Broadband DOA estimation using frequency-invariant beam-space processing

This paper presents a new method of beam-space direction of arrival (DOA) estimation for multiple far-field broadband signals. A novel multi-rate beamforming structure having a frequency invariant property is applied to the array outputs. Using this multi-rate structure, only a single vector of parameters is required to implement a desired frequency invariant beam pattern regardless of the bandwidth or number of sensors in the array. This frequency-invariant beamformer performs focusing over a very wide bandwidth without resorting to the frequency bin design approach of other methods in which the solution of a multiparameter optimisation problem is required to design the beam-space focusing matrices