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this isn't better

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KubaPro010
2025-01-01 02:07:45 +01:00
parent e77a10f33c
commit 6fecb974d5
2 changed files with 30 additions and 20 deletions
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18
lib/hilbert.c
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@@ -1,24 +1,8 @@
#include "hilbert.h"
static float generate_coefficient(int i, int nzeros) {
if (i == nzeros/2) return 0.0f;
float n = i - nzeros/2;
// Basic Hilbert transform coefficient
float h = (i == nzeros/2) ? 0.0f : (2.0f/(PI * n));
// Apply Blackman window for better stopband attenuation
float w = 0.42f - 0.5f * cosf(2.0f * PI * i / nzeros) +
0.08f * cosf(4.0f * PI * i / nzeros);
return h * w;
}
void init_hilbert(HilbertTransformer *hilbert) {
hilbert->delay = calloc(D_SIZE, sizeof(float));
hilbert->dptr = 0;
for(int i = 0; i < NZEROS; i++) {
hilbert->coeffs[i] = generate_coefficient(i, NZEROS);
}
}
void apply_hilbert(HilbertTransformer *hilbert, float sample, float *output_0deg, float *output_90deg) {
@@ -27,7 +11,7 @@ void apply_hilbert(HilbertTransformer *hilbert, float sample, float *output_0deg
hilbert->delay[hilbert->dptr] = sample;
hilb = 0.0f;
for(int i = 0; i < NZEROS/2; i++) {
hilb += (hilbert->coeffs[i] * hilbert->delay[(hilbert->dptr - i*2) & (D_SIZE - 1)]);
hilb += (xcoeffs[i] * hilbert->delay[(hilbert->dptr - i*2) & (D_SIZE - 1)]);
}
*output_0deg = hilbert->delay[(hilbert->dptr - 99) & (D_SIZE - 1)];

32
lib/hilbert.h
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@@ -1,14 +1,40 @@
#include <stdlib.h>
#include <math.h>
#include "constants.h"
#define D_SIZE 256
#define NZEROS 200
/* The non-zero taps of the Hilbert transformer */
static float xcoeffs[] = {
+0.0008103736f, +0.0008457886f, +0.0009017196f, +0.0009793364f,
+0.0010798341f, +0.0012044365f, +0.0013544008f, +0.0015310235f,
+0.0017356466f, +0.0019696659f, +0.0022345404f, +0.0025318040f,
+0.0028630784f, +0.0032300896f, +0.0036346867f, +0.0040788644f,
+0.0045647903f, +0.0050948365f, +0.0056716186f, +0.0062980419f,
+0.0069773575f, +0.0077132300f, +0.0085098208f, +0.0093718901f,
+0.0103049226f, +0.0113152847f, +0.0124104218f, +0.0135991079f,
+0.0148917649f, +0.0163008758f, +0.0178415242f, +0.0195321089f,
+0.0213953037f, +0.0234593652f, +0.0257599469f, +0.0283426636f,
+0.0312667947f, +0.0346107648f, +0.0384804823f, +0.0430224431f,
+0.0484451086f, +0.0550553725f, +0.0633242001f, +0.0740128560f,
+0.0884368322f, +0.1090816773f, +0.1412745301f, +0.1988673273f,
+0.3326528346f, +0.9997730178f, -0.9997730178f, -0.3326528346f,
-0.1988673273f, -0.1412745301f, -0.1090816773f, -0.0884368322f,
-0.0740128560f, -0.0633242001f, -0.0550553725f, -0.0484451086f,
-0.0430224431f, -0.0384804823f, -0.0346107648f, -0.0312667947f,
-0.0283426636f, -0.0257599469f, -0.0234593652f, -0.0213953037f,
-0.0195321089f, -0.0178415242f, -0.0163008758f, -0.0148917649f,
-0.0135991079f, -0.0124104218f, -0.0113152847f, -0.0103049226f,
-0.0093718901f, -0.0085098208f, -0.0077132300f, -0.0069773575f,
-0.0062980419f, -0.0056716186f, -0.0050948365f, -0.0045647903f,
-0.0040788644f, -0.0036346867f, -0.0032300896f, -0.0028630784f,
-0.0025318040f, -0.0022345404f, -0.0019696659f, -0.0017356466f,
-0.0015310235f, -0.0013544008f, -0.0012044365f, -0.0010798341f,
-0.0009793364f, -0.0009017196f, -0.0008457886f, -0.0008103736f,
};
typedef struct {
float* delay;
int dptr;
float coeffs[NZEROS];
} HilbertTransformer;
void init_hilbert(HilbertTransformer *hilbert);