SPIKE – Spike filter

Block SymbolLicensing group: ADVANCED

Function Description
The SPIKE block implements a nonlinear filter for suppressing isolated peaks (pulses) in the input signal u. One cycle of the SPIKE filter performs the following transformation $(u, y) \to y$ :

delta := y - u;
if abs(delta) < gap
  then
     begin
        y := u;
        gap := gap/q;
        ifgap < mingap then gap:= mingap;
     end
  else
     begin
       if delta < 0
          then y := y + gap
          else y := y - gap;
       gap := gap * q;
     end

where mingap and q are the block parameters.

The signal passes through the filter unaffected for sufficiently large mingap parameter, which defines the minimal size of the tolerance window. By lowering this parameter it is possible to find an appropriate value, which leads to suppression of the undesirable peaks but leaves the input signal intact otherwise. The recommended value is 1 % of the overall input signal range. The q parameter determines the adaptation speed of the tolerance window.

Input

u	Input signal to be filtered	Double (F64)

Output

y	Filtered output signal	Double (F64)

Parameters

mingap	Minimum size of the tolerance window $⊙$ 0.01	Double (F64)
q	Tolerance window adaptation speed $↓$ 1.0 $⊙$ 2.0	Double (F64)

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