+++ /dev/null
-#
-# GMSK modulation and demodulation.
-#
-#
-# Copyright 2005,2006 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/gmsk2 for examples
-
-from gnuradio import gr
-from gnuradio import modulation_utils
-from math import pi
-import Numeric
-from pprint import pprint
-import inspect
-
-# default values (used in __init__ and add_options)
-_def_samples_per_symbol = 2
-_def_bt = 0.35
-_def_verbose = False
-_def_log = False
-
-_def_gain_mu = 0.05
-_def_mu = 0.5
-_def_freq_error = 0.0
-_def_omega_relative_limit = 0.005
-
-
-# /////////////////////////////////////////////////////////////////////////////
-# GMSK modulator
-# /////////////////////////////////////////////////////////////////////////////
-
-class gmsk_mod(gr.hier_block):
-
- def __init__(self, fg,
- samples_per_symbol=_def_samples_per_symbol,
- bt=_def_bt,
- verbose=_def_verbose,
- log=_def_log):
- """
- Hierarchical block for Gaussian Minimum Shift Key (GMSK)
- modulation.
-
- The input is a byte stream (unsigned char) and the
- output is the complex modulated signal at baseband.
-
- @param fg: flow graph
- @type fg: flow graph
- @param samples_per_symbol: samples per baud >= 2
- @type samples_per_symbol: integer
- @param bt: Gaussian filter bandwidth * symbol time
- @type bt: float
- @param verbose: Print information about modulator?
- @type verbose: bool
- @param debug: Print modualtion data to files?
- @type debug: bool
- """
-
- self._fg = fg
- self._samples_per_symbol = samples_per_symbol
- self._bt = bt
-
- if not isinstance(samples_per_symbol, int) or samples_per_symbol < 2:
- raise TypeError, ("samples_per_symbol must be an integer >= 2, is %r" % (samples_per_symbol,))
-
- ntaps = 4 * samples_per_symbol # up to 3 bits in filter at once
- sensitivity = (pi / 2) / samples_per_symbol # phase change per bit = pi / 2
-
- # Turn it into NRZ data.
- self.nrz = gr.bytes_to_syms()
-
- # Form Gaussian filter
- # Generate Gaussian response (Needs to be convolved with window below).
- self.gaussian_taps = gr.firdes.gaussian(
- 1, # gain
- samples_per_symbol, # symbol_rate
- bt, # bandwidth * symbol time
- ntaps # number of taps
- )
-
- self.sqwave = (1,) * samples_per_symbol # rectangular window
- self.taps = Numeric.convolve(Numeric.array(self.gaussian_taps),Numeric.array(self.sqwave))
- self.gaussian_filter = gr.interp_fir_filter_fff(samples_per_symbol, self.taps)
-
- # FM modulation
- self.fmmod = gr.frequency_modulator_fc(sensitivity)
-
- if verbose:
- self._print_verbage()
-
- if log:
- self._setup_logging()
-
- # Connect & Initialize base class
- self._fg.connect(self.nrz, self.gaussian_filter, self.fmmod)
- gr.hier_block.__init__(self, self._fg, self.nrz, self.fmmod)
-
- 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 1
- bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method.
-
-
- def _print_verbage(self):
- print "bits per symbol = %d" % self.bits_per_symbol()
- print "Gaussian filter bt = %.2f" % self._bt
-
-
- def _setup_logging(self):
- print "Modulation logging turned on."
- self._fg.connect(self.nrz,
- gr.file_sink(gr.sizeof_float, "nrz.dat"))
- self._fg.connect(self.gaussian_filter,
- gr.file_sink(gr.sizeof_float, "gaussian_filter.dat"))
- self._fg.connect(self.fmmod,
- gr.file_sink(gr.sizeof_gr_complex, "fmmod.dat"))
-
-
- def add_options(parser):
- """
- Adds GMSK modulation-specific options to the standard parser
- """
- parser.add_option("", "--bt", type="float", default=_def_bt,
- help="set bandwidth-time product [default=%default] (GMSK)")
- 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(gmsk_mod.__init__,
- ('self', 'fg'), options)
- extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
-
-
-
-# /////////////////////////////////////////////////////////////////////////////
-# GMSK demodulator
-# /////////////////////////////////////////////////////////////////////////////
-
-class gmsk_demod(gr.hier_block):
-
- def __init__(self, fg,
- samples_per_symbol=_def_samples_per_symbol,
- gain_mu=_def_gain_mu,
- mu=_def_mu,
- omega_relative_limit=_def_omega_relative_limit,
- freq_error=_def_freq_error,
- verbose=_def_verbose,
- log=_def_log):
- """
- Hierarchical block for Gaussian Minimum Shift Key (GMSK)
- demodulation.
-
- The input is the complex modulated signal at baseband.
- The output is a stream of bits packed 1 bit per byte (the LSB)
-
- @param fg: flow graph
- @type fg: flow graph
- @param samples_per_symbol: samples per baud
- @type samples_per_symbol: integer
- @param verbose: Print information about modulator?
- @type verbose: bool
- @param log: Print modualtion data to files?
- @type log: bool
-
- Clock recovery parameters. These all have reasonble defaults.
-
- @param gain_mu: controls rate of mu adjustment
- @type gain_mu: float
- @param mu: fractional delay [0.0, 1.0]
- @type mu: float
- @param omega_relative_limit: sets max variation in omega
- @type omega_relative_limit: float, typically 0.000200 (200 ppm)
- @param freq_error: bit rate error as a fraction
- @param float
- """
-
- self._fg = fg
- self._samples_per_symbol = samples_per_symbol
- self._gain_mu = gain_mu
- self._mu = mu
- self._omega_relative_limit = omega_relative_limit
- self._freq_error = freq_error
-
- if samples_per_symbol < 2:
- raise TypeError, "samples_per_symbol >= 2, is %f" % samples_per_symbol
-
- self._omega = samples_per_symbol*(1+self._freq_error)
-
- self._gain_omega = .25 * self._gain_mu * self._gain_mu # critically damped
-
- # Demodulate FM
- sensitivity = (pi / 2) / samples_per_symbol
- self.fmdemod = gr.quadrature_demod_cf(1.0 / sensitivity)
-
- # the clock recovery block tracks the symbol clock and resamples as needed.
- # the output of the block is a stream of soft symbols (float)
- self.clock_recovery = gr.clock_recovery_mm_ff(self._omega, self._gain_omega,
- self._mu, self._gain_mu,
- self._omega_relative_limit)
-
- # slice the floats at 0, outputting 1 bit (the LSB of the output byte) per sample
- self.slicer = gr.binary_slicer_fb()
-
- if verbose:
- self._print_verbage()
-
- if log:
- self._setup_logging()
-
- # Connect & Initialize base class
- self._fg.connect(self.fmdemod, self.clock_recovery, self.slicer)
- gr.hier_block.__init__(self, self._fg, self.fmdemod, self.slicer)
-
- 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 1
- bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method.
-
-
- def _print_verbage(self):
- print "bits per symbol = %d" % self.bits_per_symbol()
- print "M&M clock recovery omega = %f" % self._omega
- print "M&M clock recovery gain mu = %f" % self._gain_mu
- print "M&M clock recovery mu = %f" % self._mu
- print "M&M clock recovery omega rel. limit = %f" % self._omega_relative_limit
- print "frequency error = %f" % self._freq_error
-
-
- def _setup_logging(self):
- print "Demodulation logging turned on."
- self._fg.connect(self.fmdemod,
- gr.file_sink(gr.sizeof_float, "fmdemod.dat"))
- self._fg.connect(self.clock_recovery,
- gr.file_sink(gr.sizeof_float, "clock_recovery.dat"))
- self._fg.connect(self.slicer,
- gr.file_sink(gr.sizeof_char, "slicer.dat"))
-
- def add_options(parser):
- """
- Adds GMSK demodulation-specific options to the standard parser
- """
- parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
- help="M&M clock recovery gain mu [default=%default] (GMSK/PSK)")
- parser.add_option("", "--mu", type="float", default=_def_mu,
- help="M&M clock recovery mu [default=%default] (GMSK/PSK)")
- parser.add_option("", "--omega-relative-limit", type="float", default=_def_omega_relative_limit,
- help="M&M clock recovery omega relative limit [default=%default] (GMSK/PSK)")
- parser.add_option("", "--freq-error", type="float", default=_def_freq_error,
- help="M&M clock recovery frequency error [default=%default] (GMSK)")
- 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(gmsk_demod.__init__,
- ('self', 'fg'), options)
- extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
-
-
-#
-# Add these to the mod/demod registry
-#
-modulation_utils.add_type_1_mod('gmsk', gmsk_mod)
-modulation_utils.add_type_1_demod('gmsk', gmsk_demod)
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