MATLAB: How to make a rectangular pulse train at 50 kHz frequency

MATLABpulstranrectpuls

HI,

I have a code –

t = 0 : 1/1e3 : 1;         % 1 kHz sample freq for 1 sec 
d = 0 : 1/3 : 1;           % 3 Hz repetition freq 
y = pulstran(t,d,'rectpuls');
plot(t,y)

which is supposed to generate a rectangular pulse at 3 Hz how to make it 50 kHz?

When I try changing it, I dont see the pulse train any more.

Thanks

Best Answer

You did not specify the width of the pulse. I've made it 10 microseconds.

t = 0 : 1/1e6 : .01;         
d = 0 : 1/50e3 : .01;           
y = pulstran(t,d,@rectpuls,1e-5);
plot(t,y); 
axis([0 0.001 0 1.5])

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Starting point could be something (from the pulstran example)...

>> t = 0 : 1/1e3 : 1;         % 1 kHz sample freq for 1 sec 
   d = 0 : 1/5 : 1;           % 5 Hz repetition freq 
   y = pulstran(t,d,@tripuls,0.01);
   plot(t,y)
>> xlim([-0.05 1.05])

You can then apply a windowing function of length(y) to desired shape to modify amplitude and add noise as desired. Fix up frequencies, etc., as desired, obviously; I just fiddled with the example parameters slightly to show more pulses over the same frequency as the example and with a symmetric pulse.

MATLAB: How to generate a pulse train which starts at the origin using functions in the Signal Processing Toolbox 6.10 (R2008b)

This can be done using the PULSTRAN function in the Signal Processing Toolbox.

As mentioned in the Signal Processing Toolbox 6.10 (R2008b) documentation, the default 'rectpuls' function extends from -0.5 to 0.5. Additionally, the PULSTRAN function returns "func(t-d(1))+func(t-d(2)) +...", where 't' and 'd' are the time and delay vectors respectively. Thus, the number of "pulses" in the "train" will be the same as the number of elements in 'd'.

In order to generate pulses that do not overlap, the elements of 'd' must be greater than the pulse width (which is 1 by default for the 'rectpuls' function). Therefore, as an example, the first term should be "func(t-0.5)" so that the train of rectangular pulses starts at "t=0". In other words, the first element of 'd' must be half the width of the function (i.e. 'rectpuls') if the pulse train is to start at "t=0".

The following code is an example of how this can be implemented:

t=0:.01:10;   %Time vector 
w = 1; %pulse width
d= w/2:w*2:10; %delay vector
y2=pulstran(t,d,'rectpuls',w); 
plot(t,y2); 
set(gca,'Ylim',[-0.1 1.1]);

Best Answer

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MATLAB: Need data about tach signal

MATLAB: How to generate a pulse train which starts at the origin using functions in the Signal Processing Toolbox 6.10 (R2008b)

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