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C1 receiver with better filtering

pull/18/head
Xael South 2021-02-04 14:20:04 +00:00
rodzic 8bec4a2b08
commit 8ac790dc16
2 zmienionych plików z 12 dodań i 5 usunięć
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10
filter/lp_fir_butter_1600kHz_160kHz_200kHz.m
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@ -9,7 +9,13 @@ Rp = 1;
Rs = 40;
[n, Wc] = buttord(Wp1, Ws1, Rp, Rs);
[b] = fir1(n, Wc);
[h] = fir1(n, Wc);
f_delta = 50e3;
h_length = length(h);
h_new = h.*cos(2*pi*f_delta*[0:h_length-1]/samplerate);
print_fir_filter_coef(h);
print_fir_filter_coef(h_new);
print_fir_filter_coef(b);

7
rtl_wmbus.c
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@ -124,6 +124,7 @@ static inline float lp_fir_butter_1600kHz_160kHz_200kHz(int sample, size_t i_or_
{
#define COEFFS 23
static const float b[COEFFS] = {0.000140535927, 1.102280392e-05, 0.0001309279731, 0.001356012537, 0.00551787474, 0.01499414005, 0.03160167988, 0.05525973093, 0.08315031015, 0.1099887688, 0.1295143636, 0.1366692652, 0.1295143636, 0.1099887688, 0.08315031015, 0.05525973093, 0.03160167988, 0.01499414005, 0.00551787474, 0.001356012537, 0.0001309279731, 1.102280392e-05, 0.000140535927, };
//static const float b[COEFFS] = {0.001645672124, 0.0004733757463, -0.002542116469, -0.008572441674, -0.01545406295, -0.01651661113, -0.002914917097, 0.03113207374, 0.08317149659, 0.1410058012, 0.1866042197, 0.2039350204, 0.1866042197, 0.1410058012, 0.08317149659, 0.03113207374, -0.002914917097, -0.01651661113, -0.01545406295, -0.008572441674, -0.002542116469, 0.0004733757463, 0.001645672124, };
static float i_hist[COEFFS] = {};
static float q_hist[COEFFS] = {};
@ -316,9 +317,9 @@ static inline float polar_discriminator(float i, float q)
const float complex s = i + q * _Complex_I;
const float complex y = s * conj(s_last);
#if 0
#if 1
const float delta_phi = atan2_libm(y);
#elif 1
#elif 0
const float delta_phi = atan2_approximation(y);
#else
const float delta_phi = atan2_approximation2(y);
@ -630,7 +631,7 @@ int main(int argc, char *argv[])
// The sample rate decimation is realised as sum over i and q,
// which must not be divided by decimation factor before
// demodulating (atan2(q,i)).
#if 0
#if 1
i = lp_fir_butter_1600kHz_160kHz_200kHz(i_unfilt, 0);
q = lp_fir_butter_1600kHz_160kHz_200kHz(q_unfilt, 1);
#elif 0