# # Copyright 2005,2006,2007 Free Software Foundation, Inc. # # 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 """ QAM256 modulation and demodulation. """ from gnuradio import gr, gru, modulation_utils from math import pi, sqrt import qam import cmath from pprint import pprint # default values (used in __init__ and add_options) _def_samples_per_symbol = 2 _def_excess_bw = 0.35 _def_gray_code = True _def_verbose = False _def_log = False _def_costas_alpha = None _def_gain_mu = 0.03 _def_mu = 0.05 _def_omega_relative_limit = 0.005 # ///////////////////////////////////////////////////////////////////////////// # QAM256 modulator # ///////////////////////////////////////////////////////////////////////////// class qam256_mod(gr.hier_block2): def __init__(self, samples_per_symbol=_def_samples_per_symbol, excess_bw=_def_excess_bw, gray_code=_def_gray_code, 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 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, "qam256_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 self._gray_code = gray_code 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 = pow(2, self.bits_per_symbol()) # turn bytes into k-bit vectors self.bytes2chunks = \ gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST) if self._gray_code: self.symbol_mapper = gr.map_bb(qam.binary_to_gray[arity]) else: self.symbol_mapper = gr.map_bb(qam.binary_to_ungray[arity]) self.diffenc = gr.diff_encoder_bb(arity) rot = 1.0 print "constellation with %d arity" % arity rotated_const = map(lambda pt: pt * rot, qam.constellation[arity]) self.chunks2symbols = gr.chunks_to_symbols_bc(rotated_const) # pulse shaping filter self.rrc_taps = gr.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 = gr.interp_fir_filter_ccf(self._samples_per_symbol, self.rrc_taps) if verbose: self._print_verbage() if log: self._setup_logging() # Connect 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 def bits_per_symbol(self=None): # staticmethod that's also callable on an instance return 8 bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM def _print_verbage(self): 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, "bytes2chunks.dat")) self.connect(self.symbol_mapper, gr.file_sink(gr.sizeof_char, "graycoder.dat")) self.connect(self.diffenc, gr.file_sink(gr.sizeof_char, "diffenc.dat")) self.connect(self.chunks2symbols, gr.file_sink(gr.sizeof_gr_complex, "chunks2symbols.dat")) self.connect(self.rrc_filter, gr.file_sink(gr.sizeof_gr_complex, "rrc_filter.dat")) def add_options(parser): """ Adds QAM modulation-specific options to the standard parser """ parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw, help="set RRC excess bandwith 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)") add_options=staticmethod(add_options) def extract_kwargs_from_options(options): """ Given command line options, create dictionary suitable for passing to __init__ """ return modulation_utils.extract_kwargs_from_options(qam256_mod.__init__, ('self',), options) extract_kwargs_from_options=staticmethod(extract_kwargs_from_options) # ///////////////////////////////////////////////////////////////////////////// # QAM256 demodulator # # ///////////////////////////////////////////////////////////////////////////// class qam256_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): gr.hier_block2.__init__(self, "qam256_demod", gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature gr.io_signature(1, 1, gr.sizeof_char)) # Output signature # do this pass def bits_per_symbol(self=None): # staticmethod that's also callable on an instance return 8 bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM # # Add these to the mod/demod registry # # NOT READY TO BE USED YET -- ENABLE AT YOUR OWN RISK #modulation_utils.add_type_1_mod('qam256', qam256_mod) #modulation_utils.add_type_1_demod('qam256', qam256_demod)