Estimation of time delays with fewer sensors than sources

A number of papers have been dealing with the problem of estimating the differential delay of an unknown signal impinging on two sensors. The present contribution deals with the presence of more than one source, which is a case that has never been dealt with before. The solution resorts to slices of high-order spectra, and the full spectral band of the signals is utilized in order to recover the delays. It can be viewed as an improvement to the classical procedure consisting of searching the autocorrelation for local maxima, which does not work when delays are smaller than the source correlation length