National Instruments 370753C-01 makecontinuous( )

Chapter 2 Linear System Representation

gain_z = 20*log10(abs(freq(Hd_z,F)));

gain_e = 20*log10(abs(freq(Hd_e,F)));

and plot it (as shown in Figure 2-1).

plot ([gainc,gain_f,gain_b,gain_t,gain_z,gain_e],

{legend = ["Continuous", "Forward",

"Backward", "Tustins", "Pole Zero",

"Exponential"], x_log,

xlab="Frequency (Hz)",ylab="Magnitude (dB)"})

Figure 2-1. Comparison of Different Frequency Response Techniques

Although most of the discretizations used would give acceptable

approximations to the continuous-time response, notice that most of them

diverge greatly at higher frequencies. You may find it illustrative to run this

example with larger and smaller sampling intervals to see how the choice

of sampling rate, as well as the choice of method, affects the accuracy of

the discretized frequency response.

makecontinuous( )

Sys=makecontinuous(SysD,{exponential, forward,

backward,tustins, ztransform})