Multidimensional digital smoothing filters for target detection

• Recursive, causal and non-causal, multidimensional digital filters are designed.
• The low-pass filters have an IIR with a maximally flat frequency response.
• Laguerre polynomials are used to design the filters for use in a 2-stage system.
• Stage 1 negates correlated clutter and interference in the background.
• Stage 2 accumulates power due to dim targets in the foreground.

Recursive, causal and non-causal, multidimensional digital filters, with infinite impulse responses and maximally flat magnitude and delay responses in the low-frequency region, are designed to negate correlated clutter and interference in the ‘background’ and to accumulate power due to dim targets in the ‘foreground’ of a surveillance sensor. Expressions relating mean impulse-response duration, frequency selectivity and group delay, to low-order linear-difference-equation coefficients are derived using discrete Laguerre polynomials and discounted least-squares regression, then verified through simulation.

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