Matlab z-transform Bode plot


by bmalp
Tags: bode, matlab, plot, ztransform
bmalp
bmalp is offline
#1
Jan4-07, 03:58 AM
P: 1
Hi,

I try to visualize a sine wave, z-transformed in a Bode plot. The frequency shows up correctly, but the amplitude is way off - why?

Thanks for your comments.
Bmalp



function zdemo

format compact
syms w Ts n z phi t

Ts = 1
w = 0.1
phi = 0

vz = simplify(ztrans(sin(w*n*Ts+phi))) % correct

if 0 % method 1
[num,den] = numden(simplify(vz));
num = collect(num,'z')
den = collect(den,'z')
num1 = sym2poly(num)
den1 = sym2poly(den)
[h,w] = freqz(num1,den1,512,'whole');
else % method 2
fs = 1;
f = linspace(0,fs,256);
w = 2*pi*f;
ss = sqrt(-1)*w;
Z = exp(ss/fs);
h = double(subs(vz,z,Z));
end
plot(w,abs(h)) % amplitude way too big
Phys.Org News Partner Science news on Phys.org
SensaBubble: It's a bubble, but not as we know it (w/ video)
The hemihelix: Scientists discover a new shape using rubber bands (w/ video)
Microbes provide insights into evolution of human language
Mesmer
Mesmer is offline
#2
Jan7-07, 09:37 PM
P: 40
Why don't you try this site http://www.kluid.com/. It's pretty much dedicated to matlab :)


Register to reply

Related Discussions
Bode plot axes Electrical Engineering 4
Bode Plot Sketching Engineering, Comp Sci, & Technology Homework 4
bode plot Electrical Engineering 2
Bode Plot... Plotting Engineering, Comp Sci, & Technology Homework 1
Circuits: Bode Plot Help Engineering, Comp Sci, & Technology Homework 1