In 1968 and ’69, the large applied dynamics computer in the
Department of Electrical Engineering at the University of Cincinnati
was used to develop a software program that used the analog part
of the hybrid computer to digitize the force and the response (accelerometer) signal measured by testing a machine tool base. The
IBM 1130 computer (digital part of a hybrid computer) was used to
compute FRFs and coherence functions. These measurements were
compared to the FRF function measured with a Spectral Dynamics
transfer analyzer, and the comparisons were good.