mordae/pico-sdr
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Make AGC decay and LPF order configurable

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This commit is contained in:
Jan Hamal Dvořák 2024-03-03 00:40:16 +01:00
parent 92f69b56ae
commit 091379cffb
1 changed files with 21 additions and 2 deletions
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23
src/main.c
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@ -41,11 +41,14 @@
#define BANDWIDTH 1280000
#define DECIMATION_BITS 6
#define IQ_BLOCK_LEN 64
#define LPF_ORDER 3
#define AGC_DECAY_BITS 16
#define RX_SLEEP_US (DECIMATION * BANDWIDTH / (1 * MHZ) / 4)
#define DECIMATION (1 << DECIMATION_BITS)
static_assert(RX_SLEEP_US > 0, "RX_SLEEP_US must be positive");
static_assert(LPF_ORDER <= 3, "LPF_ORDER must be 0-3");
#define XOR_ADDR 0x1000
#define LO_COS_ACCUMULATOR (&pio1->sm[2].pinctrl)
@ -56,7 +59,11 @@ static_assert(RX_SLEEP_US > 0, "RX_SLEEP_US must be positive");
static uint32_t lo_cos[LO_WORDS] __attribute__((__aligned__(LO_WORDS * 4)));
static uint32_t lo_sin[LO_WORDS] __attribute__((__aligned__(LO_WORDS * 4)));
#if DECIMATION_BITS >= 5
#define RX_BITS_DEPTH (DECIMATION_BITS + 2)
#else
#define RX_BITS_DEPTH 7
#endif
#define RX_WORDS (1 << RX_BITS_DEPTH)
static uint32_t rx_cos[RX_WORDS] __attribute__((__aligned__(RX_WORDS * 4)));
static uint32_t rx_sin[RX_WORDS] __attribute__((__aligned__(RX_WORDS * 4)));
@ -565,20 +572,26 @@ static void rf_rx(void)
uint32_t prev_transfers = dma_hw->ch[dma_ch_in_cos].transfer_count;
unsigned pos = 0;
#if LPF_ORDER >= 1
static int lpIh1[DECIMATION];
static int lpQh1[DECIMATION];
int lpIa1 = 0;
int lpQa1 = 0;
#endif
#if LPF_ORDER >= 2
static int lpIh2[DECIMATION];
static int lpQh2[DECIMATION];
int lpIa2 = 0;
int lpQa2 = 0;
#endif
#if LPF_ORDER >= 3
static int lpIh3[DECIMATION];
static int lpQh3[DECIMATION];
int lpIa3 = 0;
int lpQa3 = 0;
#endif
int64_t dcI = 0, dcQ = 0;
@ -623,6 +636,7 @@ static void rf_rx(void)
I = I * amp_scale;
Q = Q * amp_scale;
#if LPF_ORDER >= 1
int lpP = d & (DECIMATION - 1);
lpIa1 += I - lpIh1[lpP];
@ -633,7 +647,9 @@ static void rf_rx(void)
I = lpIa1 / DECIMATION;
Q = lpQa1 / DECIMATION;
#endif
#if LPF_ORDER >= 2
lpIa2 += I - lpIh2[lpP];
lpQa2 += Q - lpQh2[lpP];
@ -642,7 +658,9 @@ static void rf_rx(void)
I = lpIa2 / DECIMATION;
Q = lpQa2 / DECIMATION;
#endif
#if LPF_ORDER >= 3
lpIa3 += I - lpIh3[lpP];
lpQa3 += Q - lpQh3[lpP];
@ -651,6 +669,7 @@ static void rf_rx(void)
I = lpIa3 / DECIMATION;
Q = lpQa3 / DECIMATION;
#endif
dI += I;
dQ += Q;
@ -658,7 +677,7 @@ static void rf_rx(void)
/*
* Original dI/dQ are scaled to 32 bits.
* These are part of DC removal alpha.
* These "<< 19" are part of DC removal alpha.
*/
int64_t dI19 = (int64_t)dI << 19;
int64_t dQ19 = (int64_t)dQ << 19;
@ -670,7 +689,7 @@ static void rf_rx(void)
dQ = (dQ19 - dcQ) >> 19;
/* Slowly decay AGC amplitude. */
agc -= (agc >> 16) | 1;
agc -= (agc >> AGC_DECAY_BITS) | 1;
if (abs(dI) > agc)
agc = abs(dI);