Efficient Aperture Fill Time Correction for Wideband Sparse Array Using Improved Variable Fractional Delay Filters.

Area of Science:

• Signal Processing
• Array Signal Processing
• Filter Design

Background:

• Wideband sparse arrays face aperture fill time (AFT) challenges due to linear coupling.
• Variable fractional delay (VFD) FIR filters are used but lead to high system complexity.
• Existing minimax models suffer from overfitting and non-unique solutions.

Purpose of the Study:

• To develop a computationally efficient method for designing VFD FIR filters.
• To reduce the system complexity associated with AFT correction in wideband sparse arrays.
• To improve the optimization of VFD filter coefficients.

Main Methods:

• A novel multi-regularization minimax (MRMM) model is proposed, incorporating sparse representation.
• L2-norm and multiple L1-norms are used for regularization within the minimax criterion.
• An improved sequential-alternating direction method of multipliers (S-ADMM) algorithm is developed to solve the nonconvex model.

Main Results:

• The MRMM model effectively constrains the error function, mitigating overfitting and non-unique solutions.
• Multiple L1-norms facilitate the optimal design of VFD filters with minimal sub-filter count and order.
• The proposed S-ADMM algorithm efficiently solves the nonconvex optimization problem.

Conclusions:

• The optimized VFD filter significantly reduces system complexity.
• The proposed method effectively corrects aperture fill time in wideband sparse arrays.
• This approach offers a practical solution for enhancing wideband sparse array performance.