Matlab Code Help for x[n]=x(n2Ts)

[lcw1972]

Homework Statement

x(t)=4sin(0.5t).3u(t)
x[n]=x(n2Ts)

The 1st equation, x(t)=4sin(0.5t).2u(t)
Code :
>> A=2;
>> wo=0.5;
>> t=5:0.25:50;
>> x=A*sin(wo*t).3*(t>=0);
>> plot(t,x), grid on
>> xlabel('t (s)'); ylabel('Amplitude(unit)')

But the second one,x[n]=x(n2T_s), I don't know what code should I use to plot it out,pls help,thanks.

 

[n.karthick]

Hi,
The second part is just down sampling the x(t) by 2. You have already chosen Ts=0.25. So just leave a sample between every two samples and you will get x[n]

 

[lcw1972]

Hi,
U mean I just use below code to plot it out?
>> T=0.25;
>> x=2*T*(A*sin(wo*n).3*(n>=0));

 

[lcw1972]

No one else can help?

 

[DeeNos]

To plot x[n], you can use the same code as before, but with a few modifications. First, you need to define n as the index of the samples, rather than t as the time variable. Then, you can use the same formula for x[n] as x(t), but with n instead of t. Finally, you can use the "stem" function instead of "plot" to plot the discrete values of x[n]. The code would look like this:

>> A=2;
>> wo=0.5;
>> n=5:1:50; % or any other range of n that you want to plot
>> x=A*sin(wo*n*2*Ts).3*(n>=0);
>> stem(n,x), grid on
>> xlabel('n'); ylabel('Amplitude(unit)')

Note that the value of Ts is not given in the question, so you will need to define it yourself based on the sampling rate used in your system.