Apply a digital filter (direct form II transposed): Difference between revisions
Apply a digital filter (direct form II transposed) (view source)
Revision as of 18:02, 16 November 2019
, 4 years agoAda version
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The signal that needs filtering is the following vector: [-0.917843918645, 0.141984778794, 1.20536903482, 0.190286794412, -0.662370894973, -1.00700480494, -0.404707073677 ,0.800482325044, 0.743500089861, 1.01090520172, 0.741527555207, 0.277841675195, 0.400833448236, -0.2085993586, -0.172842103641, -0.134316096293, 0.0259303398477, 0.490105989562, 0.549391221511, 0.9047198589]
=={{header|Ada}}==
<lang Ada>with Ada.Text_IO;
procedure Apply_Filter is
generic
type Num is digits <>;
type Num_Array is array (Natural range <>) of Num;
A : Num_Array;
B : Num_Array;
package Direct_Form_II_Transposed is
pragma Assert (A'First = 0 and B'First = 0);
pragma Assert (A'Last = B'Last);
pragma Assert (A (0) = 1.000);
function Filter (X : in Num) return Num;
end Direct_Form_II_Transposed;
package body Direct_Form_II_Transposed
is
W : Num_Array (A'Range) := (others => 0.0);
function Filter (X : in Num) return Num is
Y : constant Num := X * B (0) + W (0);
begin
-- Calculate delay line for next sample
for I in 1 .. W'Last loop
W (I - 1) := X * B (I) - Y * A (I) + W (I);
end loop;
return Y;
end Filter;
end Direct_Form_II_Transposed;
type Coeff_Array is array (Natural range <>) of Float;
package Butterworth is
new Direct_Form_II_Transposed (Float, Coeff_Array,
A => (1.000000000000, -2.77555756e-16,
3.33333333e-01, -1.85037171e-17),
B => (0.16666667, 0.50000000,
0.50000000, 0.16666667));
subtype Signal_Array is Coeff_Array;
X_Signal : constant Signal_Array :=
(-0.917843918645, 0.141984778794, 1.20536903482, 0.190286794412, -0.662370894973,
-1.00700480494, -0.404707073677, 0.800482325044, 0.743500089861, 1.01090520172,
0.741527555207, 0.277841675195, 0.400833448236, -0.2085993586, -0.172842103641,
-0.134316096293, 0.0259303398477, 0.490105989562, 0.549391221511, 0.9047198589);
package Float_IO is
new Ada.Text_IO.Float_IO (Float);
Y : Float;
begin
for Sample of X_Signal loop
Y := Butterworth.Filter (Sample);
Float_IO.Put (Y, Exp => 0, Aft => 6);
Ada.Text_IO.New_Line;
end loop;
end Apply_Filter;</lang>
=={{header|C}}==
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