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-rw-r--r--controller/fw/Makefile7
-rw-r--r--controller/fw/src/dsss_demod.c64
-rw-r--r--controller/fw/src/dsss_demod.h33
-rw-r--r--controller/fw/tools/butter_filter_gen.py35
4 files changed, 117 insertions, 22 deletions
diff --git a/controller/fw/Makefile b/controller/fw/Makefile
index 3b9cca6..c549e47 100644
--- a/controller/fw/Makefile
+++ b/controller/fw/Makefile
@@ -52,11 +52,14 @@ FMEAS_SAMPLING_RATE ?= 10.0
DSSS_GOLD_CODE_NBITS ?= 5
DSSS_DECIMATION ?= 10
# TODO maybe auto adjust this based on detection rate?
-DSSS_THESHOLD_FACTOR ?= 5.0f
+DSSS_THESHOLD_FACTOR ?= 6.0f
DSSS_WAVELET_WIDTH ?= 7.3
DSSS_WAVELET_LUT_SIZE ?= 69
DSSS_FILTER_FC ?= 3e-3
DSSS_FILTER_ORDER ?= 12
+DSSS_GROUP_CACHE_SIZE ?= 12
+
+PAYLOAD_DATA_BIT ?= 64
CC := $(PREFIX)gcc
CXX := $(PREFIX)g++
@@ -102,6 +105,8 @@ COMMON_CFLAGS += -DDSSS_DECIMATION=$(DSSS_DECIMATION)
COMMON_CFLAGS += -DDSSS_THESHOLD_FACTOR=$(DSSS_THESHOLD_FACTOR)
COMMON_CFLAGS += -DDSSS_WAVELET_WIDTH=$(DSSS_WAVELET_WIDTH)
COMMON_CFLAGS += -DDSSS_WAVELET_LUT_SIZE=$(DSSS_WAVELET_LUT_SIZE)
+COMMON_CFLAGS += -DDSSS_GROUP_CACHE_SIZE=$(DSSS_GROUP_CACHE_SIZE)
+COMMON_CFLAGS += -DPAYLOAD_DATA_BIT=$(PAYLOAD_DATA_BIT)
# for musl
CFLAGS += -Dhidden=
diff --git a/controller/fw/src/dsss_demod.c b/controller/fw/src/dsss_demod.c
index cc1c34e..1cad6f8 100644
--- a/controller/fw/src/dsss_demod.c
+++ b/controller/fw/src/dsss_demod.c
@@ -46,17 +46,16 @@ void debug_print_vector(const char *name, size_t len, const float *data, size_t
#endif
#ifdef SIMULATION
-void dsss_demod_step(struct dsss_demod_state *st, float new_value, size_t sim_pos, int record_channel) {
+void dsss_demod_step(struct dsss_demod_state *st, float new_value, uint64_t ts, int record_channel) {
bool debug = (record_channel == -1)
- && (sim_pos > 1000)
- && (sim_pos % DSSS_CORRELATION_LENGTH == DSSS_CORRELATION_LENGTH-1);
+ && (ts > 1000)
+ && (ts % DSSS_CORRELATION_LENGTH == DSSS_CORRELATION_LENGTH-1);
- if (debug) DEBUG_PRINT("Iteration %zd: signal=%f", sim_pos, new_value);
+ if (debug) DEBUG_PRINT("Iteration %zd: signal=%f", ts, new_value);
#else
void dsss_demod_step(struct dsss_demod_state *st, float new_value) {
#endif
- //const float peak_group_threshold = 0.05 * DSSS_CORRELATION_LENGTH;
//const float hole_patching_threshold = 0.01 * DSSS_CORRELATION_LENGTH;
st->signal[st->signal_wpos] = new_value;
@@ -89,7 +88,7 @@ void dsss_demod_step(struct dsss_demod_state *st, float new_value) {
float max_val = st->group.max;
int max_ch = st->group.max_ch;
- int max_idx = st->group.max_idx + 1;
+ int max_ts = st->group.max_ts;
bool found = false;
for (size_t i=0; i<DSSS_GOLD_CODE_COUNT; i++) {
float val = cwt[i] / avg[i];
@@ -100,7 +99,7 @@ void dsss_demod_step(struct dsss_demod_state *st, float new_value) {
if (fabs(val) > fabs(max_val)) {
max_val = val;
max_ch = i;
- max_idx = st->group.len;
+ max_ts = ts;
}
}
@@ -109,7 +108,7 @@ void dsss_demod_step(struct dsss_demod_state *st, float new_value) {
st->group.len++;
st->group.max = max_val;
st->group.max_ch = max_ch;
- st->group.max_idx = max_idx;
+ st->group.max_ts = max_ts;
return;
}
@@ -120,15 +119,60 @@ void dsss_demod_step(struct dsss_demod_state *st, float new_value) {
/* A group ended. Process result. */
if (record_channel == -1)
DEBUG_PRINT("GROUP FOUND: %8d len=%3d max=%f ch=%d offx=%d",
- sim_pos, st->group.len, st->group.max, st->group.max_ch, st->group.max_idx);
+ ts, st->group.len, st->group.max, st->group.max_ch, st->group.max_ts);
/* reset grouping state */
st->group.len = 0;
- st->group.max_idx = 0;
+ st->group.max_ts = 0;
st->group.max_ch = 0;
st->group.max = 0.0f;
}
+float score_group(const struct group *g, uint64_t ts) {
+ return fabs(g->max); /* Possibly at time penalty 1/(ts-max_ts) later */
+}
+
+ssize_t group_cache_insertion_index(const struct group *g, const struct group *cache, size_t cache_size, uint64_t ts) {
+ float min_score = INFINITY;
+ ssize_t min_idx = -1;
+ for (size_t i=0; i<cache_size; i++) {
+ /* If we find an empty or expired entry, use that */
+ if (cache[i].max_ts == 0 || ts - cache[i].max_ts > group_cache_expiration)
+ return i;
+
+ /* Otherwise check weakest entry */
+ float score = score_group(&cache[i]);
+ if (score < min_score) {
+ min_idx = i;
+ min_score = score;
+ }
+ }
+
+ /* Return weakest group if weaker than candidate */
+ if (min_score < score_group(g))
+ return min_idx;
+
+ return -1;
+}
+
+void group_received(struct dsss_demod_state *st, uint64_t ts) {
+ /* TODO make these constants configurable from Makefile */
+ const uint64_t group_cache_expiration = DSSS_CORRELATION_LENGTH * DSSS_GROUP_CACHE_SIZE;
+
+ /* Insert into group cache if space is available or there is a weaker entry to replace */
+ ssize_t found = group_cache_insertion_index(&st->group, st->group_cache, DSSS_GROUP_CACHE_SIZE);
+ if (!found)
+ return; /* Nothing changed */
+ st->group_cache[found] = st->group;
+
+ float mean_phase = 0.0;
+ for (size_t i=0; i<DSSS_GROUP_CACHE_SIZE; i++)
+ mean_phase += (st->group_cache[i].max_ts) % DSSS_CORRELATION_LENGTH;
+ mean_phase /= DSSS_GROUP_CACHE_SIZE;
+
+
+}
+
float run_iir(const float x, const int order, const struct iir_biquad q[order], struct iir_biquad_state st[order]) {
float intermediate = x;
for (int i=0; i<(order+1)/2; i++)
diff --git a/controller/fw/src/dsss_demod.h b/controller/fw/src/dsss_demod.h
index b6947bc..30ec3f7 100644
--- a/controller/fw/src/dsss_demod.h
+++ b/controller/fw/src/dsss_demod.h
@@ -5,6 +5,8 @@
#define DSSS_GOLD_CODE_COUNT ((1<<DSSS_GOLD_CODE_NBITS) + 1)
#define DSSS_CORRELATION_LENGTH (DSSS_GOLD_CODE_LENGTH * DSSS_DECIMATION)
+#define PAYLOAD_DATA_BYTE ((PAYLOAD_DATA_BIT+7)/8)
+
struct iir_biquad {
float a[2];
float b[3];
@@ -18,6 +20,24 @@ struct cwt_iir_filter_state {
struct iir_biquad_state st[3];
};
+struct {
+ int len; /* length of group in samples */
+ float max; /* signed value of largest peak in group on any channel */
+ uint64_t max_ts; /* absolute position of above peak */
+ int max_ch; /* channel (gold sequence index) of above peak */
+} group;
+
+struct decoder_state {
+ int last_phase;
+ int candidate_phase;
+
+ float last_score;
+ float candidate_score;
+
+ uint8_t data[PAYLOAD_DATA_BYTE];
+ int data_pos;
+};
+
struct dsss_demod_state {
float signal[DSSS_CORRELATION_LENGTH];
size_t signal_wpos;
@@ -27,18 +47,15 @@ struct dsss_demod_state {
struct cwt_iir_filter_state cwt_filter[DSSS_GOLD_CODE_COUNT];
- struct {
- int len; /* length of group in samples */
- float max; /* signed value of largest peak in group on any channel */
- int max_idx; /* position of above peak counted from start of group */
- int max_ch; /* channel (gold sequence index) of above peak */
- } group;
+ struct group group;
+
+ struct group group_cache[DSSS_GROUP_CACHE_SIZE];
};
#ifdef SIMULATION
-void dsss_demod_step(struct dsss_demod_state *st, float new_value, size_t sim_pos, int record_channel);
+void dsss_demod_step(struct dsss_demod_state *st, float new_value, uint64_t ts, int record_channel);
#else /* SIMULATION */
-void dsss_demod_step(struct dsss_demod_state *st, float new_value);
+void dsss_demod_step(struct dsss_demod_state *st, float new_value, uint64_t ts);
#endif /* SIMULATION */
#endif /* __DSSS_DEMOD_H__ */
diff --git a/controller/fw/tools/butter_filter_gen.py b/controller/fw/tools/butter_filter_gen.py
index c77a6ec..0bb81bc 100644
--- a/controller/fw/tools/butter_filter_gen.py
+++ b/controller/fw/tools/butter_filter_gen.py
@@ -18,11 +18,21 @@ def wrap(left='{', right='}', file=None, end=''):
def print_include_guards(macro_name):
print(f'#ifndef {macro_name}')
print(f'#define {macro_name}')
+ print()
yield
+ print()
print(f'#endif /* {macro_name} */')
macro_float = lambda f: f'{f}'.replace('.', 'F').replace('-', 'N').replace('+', 'P')
+ordinal = lambda n: "%d%s" % (n,"tsnrhtdd"[(n//10%10!=1)*(n%10<4)*n%10::4])
+
+SI_TABLE = {-18: 'a', -15: 'f', -12: 'p', -9: 'n', -6: 'ยต', -3: 'm', 0: '', 3: 'k', 6: 'M', 9: 'G', 12: 'T', 15: 'P', 18: 'E'}
+def siprefix(x, space=' ', unit=''):
+ l = math.log10(x)//3*3
+ if l in SI_TABLE:
+ return f'{x/10**l}{space}{SI_TABLE[l]}{unit}'
+ return f'{x}{space}{unit}'
if __name__ == '__main__':
import argparse
@@ -36,10 +46,17 @@ if __name__ == '__main__':
sos = sig.butter(args.n, args.fc, fs=args.fs, output='sos')
print('/* THIS IS A GENERATED FILE. DO NOT EDIT! */')
+ print()
with print_include_guards(f'__BUTTER_FILTER_GENERATED_{args.n}_{macro_float(args.fc)}_{macro_float(args.fs)}__'):
+
+ print(f'/* {ordinal(args.n)} order Butterworth IIR filter coefficients')
+ print(f' *')
+ print(f' * corner frequency f_c = {siprefix(args.fc)}Hz')
+ print(f' * sampling rate f_s = {siprefix(args.fs)}Hz')
+ print(f' */')
+ print()
print(f'#define {args.macro_name.upper()}_ORDER {args.n}')
print(f'#define {args.macro_name.upper()}_CLEN {(args.n+1)//2}')
- print(f'#define {args.macro_name.upper()}_COEFF ', end='')
# scipy.signal.butter by default returns extremely small bs for the first biquad and large ones for subsequent
# sections. Balance magnitudes to reduce possible rounding errors.
@@ -48,10 +65,14 @@ if __name__ == '__main__':
mags = [approx_mag // len(sos)] * len(sos)
mags[0] += approx_mag - sum(mags)
sos[0][:3] /= 10**approx_mag
+ sos = np.array([ sec * np.array([10**mag, 10**mag, 10**mag, 1, 1, 1]) for mag, sec in zip(mags, sos) ])
+
+ ones = np.ones([100000])
+ _, steady_state = sig.sosfilt(sos, ones, zi=np.zeros([(args.n+1)//2, 2]))
- for mag, sec in zip(mags, sos):
+ print(f'#define {args.macro_name.upper()}_COEFF ', end='')
+ for sec in sos:
bs, ases = sec[:3], sec[4:6]
- bs *= 10**mag
with wrap():
print('.b=', end='')
@@ -62,3 +83,11 @@ if __name__ == '__main__':
print(', '.join(f'{v}' for v in ases), end='')
print(', ', end='')
print()
+
+ print(f'#define {args.macro_name.upper()}_STEADY_STATE ', end='')
+ for sec in steady_state:
+ with wrap():
+ print(', '.join(f'{v}' for v in sec), end='')
+ print(', ', end='')
+ print()
+
generated by cgit (git 2.34.1) at 2024-11-21 16:54:48 +0000