DOA estimation for broadband chirp signals

We derive two new methods, based on the ambiguity function, for estimating the direction-of-arrival (DOA) of broadband chirp signals. These new methods make use of the time-frequency structure of the chirp signal and can be applied to any aperture array and any chirp rate. As long as the signals are separable in the ambiguity function plane, the number of sources can be greater than the number of sensors. These methods can be applied to single chirp and multiple chirps with either the same or different chirp rates. Simulation results show that the DOA estimation performance can be improved, especially for the low SNR and spatially close sources cases.