How to add the new delayed signal to the PLOT !

Question

Susan 2011-8-29

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https://ww2.mathworks.cn/matlabcentral/answers/14726-how-to-add-the-new-delayed-signal-to-the-plot

评论： Honglei Chen 2014-12-1

Hey all, My code below is working, however by looking at the plot it seems it didn't draw the new delayed signals, It just plotted the second signal? Is it something to do with [xi,f]=ksdensity(Y+delay); I am not adding the delay?

x = sample1(:,1);
X = (x).';
y = sample2(:,1);
Y = (y).';
figure;
clf
fisrt = subplot(3,1,1);
[xi,f]=ksdensity(X); 
plot(f,xi); 
line(repmat(X,2,1),repmat([0;0.1*max(xi)],1,length(X)),'color','r' ); 
second = subplot(3,1,2);
[xi,f]=ksdensity(Y); 
plot(f,xi); 
line(repmat(Y,2,1),repmat([0;0.1*max(xi)],1,length(Y)),'color','r' );
[Rxx,lags] = xcorr(X,Y);
[Z,delay] = max(Rxx);
lags(delay);
if delay>0
  hold(first,'on');
  [xi,f]=ksdensity(Y+delay); 
  plot(first,f,xi);
else
  hold(second,'on');
  [xi,f]=ksdensity(X+delay); 
  plot(second,f,xi);
end

Cheers,

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Fangjun Jiang 2011-8-29

See my comment in your previous question. You accepted the answer. What further work have you done?

http://www.mathworks.com/matlabcentral/answers/14446-plot-problem

Fangjun Jiang 2011-8-30

The same mistake was pointed out even earlier. So, instead of making the same mistake again and again, please make your own effort to read, understand and learn it.

http://www.mathworks.com/matlabcentral/answers/13110-signal-processing

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Answer 1

Rick Rosson 2011-8-29

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Honglei's answer is correct, and it explains why simply adding 2 to an existing signal does not shift the signal in time, but merely shifts every value upward by 2.

To shift a signal in time, you need to insert zeros at the beginning of the signal, an operation which is often called zeropadding.

Please try the following example:

   % define a simple signal:
   x = (1:20)';
   % now shift the signal in time by zeropadding at the beginning:
   N = 5;
   y = [  zeros(N,1)  ;   x     ];
   % Also, let's zeropad x at the end so that it has the same length as y:
   x = [   x   ;   zeros(N,1)   ];
   % Create a simple time domain:
   n = (1:size(x,1))';
   % plot both signals:   
   figure;
   plot(n,x,n,y);
   legend('x','y');

You should see that y is a shifted version of x.

HTH.

Rick

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lamawal Jonathan 2014-11-30

Hello All! i'm on a similar problem (zero pad a signal), the slight difference is that my signal is a vector of single row and 2400 columns. each time i zero pad, it gives me the following error;

"Error using vertical

Dimensions of matrices being concatenated are not consistent."

i even tried running your code several times but it repeats same error on line 5 (y = [ zeros(N,1) ; x ];) of your code. pls, help i'm very new to matlab and it's very important for me.

Honglei Chen 2014-12-1

Your signal is a row vector, so it should be y=[zeros(1,N) x].

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Answer 2

Honglei Chen 2011-8-29

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https://ww2.mathworks.cn/matlabcentral/answers/14726-how-to-add-the-new-delayed-signal-to-the-plot#answer_20014

在 MATLAB Online 中打开

Hi Susan,

X+delay does not delay the signal, it merely adds an offset of delay's value to X. To delay a signal, you need to shift it in samples. One way to do it is to pad zeros in the front. For example, assume your delay is 1 second and your sampling frequency is also 1 second, then you need to insert 1 zero in front of signal, i.e., make

X_delay = [0 X];

HTH

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Fangjun Jiang 2011-8-29

I am amazed by the way you learn. The way for "applying it" has been given in this answer and many other answers. If you spend more time reading it and understanding it, instead of asking the same question repeatedly, your problem may already be solved.

lamawal Jonathan 2014-11-30

Hello All! i'm on a similar problem (zero pad a signal), the slight difference is that my signal is a vector of single row and 2400 columns. each time i zero pad, it gives me the following error;

"Error using vertical

Dimensions of matrices being concatenated are not consistent."

i even tried running your code several times but it repeats same error on line 5 (y = [ zeros(N,1) ; x ];) of your code. pls, help i'm very new to matlab and it's very important for me.

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Answer 3

Honglei Chen 2011-8-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/14726-how-to-add-the-new-delayed-signal-to-the-plot#answer_20036

在 MATLAB Online 中打开

Hi Susan,

Let's say I have two signals x and y. To make it simple, let's say

x = [1 1 1 1 1 ]

so if y is the same as x but delayed by 2 samples, you would see

y = [0 0 1 1 1]

for the first 5 samples. However, if you do

x+2

you will get

[3 3 3 3 3]

which is not the delayed version.

HTH

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lamawal Jonathan 2014-11-30

Hello All! i'm on a similar problem (zero pad a signal), the slight difference is that my signal is a vector of single row and 2400 columns. each time i zero pad, it gives me the following error;

"Error using vertical

Dimensions of matrices being concatenated are not consistent."

i even tried running your code several times but it repeats same error on line 5 (y = [ zeros(N,1) ; x ];) of your code. pls, help i'm very new to matlab and it's very important for me.