mordae/pico-sdr
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Fix HPF loss of precision

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Signed-off-by: Jan Hamal Dvořák <mordae@anilinux.org>
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Jan Hamal Dvořák 2024-01-27 11:13:56 +01:00
parent 16492ce7ee
commit f73e379222
1 changed files with 7 additions and 7 deletions
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14
src/main.c
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@ -40,7 +40,7 @@
#define NUM_SAMPLES 32 #define NUM_SAMPLES 32
#define RSSI_ALPHA 1 #define RSSI_ALPHA 1
#define LPF_SAMPLES 8 /* 8 */ #define LPF_SAMPLES 8 /* 8 */
#define HPF_ALPHA 2 /* 2 */ #define HPF_ALPHA 1 /* 1 */
#define IIR_ON 0 #define IIR_ON 0
#define SPEED 3 #define SPEED 3
#define PRIME_DELTA 1 #define PRIME_DELTA 1
@ -618,13 +618,13 @@ static void rf_rx(void)
Q /= NUM_SAMPLES; Q /= NUM_SAMPLES;
#if HPF_ALPHA #if HPF_ALPHA
int tmpI = I * 64; int tmpI = I * 256;
I -= hpI / 64; I -= hpI / 256;
hpI = (hpI * ((1 << 12) - HPF_ALPHA) + tmpI * HPF_ALPHA) >> 12; hpI = (hpI * ((1 << 10) - HPF_ALPHA) + tmpI * HPF_ALPHA) >> 10;
int tmpQ = Q * 64; int tmpQ = Q * 256;
Q -= hpQ / 64; Q -= hpQ / 256;
hpQ = (hpQ * ((1 << 12) - HPF_ALPHA) + tmpQ * HPF_ALPHA) >> 12; hpQ = (hpQ * ((1 << 10) - HPF_ALPHA) + tmpQ * HPF_ALPHA) >> 10;
#endif #endif
#if LPF_SAMPLES #if LPF_SAMPLES