From 3cf5214bb8dce82c943f314bd62b074ce17cb467 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Hamal=20Dvo=C5=99=C3=A1k?= <mordae@anilinux.org>
Date: Fri, 7 Jun 2024 21:32:39 +0200
Subject: [PATCH] Add small amount of additional smoothing
---
src/main.c | 28 +++++++++++++++++++++-------
1 file changed, 21 insertions(+), 7 deletions(-)
diff --git a/src/main.c b/src/main.c
index 1d19dbe..59816c7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -37,7 +37,8 @@
static uint32_t lo_cos[LO_WORDS] __attribute__((__aligned__(1 << LO_BITS_DEPTH)));
static uint32_t lo_sin[LO_WORDS] __attribute__((__aligned__(1 << LO_BITS_DEPTH)));
-#define RX_STRIDE (2 * IQ_SAMPLES)
+#define DECIMATE 2
+#define RX_STRIDE (2 * IQ_SAMPLES * DECIMATE)
#define RX_BITS_DEPTH 12
#define RX_WORDS (1 << (RX_BITS_DEPTH - 2))
@@ -318,7 +319,7 @@ static void rf_rx_start(int rx_pin, int bias_pin)
false);
/* Pacing timer for the sampling script trigger channel. */
- dma_timer_set_fraction(dma_t_samp, 1, CLK_SYS_HZ / sample_rate);
+ dma_timer_set_fraction(dma_t_samp, 1, CLK_SYS_HZ / (sample_rate * DECIMATE));
/* Sampling trigger channel. */
dma_conf = dma_channel_get_default_config(dma_ch_samp_trig);
@@ -429,6 +430,7 @@ static void rf_rx(void)
unsigned pos = 0;
int64_t dcI = 0, dcQ = 0;
+ int prevI = 0, prevQ = 0;
while (true) {
if (multicore_fifo_rvalid()) {
@@ -478,8 +480,14 @@ static void rf_rx(void)
for (int i = 0; i < IQ_SAMPLES; i++) {
uint32_t cos_neg = *cos_ptr++;
uint32_t cos_pos = *cos_ptr++;
- int I32 = cos_neg - cos_pos;
- int64_t I = I32;
+ int I1 = cos_neg - cos_pos;
+
+ cos_neg = *cos_ptr++;
+ cos_pos = *cos_ptr++;
+ int I2 = cos_neg - cos_pos;
+
+ int64_t I = (prevI + I1 + I1 + I2) / 2;
+ prevI = I2;
int64_t I16 = I << 16;
dcI = ((dcI << 16) - dcI + I16) >> 16;
@@ -497,8 +505,14 @@ static void rf_rx(void)
uint32_t sin_neg = *sin_ptr++;
uint32_t sin_pos = *sin_ptr++;
- int Q32 = sin_neg - sin_pos;
- int64_t Q = Q32;
+ int Q1 = sin_neg - sin_pos;
+
+ sin_neg = *sin_ptr++;
+ sin_pos = *sin_ptr++;
+ int Q2 = sin_neg - sin_pos;
+
+ int64_t Q = (prevQ + Q1 + Q1 + Q2) / 2;
+ prevQ = Q2;
int64_t Q16 = Q << 16;
dcQ = ((dcQ << 16) - dcQ + Q16) >> 16;
@@ -527,7 +541,7 @@ static void run_command(uint8_t cmd, uint32_t arg)
} else if (0x02 == cmd) {
/* Set the rate at which IQ sample pairs are sent */
sample_rate = arg;
- dma_timer_set_fraction(dma_t_samp, 1, CLK_SYS_HZ / sample_rate);
+ dma_timer_set_fraction(dma_t_samp, 1, CLK_SYS_HZ / (sample_rate * DECIMATE));
} else if (0x04 == cmd) {
/* Set the tuner gain level */
gain = INIT_GAIN * powf(10.0f, 0.01f * arg);