Disclosed herein is a fast method that locates nearby sources based solely
on the time-of-flight of a signal across an array of sensors. The time
delay for signal passage between all pairs of sensors is determined using
cross-correlation estimates and a vector of time delays, .tau., is
constructed from the results. In the noise free case, each point in the
plane is associated with a unique value of the .tau. vector. The plane is
searched for a source location by minimizing the difference between the
value of .tau. associated with the candidate location on the plane and
the value estimated from cross-correlations. The search takes place over
the three dimensional space that includes two coordinates in the plane
and the propagation speed. The starting point for the search is
constructed from an analytic fit of circular wave fronts to groups of
sensors within the array.