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Working with phasor re-rotation

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cnlohr
2024-10-06 23:06:59 -07:00
parent 85fe805e32
commit b2995f435f
6 changed files with 161 additions and 10 deletions
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ch32v/ch32v203-goertzel/ttest/phasor_rotation_test.c
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#include <stdio.h>
#include <stdint.h>
#include <math.h>
int main()
{
int phasor_r = 32768;
int phasor_i = 0;
double phasor = 0;
double omega = 0.1;
int omega_r = cos( omega ) * 32768;
int omega_i = sin( omega ) * 32768;
int i;
for( i = 0; i < 10000; i++ )
{
int32_t temp = (phasor_r * omega_i + phasor_i * omega_r ) >> 15;
phasor_r = (phasor_r * omega_r - phasor_i * omega_i ) >> 15;
phasor_i = temp;
phasor += omega;
// Approximate sqrt(x*x+y*y)
#define ABS(x) (((x)<0)?-(x):(x))
int s = phasor_r * phasor_r + phasor_i * phasor_i;
int intensity = (ABS(phasor_r) + ABS(phasor_i)) * 26100 / 32768 + 1; // Found experimentally (Also try to avoid divide-by-zero.
intensity = (intensity + s/intensity)/2;
intensity = (intensity + s/intensity)/2;
if( intensity < 32763 )
{
phasor_r += phasor_r >> 12;
phasor_i += phasor_i >> 12;
}
double fA = atan2( phasor_i, phasor_r );
printf( "%6d %6d / %6d %6d / %d / %f %f %f\n", omega_r, omega_i, phasor_r, phasor_i, intensity, fA, phasor, fA-phasor );
if( phasor >= 3.141592653589 ) phasor -= 3.141592653589*2;
}
}