Abstract
When an M-sequence signal is used as an input to a system to be identified, the crosscorrelation of input and output gives approximately the system impulse response provided that the shift pulse period T of the M-sequence generator is sufficiently small. However, if T is not so small, the crosscorrelation function no longer gives the impulse response.
In this paper, the effect of T on the crosscorrelation function is calculated in the case where the system is of second order. And it is shown that, with only the gain correction, the crosscorrelation function can approximate the impulse response within the error of 3%, when ωnT≤0.6where ωn is the natural frequency of the system. On the basis of this fact, a simple and practical method for system identification is described. In this method, no delay elements are used and the delay time is changed by varying T and by using several logic multipliers.
The results of analog computer simulation agreed well with the theoretical considerations.
