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#!/usr/bin/env python
#
# Copyright 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.
#
import random
from cmath import exp, pi, log
from gnuradio import gr, gr_unittest, blks2
from utils import mod_codes
import digital_swig
# import from local folder
import psk2
import qam
tested_mod_codes = (mod_codes.NO_CODE, mod_codes.GRAY_CODE)
# A list of the constellations to test.
# Each constellation is given by a 3-tuple.
# First item is a function to generate the constellation
# Second item is a dictionary of arguments for function with lists of
# possible values.
# Third item is whether differential encoding should be tested.
# Fourth item is the name of the argument to constructor that specifices
# whether differential encoding is used.
def twod_constell():
"""
"""
points = ((1+0j), (0+1j),
(-1+0j), (0-1j))
rot_sym = 2
dim = 2
return digital_swig.constellation_calcdist(points, [], rot_sym, dim)
def threed_constell():
oned_points = ((1+0j), (0+1j), (-1+0j), (0-1j))
points = []
r4 = range(0, 4)
for ia in r4:
for ib in r4:
for ic in r4:
points += [oned_points[ia], oned_points[ib], oned_points[ic]]
rot_sym = 4
dim = 3
return digital_swig.constellation_calcdist(points, [], rot_sym, dim)
tested_constellation_info = (
(psk2.psk_constellation,
{'m': (2, 4, 8, 16, 32, 64),
'mod_code': tested_mod_codes, },
True, None),
(digital_swig.constellation_bpsk, {}, True, None),
# No differential testing for qpsk because it is gray-coded.
# This is because soft decision making is simpler if we can assume
# gray coding.
(digital_swig.constellation_qpsk, {}, False, None),
(digital_swig.constellation_8psk, {}, False, None),
(twod_constell, {}, True, None),
(threed_constell, {}, True, None),
)
def tested_constellations():
"""
Generator to produce (constellation, differential) tuples for testing purposes.
"""
for constructor, poss_args, differential, diff_argname in tested_constellation_info:
if differential:
diff_poss = (True, False)
else:
diff_poss = (False,)
poss_args = [[argname, argvalues, 0] for argname, argvalues in poss_args.items()]
for current_diff in diff_poss:
# Add an index into args to keep track of current position in argvalues
while True:
current_args = dict([(argname, argvalues[argindex])
for argname, argvalues, argindex in poss_args])
if diff_argname is not None:
current_args[diff_argname] = current_diff
constellation = constructor(**current_args)
yield (constellation, current_diff)
for this_poss_arg in poss_args:
argname, argvalues, argindex = this_poss_arg
if argindex < len(argvalues) - 1:
this_poss_arg[2] += 1
break
else:
this_poss_arg[2] = 0
if sum([argindex for argname, argvalues, argindex in poss_args]) == 0:
break
class test_constellation (gr_unittest.TestCase):
src_length = 256
def setUp(self):
# Generate a list of random bits.
self.src_data = tuple([random.randint(0,1) for i in range(0, self.src_length)])
def tearDown(self):
pass
def test_hard_decision(self):
for constellation, differential in tested_constellations():
if differential:
rs = constellation.rotational_symmetry()
rotations = [exp(i*2*pi*(0+1j)/rs) for i in range(0, rs)]
else:
rotations = [None]
for rotation in rotations:
src = gr.vector_source_b(self.src_data)
content = mod_demod(constellation, differential, rotation)
dst = gr.vector_sink_b()
self.tb = gr.top_block()
self.tb.connect(src, content, dst)
self.tb.run()
data = dst.data()
# Don't worry about cut off data for now.
first = constellation.bits_per_symbol()
self.assertEqual (self.src_data[first:len(data)], data[first:])
class mod_demod(gr.hier_block2):
def __init__(self, constellation, differential, rotation):
if constellation.arity() > 256:
# If this becomes limiting some of the blocks should be generalised so that they can work
# with shorts and ints as well as chars.
raise ValueError("Constellation cannot contain more than 256 points.")
gr.hier_block2.__init__(self, "mod_demod",
gr.io_signature(1, 1, gr.sizeof_char), # Input signature
gr.io_signature(1, 1, gr.sizeof_char)) # Output signature
arity = constellation.arity()
# TX
self.constellation = constellation
self.differential = differential
self.blocks = [self]
# We expect a stream of unpacked bits.
# First step is to pack them.
self.blocks.append(
gr.unpacked_to_packed_bb(1, gr.GR_MSB_FIRST))
# Second step we unpack them such that we have k bits in each byte where
# each constellation symbol hold k bits.
self.blocks.append(
gr.packed_to_unpacked_bb(self.constellation.bits_per_symbol(),
gr.GR_MSB_FIRST))
# Apply any pre-differential coding
# Gray-coding is done here if we're also using differential coding.
if self.constellation.apply_pre_diff_code():
self.blocks.append(gr.map_bb(self.constellation.pre_diff_code()))
# Differential encoding.
if self.differential:
self.blocks.append(gr.diff_encoder_bb(arity))
# Convert to constellation symbols.
self.blocks.append(gr.chunks_to_symbols_bc(self.constellation.points(), self.constellation.dimensionality()))
# CHANNEL
# Channel just consists of a rotation to check differential coding.
if rotation is not None:
self.blocks.append(gr.multiply_const_cc(rotation))
# RX
# Convert the constellation symbols back to binary values.
self.blocks.append(digital_swig.constellation_decoder_cb(self.constellation.base()))
# Differential decoding.
if self.differential:
self.blocks.append(gr.diff_decoder_bb(arity))
# Decode any pre-differential coding.
if self.constellation.apply_pre_diff_code():
self.blocks.append(gr.map_bb(
mod_codes.invert_code(self.constellation.pre_diff_code())))
# unpack the k bit vector into a stream of bits
self.blocks.append(gr.unpack_k_bits_bb(
self.constellation.bits_per_symbol()))
# connect to block output
check_index = len(self.blocks)
self.blocks = self.blocks[:check_index]
self.blocks.append(self)
self.connect(*self.blocks)
if __name__ == '__main__':
gr_unittest.run(test_constellation, "test_constellation.xml")
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