Application of crosscorrelating equipment to linear-system identification

It is well known that the impulse response of a linear system subject to a `white-noise¿ input can be obtained by crosscorrelating input and output. In recent years, workers have, however, become aware of the benefits of employing pseudorandom test signals with idealised autocorrelation functions. The paper includes a description of equipment developed to generate and crosscorrelate such signals. Experience is then described and discussed in applying the methods to (a) analogue simulated systems, (b) a small distillation column used for teaching purposes and (c) an industrial evaporator plant.