Approximate frequency analysis in structural dynamics

Frequency analysis is often used in structural dynamics, and the precautions and requirements necessary to obtain accurate results in the frequency domain are well known. However there are applications where resources limitations mean that full accuracy has to be compromised; one example is structural health monitoring using wireless sensor systems with severe constraints on power consumption and processing power. This paper investigates two approximations that may be introduced into the Discrete Fourier Transform computation, namely the quantization of the kernel function (the mono-bit FFT) and the quantization of the time signal, and considers the errors introduced into the frequency spectrum. The paper demonstrates that surprising good results may be obtained and these approximate methods should be considered during the design of systems constrained by resource limitations.