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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 gnuradio import gr, blks2, packet_utils, gr_unittest
from utils import mod_codes, alignment
import digital_swig
from generic_mod_demod import generic_mod, generic_demod
from qa_constellation import tested_constellations, twod_constell
# Set a seed so that if errors turn up they are reproducible.
# 1234 fails
random.seed(1239)
# TESTING PARAMETERS
# The number of symbols to test with.
# We need this many to let the frequency recovery block converge.
DATA_LENGTH = 200000
# Test fails if fraction of output that is correct is less than this.
REQ_CORRECT = 0.8
# CHANNEL PARAMETERS
NOISE_VOLTAGE = 0.01
FREQUENCY_OFFSET = 0.01
TIMING_OFFSET = 1.0
# RECEIVER PARAMETERS
# Increased from normal default of 0.01 to speed things up.
FREQ_ALPHA = 0.02
# Decreased from normal default of 0.1 is required for the constellations
# with smaller point separations.
PHASE_ALPHA = 0.02
class test_constellation_receiver (gr_unittest.TestCase):
# We ignore the first half of the output data since often it takes
# a while for the receiver to lock on.
ignore_fraction = 0.8
seed = 1234
max_data_length = DATA_LENGTH * 6
max_num_samples = 1000
def test_basic(self):
"""
Tests a bunch of different constellations by using generic
modulation, a channel, and generic demodulation. The generic
demodulation uses constellation_receiver which is what
we're really trying to test.
"""
# Assumes not more than 64 points in a constellation
# Generates some random input data to use.
self.src_data = tuple(
[random.randint(0,1) for i in range(0, self.max_data_length)])
# Generates some random indices to use for comparing input and
# output data (a full comparison is too slow in python).
self.indices = alignment.random_sample(
self.max_data_length, self.max_num_samples, self.seed)
for constellation, differential in tested_constellations():
# The constellation_receiver doesn't work for constellations
# of multple dimensions (i.e. multiple complex numbers to a
# single symbol).
# That is not implemented since the receiver has no way of
# knowing where the beginning of a symbol is.
# It also doesn't work for non-differential modulation.
if constellation.dimensionality() != 1 or not differential:
continue
data_length = DATA_LENGTH * constellation.bits_per_symbol()
tb = rec_test_tb(constellation, differential,
src_data=self.src_data[:data_length])
tb.run()
data = tb.dst.data()
d1 = tb.src_data[:int(len(tb.src_data)*self.ignore_fraction)]
d2 = data[:int(len(data)*self.ignore_fraction)]
correct, overlap, offset, indices = alignment.align_sequences(
d1, d2, indices=self.indices)
self.assertTrue(correct > REQ_CORRECT)
class rec_test_tb (gr.top_block):
"""
Takes a constellation an runs a generic modulation, channel,
and generic demodulation.
"""
def __init__(self, constellation, differential,
data_length=None, src_data=None):
"""
constellation -- a constellation object
differential -- whether differential encoding is used
data_length -- the number of bits of data to use
src_data -- a list of the bits to use
"""
super(rec_test_tb, self).__init__()
# Transmission Blocks
if src_data is None:
self.src_data = tuple([random.randint(0,1) for i in range(0, data_length)])
else:
self.src_data = src_data
packer = gr.unpacked_to_packed_bb(1, gr.GR_MSB_FIRST)
src = gr.vector_source_b(self.src_data)
mod = generic_mod(constellation, differential=differential)
# Channel
channel = gr.channel_model(NOISE_VOLTAGE, FREQUENCY_OFFSET, TIMING_OFFSET)
# Receiver Blocks
demod = generic_demod(constellation, differential=differential,
freq_alpha=FREQ_ALPHA,
phase_alpha=PHASE_ALPHA)
self.dst = gr.vector_sink_b()
self.connect(src, packer, mod, channel, demod, self.dst)
if __name__ == '__main__':
gr_unittest.run(test_constellation_receiver, "test_constellation_receiver.xml")
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