diff options
| author | Ben Reynwar <ben@reynwar.net> | 2013-03-07 23:11:20 -0700 |
|---|---|---|
| committer | Ben Reynwar <ben@reynwar.net> | 2013-03-07 23:11:20 -0700 |
| commit | a7c7cf1186ec73786e6bbefb430c940c8747f857 (patch) | |
| tree | b2f39e170547202ed772d95260563a73288b3326 /gr-digital/python/digital/psk.py | |
| parent | b841288cfb261da28746c4b3aaa7a1dfc078ebfd (diff) | |
digital: Enabling uninstalled python imports.
Diffstat (limited to 'gr-digital/python/digital/psk.py')
| -rw-r--r-- | gr-digital/python/digital/psk.py | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/gr-digital/python/digital/psk.py b/gr-digital/python/digital/psk.py new file mode 100644 index 0000000000..1816ffb4ba --- /dev/null +++ b/gr-digital/python/digital/psk.py @@ -0,0 +1,138 @@ +# +# Copyright 2005,2006,2011 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. +# + +""" +PSK modulation and demodulation. +""" + +from math import pi, log +from cmath import exp + +import digital_swig +import modulation_utils +from utils import mod_codes, gray_code +from generic_mod_demod import generic_mod, generic_demod +from generic_mod_demod import shared_mod_args, shared_demod_args + +# Default number of points in constellation. +_def_constellation_points = 4 +# The default encoding (e.g. gray-code, set-partition) +_def_mod_code = mod_codes.GRAY_CODE +# Default use of differential encoding +_def_differential = True + +def create_encodings(mod_code, arity, differential): + post_diff_code = None + if mod_code not in mod_codes.codes: + raise ValueError('That modulation code does not exist.') + if mod_code == mod_codes.GRAY_CODE: + if differential: + pre_diff_code = gray_code.gray_code(arity) + post_diff_code = None + else: + pre_diff_code = [] + post_diff_code = gray_code.gray_code(arity) + elif mod_code == mod_codes.NO_CODE: + pre_diff_code = [] + post_diff_code = None + else: + raise ValueError('That modulation code is not implemented for this constellation.') + return (pre_diff_code, post_diff_code) + +# ///////////////////////////////////////////////////////////////////////////// +# PSK constellation +# ///////////////////////////////////////////////////////////////////////////// + +def psk_constellation(m=_def_constellation_points, mod_code=_def_mod_code, + differential=_def_differential): + """ + Creates a PSK constellation object. + """ + k = log(m) / log(2.0) + if (k != int(k)): + raise StandardError('Number of constellation points must be a power of two.') + points = [exp(2*pi*(0+1j)*i/m) for i in range(0,m)] + pre_diff_code, post_diff_code = create_encodings(mod_code, m, differential) + if post_diff_code is not None: + inverse_post_diff_code = mod_codes.invert_code(post_diff_code) + points = [points[x] for x in inverse_post_diff_code] + constellation = digital_swig.constellation_psk(points, pre_diff_code, m) + return constellation + +# ///////////////////////////////////////////////////////////////////////////// +# PSK modulator +# ///////////////////////////////////////////////////////////////////////////// + +class psk_mod(generic_mod): + """ + Hierarchical block for RRC-filtered PSK modulation. + + The input is a byte stream (unsigned char) and the + output is the complex modulated signal at baseband. + + Args: + constellation_points: Number of constellation points (must be a power of two) (integer). + mod_code: Whether to use a gray_code (digital.mod_codes.GRAY_CODE) or not (digital.mod_codes.NO_CODE). + differential: Whether to use differential encoding (boolean). + """ + # See generic_mod for additional arguments + __doc__ += shared_mod_args + + def __init__(self, constellation_points=_def_constellation_points, + mod_code=_def_mod_code, + differential=_def_differential, + *args, **kwargs): + constellation = psk_constellation(constellation_points, mod_code, differential) + super(psk_mod, self).__init__(constellation, differential, *args, **kwargs) + +# ///////////////////////////////////////////////////////////////////////////// +# PSK demodulator +# +# ///////////////////////////////////////////////////////////////////////////// + +class psk_demod(generic_demod): + + """ + Hierarchical block for RRC-filtered PSK modulation. + + The input is a byte stream (unsigned char) and the + output is the complex modulated signal at baseband. + + Args: + constellation_points: Number of constellation points (must be a power of two) (integer). + mod_code: Whether to use a gray_code (digital.mod_codes.GRAY_CODE) or not (digital.mod_codes.NO_CODE). + differential: Whether to use differential encoding (boolean). + """ + # See generic_mod for additional arguments + __doc__ += shared_mod_args + def __init__(self, constellation_points=_def_constellation_points, + mod_code=_def_mod_code, + differential=_def_differential, + *args, **kwargs): + constellation = psk_constellation(constellation_points, mod_code, differential) + super(psk_demod, self).__init__(constellation, differential, *args, **kwargs) + +# +# Add these to the mod/demod registry +# +modulation_utils.add_type_1_mod('psk', psk_mod) +modulation_utils.add_type_1_demod('psk', psk_demod) +modulation_utils.add_type_1_constellation('psk', psk_constellation) |