chirp plot(i dont know what`s wrong plz help me)

clear all;

close all;

% Aliasing.

ta = 0:1/4000:2/1000;

xa1 = cos(pi * 20000 * ta^2 + 2*pi*1000*ta);

tn = 0:1/8000:2/1000;

xn1 = cos(pi * 20000 * ta^2 + 2*pi*1000*ta);

figure

plot(ta, xa1)

hold on

stem(tn, xn1)

ylabel('x1(t), x1[n]')

title('f1 = 1000 Hz, fs = 8000 Hz')

Answer 1

[Thiago Henrique Gomes Lobato]

Your code had some errors in respect to element-wise operator (^ instead of .^). Also you use the old time variable for the second signal. This is a version of your code that works:

clear all; 
close all;
% Aliasing.
 
ta = 0:1/4000:2/1000;
xa1 = cos(pi * 20000 * ta.^2 + 2*pi*1000*ta); % note the .^
 
tn = 0:1/8000:2/1000;
 
xn1 = cos(pi * 20000 * tn.^2 + 2*pi*1000*tn); % tn instead of ta
 
 
figure
 
plot(ta, xa1)
hold on
stem(tn, xn1)
ylabel('x1(t), x1[n]')
title('f1 = 1000 Hz, fs = 8000 Hz')