Time to Frequency Domain Conversion of Step Response Data

Conversion of step response data to frequency form in the higher ranges of frequency, not hitherto reported, has been achieved. Theoretical analysis and simulation study indicate that the technique, although it necessitates numerical differentiation of time response data, causes significantly less error In transform amplitudes and angles. It has been found possible by this technique to identify correctly not only the major system lag but also lags due to additional subsystems. System identification, even In the presence of random noise, could also be successfully carried out. The technique, when applied to available experimental transient response data on a heat exchanger, enabled evaluation of its distributed parameter characteristics with considerably greater precision. © 1975, American Chemical Society. All rights reserved.