how to compute average power of the generated sinusoidal signal?

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Snow sin
Snow sin am 5 Apr. 2018
Beantwortet: Abraham Boayue am 6 Apr. 2018
lim1 = 0;
lim2 = 2*pi;
t = lim1:0.01:lim2;
A = 1.5;
f = 0.1;
omega= 2*pi*f;
phase= 0;
x = A*cos(omega*t+phase);
plot(t,x);
the following is my signal graph ? hohw should i compute the average power of the signal? how do i write out the formula?? for the average power signal
Px= limN→∞(1/2N+1) ∑|x(n)|^2

Antworten (2)

Abraham Boayue
Abraham Boayue am 5 Apr. 2018
Try this code, just an extension of your code.
clear variables
close all;
lim1 = -10;% no need to have t in pi
% units since omega is
% already measured in pi.
lim2 = 10;
M = 500; % length of
delta = (lim2-lim1)/(M-1);
t = lim1:delta:lim2;
A = 1.5;
f = 0.1;
omega= 2*pi*f;
phase= 0;
x = A*cos(omega*t+phase);
N = 10; % let say you want to average
% 10 terms of x
px = zeros(1,M);
for n = 1:N
px = px + (abs(A*cos(n*omega*t+phase))).^2;
end
px = (1/(2*N+1))*px;
%disp(px)
figure
plot(t,x,'linewidth',2);
hold on
plot(t,px,'linewidth',2)
a = ylabel('Signal');
set(a,'Fontsize',14);
a = xlabel('x');
set(a,'Fontsize',14);
a=title('x(t) and its average px');
legend('x(t)','px')
set(a,'Fontsize',16);
grid;
  1 Kommentar
Snow sin
Snow sin am 6 Apr. 2018
Hi, thanks for the code, i tried it and have some question... Why your px values have 2 answer? shouldn't the average power value is a single value??

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Abraham Boayue
Abraham Boayue am 6 Apr. 2018
Are you saying that px = 1/(2×N+1)[(Acos(wt))^2 + (Acos (2wt))^2 +... (Acos(N*wt))^2] should equal a single number? How possible is that? No way! According to the formula that you provided, you are simply summing a series of cosine squares and then dividing the result by 1/(2*N+1). You are actually performing an ensamble averaging on a time varying function and the result show be a time varying function. If you choose N large enough, you should end up with a delta function, a single value function that occurs at the peak of the cosine wave.

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