Solutions for leakage problems with multi-sine excitation

摘要

In many vibrometer applications, the measured structure is excited not only by the controlled excitation source, but also by secondary, unwanted excitation sources. The effects of those disturbing excitation sources can often be limited to a small frequency range by windowing. As measurements with multi-sine excitations like periodic-chirp require a rectangular window, which provides very poor leakage reduction, the unwanted excitation sources leak out to a wide frequency range. This leakage can considerably limit the signal-to-noise ratio. The disturbing excitation sources are typically at low frequencies. As velocity is scaled to acceleration by i2πf, low frequencies are better attenuated for acceleration signals than for velocity signals. Therefore it is especially important to reduce the effects of the disturbing excitation sources when measuring with vibrometers. Several methods of reducing the leakage effects of the disturbing excitation have been developed and are compared in this paper.