Point Clutter Remover

Point Clutter is a target that has strong total power in one or two successive range bins but is bordered on either side in by bins of significantly lower power. These are usually non-meteorological targets such as airplanes, ships, or other moving objects.

The first step in autocorrelation processing is the optional removal of point clutter.

There are 2 adjustable parameters for the point clutter algorithm:

TCM Point clutter threshold factor
Offset Point clutter range offset in bins

The first pass called Clutter detection is to screen all range bins to see if their Doppler filtered power exceeds the normal level before and after in range. In other words, flag all bins if:

[(R_{0} (r) > T C M * R_{0} (r - O f f s e t)) a n d (R_{0} (r) > T C M * R_{0} (r + O f f s e t))]

These flag bits are output in the optional flag word. The second pass called Clutter sensoring involves linearly interpolating all the autocorrelation values in range over the interval of clutter bins including the offsets at either sides if the offset is larger than 1:

R_{0} (r) = (\frac{r_{{e n d}^{- r}}}{r_{{e n d}^{- r} s t a r t}}) * R_{0} (r_{s t a r t}) + (\frac{{}^{r - r}{s t a r t}}{r_{{e n d}^{- r} s t a r t}}) * R_{0} (r_{e n d}), w h e r e r = r_{s t a r t}, r_{e n d}

Note that the same thing is done for all the filtered autocorrelations and crosscorrelations (lagged momentsR₁, R₂, and dual-polarization crosscorrelations) as soon as any of the filtered autocorrelation R₀_H, R₀_V, or R₀_HV exceeds the threshold. The unfiltered autocorrelations (total power) T₀_H, T₀_V, and T₀_HV are conserved.