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Restore DC bias removal with better precision

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This commit is contained in:
Jan Hamal Dvořák 2024-02-24 11:08:34 +01:00
parent efca7bda55
commit 7621d2d21a
1 changed files with 11 additions and 0 deletions
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11
src/main.c
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@ -527,6 +527,8 @@ static void rf_rx(void)
uint32_t prev_transfers = dma_hw->ch[dma_ch_in_cos].transfer_count;
unsigned pos = 0;
int64_t dcI = 0, dcQ = 0;
int noise_floor = sqrt((float)CLK_SYS_HZ / (float)BANDWIDTH * 3.0 / 4.0);
int noise_floor_inv = (1 << 16) / noise_floor;
@ -563,6 +565,15 @@ static void rf_rx(void)
int I = cos_neg - cos_pos;
int Q = sin_neg - sin_pos;
int64_t I64 = (int64_t)I << 32;
int64_t Q64 = (int64_t)Q << 32;
I = (I64 - dcI) >> 32;
Q = (Q64 - dcQ) >> 32;
dcI = ((dcI << 20) - dcI + I64) >> 20;
dcQ = ((dcQ << 20) - dcQ + Q64) >> 20;
I = (I * noise_floor_inv) >> 16;
Q = (Q * noise_floor_inv) >> 16;