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For a labI was given this code

t=0:1/2000:.02;

x=sin(2*pi*60*t);

t240=0:1/240:.02;

n240=0:length(t240)-1;

x240=sin(2*pi*60/240*n240);

stem(n240,x240,'filled','b','LineWidth',2);

axis([0 4.8 -1 1]);

and was to put that into matlab and display the sampling and function which works fine. We then needed to make this into a function of x=Asin(omega*t) where f = 10000Hz, and find the sampling at rates of 5k, 10k, and 20, 100k. However changing the values of the sampling frequency and the function frequency gives me a graph that is not at all similar and I have no idea what I need to fix or change to get the graph to look like the initial one.

=======================================

t=0:1/3300:.02;

x=sin(2*pi*10000*t);

t5000=0:1/5000:.02;

n5000=0:length(t5000)-1;

x5000=sin(2*pi*10000/5000*n5000);

stem(n5000,x5000,'filled','b','LineWidth',2);

=======================================

t=0:1/3300:.02;

x=sin(2*pi*10000*t);

t10000=0:1/10000:.02;

n10000=0:length(t10000)-1;

x10000=sin(2*pi*10000/10000*n10000);

stem(n10000,x10000,'filled','b','LineWidth',2);

========================================

that is what I changed the code too for 5k and 10k, i know those are both less than nyquist's sampling so it will result in not a good graph, but even with 20k+ the graph isnt similar to what it was before.

what I specifically dont understand is

how

t=0:1/2000:.02

; is time

what

n240=0:length(t240)-1; is

this

stem(n240,x240,'filled','b','LineWidth',2);

part of the code and what it does

how to get a proper sampling graph of 5k,10k,20k and100k, and what to change to get that

Sulaymon Eshkabilov
on 3 Apr 2021

Your code has a problem with the end time value to take into calculations and display of the calculated data points. Here are some corrected codes:

f1=240;

t=0:1/2000:.02;

%x=sin(2*pi*60*t);

t240=0:1/f1:.02;

n240=0:length(t240)-1;

x240=sin(2*pi*60/f1*n240);

figure

subplot(311)

stem(n240,x240,'filled','b','LineWidth',2);

axis([0 4.8 -1 1]);

%%

%t=0:1/2000:.02;

%x=sin(2*pi*60*t);

f1=240;

t240=0:1/f1:.02;

n240=0:length(t240)-1;

x240=sin(2*pi*f1*n240);

figure

subplot(311)

stem(n240,x240,'filled','b','LineWidth',2);

axis([0 4.8 -1 1]);

subplot(312)

f2=5000; % 5k

t5k=0:1/(f2*10):.0005;

n5k=0:length(t5k)-1;

x5k=sin(2*pi*10000/f2*n5k);

stem(n5k,x5k,'filled','b','LineWidth',2); shg

f3=1e4; % 10k

% t=0:1/(10*f3):.02;

% x=sin(2*pi*f3*t);

t10k=0:1/(10*f3):.0002;

n10k=0:length(t10k)-1;

x10k=sin(2*pi*1*n10k);

subplot(313)

stem(n10k,x10k,'filled','b','LineWidth',2); shg

Good luck.

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