# Power spectral density of jittered SQ waveform

Started by March 29, 2005

Hi All,
I am trying to plot the power spectral density of a jittered square waveform using psd() command.The program is given below.This seems to work fine but I have problems in

 scaling the y-axis (the plot shows 0 - 3.6 but psd spectrum shows around 50 dB) and for some reason the grid command has no effect in this program
 is there any method to calculate the SNR in dB.
 other than unifrnd(X1,X2) are there anyother distrubution commands
that could be used.

fs20*1e6;% Sampling frequency
N24*32;
t=0:1/fs:(N-1)*1/fs;% Time vector
m=0;
for i=1:1:1024% Loop for random phase
d(i)=unifrnd(-1.0,1.0);
m=m+d(i);
end
mean=m/1024;% Mean value of duty cycle
mean
j=1;s=[];
for i = 1:1024 % Square wave generation
s=[s 1.8+1.8*square(2*pi*1e7*t(j:j+31)+d(i),50)];
j=j+32;
end
psd(s,length(t),fs,hanning(length(t)));% power spectral density
axis([0,100*1e6,0,50]);
grid;

If some thing is not clear for then plz let me know.
Best regards,
Sudhir Devarakonda

Hello sudhir,
I could not understand the first problem ie about
scaling the y axis . I executed your code, but the
plot did not show 0-3.6, however for grid command

1.Either use it before psd command or use 'grid on'
command after the psd command.I have checked it out
and getting grid and y axis is 0-50 dB.

with regards,

--- sudhir.devarakonda@sudh... wrote:
>
> Hi All,
> I am trying to plot the power spectral density of a
> jittered square waveform using psd() command.The
> program is given below.This seems to work fine but I
> have problems in
>
>  scaling the y-axis (the plot shows 0 - 3.6 but
> psd spectrum shows around 50 dB) and for some reason
> the grid command has no effect in this program
>  is there any method to calculate the SNR in dB.
>  other than unifrnd(X1,X2) are there anyother
> distrubution commands
> that could be used.
>
> fs20*1e6;% Sampling frequency
> N24*32;
> t=0:1/fs:(N-1)*1/fs;% Time vector
> m=0;
> for i=1:1:1024% Loop for random phase
> d(i)=unifrnd(-1.0,1.0);
> m=m+d(i);
> end
> mean=m/1024;% Mean value of duty cycle
> mean
> j=1;s=[];
> for i = 1:1024 % Square wave generation
> s=[s
> 1.8+1.8*square(2*pi*1e7*t(j:j+31)+d(i),50)];
> j=j+32;
> end
> psd(s,length(t),fs,hanning(length(t)));% power
> spectral density
> axis([0,100*1e6,0,50]);
> grid;
>
> If some thing is not clear for then plz let me know.
> Best regards,
> Sudhir Devarakonda >
>
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