Plotting more than one DTMF frequencies on a graph

Hello,

I can plot single dtmf frequency. I would like to plot more than one frequency on a single graph. How do I do it?

Exampl below:

t = 0:1/32798:0.25-1/32798; x = sin(2*pi*xxx*t) + sin(2*pi*yyy*t);

x2 = sin(2*pi*aaa*t2) + sin(2*pi*bbb*t2);

if I do

plot(t, x); title('DTMF Signal for t = 0.25s'); xlabel('time (s)'); ylabel('Amplitude');

it will plot x for me.

Now I would like to plot x and x2 on the same graph. I am aware of putting frequency of zero in between.

Thank you.

[Jonathan Epperl]

It's not clear to me, what exactly you are asking. Are you asking how to put more than one line in a plot? If so, either

plot(t,x,'b',t2,x2,'k');

or

plot(t,x);
hold on
plot(t2,x2);
hold off

but please read the documentation

doc plot

[kyin gab]

I may not be clear enough.

I have two signal gotten from a keypad (number 2 and 7);

t = 0:1/32798:0.25-1/32798;

x2 = sin(2*pi*1336*t) + sin(2*pi*697*t);

x7 = sin(2*pi*1209*t) + sin(2*pi*852*t);

I want to plot these two signals in one graph. I am finding it difficult to do it. I want the graph to look like the last one on page 2 of this www.engr.mun.ca/~sircar/project1_files/dtmf.pdf

I am aware that I have to add a silence period between.

Thank you.

Answer 1

[Jonathan Epperl]

Okay, now that your question is clearer to me, I think this is what you want:

t = 0:1/32798:0.25-1/32798;

x2 = sin(2*pi*1336*t) + sin(2*pi*697*t);

x7 = sin(2*pi*1209*t) + sin(2*pi*852*t);

int_of_silence = .1; shift = t(end)+ int_of_silence;

plot(t, x2, 'b', t+shift, x7, 'b',  [t(end) t(end)+int_of_silence], [0 0], 'b', t+2*shift, x2, 'b', 2*[t(end) t(end)+int_of_silence], [0 0], 'b')

You see the trick is shifting the time axis for each segment by the right amount, I called it shift. The [t(end) t(end)+int_of_silence], [0 0], 'b' part is only to draw a line at 0 between segments.

[kyin gab]

Thank you very much.

I had to combine your first and second answer to get what I want.

Although, from the question I asked, the second answer is very correct.

I was actually trying to plot any amount of dtmf frequencies gotten from inputdlg.

After doing everthing like getting each number entered with a for loop, I could not plot them.

What I did is to use hold on and my t after the first digit becomes t = t + j*shift; where j = position of the digit - 1.

Then I did:

figure(1)

hold on

plot(t, x, 'b');

NB the value of x changes for each iteration of the for loop.

I am almost tempted to ask how to play the sound produced, but let me first do my own search/research.

Thank you.

[JAFARU IBRAHIM]

Hi, Thank you very much (both of you),

I really found this question very important and related to my problem, so please Jonathan or Kyarn, how can you play the sound of the signal above, then? Tanx

[Yusra Banday]

now if we have to plot all the12 tones on a same graph.We can use subplot but graphs cant still be hold.so how can v get all graphs plotted on same fig??