diff options
| -rw-r--r-- | gnuradio-core/src/python/gnuradio/blks2impl/dbpsk2.py | 4 | ||||
| -rw-r--r-- | gnuradio-core/src/python/gnuradio/blks2impl/dqpsk2.py | 39 |
2 files changed, 32 insertions, 11 deletions
diff --git a/gnuradio-core/src/python/gnuradio/blks2impl/dbpsk2.py b/gnuradio-core/src/python/gnuradio/blks2impl/dbpsk2.py index e36e4f011..a692e7d1f 100644 --- a/gnuradio-core/src/python/gnuradio/blks2impl/dbpsk2.py +++ b/gnuradio-core/src/python/gnuradio/blks2impl/dbpsk2.py @@ -254,7 +254,9 @@ class dbpsk2_demod(gr.hier_block2): # symbol timing recovery with RRC data filter nfilts = 32 ntaps = 11 * samples_per_symbol*nfilts - taps = gr.firdes.root_raised_cosine(nfilts, nfilts, 1.0/float(self._samples_per_symbol), self._excess_bw, ntaps) + taps = gr.firdes.root_raised_cosine(nfilts, nfilts, + 1.0/float(self._samples_per_symbol), + self._excess_bw, ntaps) self.time_recov = gr.pfb_clock_sync_ccf(self._samples_per_symbol, self._timing_alpha, taps, nfilts, nfilts/2, self._timing_max_dev) diff --git a/gnuradio-core/src/python/gnuradio/blks2impl/dqpsk2.py b/gnuradio-core/src/python/gnuradio/blks2impl/dqpsk2.py index fd1e9f0ef..b1ffb0d24 100644 --- a/gnuradio-core/src/python/gnuradio/blks2impl/dqpsk2.py +++ b/gnuradio-core/src/python/gnuradio/blks2impl/dqpsk2.py @@ -38,6 +38,7 @@ _def_gray_code = True _def_verbose = False _def_log = False +_def_freq_alpha = 4e-3 _def_costas_alpha = 0.01 _def_timing_alpha = 0.100 _def_timing_beta = 0.010 @@ -182,6 +183,7 @@ class dqpsk2_demod(gr.hier_block2): def __init__(self, samples_per_symbol=_def_samples_per_symbol, excess_bw=_def_excess_bw, + freq_alpha=_def_freq_alpha, costas_alpha=_def_costas_alpha, timing_alpha=_def_timing_alpha, timing_max_dev=_def_timing_max_dev, @@ -199,6 +201,8 @@ class dqpsk2_demod(gr.hier_block2): @type samples_per_symbol: float @param excess_bw: Root-raised cosine filter excess bandwidth @type excess_bw: float + @param freq_alpha: loop filter gain for frequency recovery + @type freq_alpha: float @param costas_alpha: loop filter gain @type costas_alphas: float @param timing_alpha: timing loop alpha gain @@ -223,6 +227,8 @@ class dqpsk2_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._costas_alpha = costas_alpha self._timing_alpha = timing_alpha self._timing_beta = _def_timing_beta @@ -238,24 +244,35 @@ class dqpsk2_demod(gr.hier_block2): self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100) #self.agc = gr.feedforward_agc_cc(16, 2.0) - self._costas_beta = 0.25 * self._costas_alpha * self._costas_alpha - # Allow a frequency swing of +/- half of the sample rate - fmin = -0.5 - fmax = 0.5 + # Frequency correction + self.freq_recov = gr.fll_band_edge_cc(self._samples_per_symbol, self._excess_bw, + 11*self._samples_per_symbol, + self._freq_alpha, self._freq_beta) - self.clock_recov = gr.costas_loop_cc(self._costas_alpha, - self._costas_beta, - fmax, fmin, arity) # symbol timing recovery with RRC data filter nfilts = 32 ntaps = 11 * samples_per_symbol*nfilts - taps = gr.firdes.root_raised_cosine(nfilts, nfilts, 1.0/float(self._samples_per_symbol), self._excess_bw, ntaps) + taps = gr.firdes.root_raised_cosine(nfilts, nfilts, + 1.0/float(self._samples_per_symbol), + self._excess_bw, ntaps) self.time_recov = gr.pfb_clock_sync_ccf(self._samples_per_symbol, self._timing_alpha, taps, nfilts, nfilts/2, self._timing_max_dev) self.time_recov.set_beta(self._timing_beta) + + # Perform phase / fine frequency correction + self._costas_beta = 0.25 * self._costas_alpha * self._costas_alpha + # Allow a frequency swing of +/- half of the sample rate + fmin = -0.5 + fmax = 0.5 + + self.clock_recov = gr.costas_loop_cc(self._costas_alpha, + self._costas_beta, + fmax, fmin, arity) + + # Perform Differential decoding on the constellation self.diffdec = gr.diff_phasor_cc() @@ -280,8 +297,7 @@ class dqpsk2_demod(gr.hier_block2): # Connect self.connect(self, self.agc, - self.clock_recov, - self.time_recov, + self.freq_recov, self.time_recov, self.clock_recov, self.diffdec, self.slicer, self.symbol_mapper, self.unpack, self) if sync_out: self.connect(self.time_recov, (self, 1)) @@ -297,6 +313,7 @@ class dqpsk2_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: %.2e" % self._costas_alpha print "Costas Loop beta: %.2e" % self._costas_beta print "Timing alpha gain: %.2f" % self._timing_alpha @@ -333,6 +350,8 @@ class dqpsk2_demod(gr.hier_block2): parser.add_option("", "--no-gray-code", dest="gray_code", action="store_false", default=_def_gray_code, help="disable gray coding on modulated bits (PSK)") + parser.add_option("", "--freq-alpha", type="float", default=_def_freq_alpha, + help="set frequency lock loop alpha gain value [default=%default] (PSK)") parser.add_option("", "--costas-alpha", type="float", default=_def_costas_alpha, help="set Costas loop alpha value [default=%default] (PSK)") parser.add_option("", "--gain-alpha", type="float", default=_def_timing_alpha, |