Aliasing-free broadband direction of arrival estimation using a frequency-difference technique.

Area of Science:

• Signal Processing
• Array Signal Processing
• Electromagnetics

Background:

• Spatial aliasing occurs in uniform linear arrays (ULAs) when intersensor spacing exceeds half the signal wavelength.
• This aliasing affects direction-of-arrival (DOA) estimation for both narrowband and broadband signals across frequency bins.
• Existing methods struggle with broadband spatial aliasing, limiting accurate DOA estimation.

Purpose of the Study:

• To propose a novel algorithm for aliasing-free broadband DOA estimation using ULAs.
• To address the limitations of current methods in handling spatial aliasing in broadband scenarios.
• To achieve accurate DOA estimation even in challenging environments with strong interference.

Main Methods:

• Constructing an array output using a Gaussian random sequence from a specific direction (ϑ).
• Applying a frequency-difference (FD) operation: multiplying array observations at frequency f by the conjugate of observations at f+Δf.
• Obtaining an equivalent array output at a desired frequency (Δf) with a wavelength twice the intersensor spacing, creating an aliasing-free spatial spectrum in the FD domain.

Main Results:

• The proposed FD method successfully generates an aliasing-free spatial spectrum.
• Direction-of-arrival (DOA) is estimated by comparing peaks in the aliasing-free spectrum with the scanned direction (ϑ).
• The algorithm demonstrates satisfactory performance even under strong interference conditions.

Conclusions:

• The developed algorithm effectively eliminates spatial aliasing in broadband DOA estimation for ULAs.
• The frequency-difference technique provides a robust solution for accurate DOA determination.
• Simulations and experimental results validate the superiority of the proposed aliasing-free method.