Chapter 4 System Analysis
© National Instruments Corporation 4-15 Xmath Control Design Module
Figure 4-4. 15-Second Impulse Response
deftimerange( )tvec = deftimerange(Sys)
deftimerange( ) computes a regular time vector (in units of seconds)
that can be used in time-domain simulations to observe the effects of all or
most of the input system’s dynamics, as indicated by pole and zero location.
Within deftimerange( ), the poles of the system are obtained using
poles( ). For continuous-time systems, the poles are scaled by a factor
of 1/2π (to convert from radians) and the time constant (in seconds) is
obtained as the reciprocal of four times the value of the pole with the
maximum absolute value (the “fastest” pole). For discrete-time systems,
the logarithm of the poles is taken and scaled by the sampling interval. The
sampling interval is automatically used as the step size for the tvec time
vector. If all system poles are integrators, the step size defaults to 0.01.