351 lines
14 KiB
Python
351 lines
14 KiB
Python
#
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# Copyright 2005,2006,2007 Free Software Foundation, Inc.
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#
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# cqpsk.py (C) Copyright 2009, KA1RBI
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#
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# This file is part of GNU Radio
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#
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# GNU Radio is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3, or (at your option)
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# any later version.
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#
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# GNU Radio is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with GNU Radio; see the file COPYING. If not, write to
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# the Free Software Foundation, Inc., 51 Franklin Street,
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# Boston, MA 02110-1301, USA.
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#
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# See gnuradio-examples/python/digital for examples
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"""
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differential PI/4 CQPSK modulation and demodulation.
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"""
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from gnuradio import gr, gru, modulation_utils
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from math import pi, sqrt
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import psk
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import cmath
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from pprint import pprint
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# default values (used in __init__ and add_options)
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_def_samples_per_symbol = 10
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_def_excess_bw = 0.35
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_def_gray_code = True
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_def_verbose = False
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_def_log = False
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_def_costas_alpha = 0.15
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_def_gain_mu = None
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_def_mu = 0.5
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_def_omega_relative_limit = 0.005
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# /////////////////////////////////////////////////////////////////////////////
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# CQPSK modulator
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# /////////////////////////////////////////////////////////////////////////////
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class cqpsk_mod(gr.hier_block2):
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def __init__(self,
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samples_per_symbol=_def_samples_per_symbol,
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excess_bw=_def_excess_bw,
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verbose=_def_verbose,
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log=_def_log):
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"""
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Hierarchical block for RRC-filtered QPSK modulation.
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The input is a byte stream (unsigned char) and the
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output is the complex modulated signal at baseband.
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@param samples_per_symbol: samples per symbol >= 2
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@type samples_per_symbol: integer
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@param excess_bw: Root-raised cosine filter excess bandwidth
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@type excess_bw: float
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@param verbose: Print information about modulator?
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@type verbose: bool
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@param debug: Print modualtion data to files?
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@type debug: bool
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"""
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gr.hier_block2.__init__(self, "cqpsk_mod",
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gr.io_signature(1, 1, gr.sizeof_char), # Input signature
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gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
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self._samples_per_symbol = samples_per_symbol
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self._excess_bw = excess_bw
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if not isinstance(samples_per_symbol, int) or samples_per_symbol < 2:
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raise TypeError, ("sbp must be an integer >= 2, is %d" % samples_per_symbol)
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ntaps = 11 * samples_per_symbol
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arity = 8
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# turn bytes into k-bit vectors
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self.bytes2chunks = \
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gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST)
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# 0 +45 1 [+1]
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# 1 +135 3 [+3]
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# 2 -45 7 [-1]
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# 3 -135 5 [-3]
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self.pi4map = [1, 3, 7, 5]
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self.symbol_mapper = gr.map_bb(self.pi4map)
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self.diffenc = gr.diff_encoder_bb(arity)
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self.chunks2symbols = gr.chunks_to_symbols_bc(psk.constellation[arity])
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# pulse shaping filter
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self.rrc_taps = gr.firdes.root_raised_cosine(
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self._samples_per_symbol, # gain (sps since we're interpolating by sps)
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self._samples_per_symbol, # sampling rate
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1.0, # symbol rate
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self._excess_bw, # excess bandwidth (roll-off factor)
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ntaps)
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self.rrc_filter = gr.interp_fir_filter_ccf(self._samples_per_symbol, self.rrc_taps)
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if verbose:
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self._print_verbage()
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if log:
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self._setup_logging()
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# Connect & Initialize base class
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self.connect(self, self.bytes2chunks, self.symbol_mapper, self.diffenc,
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self.chunks2symbols, self.rrc_filter, self)
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def samples_per_symbol(self):
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return self._samples_per_symbol
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def bits_per_symbol(self=None): # staticmethod that's also callable on an instance
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return 2
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bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
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def _print_verbage(self):
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print "\nModulator:"
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print "bits per symbol: %d" % self.bits_per_symbol()
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print "Gray code: %s" % self._gray_code
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print "RRS roll-off factor: %f" % self._excess_bw
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def _setup_logging(self):
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print "Modulation logging turned on."
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self.connect(self.bytes2chunks,
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gr.file_sink(gr.sizeof_char, "tx_bytes2chunks.dat"))
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self.connect(self.symbol_mapper,
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gr.file_sink(gr.sizeof_char, "tx_graycoder.dat"))
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self.connect(self.diffenc,
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gr.file_sink(gr.sizeof_char, "tx_diffenc.dat"))
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self.connect(self.chunks2symbols,
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gr.file_sink(gr.sizeof_gr_complex, "tx_chunks2symbols.dat"))
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self.connect(self.rrc_filter,
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gr.file_sink(gr.sizeof_gr_complex, "tx_rrc_filter.dat"))
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def add_options(parser):
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"""
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Adds QPSK modulation-specific options to the standard parser
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"""
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parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
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help="set RRC excess bandwith factor [default=%default] (PSK)")
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parser.add_option("", "--no-gray-code", dest="gray_code",
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action="store_false", default=_def_gray_code,
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help="disable gray coding on modulated bits (PSK)")
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add_options=staticmethod(add_options)
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def extract_kwargs_from_options(options):
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"""
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Given command line options, create dictionary suitable for passing to __init__
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"""
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return modulation_utils.extract_kwargs_from_options(dqpsk_mod.__init__,
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('self',), options)
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extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
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# /////////////////////////////////////////////////////////////////////////////
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# CQPSK demodulator
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#
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# /////////////////////////////////////////////////////////////////////////////
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class cqpsk_demod(gr.hier_block2):
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def __init__(self,
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samples_per_symbol=_def_samples_per_symbol,
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excess_bw=_def_excess_bw,
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costas_alpha=_def_costas_alpha,
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gain_mu=_def_gain_mu,
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mu=_def_mu,
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omega_relative_limit=_def_omega_relative_limit,
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gray_code=_def_gray_code,
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verbose=_def_verbose,
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log=_def_log):
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"""
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Hierarchical block for RRC-filtered CQPSK demodulation
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The input is the complex modulated signal at baseband.
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The output is a stream of floats in [ -3 / -1 / +1 / +3 ]
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@param samples_per_symbol: samples per symbol >= 2
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@type samples_per_symbol: float
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@param excess_bw: Root-raised cosine filter excess bandwidth
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@type excess_bw: float
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@param costas_alpha: loop filter gain
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@type costas_alphas: float
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@param gain_mu: for M&M block
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@type gain_mu: float
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@param mu: for M&M block
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@type mu: float
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@param omega_relative_limit: for M&M block
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@type omega_relative_limit: float
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@param gray_code: Tell modulator to Gray code the bits
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@type gray_code: bool
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@param verbose: Print information about modulator?
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@type verbose: bool
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@param debug: Print modualtion data to files?
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@type debug: bool
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"""
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gr.hier_block2.__init__(self, "cqpsk_demod",
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gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
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gr.io_signature(1, 1, gr.sizeof_float)) # Output signature
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self._samples_per_symbol = samples_per_symbol
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self._excess_bw = excess_bw
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self._costas_alpha = costas_alpha
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self._mm_gain_mu = gain_mu
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self._mm_mu = mu
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self._mm_omega_relative_limit = omega_relative_limit
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self._gray_code = gray_code
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if samples_per_symbol < 2:
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raise TypeError, "sbp must be >= 2, is %d" % samples_per_symbol
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arity = pow(2,self.bits_per_symbol())
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# Automatic gain control
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scale = (1.0/16384.0)
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self.pre_scaler = gr.multiply_const_cc(scale) # scale the signal from full-range to +-1
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#self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
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self.agc = gr.feedforward_agc_cc(16, 2.0)
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# RRC data filter
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ntaps = 11 * samples_per_symbol
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self.rrc_taps = gr.firdes.root_raised_cosine(
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1.0, # gain
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self._samples_per_symbol, # sampling rate
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1.0, # symbol rate
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self._excess_bw, # excess bandwidth (roll-off factor)
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ntaps)
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self.rrc_filter=gr.interp_fir_filter_ccf(1, self.rrc_taps)
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if not self._mm_gain_mu:
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sbs_to_mm = {2: 0.050, 3: 0.075, 4: 0.11, 5: 0.125, 6: 0.15, 7: 0.15}
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self._mm_gain_mu = sbs_to_mm[samples_per_symbol]
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self._mm_omega = self._samples_per_symbol
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self._mm_gain_omega = .25 * self._mm_gain_mu * self._mm_gain_mu
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self._costas_beta = 0.25 * self._costas_alpha * self._costas_alpha
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fmin = -0.025
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fmax = 0.025
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self.receiver=gr.mpsk_receiver_cc(arity, pi/4.0,
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self._costas_alpha, self._costas_beta,
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fmin, fmax,
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self._mm_mu, self._mm_gain_mu,
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self._mm_omega, self._mm_gain_omega,
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self._mm_omega_relative_limit)
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# Perform Differential decoding on the constellation
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self.diffdec = gr.diff_phasor_cc()
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# take angle of the difference (in radians)
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self.to_float = gr.complex_to_arg()
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# convert from radians such that signal is in -3/-1/+1/+3
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self.rescale = gr.multiply_const_ff( 1 / (pi / 4) )
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if verbose:
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self._print_verbage()
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if log:
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self._setup_logging()
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# Connect & Initialize base class
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self.connect(self, self.pre_scaler, self.agc, self.rrc_filter, self.receiver,
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self.diffdec, self.to_float, self.rescale, self)
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def samples_per_symbol(self):
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return self._samples_per_symbol
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def bits_per_symbol(self=None): # staticmethod that's also callable on an instance
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return 2
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bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
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def _print_verbage(self):
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print "\nDemodulator:"
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print "bits per symbol: %d" % self.bits_per_symbol()
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print "Gray code: %s" % self._gray_code
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print "RRC roll-off factor: %.2f" % self._excess_bw
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print "Costas Loop alpha: %.2e" % self._costas_alpha
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print "Costas Loop beta: %.2e" % self._costas_beta
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print "M&M mu: %.2f" % self._mm_mu
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print "M&M mu gain: %.2e" % self._mm_gain_mu
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print "M&M omega: %.2f" % self._mm_omega
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print "M&M omega gain: %.2e" % self._mm_gain_omega
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print "M&M omega limit: %.2f" % self._mm_omega_relative_limit
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def _setup_logging(self):
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print "Modulation logging turned on."
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self.connect(self.pre_scaler,
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gr.file_sink(gr.sizeof_gr_complex, "rx_prescaler.dat"))
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self.connect(self.agc,
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gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat"))
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self.connect(self.rrc_filter,
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gr.file_sink(gr.sizeof_gr_complex, "rx_rrc_filter.dat"))
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self.connect(self.receiver,
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gr.file_sink(gr.sizeof_gr_complex, "rx_receiver.dat"))
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self.connect(self.diffdec,
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gr.file_sink(gr.sizeof_gr_complex, "rx_diffdec.dat"))
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self.connect(self.to_float,
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gr.file_sink(gr.sizeof_float, "rx_to_float.dat"))
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self.connect(self.rescale,
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gr.file_sink(gr.sizeof_float, "rx_rescale.dat"))
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def add_options(parser):
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"""
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Adds modulation-specific options to the standard parser
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"""
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parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
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help="set RRC excess bandwith factor [default=%default] (PSK)")
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parser.add_option("", "--no-gray-code", dest="gray_code",
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action="store_false", default=_def_gray_code,
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help="disable gray coding on modulated bits (PSK)")
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parser.add_option("", "--costas-alpha", type="float", default=_def_costas_alpha,
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help="set Costas loop alpha value [default=%default] (PSK)")
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parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
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help="set M&M symbol sync loop gain mu value [default=%default] (PSK)")
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parser.add_option("", "--mu", type="float", default=_def_mu,
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help="set M&M symbol sync loop mu value [default=%default] (PSK)")
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add_options=staticmethod(add_options)
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def extract_kwargs_from_options(options):
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"""
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Given command line options, create dictionary suitable for passing to __init__
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"""
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return modulation_utils.extract_kwargs_from_options(
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cqpsk_demod.__init__, ('self',), options)
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extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
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#
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# Add these to the mod/demod registry
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#
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modulation_utils.add_type_1_mod('cqpsk', cqpsk_mod)
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modulation_utils.add_type_1_demod('cqpsk', cqpsk_demod)
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