In 1966 and ’67, a project to develop a transient testing procedure for measuring frequency response functions was initiated
for a master’s thesis.
In this initial effort, an impact hammer was
used to excite a machine tool structure, with measurement of
the transient input and response on an FM tape recorder. Tape
loops of the transient responses were played back into a transfer
function analyzer (TFA). The input and response signals were
processed by using the tracking filters in the TFA to filter and ratio
the response to the input signal, thereby estimating the frequency
response between the input signal and the response signal. This
method proved to be impractical due to signal-to-noise problems.
However, it triggered the investigation of other methodologies
including Fourier analysis.