// execute synchronizer, receiving header
// _q : frame synchronizer object
// _x : input sample
// _sym : demodulated symbol
void flexframesync_execute_rxheader(flexframesync _q,
float complex _x)
{
// step synchronizer
float complex mf_out = 0.0f;
int sample_available = flexframesync_step(_q, _x, &mf_out);
// compute output if timeout
if (sample_available) {
// save payload symbols (modem input/output)
_q->header_sym[_q->symbol_counter] = mf_out;
// increment counter
_q->symbol_counter++;
if (_q->symbol_counter == _q->header_sym_len) {
// decode header
flexframesync_decode_header(_q);
if (_q->header_valid) {
// continue on to decoding payload
_q->symbol_counter = 0;
_q->state = FLEXFRAMESYNC_STATE_RXPAYLOAD;
return;
}
// update statistics
_q->framedatastats.num_frames_detected++;
// header invalid: invoke callback
if (_q->callback != NULL) {
// set framestats internals
_q->framesyncstats.evm = 0.0f; //20*log10f(sqrtf(_q->framesyncstats.evm / 600));
_q->framesyncstats.rssi = 20*log10f(_q->gamma_hat);
_q->framesyncstats.cfo = nco_crcf_get_frequency(_q->mixer);
_q->framesyncstats.framesyms = NULL;
_q->framesyncstats.num_framesyms = 0;
_q->framesyncstats.mod_scheme = LIQUID_MODEM_UNKNOWN;
_q->framesyncstats.mod_bps = 0;
_q->framesyncstats.check = LIQUID_CRC_UNKNOWN;
_q->framesyncstats.fec0 = LIQUID_FEC_UNKNOWN;
_q->framesyncstats.fec1 = LIQUID_FEC_UNKNOWN;
// invoke callback method
_q->callback(_q->header_dec,
_q->header_valid,
NULL, // payload
0, // payload length
0, // payload valid,
_q->framesyncstats,
_q->userdata);
}
// reset frame synchronizer
flexframesync_reset(_q);
return;
}
}
}
// execute synchronizer, receiving payload
// _q : frame synchronizer object
// _x : input sample
// _sym : demodulated symbol
void flexframesync_execute_rxpayload(flexframesync _q,
float complex _x)
{
// mix signal down
float complex y;
nco_crcf_mix_down(_q->nco_coarse, _x*0.5f/_q->gamma_hat, &y);
nco_crcf_step(_q->nco_coarse);
// update symbol synchronizer
float complex mf_out = 0.0f;
int sample_available = flexframesync_update_symsync(_q, y, &mf_out);
// compute output if timeout
if (sample_available) {
// push through fine-tuned nco
nco_crcf_mix_down(_q->nco_fine, mf_out, &mf_out);
// save payload symbols for callback (up to 256 values)
if (_q->payload_counter < 256)
_q->payload_sym[_q->payload_counter] = mf_out;
// demodulate
unsigned int sym_out = 0;
modem_demodulate(_q->demod_payload, mf_out, &sym_out);
_q->payload_mod[_q->payload_counter] = (unsigned char)sym_out;
// update phase-locked loop and fine-tuned NCO
float phase_error = modem_get_demodulator_phase_error(_q->demod_payload);
nco_crcf_pll_step(_q->nco_fine, phase_error);
nco_crcf_step(_q->nco_fine);
// increment counter
_q->payload_counter++;
if (_q->payload_counter == _q->payload_mod_len) {
// decode payload and invoke callback
flexframesync_decode_payload(_q);
// invoke callback
if (_q->callback != NULL) {
// set framestats internals
_q->framestats.evm = 20*log10f(sqrtf(_q->framestats.evm / FLEXFRAME_H_SYM));
_q->framestats.rssi = 20*log10f(_q->gamma_hat);
_q->framestats.cfo = nco_crcf_get_frequency(_q->nco_coarse) +
nco_crcf_get_frequency(_q->nco_fine) / 2.0f; //(float)(_q->k);
_q->framestats.framesyms = _q->payload_sym;
_q->framestats.num_framesyms = _q->payload_mod_len > 256 ? 256 : _q->payload_mod_len;
_q->framestats.mod_scheme = _q->ms_payload;
_q->framestats.mod_bps = _q->bps_payload;
_q->framestats.check = _q->check;
_q->framestats.fec0 = _q->fec0;
_q->framestats.fec1 = _q->fec1;
// invoke callback method
_q->callback(_q->header,
_q->header_valid,
_q->payload_dec,
_q->payload_dec_len,
_q->payload_valid,
_q->framestats,
_q->userdata);
}
// reset frame synchronizer
flexframesync_reset(_q);
return;
}
}
}
// execute synchronizer, receiving header
// _q : frame synchronizer object
// _x : input sample
void flexframesync_execute_rxheader(flexframesync _q,
float complex _x)
{
// mix signal down
float complex y;
nco_crcf_mix_down(_q->nco_coarse, _x*0.5f/_q->gamma_hat, &y);
nco_crcf_step(_q->nco_coarse);
// update symbol synchronizer
float complex mf_out = 0.0f;
int sample_available = flexframesync_update_symsync(_q, y, &mf_out);
// compute output if timeout
if (sample_available) {
// push through fine-tuned nco
nco_crcf_mix_down(_q->nco_fine, mf_out, &mf_out);
#if DEBUG_FLEXFRAMESYNC
if (_q->debug_enabled)
_q->header_sym[_q->header_counter] = mf_out;
#endif
// demodulate
unsigned int sym_out = 0;
#if DEMOD_HEADER_SOFT
unsigned char bpsk_soft_bit = 0;
modem_demodulate_soft(_q->demod_header, mf_out, &sym_out, &bpsk_soft_bit);
_q->header_mod[_q->header_counter] = bpsk_soft_bit;
#else
modem_demodulate(_q->demod_header, mf_out, &sym_out);
_q->header_mod[_q->header_counter] = (unsigned char)sym_out;
#endif
// update phase-locked loop and fine-tuned NCO
float phase_error = modem_get_demodulator_phase_error(_q->demod_header);
nco_crcf_pll_step(_q->nco_fine, phase_error);
nco_crcf_step(_q->nco_fine);
// update error vector magnitude
float evm = modem_get_demodulator_evm(_q->demod_header);
_q->framestats.evm += evm*evm;
// increment counter
_q->header_counter++;
if (_q->header_counter == FLEXFRAME_H_SYM) {
// decode header and invoke callback
flexframesync_decode_header(_q);
// invoke callback if header is invalid
if (!_q->header_valid && _q->callback != NULL) {
// set framestats internals
_q->framestats.evm = 20*log10f(sqrtf(_q->framestats.evm / FLEXFRAME_H_SYM));
_q->framestats.rssi = 20*log10f(_q->gamma_hat);
_q->framestats.cfo = nco_crcf_get_frequency(_q->nco_coarse) +
nco_crcf_get_frequency(_q->nco_fine) / 2.0f; //(float)(_q->k);
_q->framestats.framesyms = NULL;
_q->framestats.num_framesyms = 0;
_q->framestats.mod_scheme = LIQUID_MODEM_UNKNOWN;
_q->framestats.mod_bps = 0;
_q->framestats.check = LIQUID_CRC_UNKNOWN;
_q->framestats.fec0 = LIQUID_FEC_UNKNOWN;
_q->framestats.fec1 = LIQUID_FEC_UNKNOWN;
// invoke callback method
_q->callback(_q->header,
_q->header_valid,
NULL,
0,
0,
_q->framestats,
_q->userdata);
}
if (!_q->header_valid) {
flexframesync_reset(_q);
return;
}
// update state
_q->state = STATE_RXPAYLOAD;
}
}
}
// execute synchronizer, receiving payload
// _q : frame synchronizer object
// _x : input sample
// _sym : demodulated symbol
void flexframesync_execute_rxpayload(flexframesync _q,
float complex _x)
{
// step synchronizer
float complex mf_out = 0.0f;
int sample_available = flexframesync_step(_q, _x, &mf_out);
// compute output if timeout
if (sample_available) {
// TODO: clean this up
// mix down with fine-tuned oscillator
nco_crcf_mix_down(_q->pll, mf_out, &mf_out);
// track phase, accumulate error-vector magnitude
unsigned int sym;
modem_demodulate(_q->payload_demod, mf_out, &sym);
float phase_error = modem_get_demodulator_phase_error(_q->payload_demod);
float evm = modem_get_demodulator_evm (_q->payload_demod);
nco_crcf_pll_step(_q->pll, phase_error);
nco_crcf_step(_q->pll);
_q->framesyncstats.evm += evm*evm;
// save payload symbols (modem input/output)
_q->payload_sym[_q->symbol_counter] = mf_out;
// increment counter
_q->symbol_counter++;
if (_q->symbol_counter == _q->payload_sym_len) {
// decode payload
_q->payload_valid = qpacketmodem_decode(_q->payload_decoder,
_q->payload_sym,
_q->payload_dec);
// update statistics
_q->framedatastats.num_frames_detected++;
_q->framedatastats.num_headers_valid++;
_q->framedatastats.num_payloads_valid += _q->payload_valid;
_q->framedatastats.num_bytes_received += _q->payload_dec_len;
// invoke callback
if (_q->callback != NULL) {
// set framestats internals
int ms = qpacketmodem_get_modscheme(_q->payload_decoder);
_q->framesyncstats.evm = 10*log10f(_q->framesyncstats.evm / (float)_q->payload_sym_len);
_q->framesyncstats.rssi = 20*log10f(_q->gamma_hat);
_q->framesyncstats.cfo = nco_crcf_get_frequency(_q->mixer);
_q->framesyncstats.framesyms = _q->payload_sym;
_q->framesyncstats.num_framesyms = _q->payload_sym_len;
_q->framesyncstats.mod_scheme = ms;
_q->framesyncstats.mod_bps = modulation_types[ms].bps;
_q->framesyncstats.check = qpacketmodem_get_crc(_q->payload_decoder);
_q->framesyncstats.fec0 = qpacketmodem_get_fec0(_q->payload_decoder);
_q->framesyncstats.fec1 = qpacketmodem_get_fec1(_q->payload_decoder);
// invoke callback method
_q->callback(_q->header_dec,
_q->header_valid,
_q->payload_dec,
_q->payload_dec_len,
_q->payload_valid,
_q->framesyncstats,
_q->userdata);
}
// reset frame synchronizer
flexframesync_reset(_q);
return;
}
}
}