic signal analyzers. Generating multitone periodic signals requires an equidistant frequency grid which conflicts with the logarithmic distribution, particularly at the low frequencies. In this paper, we offer an elegant solution to get around this problem using an improved choice for the amplitude spectrum of the multitone. We also offer a simple way to tune the frequency spacing of such a signal to allow for robust identification of the system under test.