diff options
| author | Tom Rondeau <tom@trondeau.com> | 2013-09-04 15:44:20 -0400 |
|---|---|---|
| committer | Tom Rondeau <tom@trondeau.com> | 2013-09-04 15:44:20 -0400 |
| commit | 02fd90029a1ec465f7c8da4a0d97dcdb8b3f438f (patch) | |
| tree | 9bc144a9cb5b0e877108302d13181e50bd885528 /gr-digital/python/digital/psk_constellations.py | |
| parent | edf2ac24c9c2f723eb80918de7addf6d299958c2 (diff) | |
digital: Python functions to support soft decision making and look-up table generation.
Diffstat (limited to 'gr-digital/python/digital/psk_constellations.py')
| -rwxr-xr-x | gr-digital/python/digital/psk_constellations.py | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/gr-digital/python/digital/psk_constellations.py b/gr-digital/python/digital/psk_constellations.py new file mode 100755 index 0000000000..ee62c33a0c --- /dev/null +++ b/gr-digital/python/digital/psk_constellations.py @@ -0,0 +1,308 @@ +#!/usr/bin/env python +# +# Copyright 2013 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. +# + +import numpy +from constellation_map_generator import * + +''' +Note on the naming scheme. Each constellation is named using a prefix +for the type of constellation, the order of the constellation, and a +distinguishing feature, which comes in three modes: + +- No extra feature: the basic Gray-coded constellation map; others + will be derived from this type. +- A single number: an indexed number to uniquely identify different + constellation maps. +- 0xN_x0_x1..._xM: A permutation of the base constellation, explained + below. + +For rectangular constellations (BPSK, QPSK, QAM), we can define a +hyperspace and look for all symmetries. This is also known as the +automorphism group of the hypercube, aka the hyperoctahedral +group. What this means is that we can easily define all possible +rotations in terms of the first base mapping by creating the mapping: + + f(x) = k XOR pi(x) + +The x is the bit string for the symbol we are altering. Then k is a +bit string of n bits where n is the number of bits per symbol in the +constellation (e.g., 2 for QPSK or 6 for QAM64). The pi is a +permutation function specified as pi_0, pi_1..., pi_n-1. This permutes +the bits from the base constellation symbol to a new code, which is +then xor'd by k. + +The value of k is from 0 to 2^n-1 and pi is a list of all bit +positions. + +The total number of Gray coded modulations is (2^n)*(n!). + +We create aliases for all possible naming schemes for the +constellations. So if a hyperoctahedral group is defined, we also set +this function equal to a function name using a unique ID number, and +we always select one rotation as our basic rotation that the other +rotations are based off of. +''' + +# BPSK Constellation Mappings + +def psk_2_0x0(): + ''' + 0 | 1 + ''' + const_points = [-1, 1] + symbols = [0, 1] + return (const_points, symbols) +psk_2 = psk_2_0x0 # Basic BPSK rotation +psk_2_0 = psk_2 # First ID for BPSK rotations + +def psk_2_0x1(): + ''' + 1 | 0 + ''' + const_points = [-1, 1] + symbols = [1, 0] + return (const_points, symbols) +psk_2_1 = psk_2_0x1 + + +############################################################ +# BPSK Soft bit LUT generators +############################################################ + +def sd_psk_2_0x0(x, Es=1): + ''' + 0 | 1 + ''' + x_re = x.real + dist = Es*numpy.sqrt(2) + return [dist*x_re,] +sd_psk_2 = sd_psk_2_0x0 # Basic BPSK rotation +sd_psk_2_0 = sd_psk_2 # First ID for BPSK rotations + +def sd_psk_2_0x1(x, Es=1): + ''' + 1 | 0 + ''' + x_re = [x.real,] + dist = Es*numpy.sqrt(2) + return -dist*x_re +sd_psk_2_1 = sd_psk_2_0x1 + + +############################################################ +# QPSK Constellation Mappings +############################################################ + +def psk_4_0x0_0_1(): + ''' + 10 | 11 + ------- + 00 | 01 + ''' + const_points = [-1-1j, 1-1j, + -1+1j, 1+1j] + symbols = [0, 1, 2, 3] + return (const_points, symbols) +psk_4 = psk_4_0x0_0_1 +psk_4_0 = psk_4 + +def psk_4_0x1_0_1(): + ''' + 11 | 10 + ------- + 01 | 00 + ''' + k = 0x1 + pi = [0, 1] + return constellation_map_generator(psk_4, k, pi) +psk_4_1 = psk_4_0x1_0_1 + +def psk_4_0x2_0_1(): + ''' + 00 | 01 + ------- + 10 | 11 + ''' + k = 0x2 + pi = [0, 1] + return constellation_map_generator(psk_4, k, pi) +psk_4_2 = psk_4_0x2_0_1 + +def psk_4_0x3_0_1(): + ''' + 01 | 00 + ------- + 11 | 10 + ''' + k = 0x3 + pi = [0, 1] + return constellation_map_generator(psk_4, k, pi) +psk_4_3 = psk_4_0x3_0_1 + +def psk_4_0x0_1_0(): + ''' + 01 | 11 + ------- + 00 | 10 + ''' + k = 0x0 + pi = [1, 0] + return constellation_map_generator(psk_4, k, pi) +psk_4_4 = psk_4_0x0_1_0 + +def psk_4_0x1_1_0(): + ''' + 00 | 10 + ------- + 01 | 11 + ''' + k = 0x1 + pi = [1, 0] + return constellation_map_generator(psk_4, k, pi) +psk_4_5 = psk_4_0x1_1_0 + +def psk_4_0x2_1_0(): + ''' + 11 | 01 + ------- + 10 | 00 + ''' + k = 0x2 + pi = [1, 0] + return constellation_map_generator(psk_4, k, pi) +psk_4_6 = psk_4_0x2_1_0 + +def psk_4_0x3_1_0(): + ''' + 10 | 00 + ------- + 11 | 01 + ''' + k = 0x3 + pi = [1, 0] + return constellation_map_generator(psk_4, k, pi) +psk_4_7 = psk_4_0x3_1_0 + + + +############################################################ +# QPSK Constellation Softbit LUT generators +############################################################ + +def sd_psk_4_0x0_0_1(x, Es=1): + ''' + 10 | 11 + ------- + 00 | 01 + ''' + x_re = x.real + x_im = x.imag + dist = Es*numpy.sqrt(2) + return [dist*x_im, dist*x_re] +sd_psk_4 = sd_psk_4_0x0_0_1 +sd_psk_4_0 = sd_psk_4 + +def sd_psk_4_0x1_0_1(x, Es=1): + ''' + 11 | 10 + ------- + 01 | 00 + ''' + x_re = x.real + x_im = x.imag + dist = Es*numpy.sqrt(2) + return [dist*x_im, -dist*x_re] +sd_psk_4_1 = sd_psk_4_0x1_0_1 + +def sd_psk_4_0x2_0_1(x, Es=1): + ''' + 00 | 01 + ------- + 10 | 11 + ''' + x_re = x.real + x_im = x.imag + dist = Es*numpy.sqrt(2) + return [-dist*x_im, dist*x_re] +sd_psk_4_2 = sd_psk_4_0x2_0_1 + +def sd_psk_4_0x3_0_1(x, Es=1): + ''' + 01 | 00 + ------- + 11 | 10 + ''' + x_re = x.real + x_im = x.imag + dist = Es*numpy.sqrt(2) + return [-dist*x_im, -dist*x_re] +sd_psk_4_3 = sd_psk_4_0x3_0_1 + +def sd_psk_4_0x0_1_0(x, Es=1): + ''' + 01 | 11 + ------- + 00 | 10 + ''' + x_re = x.real + x_im = x.imag + dist = Es*numpy.sqrt(2) + return [dist*x_re, dist*x_im] +sd_psk_4_4 = sd_psk_4_0x0_1_0 + +def sd_psk_4_0x1_1_0(x, Es=1): + ''' + 00 | 10 + ------- + 01 | 11 + ''' + x_re = x.real + x_im = x.imag + dist = Es*numpy.sqrt(2) + return [dist*x_re, -dist*x_im] +sd_psk_4_5 = sd_psk_4_0x1_1_0 + + +def sd_psk_4_0x2_1_0(x, Es=1): + ''' + 11 | 01 + ------- + 10 | 00 + ''' + x_re = x.real + x_im = x.imag + dist = Es*numpy.sqrt(2) + return [-dist*x_re, dist*x_im] +sd_psk_4_6 = sd_psk_4_0x2_1_0 + +def sd_psk_4_0x3_1_0(x, Es=1): + ''' + 10 | 00 + ------- + 11 | 01 + ''' + x_re = x.real + x_im = x.imag + dist = Es*numpy.sqrt(2) + return [-dist*x_re, -dist*x_im] +sd_psk_4_7 = sd_psk_4_0x3_1_0 + |