# # Copyright 2005,2006,2007 Free Software Foundation, Inc. # # cqpsk.py (C) Copyright 2009, KA1RBI # # This file is part of GNU Radio # # GNU Radio is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 3, or (at your option) # any later version. # # GNU Radio is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with GNU Radio; see the file COPYING. If not, write to # the Free Software Foundation, Inc., 51 Franklin Street, # Boston, MA 02110-1301, USA. # # See gnuradio-examples/python/digital for examples """ differential PI/4 CQPSK modulation and demodulation. """ from gnuradio import gr, gru, analog, blocks, digital, filter from math import pi, sqrt import cmath from pprint import pprint # default values (used in __init__ and add_options) _def_samples_per_symbol = 10 _def_excess_bw = 0.35 _def_gray_code = True _def_verbose = False _def_log = False _def_costas_alpha = 0.15 _def_gain_mu = None _def_mu = 0.5 _def_omega_relative_limit = 0.005 # ///////////////////////////////////////////////////////////////////////////// # CQPSK modulator # ///////////////////////////////////////////////////////////////////////////// class cqpsk_mod(gr.hier_block2): def __init__(self, samples_per_symbol=_def_samples_per_symbol, excess_bw=_def_excess_bw, verbose=_def_verbose, log=_def_log): """ Hierarchical block for RRC-filtered QPSK modulation. The input is a byte stream (unsigned char) and the output is the complex modulated signal at baseband. @param samples_per_symbol: samples per symbol >= 2 @type samples_per_symbol: integer @param excess_bw: Root-raised cosine filter excess bandwidth @type excess_bw: float @param verbose: Print information about modulator? @type verbose: bool @param debug: Print modualtion data to files? @type debug: bool """ gr.hier_block2.__init__(self, "cqpsk_mod", gr.io_signature(1, 1, gr.sizeof_char), # Input signature gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature self._samples_per_symbol = samples_per_symbol self._excess_bw = excess_bw if not isinstance(samples_per_symbol, int) or samples_per_symbol < 2: raise TypeError, ("sbp must be an integer >= 2, is %d" % samples_per_symbol) ntaps = 11 * samples_per_symbol arity = 8 # turn bytes into k-bit vectors self.bytes2chunks = \ gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST) # 0 +45 1 [+1] # 1 +135 3 [+3] # 2 -45 7 [-1] # 3 -135 5 [-3] self.pi4map = [1, 3, 7, 5] self.symbol_mapper = gr.map_bb(self.pi4map) self.diffenc = gr.diff_encoder_bb(arity) self.chunks2symbols = gr.chunks_to_symbols_bc(psk.constellation[arity]) # pulse shaping filter self.rrc_taps = filter.firdes.root_raised_cosine( self._samples_per_symbol, # gain (sps since we're interpolating by sps) self._samples_per_symbol, # sampling rate 1.0, # symbol rate self._excess_bw, # excess bandwidth (roll-off factor) ntaps) self.rrc_filter = filter.interp_fir_filter_ccf(self._samples_per_symbol, self.rrc_taps) if verbose: self._print_verbage() if log: self._setup_logging() # Connect & Initialize base class self.connect(self, self.bytes2chunks, self.symbol_mapper, self.diffenc, self.chunks2symbols, self.rrc_filter, self) def samples_per_symbol(self): return self._samples_per_symbol @staticmethod def bits_per_symbol(): return 2 def _print_verbage(self): print "\nModulator:" print "bits per symbol: %d" % self.bits_per_symbol() print "Gray code: %s" % self._gray_code print "RRS roll-off factor: %f" % self._excess_bw def _setup_logging(self): print "Modulation logging turned on." self.connect(self.bytes2chunks, gr.file_sink(gr.sizeof_char, "tx_bytes2chunks.dat")) self.connect(self.symbol_mapper, gr.file_sink(gr.sizeof_char, "tx_graycoder.dat")) self.connect(self.diffenc, gr.file_sink(gr.sizeof_char, "tx_diffenc.dat")) self.connect(self.chunks2symbols, gr.file_sink(gr.sizeof_gr_complex, "tx_chunks2symbols.dat")) self.connect(self.rrc_filter, gr.file_sink(gr.sizeof_gr_complex, "tx_rrc_filter.dat")) @staticmethod def add_options(parser): """ Adds QPSK modulation-specific options to the standard parser """ parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw, help="set RRC excess bandwidth factor [default=%default] (PSK)") parser.add_option("", "--no-gray-code", dest="gray_code", action="store_false", default=_def_gray_code, help="disable gray coding on modulated bits (PSK)") @staticmethod def extract_kwargs_from_options(options): """ Given command line options, create dictionary suitable for passing to __init__ """ return modulation_utils.extract_kwargs_from_options(dqpsk_mod.__init__, ('self',), options) # ///////////////////////////////////////////////////////////////////////////// # CQPSK demodulator # # ///////////////////////////////////////////////////////////////////////////// class cqpsk_demod(gr.hier_block2): def __init__(self, samples_per_symbol=_def_samples_per_symbol, excess_bw=_def_excess_bw, costas_alpha=_def_costas_alpha, gain_mu=_def_gain_mu, mu=_def_mu, omega_relative_limit=_def_omega_relative_limit, gray_code=_def_gray_code, verbose=_def_verbose, log=_def_log): """ Hierarchical block for RRC-filtered CQPSK demodulation The input is the complex modulated signal at baseband. The output is a stream of floats in [ -3 / -1 / +1 / +3 ] @param samples_per_symbol: samples per symbol >= 2 @type samples_per_symbol: float @param excess_bw: Root-raised cosine filter excess bandwidth @type excess_bw: float @param costas_alpha: loop filter gain @type costas_alphas: float @param gain_mu: for M&M block @type gain_mu: float @param mu: for M&M block @type mu: float @param omega_relative_limit: for M&M block @type omega_relative_limit: float @param gray_code: Tell modulator to Gray code the bits @type gray_code: bool @param verbose: Print information about modulator? @type verbose: bool @param debug: Print modualtion data to files? @type debug: bool """ gr.hier_block2.__init__(self, "cqpsk_demod", gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature gr.io_signature(1, 1, gr.sizeof_float)) # Output signature self._samples_per_symbol = samples_per_symbol self._excess_bw = excess_bw self._costas_alpha = costas_alpha self._mm_gain_mu = gain_mu self._mm_mu = mu self._mm_omega_relative_limit = omega_relative_limit self._gray_code = gray_code if samples_per_symbol < 2: raise TypeError, "sbp must be >= 2, is %d" % samples_per_symbol arity = pow(2,self.bits_per_symbol()) # Automatic gain control scale = (1.0/16384.0) self.pre_scaler = blocks.multiply_const_cc(scale) # scale the signal from full-range to +-1 #self.agc = analog.agc2_cc(0.6e-1, 1e-3, 1, 1, 100) self.agc = analog.feedforward_agc_cc(16, 2.0) # RRC data filter ntaps = 11 * samples_per_symbol self.rrc_taps = filter.firdes.root_raised_cosine( 1.0, # gain self._samples_per_symbol, # sampling rate 1.0, # symbol rate self._excess_bw, # excess bandwidth (roll-off factor) ntaps) self.rrc_filter=filter.interp_fir_filter_ccf(1, self.rrc_taps) if not self._mm_gain_mu: sbs_to_mm = {2: 0.050, 3: 0.075, 4: 0.11, 5: 0.125, 6: 0.15, 7: 0.15} self._mm_gain_mu = sbs_to_mm[samples_per_symbol] self._mm_omega = self._samples_per_symbol self._mm_gain_omega = .25 * self._mm_gain_mu * self._mm_gain_mu self._costas_beta = 0.25 * self._costas_alpha * self._costas_alpha fmin = -0.025 fmax = 0.025 self.receiver=digital.mpsk_receiver_cc( arity, pi/4.0, 2*pi/150, fmin, fmax, self._mm_mu, self._mm_gain_mu, self._mm_omega, self._mm_gain_omega, self._mm_omega_relative_limit ) self.receiver.set_alpha(self._costas_alpha) self.receiver.set_beta(self._costas_beta) # Perform Differential decoding on the constellation self.diffdec = digital.diff_phasor_cc() # take angle of the difference (in radians) self.to_float = blocks.complex_to_arg() # convert from radians such that signal is in -3/-1/+1/+3 self.rescale = blocks.multiply_const_ff( 1 / (pi / 4) ) if verbose: self._print_verbage() if log: self._setup_logging() # Connect & Initialize base class self.connect(self, self.pre_scaler, self.agc, self.rrc_filter, self.receiver, self.diffdec, self.to_float, self.rescale, self) def samples_per_symbol(self): return self._samples_per_symbol @staticmethod def bits_per_symbol(): return 2 def _print_verbage(self): print "\nDemodulator:" 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 "Costas Loop alpha: %.2e" % self._costas_alpha print "Costas Loop beta: %.2e" % self._costas_beta print "M&M mu: %.2f" % self._mm_mu print "M&M mu gain: %.2e" % self._mm_gain_mu print "M&M omega: %.2f" % self._mm_omega print "M&M omega gain: %.2e" % self._mm_gain_omega print "M&M omega limit: %.2f" % self._mm_omega_relative_limit def _setup_logging(self): print "Modulation logging turned on." self.connect(self.pre_scaler, gr.file_sink(gr.sizeof_gr_complex, "rx_prescaler.dat")) self.connect(self.agc, gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat")) self.connect(self.rrc_filter, gr.file_sink(gr.sizeof_gr_complex, "rx_rrc_filter.dat")) self.connect(self.receiver, gr.file_sink(gr.sizeof_gr_complex, "rx_receiver.dat")) self.connect(self.diffdec, gr.file_sink(gr.sizeof_gr_complex, "rx_diffdec.dat")) self.connect(self.to_float, gr.file_sink(gr.sizeof_float, "rx_to_float.dat")) self.connect(self.rescale, gr.file_sink(gr.sizeof_float, "rx_rescale.dat")) @staticmethod def add_options(parser): """ Adds modulation-specific options to the standard parser """ parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw, help="set RRC excess bandwidth factor [default=%default] (PSK)") 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("", "--costas-alpha", type="float", default=_def_costas_alpha, help="set Costas loop alpha value [default=%default] (PSK)") parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu, help="set M&M symbol sync loop gain mu value [default=%default] (PSK)") parser.add_option("", "--mu", type="float", default=_def_mu, help="set M&M symbol sync loop mu value [default=%default] (PSK)") @staticmethod def extract_kwargs_from_options(options): """ Given command line options, create dictionary suitable for passing to __init__ """ return modulation_utils.extract_kwargs_from_options( cqpsk_demod.__init__, ('self',), options)