I have two cosine signals in MATLAB both having a frequency of 100 Hz and the second signal has been delayed in time by 0.003 seconds. Both signals have been sampled at 1 Khz. When I use the cross correlation function and plot it to verify the delay between the signals, I expect to see a single point in time at which the signals are aligned but the plot looks symmetrical about the y axis. Why is that?
Also I am not sure about the sign convention here. Does a negative x axis value at the cross correlation peak denote time lag or does a positive x axis value denote time lag?
st=1/1000; t=[0:999]*st; s1=cos(2*pi*100*t); t1=t-(3*st); s2=cos(2*pi*100*t1); [c,lags]=xcorr(s1,s2); plot(lags,c/max(c))