From 29f726894fff580dcb543a9721dcdb5d69c40d38 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Hamal=20Dvo=C5=99=C3=A1k?= <mordae@anilinux.org>
Date: Fri, 23 Feb 2024 11:31:06 +0100
Subject: [PATCH] Decrease DC bias removal alpha
This requires use of int64_t, which is emulated.
---
src/main.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/src/main.c b/src/main.c
index e22966b..2a7bf2b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -538,7 +538,7 @@ static void rf_rx(void)
uint32_t prev_transfers = dma_hw->ch[dma_ch_in_cos].transfer_count;
unsigned pos = 0;
- int dcI = 0, dcQ = 0;
+ int64_t dcI = 0, dcQ = 0;
while (true) {
if (multicore_fifo_rvalid()) {
@@ -573,11 +573,11 @@ static void rf_rx(void)
int I = cos_neg - cos_pos;
int Q = sin_neg - sin_pos;
- dcI = (dcI * 255 + I * 256) >> 8;
- dcQ = (dcQ * 255 + Q * 256) >> 8;
+ dcI = (dcI * 8191 + ((int64_t)I << 16)) / 8192;
+ dcQ = (dcQ * 8191 + ((int64_t)Q << 16)) / 8192;
- I -= dcI >> 8;
- Q -= dcQ >> 8;
+ I -= dcI >> 16;
+ Q -= dcQ >> 16;
*blockptr++ = I;
*blockptr++ = Q;