From f73e37922209dcd567623cc146cfedbd8ba0c10e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jan=20Hamal=20Dvo=C5=99=C3=A1k?= <mordae@anilinux.org> Date: Sat, 27 Jan 2024 11:13:56 +0100 Subject: [PATCH] Fix HPF loss of precision MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Jan Hamal Dvořák <mordae@anilinux.org> --- src/main.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/src/main.c b/src/main.c index 430f976..2f21326 100644 --- a/src/main.c +++ b/src/main.c @@ -40,7 +40,7 @@ #define NUM_SAMPLES 32 #define RSSI_ALPHA 1 #define LPF_SAMPLES 8 /* 8 */ -#define HPF_ALPHA 2 /* 2 */ +#define HPF_ALPHA 1 /* 1 */ #define IIR_ON 0 #define SPEED 3 #define PRIME_DELTA 1 @@ -618,13 +618,13 @@ static void rf_rx(void) Q /= NUM_SAMPLES; #if HPF_ALPHA - int tmpI = I * 64; - I -= hpI / 64; - hpI = (hpI * ((1 << 12) - HPF_ALPHA) + tmpI * HPF_ALPHA) >> 12; + int tmpI = I * 256; + I -= hpI / 256; + hpI = (hpI * ((1 << 10) - HPF_ALPHA) + tmpI * HPF_ALPHA) >> 10; - int tmpQ = Q * 64; - Q -= hpQ / 64; - hpQ = (hpQ * ((1 << 12) - HPF_ALPHA) + tmpQ * HPF_ALPHA) >> 12; + int tmpQ = Q * 256; + Q -= hpQ / 256; + hpQ = (hpQ * ((1 << 10) - HPF_ALPHA) + tmpQ * HPF_ALPHA) >> 10; #endif #if LPF_SAMPLES