fs=6.25*10^6;
P=xlsread('D:\soft install\MATLAB\work\qpsk','a:a');
Q=xlsread('D:\soft install\MATLAB\work\qpsk','b:b');
N=length(P);
yk=P+j*Q;
yk=yk.^4;
for k=2:N
m1=k-(N/2-1);
m2=N/2;
wk=(3*N)/[2*(N^2-1)]*[1-(m1/m2)^2];
delt_w=wk*angle(yk(k)*conj(yk((k-1))));
data=sum(delt_w);
end