mordae/pico-sdr
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Avoid randomness in LO and bias for better SNR

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Signed-off-by: Jan Hamal Dvořák <mordae@anilinux.org>
This commit is contained in:
Jan Hamal Dvořák 2024-01-24 23:51:36 +01:00
parent 1aaed3fe42
commit 64417f3ab7
1 changed files with 3 additions and 7 deletions
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10
src/main.c
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@ -77,7 +77,6 @@ static void bias_init(int in_pin, int out_pin)
gpio_disable_pulls(in_pin);
gpio_disable_pulls(out_pin);
pio_gpio_init(pio1, in_pin);
pio_gpio_init(pio1, out_pin);
gpio_set_input_hysteresis_enabled(in_pin, false);
@ -105,7 +104,7 @@ static void bias_init(int in_pin, int out_pin)
sm_config_set_out_pins(&pc, out_pin, 1);
sm_config_set_set_pins(&pc, out_pin, 1);
sm_config_set_wrap(&pc, 0, 0);
sm_config_set_clkdiv_int_frac(&pc, 1, 127);
sm_config_set_clkdiv_int_frac(&pc, 1, 0);
pio_sm_init(pio1, 0, 0, &pc);
pio_sm_set_consecutive_pindirs(pio1, 0, out_pin, 1, GPIO_OUT);
@ -116,7 +115,6 @@ static void bias_init(int in_pin, int out_pin)
static void watch_init(int in_pin)
{
gpio_disable_pulls(in_pin);
pio_gpio_init(pio1, in_pin);
gpio_set_input_hysteresis_enabled(in_pin, false);
@ -270,13 +268,11 @@ static float lo_freq_init(float req_freq)
unsigned bcos = 0;
for (int j = 0; j < 32; j++) {
int nudge = rand() % step - step / 2;
bcos |= (acos + nudge) >> 31;
bcos |= acos >> 31;
bcos <<= 1;
acos += step;
bsin |= (asin + nudge) >> 31;
bsin |= asin >> 31;
bsin <<= 1;
asin += step;
}