How to add a line to a freqz plot?

Hi all,

I need to add a line of y = 0 across my freqz plot for my project. What command do I need to include my script?

My script:

Fp = 1000; %Bandpass Freq

Fs = 2000; %BandStop Freq

SF = 10000; %Sampling Freq

Pr = 0.1; %Passband ripple

Sr = 0.001; %Stopband ripple

[n,fo,ao,w] = firpmord([Fp Fs],[1 0],[Pr Sr],SF);

b = firpm(n,fo,ao,w);

freqz(b,1)

Thanks in advance.

Answer 1

[Star Strider]

Since freqz plots are ordinary subplots, just address them as such —

Fp = 1000;  %Bandpass Freq
Fs = 2000;  %BandStop Freq
SF = 10000; %Sampling Freq
Pr = 0.1;  %Passband ripple
Sr = 0.001;  %Stopband ripple
[n,fo,ao,w] = firpmord([Fp Fs],[1 0],[Pr Sr],SF);
b = firpm(n,fo,ao,w);

figure
freqz(b,1)
Ax1 = subplot(2,1,1);
yline(Ax1, 0, '-r', 'LineWidth',2)

The horizontal line at y=1 is going to be a bit difficult to see, so I emphasized it. Change the yline call appropriately if necessary to change its appearance.

.

Answer 2

[Kevin Holly]

yline(0)