diff options
Diffstat (limited to 'gnuradio-core/src')
4 files changed, 29 insertions, 22 deletions
diff --git a/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.cc b/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.cc index 030e45ddf..7f2c468b7 100644 --- a/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.cc +++ b/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.cc @@ -53,7 +53,7 @@ gr_fll_band_edge_cc_sptr gr_make_fll_band_edge_cc (float samps_per_sym, float ro } -static int ios[] = {sizeof(gr_complex), sizeof(float), sizeof(float), sizeof(float)}; +static int ios[] = {sizeof(gr_complex), sizeof(float), sizeof(float), sizeof(gr_complex)}; static std::vector<int> iosig(ios, ios+sizeof(ios)/sizeof(int)); gr_fll_band_edge_cc::gr_fll_band_edge_cc (float samps_per_sym, float rolloff, int filter_size, float alpha, float beta) @@ -83,10 +83,11 @@ gr_fll_band_edge_cc::~gr_fll_band_edge_cc () void gr_fll_band_edge_cc::set_alpha(float alpha) { - float eta = sqrt(2.0)/2.0; - float theta = alpha; - d_alpha = (4*eta*theta) / (1.0 + 2.0*eta*theta + theta*theta); - d_beta = (4*theta*theta) / (1.0 + 2.0*eta*theta + theta*theta); + //float eta = sqrt(2.0)/2.0; + //float theta = alpha; + //d_alpha = (4*eta*theta) / (1.0 + 2.0*eta*theta + theta*theta); + //d_beta = (4*theta*theta) / (1.0 + 2.0*eta*theta + theta*theta); + d_alpha = alpha; } void @@ -160,11 +161,12 @@ gr_fll_band_edge_cc::work (int noutput_items, const gr_complex *in = (const gr_complex *) input_items[0]; gr_complex *out = (gr_complex *) output_items[0]; - float *frq, *phs, *err; + float *frq, *phs; + gr_complex *err; if(output_items.size() > 2) { frq = (float *) output_items[1]; phs = (float *) output_items[2]; - err = (float *) output_items[3]; + err = (gr_complex *) output_items[3]; } if (d_updated) { @@ -174,16 +176,17 @@ gr_fll_band_edge_cc::work (int noutput_items, int i; gr_complex nco_out; - float out_upper, out_lower; + gr_complex out_upper, out_lower; float error; + float avg_k = 0.1; for(i = 0; i < noutput_items; i++) { nco_out = gr_expj(d_phase); out[i] = in[i] * nco_out; - out_upper = norm(d_filter_upper->filter(&out[i])); - out_lower = norm(d_filter_lower->filter(&out[i])); - error = out_lower - out_upper; - d_error = 0.01*error + 0.99*d_error; // average error + out_upper = (d_filter_upper->filter(&out[i])); + out_lower = (d_filter_lower->filter(&out[i])); + error = -real((out_upper + out_lower) * conj(out_upper - out_lower)); + d_error = avg_k*error + avg_k*d_error; // average error d_freq = d_freq + d_beta * d_error; d_phase = d_phase + d_freq + d_alpha * d_error; diff --git a/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.h b/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.h index 09baf7fde..178e18f3e 100644 --- a/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.h +++ b/gnuradio-core/src/lib/general/gr_fll_band_edge_cc.h @@ -45,8 +45,12 @@ class gri_fft_complex; * (e.g., rolloff factor) of the modulated signal. The placement in frequency of the band-edges * is determined by the oversampling ratio (number of samples per symbol) and the excess bandwidth. * The size of the filters should be fairly large so as to average over a number of symbols. - * The FLL works by calculating the power in both the upper and lower bands and comparing them. The - * difference in power between the filters is proportional to the frequency offset. + * + * The FLL works by filtering the upper and lower band edges into x_u(t) and x_l(t), respectively. + * These are combined to form cc(t) = x_u(t) + x_l(t) and ss(t) = x_u(t) - x_l(t). Combining + * these to form the signal e(t) = Re{cc(t) \times ss(t)^*} (where ^* is the complex conjugate) + * provides an error signal at the DC term that is directly proportional to the carrier frequency. + * We then make a second-order loop using the error signal that is the running average of e(t). * * In theory, the band-edge filter is the derivative of the matched filter in frequency, * (H_be(f) = \frac{H(f)}{df}. In practice, this comes down to a quarter sine wave at the point diff --git a/gnuradio-core/src/python/gnuradio/blks2impl/dbpsk2.py b/gnuradio-core/src/python/gnuradio/blks2impl/dbpsk2.py index 1d1bfc298..135b38e1f 100644 --- a/gnuradio-core/src/python/gnuradio/blks2impl/dbpsk2.py +++ b/gnuradio-core/src/python/gnuradio/blks2impl/dbpsk2.py @@ -38,7 +38,7 @@ _def_gray_code = True _def_verbose = False _def_log = False -_def_freq_alpha = 4e-3 +_def_freq_alpha = 0.010 _def_costas_alpha = 0.1 _def_timing_alpha = 0.100 _def_timing_beta = 0.010 @@ -226,7 +226,7 @@ class dbpsk2_demod(gr.hier_block2): self._samples_per_symbol = samples_per_symbol self._excess_bw = excess_bw self._freq_alpha = freq_alpha - self._freq_beta = 0.25*self._freq_alpha**2 + self._freq_beta = 0.10*self._freq_alpha self._costas_alpha = costas_alpha self._timing_alpha = timing_alpha self._timing_beta = _def_timing_beta @@ -308,11 +308,11 @@ class dbpsk2_demod(gr.hier_block2): print "bits per symbol: %d" % self.bits_per_symbol() print "Gray code: %s" % self._gray_code print "RRC roll-off factor: %.2f" % self._excess_bw - print "FLL gain: %.2f" % self._freq_alpha - print "Costas Loop alpha: %.2f" % self._costas_alpha - print "Costas Loop beta: %.2f" % self._costas_beta - print "Timing alpha gain: %.2f" % self._timing_alpha - print "Timing beta gain: %.2f" % self._timing_beta + print "FLL gain: %.2e" % self._freq_alpha + print "Costas Loop alpha: %.2e" % self._costas_alpha + print "Costas Loop beta: %.2e" % self._costas_beta + print "Timing alpha gain: %.2e" % self._timing_alpha + print "Timing beta gain: %.2e" % self._timing_beta print "Timing max dev: %.2f" % self._timing_max_dev def _setup_logging(self): diff --git a/gnuradio-core/src/python/gnuradio/blks2impl/dqpsk2.py b/gnuradio-core/src/python/gnuradio/blks2impl/dqpsk2.py index 81dccc2eb..f852a324c 100644 --- a/gnuradio-core/src/python/gnuradio/blks2impl/dqpsk2.py +++ b/gnuradio-core/src/python/gnuradio/blks2impl/dqpsk2.py @@ -38,7 +38,7 @@ _def_gray_code = True _def_verbose = False _def_log = False -_def_freq_alpha = 4e-3 +_def_freq_alpha = 0.010 _def_costas_alpha = 0.01 _def_timing_alpha = 0.100 _def_timing_beta = 0.010 |