unit delay in z-domain, is this correct? I do not think the bode is correct. Thanks

z = tf('z',1e-4);
%L = T/S;                    % open loop in s domain
%L_z = c2d(L, 1e-4, 'zoh'); % sample L 
delay = 1/z;                % delay transfer function
%L_z_delayed = L_z * delay;  % delayed L
%margin(L_z_delayed); 
bode(delay)

Answer 1

[Paul]

Hi Mohammad,

What exactly about the Bode plot appears to be incorrect?

The gain of the unit delay should be 1 (or 0 dB) at all frequencies, which is what the plot shows insofar as 2e-15 dB is essentially 0 dB. The phase plot looks as expected as well.

[Mohammad]

I meant the phase, If I remember correctly, shouldnt the phase changes in a linear manner?

[Paul]

That's true if the frequency axis is linear, not logarithmic as is the case with bode

z = tf('z',1e-4);
delay = 1/z;                % delay transfer function
h = bodeplot(delay);
setoptions(h,'FreqScale','linear')

[Mohammad]

Thanks