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WIP DSSS decoding

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jaseg 2020-03-06 11:09:35 +01:00
parent 4b419bd1ad
commit ad9e17c35c
18 changed files with 578 additions and 31753 deletions
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61
controller/fw/src/dsss_demod.c
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@ -11,17 +11,14 @@
#include "simulation.h"
#include "generated/dsss_gold_code.h"
#include "generated/dsss_butter_filter.h"
/* Generated CWT wavelet LUT */
extern const float * const dsss_cwt_wavelet_table;
struct iir_biquad cwt_filter_bq[3] = {
{.a = {-1.993939440f, 0.993949280f}, .b = {0.2459934300683e-5, 0.4919868601367e-5, 0.2459934300683e-5}},
{.a = {-1.995557124f, 0.995566972f}, .b = {0.2461930046414e-5, 0.4923860092828e-5, 0.2461930046414e-5}},
{.a = {-1.998365254f, 0.998375115f}, .b = {0.2465394452097e-5, 0.4930788904195e-5, 0.2465394452097e-5}},
};
struct iir_biquad cwt_filter_bq[DSSS_FILTER_CLEN] = {DSSS_FILTER_COEFF};
float gold_correlate_step(const size_t ncode, const float a[DSSS_CORRELATION_LENGTH], size_t offx);
float gold_correlate_step(const size_t ncode, const float a[DSSS_CORRELATION_LENGTH], size_t offx, bool debug);
float cwt_convolve_step(const float v[DSSS_WAVELET_LUT_SIZE], size_t offx);
float run_iir(const float x, const int order, const struct iir_biquad q[order], struct iir_biquad_state st[order]);
float run_biquad(float x, const struct iir_biquad *const q, struct iir_biquad_state *const restrict st);
@ -34,7 +31,7 @@ void dsss_demod_step(struct dsss_demod_state *st, float new_value) {
//#define DEBUG_PRINT(...) ((void)0)
//#define DEBUG_PRINTN(...) ((void)0)
bool debug = sim_pos % DSSS_CORRELATION_LENGTH == 0;
bool debug = sim_pos % DSSS_CORRELATION_LENGTH == DSSS_CORRELATION_LENGTH-1;
if (debug) DEBUG_PRINT("Iteration %zd", sim_pos);
//const float peak_group_threshold = 0.05 * DSSS_CORRELATION_LENGTH;
//const float hole_patching_threshold = 0.01 * DSSS_CORRELATION_LENGTH;
@ -45,14 +42,14 @@ void dsss_demod_step(struct dsss_demod_state *st, float new_value) {
/* use new, incremented wpos for gold_correlate_step as first element of old data in ring buffer */
for (size_t i=0; i<DSSS_GOLD_CODE_COUNT; i++)
st->correlation[i][st->correlation_wpos] = gold_correlate_step(i, st->signal, st->correlation_wpos);
st->correlation[i][st->correlation_wpos] = gold_correlate_step(i, st->signal, st->signal_wpos, debug);
/* debug */
/*
DEBUG_PRINTN(" correlation: [");
for (size_t i=0; i<DSSS_GOLD_CODE_COUNT; i++)
DEBUG_PRINTN("%f, ", st->correlation[i][st->correlation_wpos]);
DEBUG_PRINTN("]\n");
*/
if (debug) {
DEBUG_PRINTN(" correlation: [");
for (size_t i=0; i<DSSS_GOLD_CODE_COUNT; i++)
DEBUG_PRINTN("%f, ", st->correlation[i][st->correlation_wpos]);
DEBUG_PRINTN("]\n");
}
/* end */
st->correlation_wpos = (st->correlation_wpos + 1) % ARRAY_LENGTH(st->correlation[0]);
@ -60,10 +57,12 @@ void dsss_demod_step(struct dsss_demod_state *st, float new_value) {
for (size_t i=0; i<DSSS_GOLD_CODE_COUNT; i++)
cwt[i] = cwt_convolve_step(st->correlation[i], st->correlation_wpos);
/* debug */
/*
if (debug) DEBUG_PRINTN(" cwt: [");
for (size_t i=0; i<DSSS_GOLD_CODE_COUNT; i++)
if (debug) DEBUG_PRINTN("%f, ", cwt[i]);
if (debug) DEBUG_PRINTN("]\n");
*/
/* end */
float avg[DSSS_GOLD_CODE_COUNT];
@ -82,10 +81,10 @@ void dsss_demod_step(struct dsss_demod_state *st, float new_value) {
int max_ch = st->group.max_ch;
int max_idx = st->group.max_idx + 1;
bool found = false;
if (debug) DEBUG_PRINTN(" rel: [");
//if (debug) DEBUG_PRINTN(" rel: [");
for (size_t i=0; i<DSSS_GOLD_CODE_COUNT; i++) {
float val = cwt[i] / avg[i];
if (debug) DEBUG_PRINTN("%f, ", val);
//if (debug) DEBUG_PRINTN("%f, ", val);
if (fabs(val) > DSSS_THESHOLD_FACTOR)
found = true;
@ -96,7 +95,7 @@ void dsss_demod_step(struct dsss_demod_state *st, float new_value) {
max_idx = st->group.len;
}
}
if (debug) DEBUG_PRINTN("]\n");
//if (debug) DEBUG_PRINTN("]\n");
/* debug */
if (debug) DEBUG_PRINT(" found=%d len=%d idx=%d ch=%d max=%f",
@ -162,19 +161,27 @@ float cwt_convolve_step(const float v[DSSS_WAVELET_LUT_SIZE], size_t offx) {
*
* [0] https://docs.scipy.org/doc/numpy/reference/generated/numpy.correlate.html
*/
float gold_correlate_step(const size_t ncode, const float a[DSSS_CORRELATION_LENGTH], size_t offx) {
float gold_correlate_step(const size_t ncode, const float a[DSSS_CORRELATION_LENGTH], size_t offx, bool debug) {
float acc_outer = 0.0f;
uint8_t table_byte = 0;
for (size_t i=0, pos=0; i<DSSS_GOLD_CODE_LENGTH; i++, pos += DSSS_DECIMATION) {
float acc_inner = 0.0f;
for (size_t j=0; j<DSSS_DECIMATION; j++) {
if ((pos&7) == 0)
table_byte = dsss_gold_code_table[ncode][pos>>3]; /* Fetch sequence table item */
int bv = table_byte & (1<<(pos&7)); /* Extract bit */
bv = !!bv*2 - 1; /* Map 0, 1 -> -1, 1 */
acc_inner += a[(offx + i + j) % DSSS_CORRELATION_LENGTH] * bv; /* Multiply item */
if (debug) DEBUG_PRINTN("Correlate n=%d: ", ncode);
for (size_t i=0; i<DSSS_GOLD_CODE_LENGTH; i++) {
if ((i&7) == 0) {
table_byte = dsss_gold_code_table[ncode][i>>3]; /* Fetch sequence table item */
if (debug) DEBUG_PRINTN("|");
}
acc_outer += acc_inner;
int bv = table_byte & (0x80>>(i&7)); /* Extract bit */
bv = !!bv*2 - 1; /* Map 0, 1 -> -1, 1 */
if (debug) DEBUG_PRINTN("%s%d\033[0m", bv == 1 ? "\033[92m" : "\033[91m", (bv+1)/2);
float acc_inner = 0.0f;
for (size_t j=0; j<DSSS_DECIMATION; j++)
acc_inner += a[(offx + i*DSSS_DECIMATION + j) % DSSS_CORRELATION_LENGTH]; /* Multiply item */
//if (debug) DEBUG_PRINTN("%.2f ", acc_inner);
acc_outer += acc_inner * bv;
}
if (debug) DEBUG_PRINTN("\n");
return acc_outer / DSSS_CORRELATION_LENGTH;
}