我有两个信号,我们称它们为“a”和“b”。但是,它们都是几乎相同的信号(从相同的输入记录并包含相同的信息),因为我在两个不同的“b”处记录了它们,它们的时间偏移量未知。显然,每个都有随机噪声。
目前,我正在使用互相关来计算时间偏移,但是,我仍然得到不正确的结果。
这是我用来计算时移的代码:
function [ diff ] = FindDiff( signal1, signal2 )
%FINDDIFF Finds the difference between two signals of equal frequency
%after an appropritate time shift is applied
% Calculates the time shift between two signals of equal frequency
% using cross correlation, shifts the second signal and subtracts the
% shifted signal from the first signal. This difference is returned.
length = size(signal1);
if (length ~= size(signal2))
error('Vectors must be equal size');
end
t = 1:length;
tx = (-length+1):length;
x = xcorr(signal1,signal2);
[mx,ix] = max(x);
lag = abs(tx(ix));
shifted_signal2 = timeshift(signal2,lag);
diff = signal1 - shifted_signal2;
end
function [ shifted ] = timeshift( input_signal, shift_amount )
input_size = size(input_signal);
shifted = (1:input_size)';
for i = 1:input_size
if i <= shift_amount
shifted(i) = 0;
else
shifted(i) = input_signal(i-shift_amount);
end
end
end
plot(FindDiff(a,b));
然而,函数的结果是周期波,而不是随机噪声,因此滞后必须仍然关闭。我会发布该情节的图片,但 imgur 目前不合作。
除了互相关之外,有没有更准确的方法来计算滞后,或者有没有办法改善互相关的结果?