The autocorrelation of a signal composed of 2 delayed Diracs is a symmetric signal composed of a central Dirac positioned at the null delay and of 2 lateral Diracs which are symmetric about the central Dirac. The delays of the lateral Diracs, in comparison with the central one, are equal to the differential delays between the Diracs.
The picking of the position of the lateral Diracs allows the measurement of the delay between the Diracs which make up the initial signal. The amplitude of autocorrelation at lag 0 gives the energy of the signal

The example shows the initial signal made up of 2 delayed Diracs, for whom it is possible to adjust their position in time, the autocorrelation function composed of the 3 Diracs and the modulus of the Fourier transform of the initial signal. The modulus of the FT of the initial signal is a cosine whose period is due to the time variation between the 2 Diracs.