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improved dopper estimation from adaptive filter taps (intermediate)

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cmayer 2019-05-13 10:15:30 +02:00
parent 6c6c8520ea
commit f0dc97ed64
2 changed files with 17 additions and 14 deletions
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29
lib/adaptive_dfe_impl.cc
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@ -94,7 +94,7 @@ adaptive_dfe_impl::adaptive_dfe_impl(int sps, // samples per symbol
, _num_samples_since_filter_update(0)
, _rotated_samples()
, _rotator()
, _control_loop(2*M_PI/100, 5e-3, -5e-3)
, _control_loop(2*M_PI/100, 5e-5, -5e-5)
{
GR_LOG_DECLARE_LOGPTR(d_logger);
GR_LOG_ASSIGN_LOGPTR(d_logger, "adaptive_dfe");
@ -287,23 +287,12 @@ gr_complex adaptive_dfe_impl::filter(gr_complex const* start, gr_complex const*
// std::cout << "FILTER: " << filter_output <<" " << known_symbol << " " << start[_nB+1] << std::endl;
// (3) filter update
if (is_known || update_taps) {
// (3a) control loop update for doppler correction using the adaptibve filter taps
gr_complex acc(0);
for (int j=_nB+1-2*_sps; j<_nB+1+2*_sps+1; ++j)
acc += std::conj(_last_taps_samples[j]) * _taps_samples[j];
float const frequency_err = gr::fast_atan2f(acc)/_num_samples_since_filter_update; // frequency error (rad/sample)
_control_loop.advance_loop(frequency_err);
_control_loop.phase_wrap();
_control_loop.frequency_limit();
_rotator.set_phase_incr(gr_expj(_control_loop.get_frequency()));
// (3b) update of adaptive filter taps
// (3a) update of adaptive filter taps
gr_complex const err = filter_output - known_symbol;
// taps_samples
for (int j=0; j<_nB+_nF+1; ++j) {
_last_taps_samples[j] = _taps_samples[j];
_taps_samples[j] -= _mu*err*std::conj(start[j]);
_num_samples_since_filter_update = 0;
}
// taps_symbols
if (_use_symbol_taps) {
@ -316,6 +305,20 @@ gr_complex adaptive_dfe_impl::filter(gr_complex const* start, gr_complex const*
_hist_symbol_index = 0;
}
}
// (3b) control loop update for doppler correction using the adaptibve filter taps
if (_symbol_counter+1 == _symbols.size()) {
gr_complex acc(0);
for (int j=_nB+1-2*_sps; j<_nB+1+2*_sps+1; ++j)
acc += std::conj(_last_taps_samples[j]) * _taps_samples[j];
float const frequency_err = gr::fast_atan2f(acc)/(1+0*_num_samples_since_filter_update); // frequency error (rad/sample)
std::cout << "frequency_err " << frequency_err << " " << _num_samples_since_filter_update << std::endl;
_control_loop.advance_loop(frequency_err);
_control_loop.phase_wrap();
_control_loop.frequency_limit();
_rotator.set_phase_incr(gr_expj(_control_loop.get_frequency()));
_num_samples_since_filter_update = 0;
}
// (4) save the descrambled symbol (-> frame_info)
_descrambled_symbols[_symbol_counter] = filter_output*std::conj(_scramble[_symbol_counter]);
return _descrambled_symbols[_symbol_counter++];

2
python/physical_layer_driver.py
View file

@ -55,7 +55,7 @@ class physical_layer_driver(gr.hier_block2):
self._rrc_taps = filter.firdes.root_raised_cosine(1.0, samp_rate, samp_rate/sps, 0.35, 11*sps)
preamble_offset,preamble_samples = self._physical_layer_driver_description.get_preamble_z()
preamble_length = self._sps * len(self._physical_layer_driver_description.get_preamble()) ## len(preamble_samples)
preamble_length = len(preamble_samples)
##preamble_length = len(preamble_samples)
self._rrc_filter = filter.fir_filter_ccc(1, (self._rrc_taps))
self._corr_est = digital.corr_est_cc(symbols = (preamble_samples.tolist()),
sps = sps,