scaling for periodic signal using hann window

How can i scale for periodic signal using hann window. i know for flattop i.e 1/sum(window)but i do not know how to scale with hann window with a periodic signal. kindly help

[Lisa Justin]

xn=signal;%%%periodic signal

w=flattopwin(length(xn));

x=xn.*w;

sc=1/sum(w);%%%%scaling

y=(fft(x)).*sc

please how would i scale if i want to usse hann window instead. what would 'sc' be?

Answer 1

[Wayne King]

Hi Lisa, it should be the same:

t = 0:0.001:1-0.001;
xn = cos(2*pi*100*t);
w = hanning(length(xn));
x = xn'.*w; 
sc = 1/sum(w);
xdft = fft(xn);
xdft = xdft(1:length(xn)/2+1);
y = sc*xdft;
plot(abs(y));

[Lisa Justin]

sc is same as flattop you mean. no not true

[Lisa Justin]

the signal is periodic remember

[Wayne King]

It's not the same as the flat top window, because the sum of the two windows is not the same.

w = hanning(length(xn));

w1 = flattopwin(length(xn));

sum(w)

sum(w1)

Accordingly the reciprocal of the sums is not the same.