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注册: 2012-10-22
专业: 信号理论与信号处理

[交流] 下载了matlab循环相关的工具箱,但是里面的循环相关程序和循环相关的定义不符

源程序:
function R=cyclic_cross_correlation(x,y,alpha,max_tau)
%
% CYCLIC_CROSS_CORRELATION
%
%             calculates the cyclic cross correlation between
%             two signals x,y at frequency alpha
%
%             R(k*alpha,tau)=E{x(t-tau/2)y(t+tau/2)exp(-jk(alpha)t)}
%             for k=0 ... 2*pi/alpha-1
%
% USAGE
%             R=cyclic_cross_correlation(x,y,alpha,max_tau)
%
%             calculate cross correlation up to max_tau time lags

% File: cyclic_cross_correlation.m
% Last Revised: 23/4/98
% Created: 24/11/97
% Author: Andrew C. McCormick
% (C) University of Strathclyde

% Simple error checks
if nargin~=4
  error(\'Incorrect number of arguments for function cyclic_cross_correlation\');
end
if alpha>2*pi
  error(\'Cyclic frequency must be less than 2 pi in function cyclic_cross_correlation\');
end

T=ceil(2*pi/alpha)-1;%取整
lx=length(x);%时间序列长度
t=0:lx-1;
R=zeros(max_tau*2+1,T+1);

% Compute even time shift segments偶数项
for tau=-max_tau:2:max_tau
  for k=0:T
R(tau+1+max_tau,k+1)=mean(x(1:lx-max_tau-tau).*y(max_tau+tau+1:lx) ...
.*exp(-j*k*alpha*t(1+(max_tau+tau)/2:lx-(max_tau+tau)/2)));
  end
end

% Compute odd time shift segments奇数项
t=t+0.5;
for tau=-max_tau+1:2:max_tau
  for k=0:T
R(tau+1+max_tau,k+1)=mean(x(1:lx-tau-max_tau).*y(max_tau+tau+1:lx) ...
.*exp(-j*k*alpha*t(1+(max_tau+tau-1)/2:lx-(max_tau+tau+1)/2)));
  end
end
为什么在求循环互相关的时候没有取共轭,但是定义中的是有共轭的

循环相关定义式.jpg

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