mordae/pico-sdr
1
2
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Use 8 bit samples

Browse source 
After adjusting for the noise floor, we can use 8 bit samples for all
supported bandwidths.
This commit is contained in:
Jan Hamal Dvořák 2024-02-23 23:20:42 +01:00
parent d3e403df33
commit 78b07b9c09
1 changed files with 9 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

20
src/main.c
View file

@ -40,7 +40,7 @@
#define CLK_SYS_HZ (250 * MHZ)
#define BANDWIDTH 100000
#define IQ_BLOCK_LEN 32
#define IQ_BLOCK_LEN 64
#define XOR_ADDR 0x1000
#define LO_COS_ACCUMULATOR (&pio1->sm[2].pinctrl)
@ -530,11 +530,12 @@ static void rf_tx_stop()
static void rf_rx(void)
{
static int16_t block[IQ_BLOCK_LEN];
static int8_t block[IQ_BLOCK_LEN];
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;
while (true) {
if (multicore_fifo_rvalid()) {
@ -558,7 +559,7 @@ static void rf_rx(void)
pos = (pos + IQ_BLOCK_LEN) & (RX_WORDS - 1);
int16_t *blockptr = block;
int8_t *blockptr = block;
for (int i = 0; i < IQ_BLOCK_LEN / 2; i++) {
uint32_t cos_pos = *cos_ptr++;
@ -569,11 +570,8 @@ static void rf_rx(void)
int I = cos_neg - cos_pos;
int Q = sin_neg - sin_pos;
dcI = (dcI * 8191 + ((int64_t)I << 16)) / 8192;
dcQ = (dcQ * 8191 + ((int64_t)Q << 16)) / 8192;
I -= dcI >> 16;
Q -= dcQ >> 16;
I = (I * noise_floor_inv) >> 16;
Q = (Q * noise_floor_inv) >> 16;
*blockptr++ = I;
*blockptr++ = Q;
@ -679,7 +677,7 @@ static void do_rx(int rx_pin, int bias_pin, float freq, char mode)
printf("Frequency: %.0f\n", actual);
static int16_t block[IQ_BLOCK_LEN];
static int8_t block[IQ_BLOCK_LEN];
while (queue_try_remove(&iq_queue, block))
/* Flush the queue */;
@ -870,7 +868,7 @@ int main()
printf("\nPuppet Online!\n");
printf("clk_sys = %10.6f MHz\n", (float)clock_get_hz(clk_sys) / MHZ);
queue_init(&iq_queue, IQ_BLOCK_LEN * 2, 256);
queue_init(&iq_queue, IQ_BLOCK_LEN * sizeof(int8_t), 256);
static char cmd[83];
int cmdlen = 0;